Aging shuttle-era spacesuits aboard the International Space Station have been declared ‘banned’ for normally-planned operational spacewalks, pending analysis to determine what led to the excess water in an astronaut’s helmet during a field trip in March, officials confirmed on Tuesday.
But bulky spacesuits — “extra-vehicular mobility units,” or EMUs — can still be used for emergency repairs or to troubleshoot other unexpected problems if agency officials agree after evaluating the overall risk.
“Until we better understand what the causal factors may have been during the last EVA with our EMU, we’re not going for the nominal (spacewalk) EVA,” said Dana Weigel, deputy director of the space station program at Johnson Space Center in Houston. “So we won’t do a planned EVA until we’ve had a chance to really address and rule out the major failure modes in the system.”
Water intrusion has been a cause for concern since a July 2013 spacewalk in which European Space Agency astronaut Luca Parmitano’s helmet was flooded with water, a frightening malfunction and life-threatening event that forced the excursion to end prematurely.
Parmitano was not injured, but after the spacewalk NASA said he reported “reduced visibility and breathing with water covering his eyes, nose and ears.” “Astronaut’s calm attitude to his water-filled helmet may have saved his life.”
The “high visibility close call” sparked a major investigation to determine the source of the leak. A detailed inspection revealed clogs in a component that inadvertently diverted water into a vent line that allowed intrusion into the helmet.
While working to resolve suit maintenance to prevent such clogs in the future, NASA implemented two steps to help a spacewalker return to the station airlock in a similar emergency.
A “Helmet Absorption Pad”, or HAP, is now placed at the rear of the helmet to absorb any excess water that may enter the helmet and a separate straw-like breathing tube has been added to provide unobstructed air supply. if necessary. Astronauts now report the status of their PAHs throughout a spacewalk.
More recently, Weigel said, another absorbent pad was added to form a kind of dam, preventing the movement of any water forward of the helmet.
There have been no serious cases of water intrusion since Parmitano’s spacewalk, but at the end of the last EVA on March 23, astronaut Kayla Barron, helping German astronaut Matthias Maurer out of his spacesuit, found water inside the helmet.
“It’s a bit difficult to judge the volume because it’s spread across the front of his visor,” Barron said. “But I think we should speed up the steps to get him out of his suit here.”
After the helmet was removed, the crew estimated that up to 50% of the visor was covered with a thin film of water and that the absorbent pad on the back of the helmet was wet.
“The HAP is a little wet, but I think it would have been difficult to detect it through a comms cap,” Barron reported. “Basically, maybe an eight to 10 inch diameter circle, a thin film of water on the helmet. And there’s water in his vent hole on the back of his neckband. “
NASA plans to return Maurer’s EMU to Earth in July aboard a SpaceX Dragon freighter for technical analysis.
Four spacewalks to continue upgrading the station’s solar power system had been tentatively planned for the rest of the year, two in August and two in November, but those EVAs are now on hold pending analysis. of Maurer’s pursuit.
“So far, we haven’t found anything unusual,” Weigel said of the inspections aboard the space station. “We’re looking for any obvious signs of contamination or fouling or anything else that may have entered our system. We don’t see it yet.”
While planned spacewalks are on hold, she said an emergency EVA could be approved after review and a “risk versus risk” assessment.
“Depending on what went wrong and the risk to the spacecraft and to the mission as a whole, we will see where we are with the investigation, where we are with the additional mitigation measures that we put in place. and we will specifically make a call depending on the eventuality and where we are at any given time,” she said.