Whatever missions astronauts must send to the mission, the engineers who send them must solve two fundamental problems: how to keep travelers off the Earth (and put them in orbit or on the Moon or Mars road) and bring them back again. With decades of experience in transferring payloads into space, the world's space powers unanimously adopted the chemical rocket as a means of launching astronauts. The question that engineers continue to debate is: what is the best way to land them?
Boeing and SpaceX, who are scheduled to send astronauts to the International Space Station next year as part of NASA's commercial team program, have been asked to answer two fundamental problems with spaceflight: ingenuity, economy and state-of-the-art technology to meet future cosmic challenges. Yet one of the most visible elements of their privately designed spacecraft will return deep into the last century: they are capsule-shaped, counting on their rounded shapes and great drag and a pair of parachutes to slow them down. an orbital speed of 17,000 mph at a speed at which human occupants can survive when they touch the Earth's surface.
The Space Shuttle was to put an end to all this on its first flight in 1981, providing comfort comparable to that of an airliner when it smoothly touched the runway. And by creating the next generation of space transportation, SpaceX, at first, really tried to look into the future. Elon Musk and his team have called for a new type of undercarriage, based on propulsive propellants, instead of parachutes, to slow the ship and on stretchable legs to rebalance it to touch, a so-called propulsive landing. "This is how a twenty-first century spacecraft should land," Musk boasted in 2014, "anywhere on Earth with the precision of a helicopter." SpaceX has largely landed propulsively for its payload delivery rockets – the regular and impressive Falcon 9 first-floor landing on an ocean barge or at Cape Canaveral. But such jumps with astronauts living in the interior require time and money, which NASA did not want to engage in a mission whose main selling point was the fact that NASA did not want to be involved. ;economy. At least that's what space observers think of the laconic abandonment of Musk's approach in 2017. So the parachutes are out again.
The NASA astronauts' splash has acquired a nostalgic, even mythical, half-century of distance. But it was hairy business in real life. Gus Grissom nearly drowned after Mercury's second flight in 1961 – a famous incident made famous by his misrepresentation in the 1983 film The good stuff. The following year, Scott Carpenter landed 250 km away and spent three hours in a life raft before being rescued by the USS. Intrepid.
The bursting adventures continued after the lunar missions, even after more than a decade of rapid technological progress. The crews of the Skylab 4 mission of 1974 and the Apollo-Soyuz test project a year later found themselves face to face in the ocean for a while, as the rough seas caught their parachute and capsized the landing craft. Apollo-Soyuz's problems were exacerbated by a propellant exhaust leak in the cabin, forcing astronauts to grab oxygen masks, which were harder to reach when they were upside down. The crew member, Vance Brand, lost consciousness during the race, and one of his team members had to put his mask on for him. In both cases, the inflatable "spheres of recovery" located on the outside of the capsule functioned as expected. The ships returned to the surface and the astronauts came out relatively unharmed.
Of course, there is an alternative to landing at sea: landing on land, as the Soviet and Russian space program has done since its creation. The Soyuz spacecraft, launched in 1967 and still performing, returns to Earth in the vast flat steppes of Kazakhstan. It's not the most comfortable experience, say ex-passengers. "It's like a series of explosions followed by a car accident," said Michael Lopez-Alegria, a former NASA astronaut who returned from the International Space Station on a Soyuz in 2007. "After seven months in the space, feel good. "
Soyouz had an almost fatal accident in 1976, when the reentry capsule broke off and landed on a partially frozen lake five miles from the coast at night in the middle of a snowstorm. The rescuers, who reached the partially submerged ship nine hours later, did not care to open the hatch for two hours because they thought the cosmonauts had died of cold. The robust Soviets survived, even though they never left again.
Nevertheless, Lopez-Alegria would prefer to return from space on the mainland, given the choice. "Landing on the water seems to give affinity, so I'm not sure the impact is much less," he says. "And after that, I think I would be happier on earth than to walk in the ocean." Ken Bowersox, another Soyuz veteran who lands, also thinks the land is safer than water. "On land, you can have a hard landing and get out of the car," he says. "If things are not going well on the water, it can become exciting quite quickly." Describing the return of Bowersox's Sowers in 2003 as a "little hard landing" could be a euphemism. The capsule headed for a ballistic landing that led to hundreds of kilometers from the target. But "we just waited a few hours," he recalls. "On the water, it would have been a lot less comfortable." In regards to the impact, Bowersox compares it to the aircraft carrier landings that he exercised as a Navy pilot. "It's your attention, but it's not worse than a carnival hike," he says.
NASA has studied the land landing at different times in the pre-shuttle period, but rejected it for several reasons. At the time, the agency had concluded that the United States did not have a sufficiently large, empty and flat area in neighboring states. At least compared to the open and undifferentiated space of the Kazakhstan plain, even the Southwest desert can not compete with its canyons, plateaus, isolated towns and reserves. Downhill targeting was simply not accurate enough and reliable. The country had a large amount of open water: rich access to two oceans, a coastal launch site and existing maritime infrastructure to recover astronauts from the water.
Another important consideration in these terrestrial studies was the weight of the spacecraft. A water landing may end in a sudden fall, but the liquid still has some reserve; To return to a sudden stop, the return to earth requires additional features, such as the retro rocket that Soyuz pulls when he is several feet from the ground for a final braking a few seconds before the impact. This equipment, however, is a heavier vehicle, and in the early 1960s, NASA's brain trust, pressed for time, did not think it could weigh heavily on the moon (see box).
But the technology is improving and the goals are changing. So, Boeing reconsidered the issue of land landing by starting to design its passenger vehicle, the Starliner, around 2010. "Returning to land has the advantage of being immediate on the sea because it allows immediate access to the crew and all the cargo on board, "said Michael McCarley. a Boeing career man who worked on the shuttle throughout his final flight before moving on to the Starliner project as head engineer for the fall season. But the weight of this type of capsule still poses a problem – or, as McCarley calls it, "the mass challenge".
Soyuz may have solved his mass challenge in the year of the Beatles Sgt. Pepper, but the Russian ship can only stack in three astronauts, or half of a crew of the space station. One of the keys to the seven-passenger vehicle at the expanded land landing was to replace the retro rockets with airbags. The Starliner will support six of them (one seventh, in the center, only deploys for an emergency landing). They are inflated with nitrogen and oxygen like those of automobiles, but designed as bicycle tires with discrete internal and external layers. The outer bag has holes that release the pressure on landing, while the inner tube remains firm. J & # 39; hope.
The airbag system is not only lighter than Soyuz rockets, but it should also be easier for bodies already exhausted after six months in space, says McCarley. Ken Bowersox is passionate. "If you look at stuntmen jumping buildings and landing on airbags, that should be a pretty reasonable landing," he says.
Then there is McCarley's personal project: the headquarters. In one way or another, a space capsule returning to Earth with parachutes slows down in the atmosphere about 4 G before it suddenly stops, said Lopez-Alegria, who still sits on the advisory board on the human exploration of NASA. This compares to a tolerance of 1.5 G for the space shuttle gliding landing. But the impact on the body of astronauts literally depends on where and how they sit. Or actually lie, because the spine of a human and other vital organs are not designed to absorb 4 G in a vertical position. Soyuz passengers land already inclined, with an individually designed seat liner. But McCarley was determined to improve this with modern ergonomics. He started with a pile of plywood in his garage.
"The overall concept of the seat has not changed from the plywood model, but we have added more advanced materials," said McCarley. The company has also added 3D printing technology to create a complete seat for each Starliner passenger. Given the small size of the available space, it was necessary to study intensively the types of human bodies.
McCarley, who is a stocky, and Melanie Weber, systems engineer Starliner, a little behind five feet, modeled itself on the outer limits of the allowed size. By digging deeper into the nuances, the engineers worked to create a range of body types, which they attribute to animal names such as The Orangutan ("long arms that can practically touch the capsule," says McCarley), or the T-Rex (large torso with short arms). the team will be better able to customize each seat using the body scanners of an astronaut.
Boeing's team also wanted to improve the parachutes of the Soyuz era. For reasons now lost in the scientific history of the cold war, the series of parachutes of the Russian ship – pilot, drug and finally the main chute – opens on one side of the capsule followed by the pyrotechnic release of a rigging system that forces the capsule to hang straight. Lopez-Alegria describes the result as "a rather violent movement from one side to the other, as in Mr Toad's Wild Ride". Boeing promises to smooth the process with two symmetrical anchor channels, followed by three main chutes for added stability, not to mention redundancy.
As for the location of the capsule, the Starliner team is more comfortable with its precision landing than were the first NASA engineers. The company has a list of five sites in the West – two in the White Sands missile battlefield in New Mexico, the Dugway Proving Ground in Utah, Edwards Air Force Base in California and Wilcox Playa in Arizona – among which they will choose and rescue locations shortly before the end of each mission. Ground crews have been searching for long-forgotten telephone poles and other obstacles and have conducted extensive environmental and cultural surveys to ensure the safety of astronauts and the integrity of the terrain. The Dugway Proving Ground, for example, was created by the Army during the Second World War to test chemical and biological weapons. It is also a true archaeological treasure of artifacts created by 13,000-year-old Indians.
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While Boeing's engineers were seriously pondering the earthy details of the descent of their capsule on hard ground, SpaceX began its work dreaming of Mars. In January 2011, the company released a 15-second futuristic video depicting a tidy trapezoidal spacecraft performing an unhurried vertical landing, supported by flames from all four corners of its base, at angles of about 30 degrees. Elon Musk, in the voiceover, describes it as "a propulsive landing with gear, much like [how Apollo 11’s] Eagle landed on the moon. It was very cool.
But these flaming SuperDraco thrusters, as it was later called Musk, aimed more at lowering a 14,000-pound crew dragon capsule on a helicopter platform anywhere on Earth. SpaceX insisted they could bring a similar mass ship safely to the surface of Mars, where the atmosphere is too thin to land anything of this parachute weight. The heaviest object that has been dropped so far is NASA's Curiosity rover, which has about one-seventh of this mass and, of course, no fragile human passenger.
SpaceX unveiled a Crew Dragon prototype in 2014 with high hopes for its two-planet perspectives. In 2016, he released the video of a test model hovering confidently several meters above a platform in Texas. Then Musk called. While the crew Dragon was still technically capable of landing propulsively, he said at a conference on space station research and development in July 2017, it would require "tremendously of efforts to qualify this in terms of safety ". much better approach "to land on Mars, of which he kept the details secret.The capsule still contains SuperDraco engines, but they should only be used in case of abandonment of the launch. (See" Abort! "Oct./ Nov. 2018.) A crew Dragon at the routine landing seems destined to become a footnote in the history of exploration, although SpaceX continues to work on the technology of its other vehicles, including the next generation BFR rocket – an untested space bus that promises to carry up to 100 passengers on the Moon or beyond.The first paying customer of this trip, Japanese billionaire Yusaku Maezawa, was announced in September.
Fortunately, the company had a proven plan B to bring the crew to the space station. While SpaceX was handling the futuristic system for a crewed ship, this magazine was going to put pressure: its cargo ship quietly made 15 successful missions to and from the space station, the capsule splashing without incident. The company has so far managed to reuse four of the capsules despite immersion in salt water.
The Crew Dragon is about 50% heavier than the cargo model. SpaceX thus compensates for this excess mass thanks to a system of four parachutes releasing symmetrically above the vehicle, offering more drag than the classic triangle deployed above the capsules of the 1960s. More than Boeing's Starliner, a statement of the company implies: "The Crew Dragon parachute system is the most efficient system ever designed in terms of filling density and aerodynamic braking capability."
The modest SpaceX flotilla deployed to recover Dragon astronauts at sea will be even more significant compared to the past days. Published plans provide for a single vessel of 164 feet, the GO Searcher, with the support of several inflatable boats capable of maneuvering closer to the splashed capsule. the GO Searcher will be equipped with a heliport to quickly transport astronauts to the coast if necessary.
This is in stark contrast to the fleet of US Navy ships that met space travelers in the 1960s and 1970s. After the first US-style flight in 1962, no fewer than 24 Navy ships were waiting for the John Glenn's attack with the air force in reserve. Landings quickly became more precise and the welcoming party dropped on four ships during the last Apollo lunar flight in 1972. SpaceX's clean crew was therefore not as minimalist as it might seem. (The company has a more elaborate system, thanks to a partnership with Air Force pararescue teams, for the recovery of astronauts after a launch abandonment.)
As expected, SpaceX also wants to extend its reusable technology to the Crew Dragon. The team has gained extensive experience in watertightness and corrosion prevention through the redevelopment of four of their cargo ships. But for now, SpaceX is only allowed to fly a crew with a new spacecraft, which creates a somewhat ironic situation when Boeing, his rival, deploys a reusable capsule before SpaceX. Rocket observers believe the holdup will be temporary.
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Human space flight inevitably involves relying on the worst scenarios. "I always think: is there something hidden that we do not know?" Explains Mike McCarley of Boeing. "Have I looked behind every door and at the back of every closet? It is a kind of personal neurosis, but also of professional neurosis. Since the 1960s space race, human spaceflight also seems to involve inevitable delays and frustrating mid-course corrections – adjustments that only engineers can understand to set aside promising systems like the propulsive landing plane of SpaceX. At the beginning of the program, commercial crew missions had been optimistically targeted for 2015. Currently, they are targeting mid-2019.
None of this should overshadow the fact that private contractors are gradually gaining NASA confidence, as well as astronauts of the past and the future, regardless of their trajectory. "For me, I do not care. They're both going to work, "Ken Bowersox concludes. "Going down to land or sea is no longer an economic decision."
The delays of the program also do not reverse a clear direction: commercial flight crews, retro landing systems and everything else, pave the way for an exciting new chapter in space exploration, where Private companies support futuristic projects ranging from asteroid extraction to colonization on Mars. "It's revolutionary in many ways," says Lopez-Alegria. "This is the first time the government has released the reins on the size of washer to use. It will be a kind of rebirth. This is a door that he and many others are eager to cross. The current Lopez-Alegria position is responsible for the commercial development of Axiom Space, which wants to create a privately funded successor to the space station at an estimated cost of $ 1.5 billion.
First, the new commercial vehicles and their spectacular parachute return – not only on Earth, but for the first time for almost a decade, in their own country.