January 27, 2008
NASA Upgrading Astronauts’ Wardrobe
While teams of engineers for NASA and its contractors are drawing up plans for a future moon base, other scientists are developing a new wardrobe for spacewalking astronauts -- the first change of garb for the outer space set in three decades.
The puffy, white 300-pound spacesuits now worn by American astronauts when they venture into space to assemble additions to the international space station or to overhaul the Hubble Telescope won't work when it comes to romping around the lunar landscape.Experts plan something lighter, easier to move around in and less trouble to care for. Yet the new suit also must be rugged enough to protect astronauts from the deadly space vacuum, shield them from solar radiation and fend off temperatures that range from 250 degrees Fahrenheit below zero to 250 degrees above.
"Our mission is to develop a (spacesuit) system with low overhead that is a pleasure to work in -- one that I would want to go off in on my day off to explore," said Mike Gernhardt, a veteran astronaut and bio-engineer assigned to the design effort.
At NASA's request, competing teams at aerospace companies submitted proposals in December for the development work. The space agency expects to announce a contract winner in June.
President Bush in 2004 directed NASA to send human explorers to the moon by 2020, ending an absence that began with the departure of Apollo 17's crew in December 1972.
The lunar astronauts would establish a base to serve both as a command post and as crew quarters for missions lasting up to six months. Over time, the outpost would become a proving ground for new equipment needed to mount a mission to Mars.
Under current plans, the astronauts would leave the base on road trips lasting up to two weeks and ranging more than 600 miles away. The long-range explorers would travel in pairs in enclosed rovers. The new vehicles, which also are under development, would be equipped with spacesuits designed to be donned quickly for short walks on the surface.
"This could really change the way we operate on the moon," Gernhardt said, referring to the rover. "It cuts the (spacewalk) time, but extends the range and raises the science return."
During the Apollo era, a half-dozen landers reached the lunar surface, each with two astronauts. Their cramped spaceship served as a temporary habitat. The longest moon visit lasted just over three days, and the final three missions carried open rovers. Yet the longest rover trip covered less than 23 miles.
Engineers learned several lessons from the Apollo landings that will change the way the new suits are designed and worn.
Pesky lunar dust The lunar terrain is covered with an abrasive dust that coated the Apollo suits, and the astronauts tracked the grit into the lander, where it stuck to their skin and invaded their eyes and mouths. The sticky dust also clogged bearings and other mechanisms of the suits, making it more difficult for the astronauts to move their arms and legs and turn their heads.
"The dust is a big problem, and there will be no dry cleaner," said Scott Cupples, a veteran NASA spacesuit engineer. "I haven't seen any design solutions or a slam dunk yet."
So far, experts have discussed several approaches to controlling the dust. One would require something like a mud room at the entry to the lunar station where the suits would undergo a vigorous brushing after each use and an air shower to blow the grit out of the living quarters.
Another proposal is to design a moon suit that would be left outside. The suit, secured to the outside of the habitat or a rover with an air-tight seal, would leave an opening in the back. The astronauts would climb into the suit from the inside of their living quarters or from the inside of the rover, disconnect the suit and walk away.
The Apollo spacesuit had shortcomings of its own, said Joe Kosmo, who manages NASA's spacesuit development lab.
The garments were fabricated with rubber shells to protect the shoulders and the joints of the arms and legs. Sculpted from Neoprene, the coverings grew brittle with time, and the suits had a useful life of about four years, Kosmo said.
The old moon suits also relied on zippers to seal the astronauts inside the airtight garments. But the zippers were so fragile that technicians had to X-ray them before each mission to ensure that their metal teeth had not fractured. In space, the zippers often jammed, requiring a liberal use of messy lubricants to open and close them.
The Apollo suits also were designed to be worn by the astronauts during the launch and landing segments of their missions to protect them in the event of a sudden air loss.
Alterations That approach changed when NASA began launching the space shuttle in 1981. Shuttle crews wore pressure suits tailored for the launching and landing phases of the flight and a separate garment for spacewalks.
The shuttle suits far outlived their original 15-year design life. More than a decade ago, the venerable suits underwent alterations to make them suitable for use on the space station.
Unlike the Apollo garb, the shuttle spacesuits were not designed for strolling across a planetary surface, where gravity offers a stabilizing force.
Instead, most of the mobility of the shuttle suits was built into their upper bodies, especially for the arms and hands.
During orbital missions, astronauts float. Without gravity, they either anchor themselves in portable foot restraints or on the tip of a robot arm so they can work with their hands.
The technique works for fastening pieces of a space station together or making repairs.
The aging suits also are essential to a shuttle mission planned for later this year to overhaul the Hubble Telescope.
Space station work The space agency will rely on the suits to finish the construction of the space station by 2010.
At that point, the suits will likely be stowed aboard the station and worn during external maintenance and repairs.
Scientists and engineers began working on the first spacesuit during the flights of the original seven Mercury astronauts in the early 1960s.
During their brief flights into space, the astronauts wore protective clothing derived from Navy flight suits and intended only to protect them from high altitude air leaks in their spacecraft.
Gemini astronaut Ed White conducted the first American spacewalk on June 3, 1965, wearing a suit hastily adapted from an Air Force research garment. White's 20-minute outing came 11 weeks after Soviet cosmonaut Alexi Leonov conducted the world's first spacewalk.
Since White's excursion, American astronauts have conducted 185 outings into space without death or injury.
"What turns us on is the physiology and engineering that must come together to keep a human alive in something so small," said Lara Kearney, a NASA biomedical engineer who works on the moon suit project.
"It feels more personal than working on a large spacecraft."