I
18 June 2019 _ PopularMechanics.comNASAT’S JUNE 3, 1965, and astronaut Ed White, in orbit over
Hawaii, emerges from a space capsule, becoming the first
American to conduct an extravehicular activity, or EVA.
Connected with a single tether, he maneuvers using an oxy-
gen gun for propulsion, and poses for pictures. “I feel like a
million dollars,” White says.
These days, EVAs are not done for the photos. They’re
required for maintenance and operation of the International
Space Station and are planned to the minute. Astronauts sel-
dom have time for a selfie or joyriding with jet-guns.
“Statistically, doing an EVA is just as dangerous as launch-
ing and reentry,” says Garrett Reisman, professor and former
NASA astronaut with a
seven-plus-hour space
walk on his résumé. EVAs
are hard, dangerous, and
time consuming, so it
makes sense that engi-
neers want alternatives
when designing the next
generation of hardware.
“It comes back down to
design decisions that you
make in the very early
stages of designing your
space station,” Reisman
says. “How are you going to
cope with failures?”
The easiest way to limit
the number of space walks
is to put things that need
maintenance inside. But
future space stations will
be far smaller than the
ISS. NASA’s planned lunar
Gateway has a minimum habitable volume of around 2,
cubic feet, compared to 13,696 in the ISS. Part of the current
proposal is to keep the Gateway partially crewed by robots, capa-
ble of operating on their own. Still, NASA is planning orbital
space walks, requiring that Gateway accommodate “astro-
naut EVAs.”
Bill Pratt, Lockheed Martin’s NextSTEP habitat program
manager, says that its proposed Gateway design includes a
separate EVA module, but the real heavy lifting will be done by
machines like a Canadarm and autonomous docking systems.
But humans, especially in emergencies, will still play a role.
“There w ill a lways be some sit uations that we can’t anticipate,”
Pratt says. “A human is uniquely qualified to address unfore-
seen challenges and solve problems in real time.”During an EVA on STS-132, Reisman and Steve Bowen had to
install a new Ku-band antenna on the top of the ISS. The assem-
bly went routinely, with Reisman perched on the end of a robotic
arm. But when it came time to connect the cable carrying power
and data, the connectors didn’t fit. “We tried really hard to push
the thing together. We’re yanking on that thing and shoving
with all of our might,” Reisman says. “Inside, they could feel
the space station shaking because we were pushing so hard.”
The solution came with the sunrise as Reisman put the
male connector in the shade and the female connector in the
sun. “We used thermal expansion,” says Reisman. “I waited
for a few minutes, and then I took the connector...and I put
it right in place.”
Apart from a robot’s
inability to problem-solve
like Reisman, there’s
another more straightfor-
ward reason to preserve
human space walks: “We
can make a better suit,”
Reisman says.
Currently, ISS astro-
nauts are stuck with suits
from the space shut-
tle program, basically
unchanged since almost
40 years ago. Back then,
EVAs were not a priority,
says Pablo De León, the
director of the University
of North Dakota’s Human
Spacef light Laboratory.
In fact, they were only
developed as contingency
equipment. “We’ve gotten
good at working around it,” Reisman says. “We’ve developed all
kind of tools and equipment to compensate for the restrictions
that the suit places on you.”
A new generation of orbital EVA suits will likely be designed
by companies in the private space industry, which are already
making their own spacecraft and space stations. “NASA is
just leaving the companies to design whatever is best for their
projects,” De León says. New materials, especially compos-
ites and fabrics, could shave weight for easier transport and
extend an astronaut’s range of movement. “If we can make a
better suit, then human EVA capability will vastly improve,”
Reisman says.
Robots will be an important part of the next era of space explo-
ration. But there are some jobs only an astronaut can handle.Should Humans
Still Spacewalk?
Robots can handle many dangerous jobs. But sometimes,
you need an astronaut’s brain. / BY JOE PAPPALARDO /↓SPACE
HOW YOUR WORLD WORKSOperators in Houston remotely
control the Canadarm 2 for jobs
like helping dock the SpaceX
Dragon cargo craft, shown here.