Engineers fashion ways to survive on Mars
We’re likely still at least a couple of decades away from landing people on Mars, but the space suits that will protect those astronauts are very much in development.
Last year, NASA made headlines when it invited the public to choose the design that would decorate the exterior of the Z-2, a new suit designed to be mobile enough to explore the Red Planet. And its manufacturer, longtime space-suit maker ILC Dover, based in Frederica, Del., has now put the finishing touches on that suit, which is set for a public unveiling in a few months.
Some would argue that we can’t get started on Mars suits soon enough. Today’s space suits are designed for delicate work in zero gravity, not the rigors of a months-long trek around the base of Olympus Mons.
So what will that first Martian space suit look like? Will it be similar to today’s suits—a rigid, human-shaped balloon inflated with gas? Or will we wind up with something sleek, like MIT’s BioSuit concept, which would use form-fitting elastic materials to apply pressure directly, by squeezing the body?
Chances are we’ll see an evolution in design, says David Klaus, a professor of aerospace engineering sciences at the University of Colorado Boulder. “The first suits on Mars will probably be like the Z-2,” he says. “They may not be perfect, but they’ll get the job done.”
The Z-2 isn’t yet a complete suit, but discussions with its engineers and other space-suit experts provide a sketch of what the first people to land on Mars might wear.
The most important requirement, of course, is that the suit offer future Martian explorers adequate protection. By physiological standards, conditions on the surface of Mars are effectively equivalent to those of a vacuum, the atmosphere having less than 1 percent of the surface pressure of Earth’s. As a result, future Martian explorers will face the same basic danger that spacewalking astronauts do today: A large breach in their space suits would quickly turn the liquid water in their tissues and veins into vapor. The body would swell drastically, and blood would stop circulating within about a minute.
But Mars poses new challenges. The weak magnetic field of that planet offers little protection from solar-wind particles and cosmic radiation. And the thin atmosphere complicates suit design. The space suits worn outside the International Space Station (ISS) use vacuum to their advantage—that vacuum provides thermal insulation between outer layers of the suit. Transport such a suit down to the surface of Mars and gas molecules will slip between those layers and carry heat away from the astronaut’s body.
Astronauts will also have to contend with something that they haven’t had to tackle since the days of the Apollo moon missions: dust. Whipped by wind and once shaped by water, Martian dust is likely less sharp than moon dust, but the Martian variety is readily lofted into the air. The dust can scratch up visors, bind up bearings, and coat space suits, altering their reflective properties. Should it get into a rover or habitat, scientists say it could pose a significant health hazard.
Even if today’s suits could perfectly protect Martian explorers, they’d be quite difficult to work in. They’d be a lot to lug around, for one thing: Mars has 38 percent of the gravity of Earth. The current suits are also optimized for moving about in zero gravity using handholds, so their hip, waist, and knee joints aren’t particularly flexible. “The suits that are up there are not designed for walking around,” says former astronaut Jeffrey Hoffman, now director of MIT’s Man Vehicle Laboratory. “I had to take [one] on a treadmill once. You sort of turn your body and throw one foot in front of the other. It’s very awkward.”
NASA’s Z-2 is designed to tackle this mobility problem. “Our current goal is to work toward a suit that we could fly on the space station as a demonstration,” says Amy Ross, who heads the advanced space-suit engineering team at NASA Johnson Space Center, in Houston. “But it is a planetary-surface walking suit.”
Like its predecessors, the Z-2 is filled with gas and consists of three basic layers: a restraint layer to hold in the air, a structural layer that helps shape the suit and allows joints to move, and a set of environmental layers that provide thermal insulation and protect the suit from punctures. Where the Z-2 diverges most is in how it bends and flexes. The suit comes with improved joints and bearings, particularly at the shoulder, hip, and waist.
As with the suits used by today’s Russian cosmonauts, astronauts enter at the back. The idea is that, to avoid contact with dust, explorers could hang the suits outside their vehicles or habitats. The suits would be part of a compact air-lock system; a Mars walker would enter his or her suit through a combination hatch-backpack containing the suit’s life-support equipment. When open, the suit hatch would nestle inside the vehicle’s inner hatch. After the astronaut enters the suit, both hatches would close and the astronaut could release the latches holding the suit to the vehicle.
In theory, an astronaut could get in the suit and go fairly quickly. To improve their flexibility, existing Russian and American suits are kept at a relatively low pressure. Astronauts must go through a lengthy “prebreathe,” in which the air is slowly depressurized to lower the risk of developing the bends. This is the same hazard scuba divers face upon returning to the surface from deep water—dangerous bubbles that are created when the lower pressure causes dissolved gases in the body to come out of solution.
The Z-2 is designed to operate at 8.3 pounds per square inch (about 57,000 pascals). Although still just over half the pressure at sea level and inside the ISS, the level is high enough for astronauts to forgo the prebreathe procedure. To resist the higher pressure, some of the widest parts of the suit, namely the chest and pelvic area, employ rigid components made from a composite of fiber and resin. These rigid parts could also help protect the astronaut against falls, says Jinny Ferl, a space-suit engineering manager at ILC Dover.
But the Z-2 isn’t quite ready for a Mars debut. The suit’s environmental garment doesn’t yet have any layers to help protect against extreme temperatures and radiation, says Ferl.
What’s more, there’s the pesky matter of overall heft. The Z-2 is being developed in tandem with an improved life-support system that can better remove carbon dioxide. Together, the mass of the pair comes to roughly 140 kg, says NASA’s Ross, on par with the mass of the U.S. suits currently used on the ISS, if you don’t include their emergency thrusters. But, she adds, the new system does more with that mass: The Z-2 suit has better mobility, and the new life-support technology is more reliable and can operate longer.
In the future, we could see sleeker, more-capable suits emerge. MIT’s BioSuit project is blazing that trail, although it is still in its earliest stages, Hoffman explains. The approach presents some significant challenges, including finding a way to provide pressure in concave areas, such as behind the knees and between the knuckles. At present, the MIT team has not developed a prototype that can provide enough pressure to protect against vacuum. But they are working on it.
In parallel, UC Boulder’s Klaus and others are exploring additional ways to make suits more capable. Earlier this year, for example, he and graduate student Christopher Massina reported that it should be possible to save on the water now used to help keep temperatures steady by transforming the space suit into a dynamic, full-body radiator. The approach uses materials that change their surface properties—and thus how strongly they reflect or absorb light—in response to an applied voltage.
“That’s definitely next-generation stuff,” Klaus acknowledges. But when it comes to Mars, it’s good to plan ahead.