An outfit suitable for Mars
Slimmer space suits on the rack for astronauts.
The gas-pressurized space suits used by astronauts for space walks and moon landings would never work on Mars. That's the consensus, at least among astrobiologists and simulation experts at the Eighth International Mars Society Convention, which took place 11-14 August in Boulder, Colorado.
A solution, they say, may lie with an old idea.
The Mechanical Counter Pressure (MCP) suit aims to use elasticity to provide pressure instead. Paul Webb, a physician from Yellow Springs, Ohio originally proposed this idea in 1968, as a safer and more flexible alternative to the bulky Apollo mission suits. His idea didn't take flight until recently, however, when the US space programme began casting an eye towards the red planet.
"For future field work on Mars, our number one problem is a space suit that works," says Chris McKay, an astrobiologist at NASA Ames Research Center in Moffett Field, California. Astronauts need something that is light and flexible enough to allow them to scramble about and dig holes, while still protective against the harsh conditions.
Webb's suit is made of a stretchy Lycra-like fabric that squeezes the body five times harder than medical support stockings. This makes it difficult to put on, admits Webb. But it is reasonably comfortable so long as the air the astronaut breathes is pressurized to match the suit's constrictiveness. "Otherwise," he says, "it hurts like hell."
The inner suit would have to be covered with an insulating outer shell to regulate body temperature and protect the astronaut against radiation.
Unlike an air-filled suit, an MCP suit would still function properly even with a small rip, says Webb; the astronaut's skin would simply bulge slightly to fill the hole. And it weighs only 39 kg, much less than the 180 kg of a standard suit, which in Mars's one-third gravity would be like carting the weight of a person.
Webb's suit has been tested in a pressure chamber at an air pressure close to martian levels, about the equivalent of 24,300 metres above Earth's sea level. A test subject managed to pedal a bicycle for an hour in these conditions.
A similar MCP suit developed by James Waldie of aerospace company BAE Systems, in Melbourne, Australia, has faced trials by two recent 'crews' at the Mars Desert Research Station near Hanksville, Utah, a test bed for Mars fieldwork. The 'pretend astronauts' roaming the desert in their space suits reportedly found the "really tight long johns" more dexterous and cooler than the standard outfit.
But experts at the Mars Society meeting were keen to get even more creative with their imagined space suits for the future.
One option, described by Erik Clacey of the International Space University in Strasbourg, France, would be to have a suit made of an algae-impregnated fabric that could produce oxygen for the astronaut on-site. The main problem there is in finding a source of nitrogen to feed the bugs. "That might be supplied by urea [from urine]. So you might not want to share suits," he quips.