How to land a spaceship Space

It does not matter which mission astronauts are sent to accomplish, the engineers they send have to solve two fundamental problems: how to get the space travelers off the earth (and in orbit or on their way to the moon or Mars) and how they return to bring one more time. With decades of experience in moving loads into space, space capabilities worldwide have unanimously decided to use chemical missiles as the best way to launch astronauts. The question that engineers still discuss is: what is the best way to let them land?

Boeing and SpaceX, which are scheduled to send astronauts to the International Space Station next year via NASA's Commercial Crew Program, have been asked to respond to the two fundamental problems of space travel with ingenuity, economy and geo whiz technology for the cosmic challenges ahead. Yet one of the most visible elements of their privately designed spacecraft will go back to the depths of the last century: they take the form of capsules, count on their dull forms with high resistance and parachute parachutes to slow them from a turnover rate of 17,000 to a speed that human occupants can survive if they hit the earth's surface.

The space shuttle would have to end it all when it made its first flight in 1981, with airliner-like comfort during the soft runway. And when creating the next generation of space transport, SpaceX initially tried to lean towards the future. Elon Musk and his team insisted on a new type of lander, one that relied on thrusters, instead of parachutes, to slow down the ship and extend legs to balance it when landing – a so-called propelling landing. "A 21st century spacecraft would have to land," Musk boasted in 2014, "with the accuracy of a helicopter all over the world." SpaceX has largely succeeded with propulsion landing for its rockets for the delivery of payload – the first stage of Falcon 9 regularly, and impressively, lands upright on an ocean barge or back at Cape Canaveral. But such leaps ahead with living astronauts inside need time and money that NASA did not want to commit to a mission whose main selling point was economy. At least that is what the viewers of the space guess from Musk's laconic cessation of the approach in 2017. So the parachutes came out again.

NASA & # 39; s astronaut splashdowns have become nostalgic or even mythical in the distance of half a century. But they were hairy affairs in real life. Gus Grissom nearly drowned after the second Mercury flight in 1961 – a famous incident that gained more prominence due to his inaccurate representation in the 1983 film The good stuff. The following year Scott Carpenter landed 250 miles of course and spent three hours in a liferaft before being rescued by the USS fearless.

Splashdown adventures continued after the moon missions, even after more than a decade of rapid technological progress. The crews on both the Skylab 4 mission of 1974 and the Apollo-Soyuz test project a year later ended a long time underwater in the ocean, when heavy seas picked up their parachutes and capsized the landing craft. Apollo-Soyuz's problems were aggravated by a leakage of thrust window in the cabin that required astronauts to pack oxygen masks that were harder to reach while upside down. Crew member Vance Brand fell out while clambering and one of his crew had to get his mask for him. In both cases inflatable "upright spheres" worked outside the capsule as planned. The ships returned to the surface and the astronauts went relatively unharmed.

Of course there is an alternative for countries at sea: countries on land, which the Russian and Russian space program has done since the beginning. The Soyuz spacecraft, first launched in 1967 and still going strong, is thrown back to earth on the vast, flat steppes of Kazakhstan. It is not the most comfortable experience, ex-passengers report. "It looks like a series of explosions followed by a car accident," says Michael Lopez-Alegria, a former NASA astronaut who returned from the International Space Station in 2007 to a Soyuz. "After seven months in space, it does not feel great."

Soyuz had an almost fatal accident in 1976, when the return capsule hit course and landed on a partially frozen lake – five miles off the coast, at night, in the midst of a blizzard. Rescuers, who reached the partially submerged ship nine hours later, did not open the hatch for two hours because they thought the cosmonauts were frozen to death. The hardened Soviets survived, although they never flew again.

Nevertheless, Lopez-Alegria prefers to return from space to the solid ground, given the choice. "Landing on water is like a giant belly flop, so I'm not sure if the impact is much less," he says. "And then I think I would be happier on the land than float around in the ocean." Ken Bowersox, another Soyuz landing veteran, also thinks that land is safer than water. "On land you can make a bit of a heavy landing and still get out of the vehicle", he remarks. "If things do not go well with water, it can become exciting quickly." Describing Bowersox's own Soyuz return in 2003 as a "little bit of a rugged landing" can be an understatement. The capsule changed into a ballistic landing that took him hundreds of kilometers away from the target. But "we just waited a few hours", he recalls. "It would have been a lot less comfortable on the water." As far as the impact is concerned, Bowersox compares it with the landings of aircraft carriers that he carried out as a pilot of the navy. "It gets your attention, but it's no worse than a ride at a carnival," he says.

NASA has studied terrestrial landing at various points in the pre-shuttle age but has rejected it for various reasons. At that time, the agency concluded that the United States was missing a fairly vast, empty, flat area in the neighboring states. At least in comparison with the open, undifferentiated space of the Kazakh plain, even the desert in the southwest could not compete, with its canyons, plateaus and remote cities and reserves. The focus on descent was simply not precise and reliable enough. What the country did have was an enormous amount of open water: ample access to two oceans, a coastal launch site and the existing maritime infrastructure to get astronauts out of the water.

Another important consideration in these earthly studies was the weight of the spacecraft. A water landing can end with a smacking dive, but liquid still has a bit to give; Returning on the land requires some extra function to make up for the hard stop, such as the retro rockets that Soyuz fires when he stands a few meters from the ground for a final brake in the seconds before the collision. However, that equipment makes for a heavier vehicle and in the early sixties NASA brain confidence, achieved for time, did not believe they could get all that weight to the moon (see sidebar).

But the technology improves and the objectives change. So Boeing revised the land-landing question when he started designing his commercial crew vehicle, the Starliner, around 2010. "Returning on land has an advantage over the sea in having direct access to the crew and all cargo on board" says Michael McCarley, a Boeing career man who worked on the shuttle during his last flight before moving to the Starliner project as the chief engineer for return. But the weight of this type of capsule is still a problem, or as McCarley calls it, the massive challenge.

Soyuz may have resolved his massive challenge in the year that the Beatles recorded Sgt. Pepperbut the Russian ship can only cram in three astronauts – half of a crew member of the space station. One key to the extensive seven-person landing vehicle on land was replacing those retro missiles with airbags. The Starliner will rely on six of them (a seventh, in the middle, only for an emergency landing). They are inflated with nitrogen and oxygen like those in cars, but designed as bicycle tires with discrete inner and outer layers. The outer bag has ventilation openings that exert pressure when landing, while the inner tube remains firm. Hopefully.

Not only is the airbag system lighter than the Soyuz rockets, it should also be easier on bodies that have been empty for six months in space, McCarley says. Ken Bowersox is a lover. "If you look at the stunt people jumping from buildings and landing on airbags, that should be a reasonably reasonable landing," he says.

Then there is McCarley & # 39; s personal pet project: the chair. Somehow, a space capsule that returns to the earth under parachutes through the atmosphere slows down to about 4 Gs before the sudden stop, says Lopez-Alegria, who is still on the NASA Human Reconnaissance Advisory Board. That is comparable to an acceptable 1.5 Gs for the glide-to-a-landing space shuttle. But the impact on the bodies of the astronauts depends, literally, on where and how they are. Or actually lie, because the backbone of a human and other vital organs are not designed to absorb 4 G's in a vertical position. Soyuz passengers already land on the back with an individually designed seat. But McCarley was determined to improve that with modern ergonomics. He started with a pile of plywood in his garage.

"The overall concept of the chair has not changed compared to the triplex model, but we've added some more advanced materials," says McCarley. The company has also added 3D printing technology to form a fully customized seat for every Starliner passenger. Given the compact available space, this involved an intensive study of human body types.

McCarley, who is a stocky 6 & # 39; 1 ", and Starliner system engineer Melanie Weber, who is a bit shy at five feet, modeled herself at the outer limits of the allowable size." Digging deeper into the nuances, the engineers worked hard to to accommodate a range of body types, which they donated with nicknames such as The Orangutan ("long arms that can practically reach the capsule," explains McCarley), or The T-Rex (wide torso with short arms). of designing extremes, the team will be able to adjust each seat better on the basis of scans of an astronaut.

The Boeing team also wanted to improve the Soyuz parachutes. For reasons that have now been lost to the scientific history of the cold war, the series of parachutes of the Russian ship – pilot, dredge and eventually the main slide – opens up on one side of the capsule, followed by the pyrotechnic release of a rigging system hang the capsule straight down. Lopez-Alegria describes the result as "pretty violent side-to-side movement, like Mr. Toad & # 39; s Wild Ride." Boeing promises to soften the process with two drogue slides for symmetry, followed by three main tubes for extra stability, not to mention redundancy.

Where the capsule will come down, the Starliner team is more comfortable with their precise landing than the early NASA engineers. The company has a list of five locations in the West two on the White Sands Missile Range in New Mexico, the Dugway Proving Ground in Utah, Edwards Air Force Base in California and Wilcox Playa in Arizona, from which they will primarily choose. and backup locations shortly before the end of each mission. Ground staff used long forgotten telephone poles and other obstacles and carried out extensive environmental and cultural studies to ensure both the safety of the astronauts and the integrity of the country. The Dugway Proving Ground, for example, was founded by the military during the Second World War to test chemical and biological weapons, and happens to be an archaeological treasure trove of native American objects that are 13,000 years old.

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While boeing engineers have been thinking hard about the earth's details of the descent from their capsule to hard ground, SpaceX began dreaming about Mars. In January 2011, the company placed a 15-second futuristic video with a tidy trapezoidal spacecraft that made a leisurely vertical landing without a parachute, supported by flames that shot from around the corner of the base at around 30 degrees. Elon Musk describes it in the voice-over as & # 39; a propulsive landing with acceleration, a bit like [how Apollo 11’s] Eagle landed on the moon. "It looked really cool.

But those flashing SuperDraco nozzles, as Musk later called them, were aimed at more than lowering a 1,400 kilo Crew Dragon capsule on a helipad somewhere in the world. SpaceX insisted that they could bring a ship with a comparable mass safely to the surface of Mars, where the atmosphere is too thin to land anything of that weight by parachute. The heaviest object that had fallen to date was NASA's curiosity drifter, which had about one-seventh of that mass and, of course, no fragile human passengers.

SpaceX unveiled a Crew Dragon prototype in 2014 with high expectations for its outlook on two planets. In 2016, the video placed a test model that hangs confidently a few meters above a platform in Texas. Then Musk called it out. Although the Crew Dragon was still technically able to land energetically, he said at a conference on research and development in the space station in July 2017, it would be "a huge effort to qualify that for safety." Moreover, he has since had a "much better approach" to land on Mars, whose details he keeps in mind. The capsule still carries SuperDraco engines, but they can only be used if the launch is canceled. (See "Abort!" October / November 2018.) A routine propulsion-landing Crew Dragon seems destined to become a footnote in the exploration history, although SpaceX continues to work on the technology for its other vehicles, including the BFR of the next generation rocket – a not tested space bus that promises to transport a maximum of 100 passengers to the moon or beyond. The first paying customer for that trip, the Japanese billionaire Yusaku Maezawa, was announced in September.

Fortunately, the company had a proven plan B to get the crew to the space station. While SpaceX was playing with the futuristic system for a manned ship, while this magazine was squeezing, the freighter flew silently 15 successful missions to and from the space station, with the capsule crashing without any problem. The company has so far managed to reuse four of the capsules despite the saltwater dunking.

The Crew Dragon is about 50 percent heavier than the cargo model, so SpaceX compensates for the extra mass with a system of four parachutes that releases symmetrically above the vehicle, offering more resistance than the classic triangle that deployed above the returning 60s capsules. . More than Boeing's Starliner means a company statement: "The Crew Dragon Parachute is the most efficient system ever designed in terms of gasket density and aerodynamic braking capacity."

An even more noticeable difference compared to the past will be the modest fleet that SpaceX uses to restore Dragon astronauts at sea. Published plans ask for a ship of 180 meters long, the GO viewfinder, with support of several inflatable boats that can maneuver closer to the deposited capsule. The GO viewfinder will be equipped with a helipad to bring astronauts to the coast quickly if necessary.

That is a dramatic contrast to the fleet of ships of the American navy that steamed to astronauts from the sixties and seventies. No less than 24 naval vessels waited for John Glenn's descent after the first US orbital flight in 1962, with the Air Force in eager reservation. The arrival became more accurate, however, and the welcoming party fell to four ships during the last Apollo lunar flight in 1972. The spacecraft spacecraft is therefore not as minimalistic as it seems. (The company has a more extensive system, through a partnership with Air Force pararescue teams, for the recovery of astronauts after a start of the launch.)

SpaceX is also predictably prepared to extend its reusable technology to the Crew Dragon. The team has gained extensive experience with water sealing and corrosion prevention to fill four of their cargo ships. But at the moment SpaceX is only approved to pilot a crew with new spacecraft, creating a somewhat ironic situation in which arch-rival Boeing uses a reusable capsule before SpaceX. Missile guards guess that the delay will be temporary.

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Human space flight inevitably implies a stay in worst case scenario & # 39; s. "I always think: is there something hidden that we do not know?", Says Mike McCarley of Boeing. "I have looked behind every door and in the back of every closet – it is a kind of personal neurosis, but also a professional neurosis." Since the space-long space race in the 1960s, human space flight also seems to have inevitable delays and frustrating mid-course corrections. to bring – from tweaks that only engineers can fathom to clear up very promising systems like the propulsive landing scheme of SpaceX. At the start of the program, missions of commercial crew members were optimistic for 2015. Currently they are aiming for mid-2019.

All this must not hide the fact that private contractors receive steady trust from NASA, and from astronauts from the past and the future, whatever way they pursue. "I do not care for them, they both work", concludes Ken Bowersox. "Getting to the land or the sea is more of an economic decision."

Nor do program delays have a clear direction: the commercial crew flights, retro landing systems and all, point the way to an exciting new chapter in space travel, where private companies assume futuristic projects from asteroid mining to Mars colonization. "This is revolutionary in many different ways," says Lopez-Alegria. "It is the first time the government has loosened the reins on which size to use a washing machine, it will be a kind of renaissance." This is a doorway that he, and many others, want to go through. The current performance of Lopez-Alegria is head of business development for Axiom Space, who wants to build a privately funded successor to the space station at an expected cost of $ 1.5 billion.

But first the new commercial vehicles and their dramatic parachute will return – not only to the earth, but for the first time in almost a decade to their own country.