NASA's spacesuits are getting old. The extra-vehicular mobility units—EMUs
for short—were designed and built for spacewalks outside NASA's space
shuttles, which flew for the last time in 2011. Nowadays, the EMUs are an
integral part of maintaining and upgrading the International Space Station
(ISS) exterior, providing the crew with the ability to live and work in the
vacuum of space for extended periods of time (spacewalks regularly last from
6 to 8 hours). However, at the end of the most recent spacewalk on March 23,
NASA astronaut Kayla Barron discovered water in the helmet of German
astronaut Matthias Maurer while she helped him remove the suit.
In microgravity, water can bead up in clumps and cling to the face and eyes,
causing serious danger to the astronaut inside a leaking suit. As a
precaution and preventative measure, future spacewalks have been put on
hold.
At a press conference on May 17, NASA officials shared details of the
decision to pause upcoming Extravehicular Activities (EVAs). "Until we
understand better what the causal factors might have been during the last
EVA with our EMU, we are no-go for nominal EVA," said Dana Weigel (Deputy
Manager, Space Station Program). "We won't do a planned EVA until we've had
a chance to really address and rule out major system failure modes."
There were four upcoming EVAs scheduled for 2022, two each in August and
November. These spacewalks were meant to carry out upgrades to the station's
power systems, but now will only go ahead after careful inspection of the
malfunctioning suit.
So far, they've yet to find the cause of the problem. "We're looking for any
obvious signs of contamination or fouling or something else that might have
gotten into our system. We're not seeing that yet," said Wiegel.
New spacesuit designs are in the works, but these are tailored towards EVAs
on the lunar surface for the upcoming Artemis program. And with the ISS due
for retirement in the next decade (currently set for 2031), the likelihood
of new EMUs for the ISS is small. According to a 2017 Office of the
Inspector General report, eighteen EMUs were manufactured during the shuttle
era, and of these, eleven remain, four of which are on the station, while
the rest are used on the ground for testing and training.
That doesn't mean we won't see any more EVAs in the near future. Further
testing might find the source of the fault, and additional precautions could
enable the EVA schedule to proceed. Water samples from the failed suit will
be returned to Earth for analysis—any identifiable contaminants they find
will help determine where the leak originated.
In the last decade, there have already been several upgrades to the EMUs to
protect against water, which is required in the suits for both drinking and
cooling. An absorbent pad was added to the back of the astronaut's head in
2014, as well as a breathing tube, for use in the event that water covers
the astronaut's mouth and nostrils. These changes were instigated by a close
call in 2013, when astronaut Luca Parmitano found his helmet filling with
water, making it difficult to see and breathe. He had to cut his spacewalk
short and return to the safety of the station to deal with the dangerous
situation before it cut off his airways.
For the near future, while the investigation proceeds, NASA says it would
consider using the EMUs if necessary in an emergency situation.
"Depending upon what has failed and what the risk is to the spacecraft and
to the mission overall, we'll look at where we are with the investigation,
where we are with the additional mitigations that we're putting in place and
we'll specifically make a call based on the contingency and where we are at
the given moment," Wiegel said.
In addition, the Sokol spacesuits used by Russian crew members aboard the
ISS still function (Russian cosmonauts last performed an EVA on April 28),
providing a secondary option in case the need for an emergency EVA arises.
Additional absorption pads for installation into the EMU helmets arrived at
the ISS aboard the Boeing Starliner last week, which made its first-ever
successful docking with the ISS during an uncrewed test flight on May 20th.
What additional EMU upgrades are required will become clear as the
investigation continues.
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Space & Astrophysics