The world of tests of strength and survival is a world where people and iron rule. The testing lab at the Ohio Transportation Research Center is an echoing hall the size of a good hangar. There is almost nowhere to sit, and the available seats are bare metal without any upholstery. The room is almost empty - only a bump test sled installed right in the middle, and a few engineers in goggles, constantly pacing up and down with coffee mugs in their hands. Almost all of the color scheme of the room consists of orange and red spots - these are warning signs and emergency lights.
Our deceased looks almost at home. He is wearing (let's call him "subject F") sky-blue underpants and no shirt - as if he is relaxing in his own apartment. He looks really deeply relaxed - as a real deceased should have. He sprawled back in his chair, his limp hands on his hips. If our F were alive, he would be pretty nervous now. After a couple of hours, the compressed air will push the hefty piston, with the tenderness of an oak block, right under the seat to which the F is strapped. At the same time, the testers will be able to adjust both the force of the impact and the position of the chair, depending on what a particular experiment is aimed at. Today, engineers are working for NASA with the new Orion landing capsule, simulating how it would fall from space into the ocean. Mr. F plays the role of an astronaut in this experiment.
In reentry vehicles, each landing is a strength test. Unlike the space shuttle, which is to be replaced by the Orion with its booster rocket, this reentry capsule has no wings or any landing gear. It doesn't come from space - it just falls. (If President Obama succeeds in closing the Constellation program, the Orion capsule's only purpose would be to simply drop to the ground and be used as a lifeboat for the emergency evacuation of the ISS crew.) orbit, however, their power is not enough to soften the landing. When the capsule enters the upper atmosphere,its wide and flat bottom will slow down the gradually thickening air. The high drag should slow down the capsule's fall to those speeds when it will be possible to open the parachute without fear that it will break.
A humanoid test dummy at Wright-Patterson Air Force Base. It sits in an impact test sled that mimics the shape of the seat in the Orion capsule.
After that, the capsule will smoothly descend into the ocean and flop relatively gently into the water. The impact will be like a minor road accident - from 2 to 3g, maximum 7g.
It was to mitigate this last blow that the landing on the water was chosen, but here too there are difficulties. The ocean is unpredictable. What if, at the moment of landing, the capsule receives a side impact from a high wave? It turns out that its passengers need protection not only from overloads associated with a direct vertical fall, but also from side impacts and even from falling upside down.
But whatever trick the ocean throws, we need to be sure the capsule crew remains safe and sound. To do this, here, in the research center, special dummies are rolled over and over again on the sled of a percussion test rig in chairs from the Orion ship. Recently, real corpses have also been used in these experiments. The information obtained with the help of specialized dummies is insufficient. Their rigid design is very useful for analyzing frontal or side impacts, which is why they are so popular with automakers. But in order to assess how the impact at the moment of landing can act on the bone skeleton or soft tissues of a person, it is highly desirable for researchers to conduct experiments on genuine human bodies. They are found among those donated to the needs of science. The trials described here are the result of a collaboration between three organizations: a testing facility, NASA, and the Ohio State University's (OSU) Trauma Biomechanics Research Laboratory.
Accidents at NASCAR races, such as that of Carl Edwards on April 26, 2009, may serve as a good example of what awaits astronauts when the Orion capsule hard lands.
Promotional video:
The living and the dead
Working with the dead, NASA employees feel a little awkward. They don't use the word "corpse" in their documents. Instead, a euphemism was introduced into circulation - “posthumous human object”. Dead bodies end up where their owners never dreamed of getting - on the ships Challenger, Columbia, Apollo1. However, young people look at this much easier. Here are two students next to Subject F chatting and chuckling as they untangle long wires from load cells mounted right in Subject F's bones. In their eyes, this corpse is in a kind of intermediate area of life. This is no longer a person, but also not just a piece of inanimate tissue. They speak of him as something animate, but they do not treat him as something that is capable of experiencing pain.
Subject F is now sitting in a tall metal chair next to the shock piston rails. Yun-Seok Kang, a graduate student from OSU, stands behind him and uses an allen wrench to fit a wristwatch-sized electronic unit right into his open spine. Together with dynamic stress sensors, these devices will measure the forces acting on the body upon impact. Kang's gloves are shiny with grease. There is a lot of him here, because of him fingers slip, Kang's work does not go well. He's been messing around for over half an hour. At the same time, the dead man remains infinitely calm.
So, it is necessary to prepare for unpredictable blows from any direction - this situation has a good analogy - an accident in an auto race. In April 2009, NASCAR racer Carl Edwards crashed into another car while flying at 320 km / h. His apparatus flew into the air and, tumbling, like a coin thrown for good luck, crashed into the wall. After that, Edwards, as if nothing had happened, got out of the car and hobbled away from the scene without any problems. How is this possible? To quote an article from the Stapp Car Crash Journal: "It's all about the correctly sized and tightly wrap-around cocoon for the pilot." Let's pay attention to the choice of words - it says not "seat", but "cocoon". The task of rescuing a person from unpredictable blows is not much different from the task of packing a fragile vase, counting on a long journey. You cannot predict which side the loader will throw your vase into the back,therefore it must be protected from all sides. In racing cars, the seats are made to measure for each pilot. It is fastened with a waist strap, two shoulder straps and a breast strap (passing between the legs). The HANS (Head and Neck Support) system prevents the head from moving forward sharply, and the vertical support rollers on the sides of the seat keep the head and back from jerking left or right.
NASA recently ditched the use of racing car seats as a reference for the Orion capsule. First, the riders still ride sitting, not reclining. For astronauts, especially those who have already spent some time in outer space, this is not the best option. The lying position is not only less dangerous - it also insures against loss of consciousness. When we stand up, the veins in our legs tighten and prevent all the blood from flowing down. If an astronaut spends several weeks in zero gravity, this defense mechanism is simply turned off. However, there is another problem here. “We put the seat from the racing car on the back, put the test subject in it and asked him to stand up on his own,” says Dustin Homert, NASA's expert on crew survival. "The guy felt like a turtle turned over on his back."
There were also concerns that the intricate seat belt system used on races such as NASCAR could significantly delay the release procedure and the astronaut would not be able to leave the Orion capsule in time. To address this issue, Homert and colleagues conducted several experiments using standard car test dummies using only head support straps. Homert suggested that I take pictures of how these mannequins, dressed in ordinary clothes from the supermarket, behave. Poor mannequins! Scrolling through the video in slow motion, Homert explains: “Here the head remains in place, and the whole body moves forward. We were already afraid that the dummy would be completely spoiled. As a compromise, a variant with simplified shoulder straps was chosen.
And here is another challenge the astronaut faces. Attached to his spacesuit are a bunch of hoses - air ducts, fittings, cables, switches and connectors. It is necessary to be sure that the hard parts of the spacesuit will not damage the soft tissues of the astronaut during a hard landing. For this, "subject F" was dressed in a kind of imitation of a spacesuit - many different rings were glued to him with tape on different parts of his neck, shoulders and hips. These rings were meant to mimic the flexibility or seams sewn into the suit. And one more concern worries the testers: in the event of landing on its side, one of the rings of the spacesuit's flexibility system (which provides the astronaut with sufficient mobility) can rest against the lateral support roller and it will be pressed into the astronaut's arm with such force that even a bone fracture is possible.
Seating Subject F in a chair mounted on a percussion sled is not easy. Imagine getting a dead drunk friend into a taxi. Two students support F on the hips, and one on the back. F lies with its bent legs raised, - a person lies in about the same way if his chair suddenly breaks in his hind legs. The process is led by John Bolt, OSU's Trauma Biomechanics Laboratory. He shouts to the students: "One, two, three!" The piston pusher is aimed at the right side of "subject F", that is, across the normal movement. This is the most dangerous of all directions.
When the unsecured head swings from side to side, the brain dangles inside the skull. This very delicate substance undergoes periodic compression and stretching during such a blow. A severe side impact can lead to brain injury, hemorrhage, edema, and ultimately coma and death.
Similar things happen to the heart. A heart full of blood can weigh three hundred grams. There is plenty of room around, and in a side impact, it can swing freely from side to side, yanking the aorta. If a heavy heart pulls too hard on the aorta, they can pull away from each other. "Rupture of the aorta" - this is Homert's verdict.
And now "subject F" is ready. We went upstairs to watch what was happening from the control panel. A sea of lights flared up and there was a loud sigh. Nothing too dramatic. Because compressed air does all the work here, the impact sled test is surprisingly quiet, with no crashing noise. In addition, everything happens so quickly that you hardly notice anything with your eye. The whole process is filmed at ultra-high frame rate. Then all this can be carefully examined in slow motion.
We clung to the screen. Subject F's arm is lifted under the shoulder strap - exactly where the extra chest strap has been removed. It seems as if the hand has an additional joint and it bends where the hand is not supposed to bend. "This is not good," someone's comment is heard.
Subject F received a hit corresponding to 12-15g. This is precisely the line where serious injury is almost inevitable. The amount of damage received by the victim depends not only on the force of the blow, but also on the time of exposure. And the acceleration itself also depends on the time required to stop. If, say, a car stops abruptly after hitting a wall, in a fraction of a second the driver can go through an overload of 100g. If the same car has a crumpled hood (and these days such a safety feature is no longer a rarity), the braking is extended over time and the peak load will reach, say, only ten g. This option leaves a lot of chances to survive.
Students place Subject F on a stretcher and load into a van. At OSU Medical Center, it will be scanned and x-rayed. Printouts, radiographs, and then autopsy results will show all the damage caused by the impact, contributing to the general body of knowledge that will help future astronauts not to repeat the fate of "subject F" in the chair of their spacecraft.
© 2010 Mary Roach. Excerpt from Packing forMars: The Curious Science Of Life in the Void, published August 2, 2010 by WWNorton. Translated by Andrey Rakin.
Mary Roach