Space Exploration

The first rocket was an arrow that did not need a bow. Chinese alchemists had written down a recipe for gunpowder by 1044, in the military manual Wujing Zongyao , and within two centuries someone had tied a bamboo tube of it to an arrow shaft and let the burning powder do the pushing. Chronicles of the Mongol siege of Kaifeng in 1232 describe fire lances and thunder-crash bombs; historians debate exactly when the fire arrow became a true rocket, propelled by its own exhaust rather than merely carrying flame, but by the fourteenth century Chinese, Arab and Indian armies were launching them in volleys from racks.

Congreve rockets entered British service in 1806. The 32-pounder version weighed about 14.5 kilograms and could reach roughly 2.7 kilometres, further than most field guns of the day, and the Royal Navy fired around 300 of them into Copenhagen during the bombardment of September 1807, when the city burned for three days. Seven years later, on the night of 13 to 14 September 1814, the rocket ship HMS Erebus fired Congreves at Fort McHenry in Baltimore harbour. Francis Scott Key watched from a truce ship and wrote of "the rockets' red glare"; the line became the American national anthem. The fort held, which tells you something: the rockets were terrifying and wildly inaccurate.

The gunpowder rocket proved the principle, then spent a hundred years as a signal flare and a line-thrower for lifeboats. It took a new fuel, and a few obsessive dreamers, to make it a vehicle.

Long before anyone could leave the planet, people were writing the trip reports. Lucian of Samosata, a Syrian-Greek satirist of the second century, sent a ship to the Moon on a whirlwind in his True History and found the King of the Moon at war with the King of the Sun over the colonisation of the Morning Star; he introduced it by promising that every word was a lie. Fourteen centuries later Johannes Kepler wrote the Somnium , a dream in which a demon carries a traveller to the Moon during an eclipse. Kepler, who had just worked out the laws of planetary motion, used it to describe how the heavens would look from the Moon, with the Earth hanging motionless in the sky and turning once a day. Published in 1634, four years after his death, it counts as the first science fiction built on real astronomy.

Then came Jules Verne, who did his sums. In From the Earth to the Moon (1865) the Baltimore Gun Club casts a 274-metre cannon, the Columbiad , in the ground of central Florida and fires an aluminium projectile carrying three men towards the Moon. Verne chose Florida for its nearness to the equator; he computed an initial speed of around 11 kilometres per second, close to the true escape velocity; and in the sequel the capsule splashes down in the Pacific to be recovered by an American warship, the USS Susquehanna . A century later Apollo launched three men from Florida in an aluminium-alloy capsule at just under 11 kilometres per second and brought them home to a Pacific splashdown beside an aircraft carrier. Apollo 11's command module Columbia took its name partly from Verne's gun.

The pattern matters because it kept repeating. Konstantin Tsiolkovsky wrote space novels alongside his equations; Wernher von Braun wrote a Mars novel in 1949; Arthur C. Clarke proposed the communications satellite in a magazine in 1945. Fiction did not just predict spaceflight, it recruited the people who would build it.

Konstantin Tsiolkovsky lost most of his hearing to scarlet fever at ten, was turned away from school, and taught himself physics in Moscow's libraries, eating black bread so that he could afford books. From 1892 he taught arithmetic and geometry in Kaluga, a provincial town 150 kilometres south-west of Moscow, and in a workshop at home he worked out, on paper, how to leave the Earth. His notebook dates the key result to 10 May 1897. In 1903 the journal Nauchnoye Obozreniye published his paper Exploration of Outer Space by Means of Reaction Devices , and almost nobody read it.

The logarithm is the cruel part. Orbital speed is about 7.8 kilometres per second, and gravity and air drag during the climb add another 1.5 or so, so a rocket needs around 9.4 kilometres per second of Δv. A kerosene engine exhausts at roughly 3 kilometres per second. Divide, take the exponential, and the starting mass must be 23 times the final mass: 96 per cent of the vehicle on the pad has to be propellant, leaving 4 per cent for tanks, engines, structure and payload. No one can build a tank that light. Tsiolkovsky's answers, in 1903, were the two that still apply. Use the fastest exhaust you can, which is why he proposed burning liquid hydrogen with liquid oxygen, a pairing not flown until 1963. And throw away the empty tanks as you go. His 1929 paper on rocket trains described stages that burn in turn and fall away, so that each later stage starts the equation afresh with a…

The equation has not changed. Every launch vehicle flying today, from Soyuz to Starship, is an argument with that logarithm, and staging is the only answer anyone has found.

On 16 March 1926, in a snowy cabbage field on his aunt Effie's farm at Auburn, Massachusetts, Robert Goddard lit a rocket fuelled by petrol and liquid oxygen. It burned for 2.5 seconds, climbed 12.5 metres, and landed 56 metres away in the frozen field, at an average speed of about 96 kilometres per hour. Four people watched: Goddard, his wife Esther with a cine camera that ran out of film, his assistant Henry Sachs and a Clark University colleague, Percy Roope. It was the first flight of a liquid-propellant rocket , and it looked like nothing: a three-metre frame of thin pipes with a small engine at the top and the tanks below. Goddard thought an engine above the tanks would make it stable, like pulling a cart; it does not, as he soon found. The date, the figures and the photograph of Goddard beside the frame come from his own meticulous diary.

The ridicule, and a ban on further launches in Massachusetts, made him secretive. Charles Lindbergh took an interest, and from 1930 the Guggenheim family funded Goddard to move to Roswell, New Mexico, where in a decade of quiet work he solved most of the problems of the modern rocket: gyroscopic steering with movable vanes in the exhaust, turbopumps, regenerative cooling of the combustion chamber, gimballed thrust. In March 1935 one of his rockets passed the speed of sound, and in 1937 another reached around 2.7 kilometres. He filed or was granted 214 patents, many of them posthumously through Esther, and they cover almost every part of a V-2 or a Saturn V.

NASA's Goddard Space Flight Center in Maryland carries his name. The cabbage field is now a golf course with a small stone marker, which is roughly the attention he received in his lifetime.

The rocket entered the 1920s as a book. Hermann Oberth, a Transylvanian Saxon who had read Verne at eleven, submitted a dissertation on rockets to Heidelberg in 1922 and had it rejected; he published it himself in 1923 as Die Rakete zu den Planetenräumen , The Rocket into Planetary Space , 92 dense pages proving that a liquid-fuelled rocket could leave the Earth, carry people and survive the trip. It sold out, and it did something the earlier pioneers had not managed: it created a readership, which within a decade had organised itself into clubs on three continents, and the clubs were firing rockets.

Oberth himself had spent 1929 as scientific adviser on Lang's Frau im Mond , which showed a two-stage rocket, acceleration couches and weightlessness aboard, and he promised the studio a real rocket for the premiere. He was injured in a test and the rocket never flew, but the film reached audiences the book could not. In New York, the science fiction editor David Lasser and the journalist G. Edward Pendray founded the American Interplanetary Society on 4 April 1930; their second rocket flew from Staten Island on 14 May 1933 to about 75 metres before its oxygen tank burst. In Moscow, the Group for the Study of Reactive Motion, GIRD, formed in 1931 around Friedrich Zander, Mikhail Tikhonravov and a 24-year-old aircraft designer, Sergei Korolev. Their GIRD-09, burning gelled petrol with liquid oxygen, rose about 400 metres over Nakhabino on 17 August 1933, the first Soviet liquid rocket;…

Every launch count since has begun with Fritz Lang's number ten.

At 15:58 on 3 October 1942 an A-4 rocket rose from Test Stand VII at Peenemünde, on the Baltic island of Usedom, climbed to 84.5 kilometres and fell into the sea 190 kilometres away. Two earlier attempts that summer had failed; this one worked, and Walter Dornberger, the Army officer in charge, told his engineers that evening that they had opened the door to space travel. The machine he was describing is the one history calls the V-2 , for Vergeltungswaffe , the "vengeance weapon", a name the propaganda ministry attached in 1944.

The programme's leaders were Dornberger and Wernher von Braun, technical director at thirty. After the RAF bombed Peenemünde in August 1943, production moved underground to the Mittelwerk , tunnels in the Kohnstein hill near Nordhausen, where prisoners of the Mittelbau-Dora concentration camp assembled the missiles in cold, dust and hunger. About 6,000 V-2s were built. Historians estimate that around 20,000 prisoners died at Dora and its sub-camps, more than the roughly 9,000 people the V-2 killed at its targets, and the figures are not disputed: more people died building the V-2 than were killed by it.

The V-2 is where spaceflight's two stories meet, the engineering and the moral ledger, and neither can be told without the other.

The V-2 did not end in 1945; it was divided. In the final weeks of the war the American, British and Soviet armies raced for the Mittelwerk, its missiles and the people who understood them, and the shares each took set the pace of the next decade. On 2 May 1945 Wernher von Braun's younger brother Magnus cycled down a Bavarian road to find an American private and surrender the team; von Braun had already chosen his captor, moving some 500 engineers and 14 tonnes of documents south ahead of the Red Army. The US Army reached the Mittelwerk tunnels near Nordhausen on 11 April, and before handing the area to the Soviet zone on 1 June its Special Mission V-2 hauled out around 100 missiles' worth of parts in 341 railway wagons.

Britain, with no budget for a missile programme, ran Operation Backfire instead: at Cuxhaven in October 1945, German crews under British supervision launched three V-2s into the North Sea so that the procedure could be filmed and documented. The Soviet Union, arriving at an emptied Mittelwerk, assembled what it could with the Germans who had stayed, including Helmut Gröttrup, head of the V-2's guidance group. On the night of 22 October 1946, in Operation Osoaviakhim, Soviet security troops roused around 2,200 German specialists and their families and put them on trains east. Gröttrup's group spent six years on an island in Lake Seliger, consulted but kept from the real work. Sergei Korolev's own team launched its first German-built V-2 from the new range at Kapustin Yar on 18 October 1947, flew the Soviet-built copy, the R-1 , on 10 October 1948, and stretched it into the R-2 with…

Half a captured missile programme, it turned out, was enough to start a space race.

A rocket is a machine for throwing mass out of the back as fast as possible. Newton's third law does the rest: every kilogram of hot gas flung backwards pushes the vehicle forwards with equal force, in air or in vacuum, and the vacuum is in fact better, since there is no atmosphere pressing on the nozzle exit. Thrust is the mass flow rate multiplied by the exhaust velocity. The Saturn V's first stage burned about 13 tonnes of propellant every second and threw it out at around 2.6 kilometres per second, roughly 34 meganewtons, enough to lift 2,900 tonnes at 1.2 times its weight.

Getting the propellants into the chamber is the hard part. A chamber runs at 70 bar in the F-1 and over 250 bar in the Russian RD-180, so the turbopumps, turbines spun by hot gas, must push harder than that: the F-1's delivered 41 megawatts, as much as a large ship's engines. Where the hot gas comes from defines the engine cycle. A gas-generator engine, like the F-1 or the Merlin, burns a little propellant in a separate combustor and dumps the exhaust overboard, simple and slightly wasteful. A staged-combustion engine, like the RS-25 or the RD-180, sends that exhaust into the main chamber to be burned again, gaining efficiency and complexity. Raptor runs full-flow staged combustion, with every gram of propellant passing through a turbine first.

The F-1 gave 6.77 meganewtons at sea level, the RD-180 3.83, the RS-25 1.86, a Raptor 3 about 2.75; today's heaviest rockets simply fit more of them. Each is a controlled explosion held steady for minutes, and that they work at all is the quiet miracle of the business.

An orbit is a fall that keeps missing. Isaac Newton drew the picture in the 1680s: a cannon on a high mountain fires faster and faster, each ball landing further away, until one goes so fast that the ground curves away as quickly as it drops, and it comes round to hit the gunner from behind. Nothing is holding a satellite up. The International Space Station, 400 kilometres above the Earth, is falling the whole time; it simply moves sideways at 7.7 kilometres per second, and the planet curves out of its way. The weightlessness aboard is the weightlessness of a lift whose cable has snapped.

That rotational bonus explains the map. Kourou in French Guiana, Cape Canaveral at 28 degrees, Sriharikota at 13, Wenchang at 19: launch sites hug the equator and fire east over water. Russia's Baikonur, at 46 degrees in Kazakhstan, gets only 320 metres per second from the spin, and Plesetsk, at 63 degrees, about 210, and the ISS orbits at 51.6 degrees because that is the lowest inclination Baikonur can reach without dropping spent stages on China.

What goes up comes down, slowly. Even at 400 kilometres there is enough air to drag the ISS down by about 2 kilometres a month, so it is reboosted a few times a year; Sputnik lasted 92 days, Skylab fell on Western Australia in 1979 and Mir was steered into the Pacific in 2001. Above about 1,000 kilometres a satellite will stay for centuries, which is the beginning of the space-junk problem. Orbit is not a place but a speed, and every launch is an argument about how to buy it cheaply.

The space race was run by two engineers who never met and could not have been introduced. One was a name the whole world knew: Wernher von Braun, baron, television presenter, father of the Saturn V. The other was a state secret. Until the day after he died in January 1966, Soviet newspapers called Sergei Korolev only the Chief Designer , and when the Nobel committee asked whom to honour for Sputnik, Nikita Khrushchev replied that the achievement belonged to the whole Soviet people.

Von Braun, born in Wirsitz in 1912, joined the Nazi Party in 1937 and the SS in 1940, rising to major; the records show he visited the Mittelwerk and knew the prisoners' conditions. He said afterwards that he could have done nothing; historians judge that he chose not to try. A brief Gestapo arrest in 1944, for talking about spaceflight rather than weapons, and his surrender to the Americans let him be recast. In the United States he built the Redstone, the Jupiter and the Juno I that orbited Explorer 1 on 31 January 1958, after the Navy's Vanguard had exploded on television. He sold space to the public through Collier's and three Disney television films from 1955, the first of which, Man in Space , drew around 40 million viewers. From Huntsville, Alabama, he led the Saturn V and watched it fly thirteen times without failure.

The race was between two men as much as two systems, and the one who won it is still the harder to judge.

On the evening of 4 October 1957, from a launch pad at Tyuratam in the Kazakh steppe that the world would come to call Baikonur, a converted intercontinental missile lifted a polished aluminium sphere into orbit. Sputnik 1 weighed 83.6 kilograms, measured 58 centimetres across and trailed four whip antennas between 2.4 and 2.9 metres long. Inside were two radio transmitters and a battery pack that took up most of the mass. It circled the Earth every 96 minutes on an orbit that dipped to 215 kilometres and rose to 939, and it did almost nothing except beep.

The satellite was a stand-in. Sergei Korolev's design bureau had been building a heavier scientific payload for the International Geophysical Year, the eighteen-month programme of coordinated research that began in July 1957, but it was running late, and Korolev, hearing that the Americans might fly first, ordered a prosteishiy sputnik , a "simplest satellite", built in a few months by Mikhail Tikhonravov's team. The real achievement was the R-7 Semyorka beneath it: a 280-tonne missile with four strap-on boosters and twenty main combustion chambers, designed to carry a hydrogen bomb across the Atlantic. A rocket that could put 84 kilograms in orbit could, Washington understood at once, put a warhead on any city on Earth.

The name of the chief designer stayed secret until his death in 1966, and the launch site stayed secret rather longer. The satellite itself was a sphere of almost nothing. What it carried into the sky was proof that the rocket worked, and from that night the race had a starting gun.

America's answer to Sputnik was broadcast live, and it rose about a metre. On 6 December 1957 the Navy's Vanguard TV-3 lost thrust two seconds after ignition, settled back onto its pad at Cape Canaveral and exploded; its grapefruit-sized satellite was thrown clear and lay beeping in the scrub. The newspapers called it Flopnik and Kaputnik. The humiliation unlocked a rocket the Army had been forbidden to use: Wernher von Braun's Jupiter-C, a Redstone missile with clustered solid upper stages, which his team at Huntsville had quietly kept ready since 1956.

Van Allen's instrument was a single Geiger counter. It behaved oddly: at low altitude it clicked away at the expected rate, and at high altitude it went silent. His student Carl McIlwain showed in the laboratory that the tube was not seeing nothing but far too much, saturated by radiation thousands of times above the predicted level. Explorer 3, launched on 26 March with a tape recorder to capture whole orbits, confirmed it, and on 1 May 1958 Van Allen announced that the Earth sits inside doughnut-shaped belts of charged particles held by its magnetic field. The Van Allen belts were the first discovery of the space age: an inner belt of protons from about 1,000 to 6,000 kilometres and a broader outer belt of electrons out to 60,000 kilometres, which every crewed mission since has crossed quickly or avoided.

Explorer 1 transmitted until 23 May 1958 and re-entered in 1970. In four months the United States had gone from a fireball on the pad to a discovery about the planet, and had built the institution that would carry the next twelve years.

For a decade the Moon belonged to a series of Soviet robots. Luna 1 , launched on 2 January 1959, was meant to hit the surface and instead missed by about 6,000 kilometres, which made it the first object to escape the Earth's gravity; on the way it released a cloud of sodium vapour visible from the ground, and its ion traps made the first direct measurement of the solar wind. Luna 2 did not miss. On 13 September 1959 it struck the surface near the crater Autolycus at over 3 kilometres a second, the first human-made object on another world, carrying steel pennants stamped with the hammer and sickle. Two days later Khrushchev presented Eisenhower with a copy at the White House.

Landing took longer. Twelve attempts failed before Luna 9 touched down in the Ocean of Storms on 3 February 1966, a 99-kilogram egg-shaped capsule that was thrown clear at the last moment and bounced to rest, opened four petals and raised its antennas. Its panorama proved that the surface would bear weight, settling a real worry that a lander might sink into dust. The pictures were first published not in Moscow but in Manchester: Bernard Lovell's team at Jodrell Bank recorded the signal, recognised the format as that of a standard newspaper fax machine, borrowed one from the Daily Express and printed the Moon's surface before the Soviet press release. Luna 10 followed on 3 April 1966 as the first spacecraft to orbit another world.

Each first was announced with fanfare and each failure went unmentioned, so the programme looked unstoppable. In truth it was a chain of narrow wins, and the firsts it collected, flyby, impact, far side, soft landing, orbit, robotic return and rover, were exactly the steps a human landing would need.

At 09.07 Moscow time on 12 April 1961 a Vostok-K rocket, another descendant of the R-7, left the same Baikonur pad as Sputnik. In the spherical capsule on top sat a 27-year-old senior lieutenant of the Soviet air force, Yuri Alekseyevich Gagarin, call sign Kedr, "Cedar". As the engines lit he said "Poyekhali!", "Let's go!", a phrase that has done duty in Russian ever since. Vostok 1 completed one orbit of the Earth in 108 minutes and he was on the ground before most of the planet had finished breakfast.

Then came the part the Soviet Union did not mention for years. At 7 kilometres the hatch blew and Gagarin's seat fired him out of the capsule, and he came down under his own parachute near the village of Smelovka, close to Engels on the Volga, where a farmer's wife and her granddaughter asked whether he had come from space. The capsule landed separately. Because the rules of the Fédération Aéronautique Internationale required a pilot to land inside his craft for a record to count, the official account said he had, and the ejection was only admitted later.

Six Vostoks flew between 1961 and 1963. The first carried a man who did almost nothing on board, because nobody yet knew what a man could do; what he proved, in 108 minutes, was that a human being could go round the world and come back smiling.

On 9 April 1959 NASA introduced seven men to the press in Washington and the reporters applauded, which had not been in the plan. The Mercury Seven , Scott Carpenter, Gordon Cooper, John Glenn, Gus Grissom, Wally Schirra, Alan Shepard and Deke Slayton, had been sifted from 508 military test pilots by rules of brutal simplicity: under 40, under 5 feet 11 inches so as to fit the capsule, a degree, 1,500 hours in jets, and a week of tests at the Lovelace Clinic in Albuquerque that included enemas and ice water in the ear. A contract with Life magazine for their family stories made them the most famous people in America before any had left the ground.

Alan Shepard flew Freedom 7 on 5 May 1961, three weeks after Gagarin, 187 kilometres up and 487 kilometres downrange in 15 minutes and 22 seconds. Gus Grissom's Liberty Bell 7 in July ended with the hatch blowing early and the capsule sinking in 5,000 metres of Atlantic; it was raised in 1999. Then, on 20 February 1962, John Glenn rode the Atlas for three orbits in Friendship 7 . At first light he reported "fireflies" around the capsule, which turned out to be frost shaken loose from the hull, and a faulty sensor suggested his heat shield had come loose, so Mercury Control told him to keep the retro-rocket pack strapped over it; he watched chunks of it burn past the window on the way down.

Six flights, 53 hours in space, no one lost. Mercury did not catch the Russians, but it taught NASA how to put a person on top of a missile and get him back, and that lesson was the one everything else was built on.

Six weeks after Gagarin's flight and five after the Bay of Pigs, John F. Kennedy stood before a joint session of Congress on 25 May 1961 and asked for something extravagant. "I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth." The applause was polite. Alan Shepard had flown twenty days earlier; the United States had fifteen minutes of human spaceflight to its name, and the president had just promised a round trip of 770,000 kilometres by 1970.

The famous speech came later, at Rice University in Houston on 12 September 1962, in punishing Texas heat. "We choose to go to the Moon in this decade and do the other things, not because they are easy, but because they are hard." Houston had been chosen a year earlier for the new Manned Spacecraft Center , and the speech was partly a thank-you to a city filling up with engineers. What the public never heard was a recording made in the White House two months later, on 21 November 1962, in which Kennedy told Webb that beating the Russians to the Moon was the only point: "otherwise we shouldn't be spending this kind of money, because I'm not that interested in space."

The decision was political, the motive was Cold War prestige, and the deadline was arbitrary. It also worked, which is the part that has puzzled every administration since: a clear goal, a fixed date and four per cent of the budget turned out to be a formula that nothing has repeated.

On 16 June 1963 a 26-year-old former textile worker from Yaroslavl became the first woman in space, and for the next nineteen years she was the only one. Valentina Tereshkova flew Vostok 6 for 48 orbits and 70 hours and 50 minutes, nearly three days, longer than all six Mercury astronauts put together. Her call sign was Chaika, "Seagull", and the flight was the second half of a double act: Valery Bykovsky had launched in Vostok 5 two days earlier and would stay up for five days, a record for a solo flight that still stands. The two capsules came within about five kilometres of each other.

The flight was uncomfortable and nearly dangerous. She was sick, found the food inedible and the suit chafing, and on the first day noticed that the automatic orientation system had been set to raise the orbit rather than lower it for re-entry, an error that Korolev's engineers confirmed and corrected by uplinking new settings. She kept the discovery quiet for thirty years at his request. On 19 June she ejected and landed near Baevo in the Altai, bruised her nose on her helmet and handed out her space food to the villagers who found her. Five months later she married the cosmonaut Andriyan Nikolayev; their daughter Elena, born in 1964, was the first child of two people who had both flown in space.

Her flight was a propaganda triumph the Soviet Union declined to follow up; the women's group was disbanded in 1969. What it proved was never in doubt among the engineers: the body in the seat did not care who it belonged to.

The first human to float free of a spacecraft nearly did not get back in. On 18 March 1965 Alexei Leonov, co-pilot of Voskhod 2 , crawled through an inflatable fabric airlock called Volga , a tube 2.5 metres long and 1.2 metres across that had been folded against the hull at launch, opened the outer hatch and pushed himself out on a 5.35-metre tether 475 kilometres above the Earth. He spent 12 minutes and 9 seconds outside, tumbling slowly, filmed by a camera on the airlock rim and by a second one on his thigh that he could not reach to operate.

The flight had more in store. The automatic re-entry system failed, and Belyayev flew the first manual re-entry of the Soviet programme, overshooting by 386 kilometres into the snowbound forest near Perm. The crew spent two nights in the capsule at around minus 25 degrees Celsius, before a rescue party on skis reached them; a helicopter lifted them out on 21 March. Voskhod itself was a Vostok with the ejection seat removed to make room: Voskhod 1, in October 1964, had carried three men, Komarov, Feoktistov and Yegorov, in shirtsleeves because there was no room for suits, a stunt timed to beat Gemini's first two-man flight.

Both men came home. Between them they had shown that a human could work outside a spacecraft, and that doing anything useful there, let alone building a station, would need handholds, training and a suit that did not fight its wearer. That took the rest of the decade to learn.

Apollo needed four things that nobody had done: find another spacecraft in orbit and dock with it, stay up for the two weeks a lunar round trip would take, work outside for hours, and come down where you meant to. Project Gemini bought all four in ten crewed flights between March 1965 and November 1966, on a two-seat capsule of 3.8 tonnes launched by the Air Force's Titan II missile, 1,900 kilonewtons of thrust burning hypergolic propellants that ignite on contact. Gemini had ejection seats instead of an escape tower, the first fuel cells flown in space, an onboard computer and sixteen manoeuvring thrusters, which made it the first spacecraft a pilot could really fly.

Docking came next and nearly ended in disaster. On 16 March 1966 Neil Armstrong and David Scott in Gemini 8 joined an unmanned Agena target vehicle, the first docking in history, and twenty-seven minutes later the combined craft began to roll. They undocked, assuming the Agena was at fault, and the spin got worse, reaching one revolution a second as a stuck thruster, number 8, kept firing. On the edge of blacking out, Armstrong shut down the manoeuvring system, steadied the capsule with the re-entry thrusters and brought it down early in the Pacific. The calm he showed that day was a large part of why he commanded Apollo 11.

Twenty months, ten crews, every objective met. When Apollo's crews later docked with the lunar module and took their spacewalks on the Moon, they were spending skills that Gemini had earned.

The Soviet answer to the Saturn V was taller, heavier at the base and had thirty engines where the American rocket had five, and it never once reached orbit. The N1 stood 105 metres on its pad at Site 110, Baikonur, and weighed 2,750 tonnes fuelled. Its first stage, Block A, was a truncated cone 17 metres across with thirty NK-15 engines arranged in two rings, producing 45 meganewtons of thrust, the most of any rocket until Starship. Above it sat Block B with eight engines, Block V with four, then the two stages of the lunar complex and at the top the LOK orbiter and a single-seat LK lander, to put 95 tonnes into low orbit and one cosmonaut on the Moon.

The four launches were four explosions. On 21 February 1969 a fire in the engine bay caused KORD to shut everything down at 69 seconds. On 3 July 1969, thirteen days before Apollo 11, a pump failure cut 29 of 30 engines just above the pad, and the rocket fell back onto Site 110 with 2,300 tonnes of propellant, destroying the pad in one of the largest non-nuclear explosions ever recorded and damaging its twin. On 26 June 1971 the third vehicle rolled uncontrollably and broke up at 51 seconds. On 23 November 1972 the fourth flew for 107 seconds, nearly to first-stage burnout, before a pump exploded. A fifth, with improved NK-33 engines, was ready in 1974 when Glushko replaced Mishin and cancelled the programme; the remaining rockets were cut up, and the Soviet Union denied for fifteen years that it had ever raced for the Moon.

The programme stayed secret until 1989. The Soviet Union lost the Moon not for want of engineers but for want of a single boss, a single budget and a test stand.

Stand it on a football pitch and the Saturn V would overhang both goals: 110.6 metres tall, 10.1 metres across at the base, and 2,970 tonnes at the moment the hold-down arms let go. Almost all of that mass was propellant. The first stage, the S-IC, carried 2,100 tonnes of kerosene and liquid oxygen and burned through it in two and a half minutes, feeding five F-1 engines that between them produced 34 meganewtons of thrust, each one drinking about 2.6 tonnes of propellant a second. By the time the stage fell away the rocket was 67 kilometres up and travelling at 2.7 kilometres a second.

How do we know it worked? Thirteen launched between 9 November 1967 and 14 May 1973 and none lost its payload, a record documented in the Marshall Space Flight Center's flight evaluation reports. Wernher von Braun's team at Marshall in Huntsville ran the design; Boeing built the S-IC at Michoud in New Orleans, North American the S-II in California, Douglas the S-IVB, Rocketdyne the engines. The boldest decision came from George Mueller, NASA's head of manned spaceflight, who in 1963 overruled the cautious German stage-by-stage tradition and ordered all-up testing : fly the complete vehicle, live, the first time.

Three complete vehicles survive on their sides in Florida, Texas and Alabama, because the last three Moon landings were cancelled and the rockets built to fly them were never used. The Saturn V was retired at the height of its powers, which is why it has had so long to become a legend.

Before anyone could build a Moon rocket, NASA had to decide what shape the journey would take, and in 1961 there were three answers on the table. Direct ascent was the version from the films: one enormous rocket, called Nova, flies to the Moon, lands tail-first on the surface and flies home again. Earth-orbit rendezvous assembled a Moon ship from two or more Saturn launches in orbit around Earth, then flew the whole thing down and back. Both put a vehicle the height of a church spire on the lunar surface and asked the crew to land it backwards, looking at the sky.

The idea was deeply unpopular. The Space Task Group dismissed it, and Houbolt broke the chain of command in November 1961 with a nine-page letter to NASA's associate administrator Robert Seamans that began, "Somewhat as a voice in the wilderness". The objection was obvious: it required two spacecraft to find each other and dock 380,000 kilometres from home, with no possibility of rescue if they failed. The persuading took months. In June 1962, after a day of briefings at Marshall, Wernher von Braun stood up and surprised his own engineers by backing lunar-orbit rendezvous, saying his team now agreed it offered the best chance of success within the decade. NASA announced the choice on 11 July 1962, Kennedy's science adviser Jerome Wiesner fought it through the autumn, and in November the contract for the lander went to Grumman.

Rendezvous worked every time it was tried. The mode that the engineers had called too risky turned out to be the only one that could have met the deadline, and the Moon was reached because one stubborn man kept writing letters.

On the afternoon of 27 January 1967, three astronauts were strapped into a command module on top of an unfuelled Saturn IB at Pad 34, rehearsing the countdown. It was called a plugs-out test, and nobody had rated it hazardous. Gus Grissom , Ed White and Roger Chaffee had been inside for more than five hours, held up by a sour smell in the oxygen supply and by a communications system so poor that Grissom asked how they were going to get to the Moon if they could not talk between two or three buildings. At 6.31 in the evening a voice on the loop said there was a fire in the cockpit. Seventeen seconds later the transmissions stopped.

The board's report, delivered in April 1967, was blunt about the spacecraft and about the agency. The Block I command module had more than a hundred engineering changes pending, poor workmanship, and no plan for fire on the pad. North American Aviation, the contractor, was overhauled; so was NASA's oversight. The next crewed version, the Block II , used a 60/40 mix of oxygen and nitrogen on the pad, a single hatch that opened outwards in a few seconds, stainless-steel coolant pipes, fire-resistant Beta-cloth suits, and wiring wrapped and routed under rules written in the fire's aftermath. Twenty months passed before Apollo 7 flew in October 1968, and the delay, in a programme racing a decade's deadline, is why the Moon was reached with five months to spare rather than two years.

Flight director Gene Kranz told his controllers the following Monday that they had been neither tough enough nor competent enough, and that the two words would be written on every blackboard in Mission Control. Pad 34 still stands at the Cape, concrete and empty, with the words "Abandon in place" stencilled on the legs.

The room most people picture when they think of Apollo is not at the Cape but 1,500 kilometres west, on the second floor of Building 30 at the Manned Spacecraft Center in Houston. The Mission Operations Control Room , the MOCR, ran its first flight in June 1965 and every Apollo mission after it. Four tiered rows of grey consoles faced a wall of maps and data, and the point of it was a single idea that Chris Kraft had worked out during Mercury: the spacecraft was too complex for a pilot to manage alone, so a team on the ground, with more information than the crew, would make the decisions, and one person, the flight director , would have the final word.

The method was procedure. Thousands of flight rules were written in advance so that a decision taken in two seconds had been argued for weeks. Before any critical moment the flight director polled the room, position by position, and any "no go" stopped the clock. The controllers were young; their average age during Apollo 11 was around 26. The room could not see the spacecraft at all without the Manned Space Flight Network : three 26-metre dishes spaced around the world at Goldstone in California, Honeysuckle Creek near Canberra and Fresnedillas near Madrid, so that one was always facing the Moon, with Australia's 64-metre Parkes radio telescope added to relay the television from the Apollo 11 landing.

The MOCR was restored to its 1969 appearance in 2019, down to the ashtrays and the rotary telephones. What it preserves is less a room than a way of thinking, in which authority goes to whoever has the best data, and everyone has agreed, in writing, what to do before it goes wrong.

In August 1968 the lunar module was months behind schedule, and NASA faced a Christmas with nothing to fly. George Low, the Apollo spacecraft manager, proposed something that had not been in any plan: send the next command module to the Moon without a lander. The CIA's reports that a Soviet Zond spacecraft might carry a cosmonaut round the Moon before the year's end made the gamble easier to accept, and Zond 5 did fly round the Moon in September with a cargo of tortoises. On 21 December 1968 Frank Borman , Jim Lovell and Bill Anders became the first crew to ride a Saturn V, and two hours and fifty minutes later the third stage relit for the translunar injection burn, the first time human beings had left Earth's orbit.

On the fourth orbit the spacecraft was rolling to a new attitude when the Earth appeared above the lunar horizon. Borman saw it first and took a black-and-white frame; Anders called for colour film, and Lovell's "Hey, don't take that, it's not scheduled" is on the transcript as a joke. Anders's photograph, frame AS8-14-2383, became Earthrise : a blue and white half-planet above a grey, lifeless edge, taken by a man who had gone to photograph the Moon. That evening, in the most watched television broadcast to that date, the three men read the first ten verses of Genesis, and Borman signed off with "good night, good luck, a Merry Christmas and God bless all of you, all of you on the good Earth".

The photograph did more than the mission. Earthrise is credited with helping to launch the modern environmental movement, and the first Earth Day followed sixteen months later. Three men went to look at the Moon and came back having discovered the Earth.

The lunar module was the first true spacecraft: a vehicle that never had to fly in air and so made no concessions to it. There was no nose cone, no smooth skin, no symmetry: two boxes of equipment bolted together, four splayed legs and two triangular windows that gave it the look of an insect. Grumman built it at Bethpage on Long Island under the engineer Tom Kelly , from a contract signed in November 1962, and the first flight-ready article arrived six years later, a delay that reshaped the whole Apollo schedule.

Weight ruled everything. Grumman's engineers chemically milled the structure, shrank the windows and removed the seats altogether: the crew stood, held by cables and harnesses, which also let them see the ground through smaller windows. In places the pressure skin of the cabin was aluminium 0.3 millimetres thick, which a dropped screwdriver could puncture, and the outer thermal blankets of gold-coloured Kapton and foil could be dented with a finger. Built for a sixth of Earth's gravity, it could never have landed on Earth, so it could never be fully tested.

Six landers reached the surface, six descent stages still stand on it, and most of the ascent stages were crashed into the Moon on purpose to ring the seismometers. The lunar module was an ugly, fragile, brilliant machine, and it is the only crewed spacecraft in history that never once failed its crew.

Apollo 11 lifted off from Pad 39A at 13:32 UTC on 16 July 1969 with Neil Armstrong , Buzz Aldrin and Michael Collins aboard, watched by around a million people on the Florida beaches. Three days later the stack was in lunar orbit, and on the afternoon of 20 July the lunar module Eagle undocked from Columbia , leaving Collins to circle alone, out of radio contact for forty-eight minutes of every two-hour orbit while he passed behind the Moon.

Six and a half hours later, at 02:56 UTC on 21 July, Armstrong stepped off the footpad. Aldrin followed nineteen minutes later and described the view as "magnificent desolation". The moonwalk lasted two hours and thirty-one minutes. They set up a seismometer and a laser reflector, planted a flag, collected 21.5 kilograms of rock and soil, and took a telephone call from President Nixon. An estimated 600 million people watched the grainy television pictures, relayed through Honeysuckle Creek and Parkes in Australia. The same week, the uncrewed Soviet probe Luna 15, sent to grab a soil sample and return it before the Americans, crashed into the Sea of Crises.

Eight days, three men, one landing. The flag they planted was knocked flat, the seismometer fell silent within weeks, and the retroreflector is still returning laser pulses. The Moon had been a place to point at for all of human history. On 20 July 1969 it became a place where people had been.

Fifty-six hours into the flight, 330,000 kilometres from Earth, Jack Swigert flipped a switch to stir the oxygen tanks in the service module, a routine request from Houston. There was a bang, and Apollo 13 's master alarm came on. Swigert's "OK, Houston, we've had a problem here" and Jim Lovell's repeat of it are on the tape, as is Lovell's report a few minutes later that he could see something venting into space. Oxygen tank 2 had exploded, tank 1 was leaking, and the fuel cells that made the command module's electricity and water were dying with them.

What followed is the finest hour of Mission Control . Gene Kranz's White Team handed the main room to Glynn Lunney and became a tiger team working the problem offline. The command module Odyssey was shut down to save its re-entry batteries, and the three men moved into the lunar module Aquarius , designed to keep two people alive for two days, now asked to keep three alive for four. Its descent engine fired for thirty seconds to restore a free-return trajectory , and for four and a half minutes after rounding the Moon to speed the journey home. The lander's carbon-dioxide scrubbers were round and the command module's spares were square; a team under Ed Smylie designed an adaptor from a plastic bag, a hose, tape and the cover of the flight plan, and Swigert built it from instructions read up by voice. The cabin fell to 3 degrees Celsius and water was rationed to a few hundred…

The film made Kranz's line "failure is not an option" famous; he never said it during the flight, and later adopted it as a book title. What the records show is a room of people in their twenties and thirties who had rehearsed disaster for years. The Moon was not reached. Everyone came home, and that is the point of the story.

Apollo 11 proved the landing; the five missions that followed turned the Moon into a field site. Apollo 12 showed what precision could do. On 19 November 1969 Pete Conrad and Alan Bean set Intrepid down 163 metres from Surveyor 3 , a robot that had landed two and a half years earlier, walked over to it and cut off its camera and scoop to see what thirty-one months on the lunar surface had done to them. They also carried the first ALSEP , the Apollo Lunar Surface Experiments Package, a nuclear-powered station that ran for years after the crew had gone. Its seismometer recorded the lander's ascent stage being crashed back into the Moon and the ground ringing for nearly an hour.

The last three missions carried a battery-powered rover, and the explorers' radius jumped from a few hundred metres to several kilometres. On Apollo 15 , in 1971, Dave Scott and Jim Irwin drove to the edge of Hadley Rille, a lava channel 300 metres deep, and picked up sample 15415, a chunk of white anorthosite about four billion years old that the press called the Genesis Rock. Before leaving, Scott dropped a hammer and a falcon feather together on live television. Apollo 16 went to the Descartes highlands in April 1972 expecting volcanic rock and found impact breccias, overturning the leading theory of the site in an afternoon. Apollo 17 , in December 1972, carried the only professional geologist to walk on the Moon, Harrison Schmitt, who spotted orange soil at Shorty crater: tiny beads of volcanic glass 3.6 billion years old, sprayed from a fire fountain.

China's Chang'e 5 and 6 have since returned nearly four kilograms more, including the first far-side rocks, but the Apollo collection remains the foundation. Every date in the history of the inner Solar System is counted, somewhere down the chain, from a rock that an astronaut picked up with a pair of tongs.

The last three landings were cancelled before the second one had flown: Apollo 20 in January 1970, Apollo 18 and 19 that September, their Saturn Vs already built. What remained went into two final projects: a laboratory the size of a house, and a handshake.

Three crews lived aboard for 28, 59 and 84 days, the last of them, Gerald Carr, Ed Gibson and Bill Pogue, setting an American duration record that stood until 1995. The Apollo Telescope Mount returned more than 150,000 images of the Sun in X-rays and ultraviolet and discovered the coronal holes from which the solar wind pours. The third crew, overscheduled, took an unplanned day off on 28 December 1973; the story that they went on strike grew in the telling, and Carr spent years correcting it. Skylab was abandoned in February 1974, awaiting a Shuttle boost that came too late, and on 11 July 1979 it fell across the Indian Ocean and Western Australia.

It was the last flight of an Apollo spacecraft and the last American crewed launch for nearly six years. The two programmes that had raced each other to the Moon ended with their crews sharing a meal in orbit, and two decades later a descendant of its androgynous docking port joined the Shuttle to Mir.

The first spacecraft to reach another planet was the second one built. Mariner 1 left Cape Canaveral on 22 July 1962 and was destroyed by the range safety officer 293 seconds later, after its Atlas wandered off course. Its twin, Mariner 2 , 203 kilograms, built at the Jet Propulsion Laboratory in Pasadena, launched on 27 August and flew past Venus on 14 December 1962 at a distance of 34,773 kilometres. Its microwave radiometer scanned the planet's disc and found the edges cooler than the centre, which meant the heat was coming from the ground, not the cloud tops: a surface above 400 °C. On the way out, Marcia Neugebauer and Conway Snyder's plasma instrument measured the solar wind blowing continuously for the first time.

Mariner 8 fell into the Atlantic in May 1971, so Mariner 9 , launched on 30 May, went to Mars alone and entered orbit on 14 November 1971, the first spacecraft to orbit another planet, thirteen days ahead of the Soviet Mars 2 . It arrived in the middle of a global dust storm that hid the entire surface. JPL simply waited. When the dust settled in January the cameras found a volcano 22 kilometres high, later named Olympus Mons, a canyon system 4,000 kilometres long now called Valles Marineris after the spacecraft, and channels that looked carved by water. It returned 7,329 pictures and mapped 85 per cent of the planet.

Flyby, orbit and gravity assist: the three tools of planetary exploration were all worked out by ten spacecraft of which three were lost. Every mission in this part of the book is a Mariner by descent.

Venus is the easier planet to reach and the harder one to survive. Its surface sits under 92 bar of carbon dioxide, the pressure found 900 metres down in the sea, at 465 °C, hot enough to melt lead, beneath clouds of sulphuric acid. Nobody knew that in 1967. Venera 4 , a 383-kilogram Soviet capsule, parachuted into the atmosphere on 18 October 1967 and transmitted for 93 minutes as its readings climbed past 262 °C and the pressure gauge ran off its scale at 18 atmospheres; it was crushed around 25 kilometres up. The American Mariner 5 flew past a day later and its radio signal, bent by the atmosphere, confirmed that the ground lay far deeper and hotter than anyone had designed for.

The photographs came in October 1975. Venera 9 and 10 were 1,560-kilogram descent craft with a disc aerobrake, a crushable landing ring and a sphere a metre across, each with an orbiter overhead to relay the signal. On 22 October 1975 Venera 9 sent the first picture from another planet's surface, a 180-degree panorama of flat, sharp-edged rocks; it lasted 53 minutes. The lens caps on Venera 11 and 12 in 1978 refused to come off. Venera 13 , landing on 1 March 1982, sent the first colour panoramas, drilled into the soil and analysed a sample by X-ray fluorescence, and survived 127 minutes at 457 °C and 89 bar, still the record for any machine on Venus. Venera 14 managed 57 minutes four days later.

The Soviet Union never managed a working Mars lander, but it owned Venus: all ten successful landings, between 1970 and 1985. Nothing has touched the surface since, and the landers planned for the 2030s will be built with Venera's numbers in front of them.

On 20 July 1976, seven years to the day after Apollo 11, Viking 1 came down on Chryse Planitia and sent back a picture of its own footpad resting on red gravel. It was meant to land on 4 July, the American bicentennial, but orbiter pictures showed the chosen site strewn with boulders and the team spent two weeks hunting for somewhere flatter. Viking 2 landed on 3 September in Utopia Planitia, on the other side of the planet. Each lander weighed about 600 kilograms, ran on two radioisotope generators, and came down on three legs under eighteen small rocket nozzles that spread the exhaust so it would not scour the soil the mission had come to test.

The argument reopened in 2008, when NASA's Phoenix lander found perchlorate salts in the Martian soil. Perchlorate heated in a spectrometer oven destroys organic molecules, so Viking may have cooked the evidence it was looking for; a 2010 reanalysis found traces of chlorinated organics had been there all along, and Curiosity has since found organics in Gale Crater. Viking's are still the only life-detection experiments run on another planet, and still ambiguous.

Every lander since has stood on Viking's shoulders. Its question, whether Martian soil has ever been alive, is still open, and is why Perseverance's sample tubes are waiting to come home.

Nobody knew whether a spacecraft could cross the asteroid belt. Pioneer 10 , a 258-kilogram spinning craft run by NASA's Ames Research Center, launched on 2 March 1972 on an Atlas-Centaur at a record 51,800 kilometres per hour, passed the Moon in eleven hours and entered the belt in July. Engineers had put the odds of a fatal collision as high as one in ten; its detectors registered a sprinkling of dust and in February 1973 it came out the other side. On 3 December 1973 it passed 132,000 kilometres above Jupiter's cloud tops, took the first close pictures and absorbed a radiation dose a thousand times what would kill a person; instruments glitched, false commands fired, and it survived. Pioneer 11 followed on 5 April 1973, flew within 42,800 kilometres of Jupiter on 2 December 1974, used its gravity to climb across the solar system, and on 1 September 1979 became the first spacecraft…

Pioneer 10 kept going. Its four plutonium generators, 155 watts at launch, faded year by year, and its last faint signal arrived on 23 January 2003 from 12.2 billion kilometres, eighty times the Earth's distance from the Sun. Pioneer 11 was last heard in 1995. Tracking had shown both craft slowing slightly more than gravity could explain, by under a billionth of a metre per second squared. The Pioneer anomaly was debated for twenty years as a possible flaw in gravity, until in 2012 Slava Turyshev and colleagues rebuilt the spacecraft from old drawings and showed that heat from the generators and electronics, radiating unevenly off the back of the dish, produced exactly the push observed.

The Pioneers were scouts, cheap and tough, sent to see whether the road was passable. It was, and the Voyagers were already built to take it.

In 1965 Gary Flandro, a summer student at JPL, noticed that in the late 1970s Jupiter, Saturn, Uranus and Neptune would line up so that a spacecraft could use each planet's gravity to reach the next, cutting a thirty-year journey to twelve. The alignment comes round every 175 years or so. NASA could not afford the full Grand Tour it proposed, so it built two cheaper craft and aimed only the second at the outer two planets. Voyager 2 launched first, on 20 August 1977; Voyager 1 , on a faster route, left on 5 September. Each weighed 825 kilograms, carried a 3.7-metre dish, eleven instruments and three plutonium generators.

Each carries a Golden Record , a gold-plated copper disc with a stylus and pictorial instructions on its cover, assembled by a committee under Carl Sagan: 115 images, greetings in 55 languages, whale song, a kiss, and ninety minutes of music from Bach to Chuck Berry. On 14 February 1990, at Sagan's urging, Voyager 1 turned its camera back from six billion kilometres and took the Pale Blue Dot , the Earth less than a pixel wide in a ray of scattered sunlight. The cameras were then switched off to save power.

NASA took a once-in-175-years chance with two spacecraft built in five years. Neither will ever reach another star, but both will outlast the Earth, carrying the record of what we sounded like.

Galileo left Earth in the cargo bay of the shuttle Atlantis on 18 October 1989, with no upper stage powerful enough to throw it straight at Jupiter. So it went the long way: past Venus in February 1990 and past Earth twice, in December 1990 and December 1992, and photographed the asteroids Gaspra and Ida on the way. In April 1991 the 4.8-metre high-gain antenna was commanded to open like an umbrella and three of its eighteen ribs stuck, probably because lubricant had worn off during years of lorry journeys while the mission waited out the Challenger grounding. Every trick failed, and the mission would have to be flown through an emergency low-gain antenna at about ten bits per second.

Over 34 orbits Margaret Kivelson's magnetometer found that Europa bends Jupiter's magnetic field as a conducting shell would, which meant a global ocean of salty water beneath the ice, and that Ganymede has a field of its own. On 21 September 2003, its fuel nearly gone, Galileo was steered into Jupiter at 48 kilometres per second so that it could never crash on Europa and contaminate the ocean it had found.

Galileo found the ocean; Juno measured the planet that heats it. Europa Clipper, launched in October 2024, is on its way to the ice to look for a way in.

Cassini-Huygens was the largest interplanetary spacecraft ever launched by the West: 5.7 tonnes at lift-off on a Titan IVB on 15 October 1997, more than half of it propellant, with a 4-metre dish supplied by the Italian Space Agency, twelve instruments on the NASA orbiter and six more on ESA's Huygens probe. No rocket could throw that at Saturn, so it borrowed speed from Venus twice, in April 1998 and June 1999, from Earth in August 1999 and from Jupiter in December 2000, and fired its engine for 96 minutes on 1 July 2004 to slip into orbit through a gap in the rings.

Cassini stayed thirteen years and 294 orbits. Its radar, peering through Titan's haze on 127 flybys, found seas of liquid methane and ethane near the north pole, the only open liquid known beyond Earth. In 2005 its magnetometer noticed Saturn's field draped round the small moon Enceladus, and the cameras then saw why: geysers of water ice jetting from four warm fractures at the south pole, feeding Saturn's E ring. The dust analyser tasted salt in the grains, and in 2015 the mass spectrometer flew through the plume at 49 kilometres altitude and found molecular hydrogen, a sign of hot rock reacting with seawater on the floor of a global ocean. In the rings it photographed the propeller-shaped wakes of embedded moonlets and waves raised by passing moons; over the north pole it mapped a hexagonal jet stream 30,000 kilometres across.

Cassini turned Saturn from a picture into a place with weather, seasons and an ocean moon that may be habitable. The next craft, NASA's Dragonfly , is a rotorcraft due to fly across Titan's dunes in the 2030s.

The first wheels on Mars were the size of a microwave oven. Sojourner , 10.6 kilograms under a solar panel the size of a tea tray, rolled off the Pathfinder lander on 5 July 1997, a day after it bounced to a stop on Ares Vallis inside a cluster of airbags. Designed for seven days, it ran for 83 and covered about 100 metres, while a new thing called the World Wide Web served its pictures to a public that had not seen Mars close up since Viking. The airbags were reused in January 2004 for Spirit and Opportunity , 185-kilogram twins built for 90 days. Spirit lasted six years and found silica from ancient hot springs before bogging down in 2009; Opportunity found rock laid down by water, drove 45.16 kilometres, more than any other vehicle on another world, and fell silent in a global dust storm in June 2018 after 14 and a half years.

Strapped to its belly was Ingenuity , a 1.8-kilogram helicopter with rotors at 2,400 revolutions per minute to grip air one per cent as dense as Earth's. Meant for five test flights, it made 72 between 19 April 2021 and 18 January 2024, scouting routes until a rotor blade broke on landing. China's Zhurong , a 240-kilogram solar rover, landed in Utopia Planitia on 14 May 2021, drove about two kilometres, found signs of ancient water in the dunes, and hibernated in May 2022 as winter dust coated its panels; it never woke.

Six rovers have driven about 150 kilometres in 28 years. The next, ESA's Rosalind Franklin , is to drill two metres down, deeper than any rover has gone, to look for life where the radiation does not reach.

New Horizons left Earth on 19 January 2006 faster than any spacecraft before it: 16.26 kilometres per second, on an Atlas V with an extra solid stage, so that it passed the Moon's orbit in nine hours. Seven months later, on 24 August 2006, the International Astronomical Union voted that its destination was no longer a planet. The spacecraft, a 478-kilogram grand piano with a 2.1-metre dish and seven instruments, had been seventeen years in the campaigning: Alan Stern and a group of young scientists calling themselves the Pluto Underground had pushed for a mission since 1989, two designs were cancelled, and in 2001 NASA chose this one, built at the Johns Hopkins Applied Physics Laboratory for a fraction of Cassini's cost.

The flyby came on 14 July 2015, 12,500 kilometres above a world 2,377 kilometres across, at 13.8 kilometres per second, 4.8 billion kilometres from Earth with a radio delay of four and a half hours. The craft could not point its dish and its cameras at the same time, so it worked blind all day and phoned home that evening. Pluto turned out to have a heart: Sputnik Planitia , a 1,000-kilometre basin of nitrogen ice churning in slow convection cells, uncratered because the surface renews itself; mountains of water ice 3.5 kilometres high; a blue haze of a dozen layers; and a moon, Charon, with a dark red cap and canyons longer than the Grand Canyon. The 6.25 gigabytes of data took until October 2016 to trickle home at a kilobit a second.

Pluto was reclassified while its first visitor was on the way, and the visit showed why the argument hardly matters: it is a small world with ice volcanoes, weather and a heart.

A picture of a rock tells you what it looks like. A grain of it in a laboratory tells you how old it is, where it formed and what water has touched it, with instruments that would never fit on a spacecraft. That is why agencies spend a decade to bring back a few grams. The first modern attempt went badly: Genesis spent two years beyond the Moon catching solar wind on wafers of sapphire and silicon, and on 8 September 2004 its capsule hit the Utah desert at 300 kilometres per hour because an accelerometer had been fitted upside down and the parachute never fired. Scientists picked through the shattered wafers for years and still showed that the Sun's oxygen differs from the Earth's.

Japan's Hayabusa , launched in 2003 to the 535-metre asteroid Itokawa, lost two reaction wheels, leaked fuel, lost contact for weeks and failed to fire its sampling projectile, but it touched down twice, and when its capsule landed at Woomera on 13 June 2010 about 1,500 grains had come along anyway. Hayabusa2 did everything its parent could not: it fired a copper slug into the asteroid Ryugu to make a crater, landed twice, and on 6 December 2020 delivered 5.4 grams, which turned out to contain 20 amino acids and uracil, a building block of RNA. NASA's OSIRIS-REx reached the asteroid Bennu, touched it for six seconds on 20 October 2020, nearly sinking into loose rubble, then dropped 121.6 grams in Utah on 24 September 2023, the largest asteroid sample ever, rich in carbon, water-bearing clays and the salts of an evaporated brine.

Mars is the sample still missing. Perseverance's tubes are sealed, but the plan to fetch them was sent back for redesign in 2024, and China has announced its own Tianwen-3 return for the early 2030s. The world that most needs a laboratory may be the last to get one.

A body in orbit is not beyond gravity. The International Space Station, 400 kilometres up, feels about 90 per cent of the pull we feel on the ground; it simply falls round the Earth fast enough never to land, and everything inside falls with it. The effect is free fall , and the body treats it as a permanent handstand. Within hours, roughly two litres of blood and tissue fluid that gravity normally holds in the legs migrate upwards. Faces puff, legs thin into what crews call "bird legs", the sinuses block, and the sense of smell dulls, which is one reason astronauts ask for hot sauce.

The eyes were a surprise. From around 2005, flight surgeons noticed that returning astronauts' eyeballs had flattened at the back, their optic discs swollen and their eyesight shifted, in some cases permanently. The condition is now called spaceflight-associated neuro-ocular syndrome , SANS, and it affects about two-thirds of long-duration crew; the leading suspect is the headward fluid shift pressing on the brain and the optic nerve. The immune system also drifts, with dormant viruses such as herpes and shingles reactivating in saliva samples.

None of this has yet stopped anyone flying. It has, instead, defined the problem for Mars: a journey of six to nine months each way, with no treadmill waiting at the far end. The body adapts to orbit remarkably well. The question is how much of Earth it needs to bring along.

A spacesuit is a spacecraft shaped like a person. It must hold pressure against vacuum, supply oxygen, scrub carbon dioxide, carry away the heat of a working body, stop micrometeoroids and 120-degree sunlight, and still bend at the fingers. The first ones barely did. Mercury's silver suits were modified Navy Mark IV pressure suits from B.F. Goodrich, meant as a backup if the cabin leaked; they were never pressurised in flight. Yuri Gagarin's SK-1 was the same idea in orange, built by the Zvezda plant outside Moscow, which still makes Russia's suits today.

The two suits in use today are old designs kept young. NASA's Extravehicular Mobility Unit, the EMU , first flew on the Shuttle in April 1983 and still services the International Space Station; with its backpack it weighs about 145 kilograms on Earth, and runs at 4.3 psi, low enough that crews must breathe pure oxygen for hours beforehand to purge nitrogen from the blood, or risk the bends. The Russian Orlan , in service since Salyut 6 in 1977, takes the other approach: the whole backpack is a hinged door, the cosmonaut climbs in through the back in about five minutes, and the suit runs at a higher 5.8 psi with a shorter pre-breathe. An Orlan is serviced in orbit and never comes home.

Every suit is a negotiation between pressure and movement, protection and weight. Sixty years on, the handshake inside the glove is still the thing engineers cannot quite perfect.

Yuri Gagarin's lunch on 12 April 1961 came from aluminium tubes: meat purée and chocolate sauce, squeezed into the mouth to prove that a human could swallow in free fall. Doctors had genuinely wondered. By Gemini the Americans had freeze-dried food and gelatin-coated bite-sized cubes, which crews disliked so much that John Young smuggled a corned-beef sandwich from a Cocoa Beach delicatessen aboard Gemini 3 on 23 March 1965. He took two bites, crumbs floated off, and the sandwich was put away; Congress held a hearing about it. Apollo added hot water and the spoon-bowl pouch, and Skylab in 1973 had a freezer, a dining table and the only shower ever flown by NASA, a collapsible cylinder that took hours to use and dry.

Water is the real engineering. Lifting a litre to orbit is so expensive that the station recycles almost all of it. The Water Recovery System in Tranquility distils urine in a spinning drum, polishes the result through filters and a catalytic reactor, and blends it with condensate scavenged from the cabin air, including sweat and breath. In 2023, with a new brine processor squeezing the last water from the urine distiller's residue, NASA reported recovering about 98 per cent of the water aboard. The crew joke that today's coffee is tomorrow's coffee is literally true.

Every mission plan to Mars begins with the same arithmetic: a crew of four needs about 30 kilograms of food, water and oxygen a day, and nothing can be sent after them. The station is where that arithmetic has been learned, one recycled litre at a time.

The International Space Station crosses from night into day every 45 minutes, sixteen sunrises in every 24 hours, so the Sun is useless as a clock. The station runs instead on Coordinated Universal Time , Greenwich time, chosen in the 1990s as a compromise between Houston and Moscow. The crew wake around 06:00, hold a morning conference with the control centres, work through a timeline planned to five-minute blocks, exercise for two hours, and are scheduled to sleep from 21:30. They rarely get the eight and a half hours the plan allows; six is typical, and sleeping pills are the most used drug in orbit.

Crews have been studied for the strain of confinement long before they leave the ground. In Moscow, six volunteers spent 520 days sealed inside the Mars-500 mock spacecraft from June 2010 to November 2011, with a simulated Mars landing in the middle, and the main finding was how much their sleep and activity drifted apart. On the slopes of Mauna Loa in Hawaii, HI-SEAS crews lived in a dome for up to a year; at Concordia station on the Antarctic plateau, ESA studies a dozen winter-over staff who cannot leave for nine months at 3,200 metres and minus 80 degrees. The pattern that emerges is that the quarrels are rarely between crew members and usually between the crew and the ground.

Sleep, time and temper are not soft problems; a tired, irritable crew is a safety risk as real as a leaking seal. For Mars, with a 20-minute radio delay and no care packages, the mind may be the hardest system to keep in balance.

Space is not empty; it is full of fast particles. Three kinds matter to a crew. Galactic cosmic rays are atomic nuclei flung from supernovae at close to the speed of light, a thin, steady drizzle that no practical shielding stops, and the heavy ones, iron nuclei among them, tear through cells like cannonballs. Solar particle events are the opposite: rare, violent floods of protons from a solar flare or coronal mass ejection, lasting hours to days, which good shielding can block. And around the Earth lie the Van Allen belts , two doughnuts of trapped particles found by Explorer 1 in 1958, an inner belt of protons from about 1,000 kilometres up and an outer belt of electrons out beyond 13,000.

Beyond the magnetic field the numbers climb. The Curiosity rover carried a Radiation Assessment Detector on its 2012 cruise to Mars and recorded about 1.8 millisieverts a day in transit; Cary Zeitlin's team at the Southwest Research Institute worked that out as roughly 0.66 sieverts for a round trip with the current rockets, more than NASA's entire career limit, which in 2021 was set at 600 millisieverts for every astronaut regardless of age or sex. Apollo was lucky as well as brief. Between 4 and 7 August 1972, in the four months between Apollo 16 and Apollo 17, the Sun produced one of the most intense proton storms ever recorded. Calculations since suggest that a crew in a suit on the lunar surface would have received a dose high enough to cause acute radiation sickness, and possibly death.

Radiation is the one hazard of spaceflight that engineering cannot yet remove, only measure and dilute. Every plan for Mars is, in the end, a plan to get there fast and hide well.

The odds of becoming an astronaut are worse than those of winning a seat in most parliaments. When NASA opened applications in 2016 it received 18,300, a record, and in June 2017 chose twelve. ESA's 2021 call drew 22,500 applicants from across Europe and in November 2022 named seventeen: five career astronauts, eleven reservists and one candidate with a physical disability, the British surgeon John McFall, cleared in 2025 for a long-duration flight. China picked its first fourteen fighter pilots from 1,500 in 1996. The requirements have softened from the test-pilot era to a science or engineering degree, good health and a temperament that can be locked in a tin with strangers.

The cathedral of this training is the Neutral Buoyancy Laboratory at the Sonny Carter Training Facility in Houston: a pool 62 metres long, 31 wide and 12 deep, holding 62 million litres of water, with full-scale mock-ups of station modules and truss sections lying on its floor. A suited astronaut is weighted until they neither sink nor float, and spends six or seven hours at a time rehearsing a spacewalk under the eyes of four safety divers, a test director and television cameras, at a ratio of about ten hours in the pool for every hour outside the station. Russia's Hydrolab at Star City, the Gagarin Cosmonaut Training Centre outside Moscow, does the same job with a 12-metre tank; the centre also owns the TsF-18 centrifuge, with an 18-metre arm, and has trained every cosmonaut since 1960.

From selection to first launch typically takes five years or more; some candidates wait a decade. Nobody flies untrained, and nobody flies alone: by the time the hatch closes, the crew has rehearsed every ordinary minute and most of the extraordinary ones.

The two most dangerous half hours of any space mission are the first and the last. On a Soyuz launch from Baikonur the crew lie on their backs in moulded seats, knees up, as the rocket builds to a peak of about four g at the end of the first stage; the whole climb to orbit takes under nine minutes, at the end of which a small toy on a string in front of the commander floats free. Above them for the first two minutes sits the launch escape system , a solid-fuel tower that can yank the descent module clear of a failing rocket. On 26 September 1983 the Soyuz T-10a booster caught fire on the pad, and controllers fired the escape tower by radio command two seconds before the rocket exploded; Vladimir Titov and Gennady Strekalov endured around 15 g and landed four kilometres away, bruised. On 11 October 2018 a strap-on booster failed to separate cleanly from Soyuz MS-10 at 119 seconds, and…

The last kilometres are national styles. A Soyuz lands on the grassland of Kazakhstan under a single 1,000-square-metre parachute, and at about 80 centimetres above the ground six solid rockets in the base fire for a jolt that crews compare to a car crash; recovery helicopters are usually there within minutes to lift the crew out. The Space Shuttle glided to a runway at 346 kilometres per hour, with no second chance. Dragon and Orion return to the water: Dragon under four main chutes into the sea off Florida or California, and Orion, after a skipping entry on Artemis I in December 2022, into the Pacific off Baja California, where a Navy ship winches it aboard.

Space stations have three nightmares, and crews drill for all of them: fire, loss of pressure and toxic air. The first great lesson came from the worst one. On 30 June 1971 the crew of Soyuz 11 , Georgy Dobrovolsky, Vladislav Volkov and Viktor Patsayev, returning from three weeks aboard Salyut 1, died when a pressure-equalisation valve jolted open as their modules separated at 168 kilometres. The cabin emptied in under a minute. They wore no pressure suits, because three men in suits would not fit, and the capsule landed itself perfectly. Since then every Soyuz crew has worn the Sokol suit for launch and landing; the ship flew with two cosmonauts until a 1980 redesign seated three in suits.

The station era's emergencies have been quieter and stranger. On 16 July 2013 Luca Parmitano's helmet began to fill with water 44 minutes into a spacewalk, from a clogged fan-pump separator in his suit; blinded, with water in his ears and nose, he felt his way back along the tether to the airlock. NASA's mishap board found the same suit had leaked a week earlier and the sign had been misread. In August 2018 a slow leak traced to a two-millimetre drill hole in the orbital module of Soyuz MS-09 , made on the ground, was sealed in orbit with gauze and epoxy. On 14 December 2022 a micrometeoroid or debris strike punctured the coolant loop of Soyuz MS-22, and a fountain of coolant sprayed into space on live camera; Roscosmos launched a replacement, MS-23, empty, in February 2023, and the crew flew home on it in September after 371 days.

Nobody has died in space since 1971, and nobody has died aboard a station at all. That record was not luck; it was drilled, module by module, from the lessons of those who did not come back.

The International Space Station was sold as a laboratory, and for its first decade the lab was mostly being built. Since 2011 it has hosted well over 3,000 investigations from more than a hundred countries, and the honest audit is more interesting than the brochure. The physics case is the clearest. Remove gravity and buoyancy, sedimentation and convection vanish with it, so fluids, flames and crystals behave as the equations say they should. In the Combustion Integrated Rack in the Destiny module, the FLEX experiments burned droplets of heptane and found, in 2012, that after the visible flame went out the droplet kept burning invisibly as a cool flame at around 500 degrees, a chemistry that engine designers had suspected but never seen cleanly. Capillary-flow experiments rewrote how spacecraft fuel tanks are designed.

Some of the station's best science simply points outward. Bolted to the main truss since May 2011, the seven-tonne Alpha Magnetic Spectrometer has recorded more than 200 billion cosmic-ray particles, measuring the antimatter and positron fractions that might betray dark matter. The Cold Atom Lab , installed in Destiny in 2018, chills clouds of rubidium and potassium atoms to within a ten-billionth of a degree of absolute zero and made the first Bose-Einstein condensates in orbit, which last far longer when they do not fall out of their trap. Europe's Columbus module, launched in February 2008, carries the Biolab, a fluid-science laboratory and an electromagnetic levitator for molten metals; Japan's Kibo , completed in 2009, is the largest module and the only one with its own airlock and exposed balcony, where small satellites are released by a robot arm.

A long-duration crew does not step out of the capsule; they are lifted. Within minutes of a Soyuz thumping down on the Kazakh steppe, recovery teams haul each crew member through the hatch and sit them in a folding chair with a blanket, where they grin, hold a fruit, and try not to be sick. The inner ear's balance organs, idle for six months, now report every head movement as a lurch; blood pools in the legs again and the heart, which has shrunk slightly in orbit, struggles to push it uphill, so standing up risks fainting. Crews describe their arms feeling like lead. Russian crews are flown to Star City, American ones to Houston, and all begin the next morning with a medical team and a tilt table.

The long stays give the clearest readings. Scott Kelly's 340 days in 2015 and 2016 ended with swollen legs, rashes where fabric touched skin and a fever, but within six months more than 90 per cent of the gene-expression changes measured against his twin had returned to baseline. Frank Rubio went up in September 2022 for six months and came down a year later, after the Soyuz MS-22 coolant leak stranded his crew, with 371 days, the American single-flight record; he walked within days but said it took months to feel normal. Peggy Whitson, flying again in 2025 at 65, holds the American cumulative record at nearly 700 days. Barry Wilmore and Sunita Williams, who had launched in June 2024 for a planned eight-day test of Boeing's Starliner, came home on a SpaceX Crew Dragon on 18 March 2025 after 286 days, and walked within a day.

The first space station was not American and it was not comfortable. Salyut 1 , launched on a Proton rocket from Baikonur on 19 April 1971, was a stepped cylinder about 15.8 metres long, 18.4 tonnes, with roughly 90 cubic metres of living space, one docking port at the front and a Soyuz propulsion block at the back. It was the Soviet answer to Apollo: having lost the Moon, they would be first to live in orbit.

Behind the civil name hid a second programme. Vladimir Chelomei's Almaz ("diamond") stations were military reconnaissance platforms with a large camera and a film-return capsule, flown under the Salyut label to disguise them: Salyut 2, which failed in 1973, Salyut 3 in 1974 and Salyut 5 in 1976. Salyut 3 carried a 23-millimetre aircraft cannon, aimed by turning the whole station. On 24 January 1975, with no crew aboard and shortly before it was deorbited, the gun was test-fired by remote command, the only time a weapon has been fired from a crewed spacecraft.

Salyut 7's finest hour came after it died. In February 1985 the empty station's electrics failed and it fell silent, drifting and freezing. In June, Vladimir Dzhanibekov and Viktor Savinykh flew Soyuz T-13 to it, docked by hand with a laser rangefinder, and found the cabin dark, freezing and furred with frost. In fur hats, they recharged the batteries from Soyuz, thawed the water tanks and had the station alive within a week. The Salyuts taught everything the later stations knew: docking modules together, robot resupply, months in a tin can, and what it costs to get it wrong.

On 12 April 1981, twenty years to the day after Gagarin, John Young and Bob Crippen rode Columbia off Pad 39A on the first flight of a vehicle nobody had flown before, not even uncrewed. The Space Shuttle was three things bolted together: a delta-winged orbiter the size of a DC-9 airliner, 37 metres long with a 24-metre wingspan; a 47-metre external tank holding about 720 tonnes of liquid hydrogen and oxygen; and two solid rocket boosters , each 45 metres tall and giving around 12 million newtons of thrust. At lift-off the stack weighed about 2,000 tonnes, and the boosters supplied most of the push for the first two minutes before splashing down under parachutes to be reused.

The record is in NASA's mission archive: 135 flights by five orbiters, Columbia , Challenger , Discovery , Atlantis and Endeavour , carrying 355 individuals from 16 countries. The Shuttle launched and then fixed the Hubble Space Telescope, repaired Solar Max in 1984 in the first on-orbit satellite service, caught the stranded Intelsat VI in 1992 with three astronauts holding it by hand, flew Europe's Spacelab laboratory from 1983 with Germany's Ulf Merbold aboard, docked nine times with Mir and delivered most of the International Space Station. Canada's robotic arm, flying from the second mission in November 1981, made much of that possible.

Atlantis rolled to a stop at Kennedy at dawn on 21 July 2011, the 135th and final landing, after thirty years that no later vehicle has matched for versatility and none has wished to copy. The capsules that replaced it are simpler, cheaper and safer. The Shuttle remains the only machine that ever carried people, built a station and brought a satellite home in the same hold.

At 11:38 on the morning of 28 January 1986, Challenger lifted off from Kennedy Space Center into air just above freezing, the coldest launch in Shuttle history. Seventy-three seconds later, about 14 kilometres up, it broke apart. Aboard were Dick Scobee, Michael Smith, Ellison Onizuka, Judith Resnik, Ronald McNair, Gregory Jarvis and Christa McAuliffe , a teacher from New Hampshire chosen from 11,000 applicants for the Teacher in Space project. Schools across America were watching.

Film from the pad cameras told the rest. At 0.68 seconds, puffs of black smoke left that joint as the O-rings failed to seal; slag from the burning propellant plugged the gap for a while. At 58 seconds, after the strongest wind shear of any Shuttle flight, a flame appeared at the joint. It burned through the strut holding the booster to the external tank; the booster swung, struck the tank, the hydrogen tank failed and aerodynamic forces tore the vehicle apart at nearly twice the speed of sound. It did not explode in the usual sense: the fireball was propellant burning in the open. The crew cabin stayed intact and fell for two minutes and forty-five seconds into the Atlantic.

The fleet was grounded for 32 months while the joints were redesigned with a third O-ring, a capture lip and heaters, the crew got pressure suits and a bail-out pole, and commercial satellites left the Shuttle for good; Discovery flew again on 29 September 1988. Barbara Morgan, McAuliffe's backup, reached orbit in 2007. Challenger is taught in every engineering school as the case where the data were in the room and the launch went ahead anyway.

Mir means peace, and also world, and also the old Russian word for a village community; the station lived up to all three. Its core module, a 20-tonne Salyut descendant with a six-port docking node at the front, was launched by Proton on 20 February 1986, three weeks after Challenger . Over the next decade the Soviet Union, and then Russia, bolted on Kvant-1 (1987, astrophysics), Kvant-2 (1989, an airlock and a shower), Kristall (1990, materials furnaces and two ports for a shuttle that would be Buran and turned out to be Atlantis ), Spektr (1995) and Priroda (1996), plus a docking module delivered by the Americans. The finished station massed about 130 tonnes and sprawled over 30 metres, the first spacecraft assembled in orbit from pieces launched years apart.

The Cold War ended in Mir's docking node. Under the Shuttle-Mir programme, Atlantis docked on 29 June 1995, forming for five days the largest spacecraft ever flown, about 225 tonnes; nine Shuttle dockings followed and seven NASA astronauts lived aboard for months, Shannon Lucid for 188 days. The Americans learned long-duration operations from the Russians; the Russians received hard currency that kept their programme alive.

By then the station was tired: mould on the walls, condensation behind panels, computers that crashed and left it tumbling. On 23 March 2001 a final Progress fired its engines and Mir came down over the South Pacific near Fiji, 86,331 orbits after launch, in a shower of fragments watched from the beaches. It had shown how to build a home in orbit piece by piece, and how to keep it alive when the pieces failed.

Columbia , the oldest orbiter, launched on 16 January 2003 on STS-107, a sixteen-day science mission with a laboratory module in its bay and a crew of seven: Rick Husband, William McCool, Michael Anderson, David Brown, Kalpana Chawla, Laurel Clark and Ilan Ramon, Israel's first astronaut. Eighty-two seconds after lift-off a piece of insulating foam about the size of a briefcase broke from the external tank's left bipod ramp and struck the leading edge of the left wing at roughly 240 metres per second. The launch cameras caught it. Nobody aboard felt it.

On 1 February Columbia began re-entry over the Pacific at 8:44 Eastern time. From 8:53, as it crossed California at Mach 23, sensors in the left wing began to fail one by one, then the left landing-gear tyre pressures, then the hydraulic lines; superheated gas was pouring through a hole in panel 8 and melting the wing from inside. At 8:59:32 Mission Control lost contact at about 61 kilometres over Texas, and the orbiter broke apart at eighteen times the speed of sound. Some 84,000 pieces were later recovered across Texas and Louisiana by 25,000 searchers, among them a videotape of the cabin in the early minutes of entry.

Discovery returned to flight on 26 July 2005 under Eileen Collins, with the tank redesigned, a 15-metre inspection boom, a back-flip under the International Space Station so its crew could photograph the belly, and a second orbiter standing by for rescue. The tank still shed foam, and the fleet was grounded again for a year. In January 2004 the White House had already decided: finish the station, then retire the Shuttle. Columbia's seven changed what came next for everyone who followed.

The International Space Station began as two spacecraft from opposite sides of the Cold War meeting 400 kilometres up. Zarya , a 19-tonne Russian-built module paid for by NASA, rode a Proton out of Baikonur on 20 November 1998. Two weeks later Endeavour brought the American node Unity , and on 6 December the crew of STS-88 pulled the two together with the Shuttle's robotic arm and bolted them with a hundred-odd cable connections over three spacewalks. For eighteen months the pair circled empty while Russia finished Zvezda , the service module with the living quarters, life support and engines, launched in July 2000. Its pressure hull had been built in the mid-1980s as the core of the never-flown Mir-2.

The order was a puzzle in logistics. The American laboratory Destiny came in February 2001, Canadarm2 in April, the airlock Quest in July; the first truss segment and the first giant solar wing had gone up in late 2000. Then Columbia was lost, and for two and a half years only Soyuz and Progress flew, with the crew cut to two to save supplies. Assembly resumed in 2005. Harmony arrived in 2007, Columbus on 7 February 2008, Kibo in three deliveries in 2008 and 2009, Tranquility and the Cupola in February 2010. The flight-by-flight record is NASA's assembly sequence, revised dozens of times.

The station is the largest thing humans have built in space and the most expensive single object ever made, and it exists because the Shuttle could carry the pieces and because former enemies agreed to depend on one another's hardware. Its successors, planned to be commercial, will be smaller. None will be built the way this one was.

The International Space Station circles the Earth about 400 kilometres up at 27,600 kilometres an hour, once every 93 minutes, so its crew of seven sees roughly sixteen sunrises a day and lives on Greenwich time, a compromise between Houston and Moscow. It has been inhabited without a break since 2 November 2000, by more than 280 people from more than twenty countries. The day runs by a timeline sent up from the ground: about six and a half hours of science and maintenance, two hours of exercise to hold off bone and muscle loss, meals from pouches, and a sleeping bag strapped to a wall in a phone-booth-sized cabin.

The station must also be flown. Thin air at that altitude drags it down by a kilometre or two a month, so a Progress or Zvezda's engines reboost it several times a year. When tracked debris threatens, controllers nudge the orbit: about forty avoidance manoeuvres since 1999, and sometimes a crew sheltering in their return craft. Since 2019 a tunnel at the back of Zvezda has leaked air through fine cracks; by 2024 the rate had reached more than a kilogram a day, the hatch is kept shut, and NASA's inspector general listed it as a top risk.

The end is scheduled. The partners have committed to operate the station to 2030, and in 2024 NASA chose SpaceX to build a deorbit vehicle, a heavily modified Dragon with 46 thrusters, to steer 420 tonnes into the South Pacific around 2031. Until then it remains what it has been for a quarter of a century: the one address in the universe that is never unoccupied.

China was never invited aboard the International Space Station. In 2011 the United States Congress passed the Wolf Amendment, barring NASA from bilateral cooperation with China, so China built its own. Tiangong , "heavenly palace", is the only other crewed station in orbit, and the first ever built by a single country alone.

Wentian docked in July 2022 and Mengtian in October, each about 23 tonnes, each swung from the forward port to a side port by a robotic arm to make a T about 55 metres across. Tianhe holds the crew quarters, the controls and the main 10-metre arm, which can inch along the hull hand over hand; Wentian carries life-science racks, a second airlock for spacewalks and a smaller arm; Mengtian carries materials and physics racks and a cargo airlock that pushes small satellites out. The complex masses about 100 tonnes, a fifth of the ISS, with 110 cubic metres of living space for three, and flies at around 390 kilometres inclined 41.5 degrees. Its orbit is held by four Hall-effect electric thrusters, the first on any crewed station.

The station is opening up. The 2-metre Xuntian survey telescope is planned to fly alongside and dock for servicing; a further module with extra ports is planned; and in 2025 China agreed to train Pakistani astronauts, the first foreign guests, with other countries lining up. When the ISS comes down around 2030, Tiangong may for a time be the only permanent human address in space, run by the one nation that was told to stay outside.

The first person to buy a seat into orbit was not an American millionaire but a Japanese television journalist. In December 1990 the Tokyo Broadcasting System paid for Toyohiro Akiyama to spend a week on Mir , broadcasting nightly; Britain's Helen Sharman followed in 1991 on a flight that began as a commercial venture. The pattern was set: a cash-starved Russian programme sold what NASA would not.

Suborbital tourism arrived in a single fortnight. On 11 July 2021 Richard Branson rode Virgin Galactic's rocket plane VSS Unity to 86 kilometres, above the 80-kilometre line the United States counts as space; on 20 July Jeff Bezos's New Shepard capsule carried four, including 82-year-old Wally Funk, to 107 kilometres, past the 100-kilometre Kármán line that most of the world uses. Each gave a few minutes of weightlessness and a view of the curve of the Earth; New Shepard has since flown dozens of passengers, William Shatner at 90 among them.

That flight, Polaris Dawn , had two days earlier reached 1,400 kilometres, the farthest from Earth anyone had travelled since Apollo 17, and tested SpaceX's new suit. In April 2025 Fram2 , chartered by a Maltese entrepreneur, Chun Wang, flew the first humans over the poles in a 90-degree orbit, with Germany's Rabea Rogge and a Norwegian film-maker and an Australian polar guide aboard. The records are SpaceX's, Axiom's and NASA's, and the flight surgeons' papers that followed.

Around 2030 the International Space Station will be steered into the ocean, and what replaces it exists so far on paper. The partners have agreed to fly to 2030; Russia, which once threatened to leave earlier, has signed on to 2028 and is designing its own station; and NASA plans to stop owning a station and start renting rooms.

Other nations are not waiting for the market. Roscosmos approved its Russian Orbital Station in 2024, with a first science-and-power module planned around 2027 and a steep 97-degree orbit that would overfly the whole of Russia, something the ISS never does. India's Bharatiya Antariksh Station is to begin with a module planned for 2028 and grow to five modules of about 52 tonnes by 2035, following the first crewed Gaganyaan flights. China plans a further Tiangong module with more docking ports. Beyond Earth orbit the lunar Gateway , a small station in a looping orbit around the Moon with modules from NASA, Europe, Japan, Canada and the United Arab Emirates, had its first elements under construction when, in 2025, the White House proposed cancelling it; its future has been argued since.

The stations to come will be smaller, more numerous and privately owned, with agencies as tenants and tourists as guests. Whether they are built in time is the open question of the decade. Humans have had a home in orbit for over fifty years; the next few will decide whether we keep one.

In October 1945 a young RAF radar officer named Arthur C. Clarke published a four-page article in Wireless World called "Extra-Terrestrial Relays". It pointed out that a satellite 35,786 kilometres above the equator would circle the Earth in exactly one day and so appear to hang motionless in the sky; three of them, spaced evenly, could relay radio to the whole planet. He later joked that he should have patented it. The geostationary orbit is still called the Clarke orbit, and most of the television beamed to rooftop dishes today comes down from it.

Low orbits meant short, interrupted sessions. Hughes engineer Harold Rosen's answer was Clarke's orbit in practice: Syncom 2 reached a geosynchronous orbit in July 1963 and Syncom 3, launched on 19 August 1964, became the first truly geostationary satellite, relaying the opening of the Tokyo Olympics to American screens that October. Intelsat I, nicknamed Early Bird, followed on 6 April 1965 with 240 telephone circuits or a single television channel, and commercial transatlantic satellite service began. The Soviet Union, whose territory sits too far north for a good view of the equator, chose instead the highly elliptical Molniya orbit , launched from April 1965, which lingers for hours over the northern hemisphere on each twelve-hour loop.

On 1 April 1960 a 122-kilogram drum called TIROS-1 rose from Cape Canaveral carrying two television cameras, and within hours meteorologists were looking at something no one had seen before: whole cloud systems, spiral storms and fronts stretching across thousands of kilometres. The satellite worked for only 78 days and returned about 23,000 pictures, many of them of the top of the spacecraft, but the point was made. Weather had been forecast from scattered station reports and balloon soundings; now it could be watched.

The decisive change came when satellite measurements were fed into numerical models. The European Centre for Medium-Range Weather Forecasts began operational forecasting in 1979 and now assimilates tens of millions of observations a day, well over ninety per cent of them from satellites: temperature and humidity soundings, winds inferred from cloud drift, sea-surface wind speed from the radar scatterometers on MetOp. The result is what meteorologists call a quiet revolution: forecast skill has gained roughly a day per decade, so a modern five-day forecast is about as reliable as a two- or three-day forecast was around 1980. We know this because every forecast is scored against what happened, and the verification archives go back decades.

A satellite image on the evening news is now so ordinary that we forget it was once a miracle. Behind it stands a global observing system that is one of the few genuinely shared pieces of infrastructure on Earth: no country's forecast works without everyone else's satellites.

On 23 July 1972 a Delta rocket from Vandenberg put the Earth Resources Technology Satellite into a 900-kilometre polar orbit. Renamed Landsat 1 , it carried a television camera system that soon failed and an experimental instrument that did not: the Multispectral Scanner, designed by Virginia Norwood at Hughes, which swept a mirror across a 185-kilometre swath and recorded the ground in four colours, two of them infrared, at about 80 metres per pixel. Plants reflect near-infrared light strongly, so for the first time crops, forests and bare soil could be told apart over whole countries, every 18 days. The record that began that day has never stopped.

For its first 36 years the archive was sold by the scene, and researchers bought a handful. In 2008 the USGS made every image free , and the field changed overnight: downloads rose from a few thousand scenes a year to millions, and scientists began to treat the archive as a time machine rather than a photograph. Matthew Hansen's team at the University of Maryland processed 650,000 scenes to map every forest gain and loss on Earth between 2000 and 2012 at 30-metre resolution. Brazil's space agency INPE had already been using Landsat since 1988 to measure Amazon clearing each year, the fishbone pattern of roads and fields in Rondônia visible from orbit before any inspector reached it.

A single satellite picture tells you what a place looks like. Fifty-three years of them tell you what it is becoming, and that is a record no nation can now afford to interrupt.

Within days of Sputnik's launch in October 1957, two physicists at the Johns Hopkins Applied Physics Laboratory, William Guier and George Weiffenbach, found they could work out the satellite's orbit from the Doppler shift of its beeps. Their boss asked the reverse question: could a known orbit fix an unknown position on the ground? The answer became Transit , operational from 1964, which told Polaris submarines where they were every hour or so. Its limitation, a fix only when a satellite passed overhead, drove the next idea: enough satellites, with clocks good enough, that four would always be in view.

Einstein is built into every fix. Moving at 3.9 kilometres a second, the satellite clocks run slow by about 7 microseconds a day; sitting higher in Earth's gravity, they run fast by about 45. The net 38 microseconds a day would, uncorrected, drift positions by about ten kilometres daily, so the clocks are set to tick slightly slow before launch.

The weakness is the faintness. Jamming and spoofing of GPS around the Baltic, the Black Sea and the Middle East have disrupted thousands of flights since 2022, and ships have found themselves apparently parked at inland airports. A free signal from 20,000 kilometres quietly rebuilt the world's logistics, farming, finance and timing; losing it, even briefly, now shows how much rests on it.

On 19 August 1960 a C-119 transport aircraft over the Pacific near Hawaii flew a trapeze into the parachute lines of a falling gold-plated capsule and reeled it aboard. Inside was a reel of film from Discoverer 14 , the first successful mission of the CIA and Air Force programme code-named Corona . That single bucket covered more of the Soviet Union than all the U-2 spy plane flights put together, at a time when U-2s had become too dangerous: Francis Gary Powers had been shot down over Sverdlovsk in May. For the first time, a country could look inside another from a place no fighter could reach.

Film has one flaw: you must wait for it to fall. The KH-11, first launched on 19 December 1976, carried a charge-coupled device instead and sent its pictures down by radio through relay satellites, so an analyst could see a Soviet shipyard within hours. Its 2.4-metre mirror was the same size as Hubble's, built at the same time by the same industry; in 2012 the National Reconnaissance Office handed NASA two spare telescopes of that class, one of which became the Nancy Grace Roman Space Telescope. The NRO itself, founded in 1961, had its existence officially admitted only in 1992, and Corona's imagery was declassified in February 1995, when historians and geographers found a 1960s baseline for everything from Siberian forests to Middle Eastern archaeology.

Spy satellites did not end secrecy, but they changed its scale. Nothing larger than a car can be hidden for long, and both the arms-control treaties of the Cold War and the open-source analysts of today rest on that fact.

The most important climate measurement of the past thirty years is a few millimetres long. TOPEX/Poseidon , launched by NASA and France's CNES on 10 August 1992, bounced radar pulses off the ocean from 1,336 kilometres up and timed the echo to measure the height of the sea surface to within a few centimetres on each pass. Averaged over the globe and over months, the errors shrink and the trend appears. Its successors Jason-1, Jason-2, Jason-3 and Sentinel-6 Michael Freilich have flown the same ground track ever since, and the record is unambiguous: the global sea has risen about ten centimetres since 1993, at roughly 3 millimetres a year on average and more than 4 a year now. Tide gauges had hinted at it for a century; the satellites made it a single global number.

The atmosphere has its monitors too. NASA's Terra, launched in 1999, and Aqua, in 2002, lead a train of satellites crossing the equator in the early afternoon, measuring clouds, aerosols, fires and the radiation budget. OCO-2 , launched on 2 July 2014, maps carbon dioxide to better than one part per million from orbit, showing emissions plumes over cities and the breathing of the forests. SMAP, from 2015, reads soil moisture with a microwave radiometer; its radar failed after three months, which is how we know radar amplifiers are harder than radiometers. Europe's Copernicus Sentinel-1 radar images the ground day and night through cloud, catching subsidence, floods and glacier flow, while ESA's Earth Explorers each ask one question: GOCE mapped gravity, CryoSat-2 measures ice thickness, SMOS reads soil moisture and ocean salt, and EarthCARE, launched in 2024, profiles clouds with lidar…

The Hubble Space Telescope left the payload bay of Discovery on 25 April 1990, the day after launch on STS-31, a school-bus-sized cylinder 13.2 metres long and weighing 11 tonnes, with a 2.4-metre primary mirror that had been polished for years. Lyman Spitzer had proposed a telescope above the atmosphere in 1946; Nancy Grace Roman had spent the 1960s and 1970s at NASA persuading astronomers and Congress to pay for it. Within weeks, the first star images came down as fuzzy haloes. The mirror had spherical aberration : its edge was too flat by about 2.2 microns, a fiftieth of the width of a human hair, and it could not bring light to one focus.

The repair, STS-61 aboard Endeavour , launched on 2 December 1993 after a year of underwater rehearsal. Over five spacewalks, a record at the time, Story Musgrave and Jeffrey Hoffman, Kathryn Thornton and Thomas Akers installed COSTAR and WFPC2, replaced the solar arrays that flexed every time the telescope crossed from night into day, and changed gyroscopes, with Claude Nicollier of ESA operating the robotic arm. The first corrected images in January 1994 were as sharp as the designers had promised, and the mission is still studied as the model for complex orbital servicing.

More than thirty-five years after launch, Hubble still observes, slower now and lower, its orbit slowly decaying from 600 kilometres towards an eventual re-entry. It is the first great telescope to have been repaired by hand in orbit, and the proof that a flaw in a mirror need not be the end of a machine.

At 12:20 Universal Time on Christmas Day 2021 an Ariane 5 lifted off from Kourou in French Guiana carrying the James Webb Space Telescope , folded like origami inside a fairing 5.4 metres wide. The telescope had taken more than twenty years to build, involved more than 10,000 people in 14 countries, and was fourteen years past its original launch date. It was also the most complex deployment ever attempted: engineers counted 344 single-point failures , mechanisms that each had to work or the mission was lost, and none could be reached for repair. Webb was heading for a halo orbit around the second Lagrange point, L2 , 1.5 million kilometres from Earth.

The launch itself turned out to be a gift. Ariane 5 flew so accurately that Webb needed far less of its own propellant than planned for course corrections, and the fuel budget for station-keeping, which limits the mission's life, roughly doubled from ten years to twenty or more. In the shade of the sunshield the mirror cooled to around 40 kelvin, while the mid-infrared instrument was chilled by a cryocooler to 7 kelvin. Over the following three months the 18 segments, each adjustable to nanometres by seven actuators, were nudged until they focused as one; fine phasing was declared complete on 11 March 2022, and the mirror performed better than specification. A micrometeoroid larger than modelled struck segment C3 in May 2022 and left a permanent small error, now compensated by the others, and operators turned the telescope to keep its mirror out of the worst of the oncoming dust.

In 1978 Donald Kessler and Burton Cour-Palais of NASA published a paper with a dull title, "Collision frequency of artificial satellites: the creation of a debris belt", and an alarming argument. Once enough objects share a band of orbit, collisions between them will produce fragments faster than the atmosphere drags them down, and the fragments will cause more collisions, a chain reaction that could make low Earth orbit unusable for generations. It is known as the Kessler syndrome . At the time there were a few thousand tracked objects. Today radar networks follow around 40,000 larger than ten centimetres, of which only some 11,000 are working satellites, and the European Space Agency estimates more than a million fragments bigger than a centimetre, each moving at around 7.5 kilometres a second.

Prevention came slowly. Guidelines from 2002 asked operators to remove satellites from low orbit within 25 years of the end of their mission; in September 2022 the US Federal Communications Commission cut that to five years for satellites it licenses. ESA's Zero Debris approach aims to leave nothing behind by 2030. Satellites now carry fuel for a final de-orbit burn or are flown low enough that drag does the work, and upper stages are vented so they cannot explode.

Low Earth orbit is a commons with no fence and no sweeper. Kessler's belt has not formed, but every new collision moves it closer, and the clean-up has barely started.

On 23 May 2019 a Falcon 9 released 60 flat-packed satellites in a line that observers on the ground mistook for a train of lights. They were the first of Starlink , and by 2026 SpaceX had launched more than 8,000 of them, so that a single company operated well over half of all working satellites in orbit. Each is a slab of about 800 kilograms with a solar wing, krypton or argon ion thrusters, and phased-array antennas that steer beams to flat user terminals on the ground. They fly at around 550 kilometres, low enough that the round trip to a user takes about 25 milliseconds, against roughly 600 for a geostationary link, and low enough that a dead satellite falls back within about five years.

The uses arrived faster than the regulators. Within days of Russia's invasion in February 2022, Starlink terminals were keeping Ukrainian hospitals, government and troops online, the first war in which a private constellation was critical infrastructure; the company's decisions about where service worked showed the power that gave one firm. Direct-to-cell satellites, launched by Starlink from January 2024 and by AST SpaceMobile, now connect ordinary phones in dead zones.

A century ago the telephone needed a wire to every house; now a tray of satellites sweeps overhead every few minutes. Whether the low orbits can be shared by half a dozen fleets and several thousand new satellites a year, without becoming the belt Kessler warned of, is the open question of the decade.

Before the computer was a machine it was a job title, and the job was mostly held by women. From 1935 the NACA's Langley laboratory in Virginia hired women with mathematics degrees to reduce wind-tunnel data by hand, working with pencils, slide rules and Friden desk calculators that weighed as much as a typewriter. From 1943 the Black women among them were seated apart in the West Area Computing unit, with separate toilets and a separate table in the canteen. Its supervisor from 1949 was Dorothy Vaughan, the first Black manager at the NACA, who later taught herself and her staff FORTRAN when the IBM machines arrived and the hand-computing pools were disbanded.

The pattern was not unique to Langley. At the Jet Propulsion Laboratory in Pasadena, Macie Roberts built an all-women computing section from the 1940s, insisting that women would be more welcome in a room run by women. Helen Ling, who succeeded her, hired mothers and rehired them after maternity leave. Sue Finley joined in January 1958, days before Explorer 1, and was still at JPL more than sixty years later, tracking spacecraft signals in the Deep Space Network, the longest-serving woman in NASA's history.

The human computers were made obsolete by the machines they helped to program, which is the way of most engineering. Their legacy is the method: every number that leaves a mission is still checked by a second pair of eyes.

In August 1961 NASA gave its first major Apollo contract not to a rocket builder but to the MIT Instrumentation Laboratory in Cambridge, Massachusetts, for a guidance and navigation system that could find its way to the Moon if the ground fell silent. The heart of it was the Apollo Guidance Computer , a 32-kilogram box drawing 55 watts, with 2,048 words of erasable memory and 36,864 words of fixed memory, in 16-bit words. The fixed memory was core rope : the program was literally woven, a wire threaded through a ferrite core for a one and around it for a zero, by women at Raytheon's plant in Waltham working from printed instructions. A change to the software meant reweaving the rope, so the code had to be right months before launch.

Margaret Hamilton led the Instrumentation Laboratory's software division through those years, having arrived in 1963 as a programmer with a mathematics degree and a young daughter who sometimes played with the simulator. She has said she began calling the work "software engineering" to win it the same respect as hardware; the NATO conference of 1968 made the phrase a discipline. The famous photograph of her beside a stack of listings as tall as she is shows the printouts of the Apollo code, around 145,000 lines across the command module and lunar module programs. Her insistence on error handling was vindicated on Apollo 8, when Jim Lovell accidentally keyed Program 01 and wiped the navigation data, which the ground then rebuilt by uploading.

Hamilton received the Presidential Medal of Freedom in 2016. The lesson she drew was simple: assume the unexpected, and write for it.

The job did not exist until Christopher Kraft invented it. A Langley flight-test engineer, Kraft was assigned in 1958 to work out how a Mercury flight should be run from the ground, and concluded that someone had to be in charge of the whole thing in real time. He wrote the first flight rules , decisions made in advance so that nobody argued in the moment, and sat as flight director for every Mercury mission. His definition stuck: the flight director may take any action necessary for crew safety and mission success, and the decision is final. Nobody, not the NASA Administrator, can overrule a flight director during a flight.

A go/no-go poll is how authority is exercised. Before the Apollo 11 descent Kranz called each console in turn, "Retro, FIDO, Guidance, Control, TELCOM, GNC, EECOM, Surgeon", and each answered "Go". Only the CAPCOM , always an astronaut, speaks to the crew: Charlie Duke passed it up as "You're go for landing". The crew never hear the room. The same cadence runs today for an ISS spacewalk or a Dragon docking, with the consoles renamed.

The flight director's power rests on preparation, not rank. Thousands of pages of flight rules, hundreds of simulations in which the training team breaks something on purpose, and a culture in which "I don't know" is an acceptable answer and a guess is not. That is why, when a lunar module computer threw alarms fifty years ago, the right word was ready.

At its peak in 1966 the Apollo programme employed around 400,000 people, and only a few dozen of them were astronauts. The rest welded, sewed, wove, wired and polished, mostly for contractors spread across the United States. The Saturn V alone was built in four places: the 10-metre first stage by Boeing at the Michoud Assembly Facility outside New Orleans, the second stage by North American at Seal Beach in California, the third by Douglas at Huntington Beach, and the instrument unit by IBM in Huntsville. The command module came from North American at Downey, the lunar module from Grumman at Bethpage on Long Island.

At Michoud the first stage's tanks were welded by hand and machine in a building large enough to hold a cathedral, then floated by barge to Mississippi for test firing. At Raytheon in Waltham the computer's program was woven wire by wire, the weavers checking each other's work against the listing. At Northrop Ventura riggers packed the three 25-metre main parachutes by hand; a mis-packed canopy cannot be inspected once stowed, so each rigger signed for his own. At Kennedy Space Center the pad leader Günter Wendt, who had closed the hatch on every Mercury and Gemini crew, ran the white room at the top of the tower and was the last face each Apollo crew saw. The Shuttle later needed 24,000 heat-shield tiles, each a unique shape, glued on by technicians at Palmdale and Kennedy.

Spaceflight has never become mass production. Each vehicle is still built by a few thousand people who know its serial number, which is why the industry calls itself, with some pride, a craft.

On 7 March 1960 twenty young Air Force pilots, none older than 35 and none taller than 1.75 metres, so that they would fit the Vostok capsule, were enrolled as the Soviet Union's first cosmonaut group . They trained at a secret base in the birch woods north-east of Moscow that became Star City , home of the Cosmonaut Training Centre, named for Yuri Gagarin after his death in 1968. Six were picked out early as the "vanguard": Gagarin, Gherman Titov, Grigori Nelyubov, Andriyan Nikolayev, Pavel Popovich and Valery Bykovsky. Their existence was a state secret; a cosmonaut's name was published only once he had flown.

A second kind of cosmonaut arrived with the engineers. Konstantin Feoktistov, who had helped design Vostok, flew on Voskhod 1 in 1964 as the first civilian in space. Georgy Grechko, another designer from Korolev's bureau, made three flights to three Salyut stations between 1975 and 1985. Svetlana Savitskaya, a test pilot and the daughter of an air marshal, became the first woman to walk in space on 25 July 1984, outside Salyut 7 for three hours and 35 minutes. The corps' records are long-duration ones: Anatoly Solovyev made sixteen spacewalks totalling more than 82 hours, Gennady Padalka logged 878 days across five flights, and Oleg Kononenko passed 1,000 cumulative days in June 2024 and finished his fifth mission with 1,111.

The corps' story is the Soviet century in miniature: brilliance, secrecy, loss and endurance, and the quiet pride of people who stayed in orbit while the map beneath them was redrawn.

For the first seventeen years of human spaceflight every traveller was American or Soviet. On 2 March 1978 Vladimír Remek, a Czechoslovak Air Force pilot, lifted off on Soyuz 28 and broke the pattern, the first person in space from a third country. He flew under Interkosmos , a Soviet programme that offered a week aboard Salyut 6 to one citizen of each allied state: Mirosław Hermaszewski of Poland and Sigmund Jähn of East Germany in 1978, then Bulgaria, Hungary, Vietnam, Cuba, Mongolia and Romania. Arnaldo Tamayo Méndez of Cuba, who flew in September 1980, was the first Black person and the first Latin American in space. In 1982 the programme opened to the West with Jean-Loup Chrétien of France, and in April 1984 Rakesh Sharma of India spent a week on Salyut 7, telling Indira Gandhi that from orbit his country looked "better than the whole world", a line from a famous Urdu poem.

China built its own road. Yang Liwei orbited alone in Shenzhou 5 on 15 October 2003, making China the third nation to launch its own astronaut; its taikonauts have since flown only on Chinese rockets, and Tiangong has hosted no foreigner yet, though a Pakistani astronaut has been announced. After the Shuttle retired, Soyuz seats again carried new flags: Marcos Pontes of Brazil in 2006, Hazzaa AlMansoori of the United Arab Emirates in September 2019, Marina Vasilevskaya of Belarus in 2024. The fourth road is private. Axiom's missions to the ISS carried the first Saudi woman, Rayyanah Barnawi, in 2023, the first Turk in January 2024, and in June 2025 Shubhanshu Shukla, an Indian Air Force pilot, forty-one years after Sharma, as a paying passenger of his government.

Whatever the motive, the view is the same, and nearly everyone who has had it has come back saying the same thing: the borders are not visible from there.

Valentina Tereshkova's three days in orbit in June 1963 were followed by a silence of nineteen years. The Soviet women's group was disbanded in 1969, and NASA had turned away the thirteen women who passed the Lovelace clinic's astronaut medical tests in 1960 and 1961, on the grounds that astronauts had to be military jet test pilots and women could not be. The silence ended with Svetlana Savitskaya , who flew to Salyut 7 in August 1982 and returned in July 1984 to make the first spacewalk by a woman, three hours and 35 minutes outside the station welding and cutting metal with an electron-beam tool. The timing was not accidental; NASA had announced that Kathryn Sullivan would walk in October.

Endurance and command followed. Peggy Whitson , a biochemist, commanded the ISS in 2007 and again in 2017, became NASA's chief astronaut, and after retiring flew twice more for Axiom as a private commander, her career total passing 675 days, more than any other American. Samantha Cristoforetti of ESA took command of the station in September 2022, the first European woman to do so. Liu Yang became the first Chinese woman in orbit in 2012, and Wang Yaping made China's first female spacewalk on 7 November 2021 from Tiangong. Kalpana Chawla, born in Haryana and killed on Columbia in 2003, was the first woman of Indian origin to fly; Yelena Serova in 2014 was only the fourth Russian woman.

The pattern of sixty years is consistent: women were excluded by rule, admitted when the rule changed, and then did the job, which is the dullest and most convincing argument there is.

NASA's first astronauts were test pilots, chosen because Eisenhower wanted people already cleared for secrets and used to risk. The scientists came in two reluctant batches. In June 1965 the agency selected six scientist-astronauts , chosen with the National Academy of Sciences: among them the physician Joe Kerwin, the physicists Owen Garriott and Ed Gibson, and a Harvard geologist named Harrison Schmitt. A second group of eleven followed in August 1967 and promptly nicknamed itself the Excess Eleven, since the lunar programme was shrinking and there were no seats. All of them were sent to Air Force flight school first, because the pilot culture that ran the office did not trust anyone who could not fly a jet.

The Shuttle created the payload specialist , a researcher flown for a single mission to run their own experiment, from Ulf Merbold and Byron Lichtenberg on Spacelab 1 in 1983 onward, and the ISS turned science into a routine. Don Pettit, a chemical engineer, filmed "Saturday Morning Science" on Expedition 6 in 2003, showing water films and spinning tools in free fall. Kate Rubins, a virologist, sequenced DNA in orbit for the first time in August 2016 with a palm-sized MinION. Jessica Watkins, a planetary geologist, spent 170 days aboard in 2022, the first Black woman on a long-duration crew.

The tension between the two cultures never fully resolved. It was settled, as such things are, by the schedule: the pilot flies the ship, the scientist runs the rack, and on a good day they are the same person.

Spaceflight has killed fewer people than a single bad year on a mountain, but each death was public, investigated and written into the rules. The first were hidden. On 24 October 1960 an R-16 missile exploded on its pad at Baikonur while Marshal Mitrofan Nedelin sat on a chair beside it to show confidence; at least 90 people died, probably more, and the Nedelin catastrophe was officially a plane crash until 1989. On 23 March 1961 the youngest cosmonaut, 24-year-old Valentin Bondarenko, dropped a cotton pad onto a hot plate in an oxygen-rich isolation chamber and died of his burns; the Soviet Union did not admit it until 1986.

The Shuttle's two losses, Challenger on 28 January 1986 and Columbia on 1 February 2003, each killed seven and each produced a famous inquiry. The Rogers Commission found that NASA had flown with a known O-ring weakness; Richard Feynman dropped a piece of rubber into iced water on television to show why. The Columbia Accident Investigation Board found a culture that had learned to live with foam strikes, and its report ended the programme by 2011. Ground deaths continued elsewhere: 48 at Plesetsk when a Vostok rocket exploded during fuelling on 18 March 1980, 21 at Brazil's Alcântara launch centre on 22 August 2003 when a VLS-1 ignited on its pad, and villagers near Xichang in 1996 when a Long March fell on their homes. On 31 October 2014 the test pilot Michael Alsbury died when SpaceShipTwo broke up over the Mojave after its feathering tail unlocked too early; the inquiry blamed a…

The modern rule, written in blood, is that a spacecraft must be designed so that no single error, by a person or a part, can kill its crew.

A space mission begins as a sentence in a report. In the United States the National Academies convene a Decadal Survey for each field, in which hundreds of scientists rank the questions and the missions that would answer them; NASA then runs competitions in three sizes. Discovery missions are led by a single principal investigator under a strict cost cap, such as Lucy, launched in 2021 to the Trojan asteroids, and Psyche in 2023. New Frontiers missions are larger, including New Horizons, Juno and the Dragonfly rotorcraft planned for Titan. Flagships are chosen directly, like Cassini, the Mars rovers and Europa Clipper, launched on 14 October 2024. A proposal passes through Phase A studies, a down-select, then Phases B, C and D of design, build and test, and a confirmation review that can kill it.

The European Space Agency , with 23 member states since Slovenia joined in 2025, works by subscription: a mandatory science programme funded by GDP share, and optional programmes, such as launchers or human spaceflight, that each country joins as it chooses, with France, Germany and Italy the largest contributors. Its launches fly from Kourou in French Guiana, and its missions are picked in Cosmic Vision calls by size class, from the small to the large. JAXA, formed in 2003 from three Japanese institutes, is famous for frugal sample return. China's CNSA, founded in 1993, publishes five-year plans and has executed them with unusual precision, from Chang'e to Tiangong. ISRO, created in 1969, landed Chandrayaan-3 near the lunar south pole on 23 August 2023. The Canadian Space Agency's contribution to every station since 1981 has been a robotic arm, and Canadarm3 is its ticket to the…

An agency is a machine for turning a question into a budget line and a budget line into a spacecraft, slowly, and with many chances to say no.

Europe's first rocket was a committee. Europa , built from 1964 by the European Launcher Development Organisation, stacked a British Blue Streak first stage on a French second and a German third, with no single authority over the whole. Of eleven launches from Woomera and Kourou between 1964 and 1971, not one placed a satellite in orbit; the Blue Streak worked every time and the stages above it failed in turn. When the European Space Agency was founded on 30 May 1975, France insisted that the new launcher be run by one prime contractor under one management, and the lesson of Europa became the design rule of Ariane .

Ariane 5 began with the most expensive software failure in the industry's history. On 4 June 1996 flight 501 broke apart 37 seconds after lift-off, because its inertial reference system reused Ariane 4 code that converted a 64-bit velocity figure into a 16-bit integer; the faster Ariane 5 overflowed the number, both redundant units shut down in the same instant, and the rocket swung its nozzles hard over. The inquiry report is still taught to software engineers. The rocket recovered to fly 117 times before its last launch on 5 July 2023, lofting Rosetta, four ATV cargo ships, BepiColombo, JUICE and Webb. Beside it the Italian-led solid-fuelled Vega flew small payloads from 2012.

Ariane 6 is not reusable, and Europe knows it; the Prometheus methane engine and the Themis hopper are its answer for the 2030s. What Ariane proved from 1979 remains true: a continent that cannot launch its own satellites is a customer, not a power.

When the Soviet Union dissolved in December 1991, its space programme woke up in the wrong country. Baikonur , the cosmodrome that had launched Sputnik and Gagarin, lay in newly independent Kazakhstan, and Russia has rented it ever since under a 1994 agreement extended to 2050. Half the industry's factories were in Ukraine, including the makers of the Zenit rocket and the control systems of the Proton. Budgets collapsed; cosmonauts on Mir went unpaid for months, and in 1993 the Russian Space Agency began selling what it had, from Soyuz seats to Proton launches and the hard-won experience of long-duration flight that made the International Space Station possible.

The state rebuilt where it could. The Vostochny cosmodrome, begun in 2012 in the Amur region of the Russian Far East to end the dependence on Baikonur, saw its first launch on 28 April 2016 and its first Angara A5 in April 2024, after a decade of construction scandals and embezzlement trials. Roscosmos became a state corporation in 2015. Then the invasion of Ukraine in February 2022 brought sanctions, the loss of Western customers, the withdrawal of Soyuz from Kourou and the suspension of the ExoMars rover partnership; thirty-six OneWeb satellites sat impounded at Baikonur. The flagship Luna 25, Russia's first Moon lander since 1976, launched from Vostochny on 11 August 2023 and crashed eight days later when an orbit-lowering burn ran for 127 seconds instead of 84.

Korolev's machine still flies, cheaply and often. What it lacks is what the old firm once had in surplus: money, youth and a next thing to build.

China's first satellite, Dong Fang Hong 1 , went up from Jiuquan on 24 April 1970 on the first Long March rocket, a 173-kilogram sphere that broadcast the song "The East Is Red" for 28 days, making China the fifth nation to orbit its own spacecraft. The programme's founder was Qian Xuesen, a co-founder of the Jet Propulsion Laboratory, deported from the United States in 1955 on suspicion of communist sympathies. For three decades afterwards China launched satellites steadily and humans not at all.

Then the samples. Chang'e 5 launched on a Long March 5 from Wenchang on 23 November 2020, landed near Mons Rümker in Oceanus Procellarum, drilled and scooped 1,731 grams of two-billion-year-old basalt, lifted off from the surface, docked in lunar orbit with its return craft and dropped a capsule in Inner Mongolia on 16 December, a miniature Apollo flown by robots. Chang'e 6 repeated the feat on the far side, returning 1,935 grams from Apollo crater on 25 June 2024, the only far-side material on Earth. Meanwhile Tianwen-1 reached Mars orbit in February 2021 and on 15 May landed the Zhurong rover in Utopia Planitia, the first nation to orbit, land and rove on its first Mars attempt.

China has reached the Moon's surface four times in eleven years without a failure. Whatever the race to return is, it now has two runners.

The Indian space programme began in a church. In 1962 the physicist Vikram Sarabhai chose the fishing village of Thumba, near Thiruvananthapuram on the magnetic equator, for a sounding-rocket range, and the bishop gave up the church of St Mary Magdalene to serve as its first workshop. Rocket parts arrived by bicycle and bullock cart, as the famous photographs show, and the first rocket, an American Nike-Apache, flew on 21 November 1963. Sarabhai's stated purpose was unusual: not prestige but satellites for television, weather and resource mapping in a poor country. The Indian Space Research Organisation was formed in 1969 and launched its first satellite, Aryabhata, on a Soviet rocket in April 1975.

The deep-space record is remarkable for a programme spending a small fraction of NASA's budget. Mangalyaan , the Mars Orbiter Mission, launched on a PSLV on 5 November 2013, too small a rocket to go direct, so the 1,337-kilogram craft raised its orbit around Earth six times before departing; it entered Mars orbit on 24 September 2014, making India the first nation to succeed at Mars on its first attempt. Chandrayaan-2's lander crashed in September 2019 during the final braking phase. Its successor Chandrayaan-3 landed on 23 August 2023 at 69° south, nearer the lunar south pole than any craft before it, with a 26-kilogram rover named Pragyan that measured sulphur in the soil; the lander later fired its engines and hopped 40 centimetres, a rehearsal for a future sample return. Aditya-L1 followed in September 2023 to watch the Sun from the L1 point.

ISRO's style is sequential, patient and cheap, and it ends at places others have not reached. The south pole of the Moon was first touched by the programme that started in a church.

Between the superpowers and the start-ups sit the programmes that cannot afford everything and therefore choose well. Japan's JAXA is the clearest case. Hayabusa, launched in 2003, lost two of its four ion engines, a reaction wheel, its fuel and contact with Earth for seven weeks, and still brought the first asteroid dust home to Woomera in June 2010, 1,500 grains from Itokawa. Hayabusa2 did it properly: it fired a copper impactor into Ryugu to expose fresh material, and on 6 December 2020 delivered 5.4 grams that contained amino acids and uracil, a base of RNA. Japan's Kibo is the largest module on the International Space Station, and nine HTV freighters supplied it between 2009 and 2020.

The European Space Agency, twenty-three member states voting on a budget around a quarter of NASA's, picks the missions the giants have skipped. Rosetta spent ten years reaching comet 67P and two years flying beside it. Gaia, launched in 2013, measured the positions and motions of nearly two billion stars, the most-cited data set in modern astronomy. ExoMars shows the cost of partnerships: its Schiaparelli demonstrator crashed in 2016, and the Rosalind Franklin rover, built for a Russian lander and a Russian rocket, was stranded by the 2022 sanctions and is now planned for 2028 on an American launcher.

What the mid-sized programmes do that giants do not is specialise: sample return, precision landing, the comet, the catalogue, the weather of Mars. Exploration is not a two-horse race but a relay, and these are the runners who take the awkward legs.