Outer space is a hostile environment for humans, characterized by an airless vacuum, thermal extremes, ionizing radiation and speeding micrometeoroids. Less well-known are the dangers posed by long-term exposure to microgravity or zero-g conditions, which over time severely saps the strength of astronauts’ muscles and bones.
“When people go into space, they encounter weightlessness, which provides less resistance to their muscles and skeleton, causing muscle atrophy and bone loss,” says Kevin R. Duda, an aerospace engineer and senior member of the technical staff at The Charles Stark Draper Laboratory’s Human Centered Engineering Group.
“Astronauts who are exposed to low gravity for long periods suffer from what we call musculoskeletal deconditioning,” explains Dava Newman, professor of aeronautics and astronautics at MIT. “This involves a 30-percent rise in muscle atrophy, a 40-percent reduction in muscle strength, as well as 1- to 2-percent loss in bone-mineral density each month.” Newman’s research focuses on aerospace biomedical engineering.
Despite daily, rigorous exercise and resistance-training routines, astronauts find it exceedingly difficult to maintain their muscle and bone strength in space. In fact, the risk of skeletal fracture is considered by many experts to be the single most important limiting aspect of long-duration spaceflight.
Skinny Spacesuits
Duda, Newman and other researchers are working to develop new spacesuit designs that could help counteract these threats as well as avoid some of the familiar drawbacks of current spacesuit models such as bulk, weight and rigidity.
The BioSuit: Next generation space garb. Illustrations courtesy MIT/Cam Brensinger
When future astronauts prepare for extravehicular activities (EVAs), for example, they may don spacesuits that are much lighter, less cumbersome and more flexible than current units. Their protective outer wear, even their interior garb, may, in addition, compensate for the negative effects of microgravity conditions, or even low or no atmospheric pressure, with body-compressing skin suits, or small, limb-mounted gyros that resist motion in certain directions.
Bulky Gas Bags
Conventional EVA spacesuits, so-called full-pressure suits, enclose the body in an oxygenated environment that not only enables astronauts to draw breath but also encases them in a layer of pressurized, temperature-controlled air that guards against exposure to vacuum decompression and extreme temperatures.
A drawback of pressurized ‘gas-bag’ suits, however, is their physical resistance to movement, which tends to tire out wearers during prolonged excursions outside. If today’s spacesuits were pressurized to Earth’s atmospheric pressure, they would be so stiff as to be all but immobile. Hence, lower pressures are used.
Squeeze Suit
A research team led by Newman has produced an alternative type of spacesuit that could give astronauts much greater freedom of movement. Their patented BioSuit is a mechanical counterpressure, or “squeeze,” suit that would supply pressurized oxygen to the helmet but would otherwise employ tight bands to squeeze the body at certain points to counteract the dearth of external pressure.
The custom-fitted BioSuit, which is designed to enhance locomotion during spacewalks or planetary exploration, is made of a stretchy fabric that is composed of spandex, nylon and an unspecified plastic material to replace compressed air, making it more lightweight and maneuverable. Micrometeorite and additional thermal protection would be provided by an outer shell or garment.
“So far we have proven the technical feasibility of the BioSuit,” she reports, adding, “we would need another three to five years of funding to produce a flight-worthy system.”
Anti-Gravity Measures
Newman and her colleagues have also developed a similar stretchy suit design that is intended to counter the ravages of low gravity to the body’s muscles and skeleton. The gravity-loading countermeasure skinsuit would employ mechanical strain from a specialized elastic mesh to produce loading on the body to mimic the gravitational effects of standing and—when integrated with other counter-measures—exercising on Earth, she says. The conceptual suit design would impose simulated weight-bearing loading by gradually increasing tension in the vertical-axis fibers, along with the application of minor tension circumferentially to prevent suit slippage.
Kevin Duda at work on the spacesuit. Courtesy Draper Laboratories
Meanwhile, an alternate approach to counteract the ramifications of microgravity is being pioneered by Draper Labs’s Duda, who is collaborating with Newman on the project. In this case, the engineers hope to retain astronauts’ muscle and bone strength by affixing cell phone-size gyroscopes to their arms and legs to imitate gravity. “The property of these control-moment gyroscopes is that they resist changes in angular momentum and thus could apply a couple of pounds of force (torque, in reality),” he says.
With a pair of the rechargeable battery-powered units on each appendage—forearms, upper arms, calves and thighs—the astronauts would feel resistance to motion that would to some degree simulate that of normal gravitational force. When floating in deep space or near asteroids, the gyroscopic units, perhaps installed in backpacks, could help astronauts to stabilize their attitude so as to “maintain orientation toward the task at hand to boost operational efficiency.”
Donning these devices could also assist astronauts to ease back into terrestrial life, because the users would not have to re-accommodate to the resistance to movement under gravitation. “The gyros would hopefully help speed up the process by which they re-acclimate themselves after they land on Earth,” Duda says. The small gyros could in addition be used in conjunction with the mechanical compression skinsuits.
Development of the gyros, which is being funded by the NASA Innovative Advanced Concepts, is still at the prototype stage, he says.
Earthly Applications
These outer space technologies could have several earth-bound spin-off applications as well. Researchers, supported by the National Science Foundation, are looking at whether children who suffer from cerebral palsy might be able to use the compression skinsuits, Newman says.
The motion-control gyroscopes could also keep patients undergoing physical rehabilitation from moving their arms or legs in an unsafe way or prompt them to move in a correct manner. “The units could be programmed to help you learn, or re-learn, specific motions,” Duda says.
Top image: Dava Newman in the 2008 silver BioSuit™ mock-up. Courtesy Professor Dava Newman, MIT: Inventor, Science and Engineering, Guillermo Trotti, A.I.A., Trotti and Associates, Inc. (Cambridge, MA): Design, Dainese (Vincenca, Italy): Fabrication, Douglas Sonders: Photography
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Steven Ashley is a contributing editor at Txchnologist. His last article covered the next generation of military hovercraft engines. His work has been published in Scientific American, Popular Science and MIT’s Technology Review, among others.