When astronauts have to step outside for a space walk or a stroll across the Moon, they must first face a daunting challenge that would overwhelm an ordinary person: getting dressed.
The heavy and complex suits currently in use are hardly the sort of outfit you can just throw on. And even in the microgravity of orbit, moving and working while wearing the massive contraptions during an extravehicular activity (EVA) can quickly exhaust an astronaut.
So Ed Hodgson of Hamilton Sundstrand, a NASA contractor, has developed a scheme for building suits that will feel more like a set of coveralls and less like a suit of medieval armor.
"The concept is to dramatically decrease the mass and volume of equipment and supplies that the EVA astronaut must carry on his back and the amount of resupply material that must be launched," Hodgson says. "(Our design) works with the environment rather than one in which we first provide complete isolation from the environment and then add equipment to replace all of the environmental interactions we normally rely on to keep us comfortable and alive."
Formal Wear
When the first American spacewalker, astronaut Ed White, stepped outside of the Gemini 4 capsule he was not burdened with as much hardware as shuttle astronauts now wear. Or so it may appear in photos. Looked at another way, his suit was hampered by a truly monstrous life support "backpack" -- the space capsule itself. Wires and hoses connected White to the craft's interior support apparatus through an open hatch. This delicate arrangement would have been extremely dangerous if White had been attempting to repair a satellite or engage in space station construction.
37 years later, shuttle space suits are marvels of self-contained life support, designed to protect the wearer from some of the solar system's harshest conditions. But the bulky backpacks and heavy layers are needed primarily to keep the wearer warm ... and cool. Well OK, it's both.
You've probably heard that it's very cold in space; but that's only partly true. In actuality how hot or cold an object becomes depends on how much heat radiation is hitting it, as there is no temperature to the surrounding vacuum. The surface of the planet Mercury for instance is baking hot on the side facing the Sun, and almost unimaginably cold on the other. An astronaut in orbit without proper heat regulation would broil in direct sunlight, or freeze in the Earth's shadow.
Historically, for extended EVAs, NASA has relied on a time-honored method of regulating heat; sweating. Beneath a suit's outer layers is a network of tubing through which courses cooling water, which essentially collects the heat next to the astronaut's skin. Pumps and other equipment in the suit's backpack regulates the water's temperature, sometimes by simply releasing it into space when it becomes too warm.
But water is heavy, to say nothing of the pumps and tubing of the circulation system itself. Balancing the needs of making the equipment effective and lightweight means it's also complex, fragile, and prone to breakdown.
Hodgson's "chameleon suit" idea, which he is developing with funding from the NASA Institute for Advanced Concepts (NIAC), looks to change all that. NIAC is the department of extremely long-range planning at NASA, where big thinkers take new and near-future technologies and concoct new ways to explore space.
"Like all NIAC studies, the chameleon suit is aimed at long-range applications (10 - 40 years away)," Hodgson says. "Based on our work so far, some aspects of the concept, specifically controlled heat rejection through the suit walls, may be realistic toward the near end of that window."
Have Spacesuit, Will Travel
It's not called a chameleon suit for stealth reasons; Hodgson compares his suit's ability to rapidly adapt to that of the reptile. In theory the suit would retain or shed heat in response to the surrounding environment, thereby keeping the wearer alive, comfortable, and able to work.
"We chose the name "chameleon suit" to reflect the fact that the suit walls change in response to changes in the environment or in the wearer's need for cooling," Hodgson explains. "Specifically it fits the way that a chameleon changes color."
"Even though the space environment is very hostile and cannot provide much of what we usually derive from the Earth's atmosphere, it does offer a useful heat sink," says Hodgson. "Vacuum conditions or a low pressure (in most destinations of current interest) atmosphere that can aid in mass transport and gas separation functions, and thermal and solar energy flows that can be used to derive power or drive transport and conversion processes."
"To me the coolest part of the concept is its central theme," Hodgson enthuses. "The idea that we can approach an EVA system in a whole new way and work with what the space environment gives us much as we have throughout the history of human expansion into demanding environments all over the earth."
But Hodgson has special fondness for the suit's recycling program.
"Of the specific implementation possibilities, the recovery of metabolic oxygen on the fly would definitely be the coolest," he says. "I have always viewed it as physically impossible, and it still strains the bounds of possible growth in process efficiencies from what we know to be achievable today, but, if we get there it will really be liberating for future space activity like nothing we've ever seen."
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