At
the bottom of NASA’s 40-foot-deep swimming pool – known
as the Neutral Buoyancy Lab – astronauts strap on
weights and plastic piping to simulate the backpack that
attaches to a spacesuit. Then they walk, hop, run, climb
and shovel. And then they rate the difficulty of each
task with each particular weight and each backpack
design. One is too heavy, another is too light. One
backpack is too low, another too high.
It's kind of a space-age Goldilocks story, with the
goal, of course, of finding the design that's just
right.
It’s been two decades since the spacesuit of the shuttle
era was designed – a 300-pound personal spaceship built
to work in weightlessness and protect astronauts from
the vacuum, searing heat and freezing cold of space.
It’s done its job well, but it’s not made for the moon.
For one thing, today’s suit is too heavy for the partial
gravity of planetary exploration. It’s built for
astronauts who will be working with their hands and
floating, not walking, riding, climbing and digging. And
since it’s only meant to be worn on spacewalks,
astronauts wear other suits for launch and landing. That
takes up precious space on a small ship.
In other words, NASA needs a new suit.
So, engineers and scientists at the Johnson Space Center
in Houston are designing a spacesuit for the
Constellation Program – the program that is building the
next human spacecraft for America, a craft that will fly
to Earth orbit, to the moon and beyond. Imitating the
moon on Earth to find the best design means going to
great lengths – suspending astronauts from the ceiling;
sending them 40 feet down and 34,000 feet up; traveling
to the bottom of the ocean and to the desert of Arizona.
And that’s in addition to the work done in conventional
laboratories at Johnson and other NASA centers.
“The suit’s made up of a bunch of different components,”
said Scott Cupples, the Constellation spacesuit element
lead. “It takes a lot of coordination. We’re looking at
each little thing and trying to decide how we can do it
better.”
Though NASA has only been actively planning to return to
the moon since 2004, engineers actually began looking at
this problem more than 10 years ago, with the first
Desert RATS – or Research and Technology Studies – trip.
Since 1997, scientists and engineers from NASA centers
across the country have gathered annually in the Arizona
desert, in some of the same places Apollo astronauts
trained for lunar missions, to simulate the kind of
activities astronauts might need to do when exploring
the moon or Mars.
"You can sit behind a computer and dream up requirements
and corresponding design approaches, but you've got to
put them into action to see if they are feasible,” said
Joe Kosmo, a senior project engineer who started the
group and has worked on every United States spacesuit
since the Gemini program. "Remote work – field testing –
helps with that."
With lessons learned from the Apollo program in mind, a
small Desert RATS team started by having a geologist in
street clothes do regular geological work while they
studied his movement. Since then, geologists and other
suit subjects have worn spacesuits while collecting
stand-in moon rocks, doing site surveys and driving a
lunar rover.
“One of the major reasons we’re going to the moon is
geology,” said Terry Hill, engineering project manager
for the new suit. “So if you can’t bend down in the
suit, you’ve missed the boat.”
The work done on Desert RATS gave engineers some idea of
where to start, but it left a whole host of details to
iron out – which is where tests like those in the
Neutral Buoyancy Laboratory come in. The NBL tests were
aimed at finding the ideal weight for the new suit and
the “sweet spot” for its center of gravity. Normally,
your center of gravity is somewhere around your belly
button. But that changes when you put on a
100-plus-pound backpack carrying your life support
system.
“Some people think that the center of gravity on the
Apollo suits was why the astronauts fell down so much,”
said Jeff Patrick, integrated testing and facilities
manager.
So astronauts tried out different backpack possibilities
in the pool to see which felt the most natural. They
even practiced getting up after a fall to see how easily
it could be done. It’s an extension of what astronauts
do 62 feet below the ocean’s surface during NEEMO
missions – NASA Extreme Environment Mission Operations.
On those missions, where underwater "spacewalks" are
staged from a habitat off the Florida coast, astronauts
face many of the same limits and safety concerns they
would encounter in space. They’re finding that the
typical backpack design might not work as well as
something more the size of a fanny pack worn on the
back.
“We’ve been pretty successful so far,” said Nick
Skytland, deputy project manager for the EVA Physiology,
Systems, and Performance Project. “Initial results from
our research are already being incorporated into the
design of the next generation spacesuit.”
Some of the same activities – and more – are also done
on dry land and even 34,000 feet in the air. In NASA’s
reduced gravity airplane, which flies in parabolas to
give passengers a few seconds of weightlessness,
astronauts and engineers get a real feel for how the
suit performs in reduced gravity. On the ground, they
use the POGO – a device that suspends a person wearing a
spacesuit from the ceiling. By supporting five-sixths of
a person's weight, it mimics the one-sixth gravity of
the moon. The contraption has been around since the
Apollo days – in fact, the device gets its name from the
way Apollo astronauts tended to bounce when suspended
from it.
Using the POGO, engineers can test things like how far
an astronaut could walk in the spacesuit if their lunar
rover broke down and they had to hike back to their
base. They can experiment with different suit pressures
and weights while monitoring heart rates, temperatures
and metabolic outputs.
Mike Gernhardt, an astronaut who has also been the
principal investigator for many of the tests involved in
the design process, said one thing they’ve noticed is
that at lunar gravity astronauts can get more mileage
out of their oxygen if they go faster. Probably due to
the momentum of the suit – it takes less work to go
faster, so you use less oxygen while doing so. But you
also put off more heat. More heat, in fact, than the
conventional suit is able to get rid of. Which means
that, to take advantage of the added mileage, the new
suit needs a better cooling system. It’s one more piece
of the puzzle engineers and scientists are carefully
putting together.
When all the pieces fall into place, the astronauts of
the Constellation program will have a spacesuit that
fits their needs. But what the suit needs to do has to
be balanced with the fact that it must be built within
the size and weight available to hold it on the Orion
spacecraft in which it will fly. It also may be asked to
pull double duty as the crew’s launch and entry suit.
Serving that need means it must be able to withstand any
of the extreme environments the crew might encounter
during an emergency landing – extreme hot or cold, or
even a water landing – in addition to those encountered
on the moon and in space.
All that, and it needs to be easy to use.
“The No. 1 driver that we need to have on the new suit
is an improved work efficiency index,” Gernhardt said.
“Right now we’re basically spending three hours inside
the spacecraft getting the suits ready to go out for
every one hour we spend outside. As we get into this
whole lunar exploration phase, we’re going to be doing
an order of magnitude more spacewalks than we’re doing
in the space station, and we simply cannot afford all of
that overhead.”
The goal, Gernhardt said, is to reverse the ratio. He
wants astronauts to spend no more than one hour getting
ready, for every three hours outside – that’s two hours
spent preparing for a six-hour moon walk, rather than
18. It’s a tall order, but he says it can be done.
“Right now, the suit that we have is in all these
pieces, and they’re stored in different places,” he
said. “You have to pull out a different kit for your
biomedical sensors, and there are three different kinds
of tape and kinds of gel that you use to attach them,
and all of that takes 30-plus minutes just to install.
In the new suit, we’re going to consider having
non-contact sensors that are built into the liquid
cooling garment – where it takes no time.”
There’s a half hour or more saved right there. More
examples: the designers hope to shave another half hour
by eliminating the need for astronauts to fill the
suit’s water bag, which involves a special tool and a
lot of time spent getting rid of bubbles. And another
two hours can be gained by keeping the habitat the
astronauts live in at a pressure low enough to eliminate
the need for long pre-spacewalk activities that must be
done today to avoid decompression sickness during
spacewalks from the shuttle.
“All these things add up,” Gernhardt said. “It’s going
to make it so much more efficient to get out the door.
My vision is that we have a suit that is a pleasure to
work in – that it could be such low overhead that there
might be days where it’s your day off and you choose to
go outside on a pleasure moonwalk, not just a working
moonwalk.”
