The spacesuits Apollo astronauts used on the moon were fine for taking giant leaps for mankind. The suits shuttle astronauts use for spacewalking are good for fixing an occasional satellite, and they will be adequate for assembling the International Space Station.

For mountaineering, spelunking, or prospecting for water on Mars, though, the suits are little better than useless.

That is why NASA is working to develop the early prototype of what, in decades to come, will become a versatile outfit for exploring the nearby planets.
 
 

NASA has hired two of its spacesuit manufacturers to build suits that are lighter and less expensive than the current suits astronauts use for Extra-Vehicular Activities (EVAs). These suits must be packable into a smaller volume than the current suits and offer astronauts better mobility.

"In order to support an astronaut for the kinds of activities that will be expected for a mission to Mars or a return to the moon, we will need a new generation of suit," said Robert Yowell of the advanced EVA projects office at NASA's Johnson Space Center.

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NASA is currently evaluating and testing the first two demonstration models of this new class of suit. The suits were built by the David Clark Company of Worcester, Mass., and ILC Dover of Dover, Del.

David Clark's effort is being called the D-Suit, while ILC Dover's is known as the I-Suit. They are essentially improved versions of the outfits the companies already make for space shuttle missions.

David Clark is the contractor that makes the orange suit that space shuttle astronauts wear during ascent and reentry from space. That suit, called the S1035 Advanced Crew Escape Suit, is basically a high-altitude flight suit that can be pressurized in case astronauts need to eject from the shuttle at high altitudes. When it is pressurized, the suit does not have the mobility that a spacewalking astronaut needs.
 
 

ILC Dover makes the white suit that astronauts use during spacewalks. That pressurized suit is worn with a backpack that contains the astronaut's life support system. Combined, this EVA equipment weighs about 300 pounds. The suit itself makes up about 100 pounds of that -- much too heavy for long days of exploring rough martian or lunar terrain, even in their lower-gravity environments. (Martian gravity is about one-third that of Earth's. On the moon, it is roughly one-sixth as strong.)

The primary challenge of making a spacesuit is building one that allows movement under pressure. Normal atmospheric pressure at sea level is 14.7 pounds per square inch, so ideally, a suit would be inflated to this pressure. But the body-shaped balloon becomes so taught at that pressure that it is rigid and immobile.

Space-mission designers have settled on a lower pressure -- 3.7 pounds per square inch. This is safe for astronauts, but also allows for suit flexibility and unhindered movement. The Apollo suits and space shuttle suits operate at this pressure. Taking adequate precautions, an astronaut can function at this pressure for many hours.

The greatest departure from the current shuttle EVA suit is that the I-suit has a soft upper-torso. The former is built around a hard fiberglass shell that covers an astronaut's upper body.

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That design was deemed too bulky and expensive for the suits of the future, so engineers at ILC Dover designed an all-fabric suit that is lighter, packs smaller and is much cheaper to make and to tailor to individual astronauts. The result is a mostly soft suit that weighs about 65 pounds.

These boots were made for walkin'

When it comes to exploring the surface of other planets, astronauts will be driving and hiking a great deal. An exploratory spacesuit, therefore, needs sturdy boots with soles that will hold up. To give astronauts the best footwear, both ILC Dover and David Clark worked with commercial boot makers to adapt a commercially-available boot to the spacesuit.
 
 

"We decided we were just going to bring in the experts," said Philip Spampinato, who is program manager of space products at ILC Dover. The company asked designers from commercial boot and shoemakers to advise on making boots for exploring planetary surfaces.

"They gave us a lot of insight into how they did their development work," Spampinato said. ILC Dover then adapted the soles and bottoms of a popular terrestrial boot to fit on the spacesuit.

The interior of the suit is a urethane and urethane-coated nylon membrane that also lines the boot. A special air bladder in the boot can be inflated to provide a snug fit.

Rotating bearings for rotating joints

When a spacesuit is inflated to 3.7 pounds per square inch, it is difficult to move. Consider a clown who ties colorful carnival balloons into animal shapes. Folding a long balloon is easy when it is soft. As it is filled to higher and higher pressures, though, it becomes tougher to fold and twist.

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To overcome this resistance, spacesuits incorporate bearings at the important rotational points. ILC Dover's suit has several bearings that allow sections of arms, legs and torso sections to swivel independently. This gives astronauts the ability to rotate their shoulders, arms and legs.
 
 

"The idea is we would take the best out of what we learned from these prototypes and incorporate that into the requirements for the next prototype that we build," Demasie said. "For Apollo and shuttle suits we had hundreds of suits that were built before we actually flew anything. This is a part of the beginning baby steps of design."