NASA puts ISS spacewalks on hold to investigate water leak

WASHINGTON — NASA continues to investigate water that leaked into a spacesuit helmet during a spacewalk earlier this year, postponing future spacewalks until engineers can fix the problem.

The leak occurred during the most recent spacewalk from the US segment of the station on March 23, which involved NASA astronaut Raja Chari and European Space Agency astronaut Matthias Maurer. At the end of the nearly seven-hour spacewalk, Maurer reported that water had accumulated on his visor, although the thin film of water, about 20 to 25 centimeters across, posed no immediate threat to him.

NASA had provided few updates on the water leak since the incident. However, at a May 12 meeting of NASA’s Aerospace Safety Advisory Panel (ASAP), Susan Helms, a former NASA astronaut serving on the panel, said the agency is “no-go” for spacewalks or EVAs right now because the ongoing investigation.

“Because NASA is considering the risk attitude for these aging suits, the EMU is currently unsuitable for planned EVAs pending an investigation into what they discover,” she said. An EMU, or Extravehicular Mobility Unit, is the spacesuit used by NASA for ISS spacewalks.

During a May 17 briefing about the upcoming Boeing CST-100 unmanned flight test, Dana Weigel, NASA ISS deputy program manager, confirmed that NASA is not doing routine spacewalks for the time being. The investigation found no signs of contamination in the water in the suit that could be linked to the helmet leak.

The suit itself, she said, cannot be inspected in detail until it has returned to Earth. NASA plans to return the suit on the next SpaceX Cargo Dragon mission, which will launch to the station in early June.

“From the EVA standpoint, until we better understand what the causative factors may have been during the last EVA with our EMU, we’re not going for nominal EVAs,” she said. “We won’t be doing a planned EVA until we’ve had a chance to really address and rule out major system failures.” This will be done through an assessment process that she compared to a flight readiness assessment.

Weigel said NASA will consider “contingency” spacewalks by weighing the risk of conducting the spacewalk against the risk of the station component requiring a spacewalk to repair or replace. “We will have to look at risk versus risk,” she said, who will include the status of the investigation and any action taken to resolve the issue.

The Crew-4 mission yielded several pads designed to be placed inside the helmet to absorb water, she said. Sixteen additional pads will be delivered on the Starliner mission.

The “no-go” rating for routine spacewalks has little practical effect on ISS operations, as spacewalks were not scheduled to install a second set of new solar panels until later this year. Weigel has not estimated how long the investigation will take.

The March incident was not nearly as serious as in 2013, when water leaked into the helmet of another ESA astronaut, Luca Parmitano, shortly after his spacewalk began. He was able to return safely to the airlock, but only after about a liter and a half of water leaked into the helmet, making it difficult for him to breathe.

Water leaks have been a periodic problem for the suits for years. “There are still issues with evidence of water in the spacesuit helmets after an EVA shutdown or even, in some cases, during an EVA,” Helms said at the ASAP meeting, with no apparent cause for the problem. In addition to the addition of the pads, she said engineers are studying “the general level of helmet moisture” that is normal for the suit.

The water leak, she suggested, is evidence that the decades-old suits are nearing the end of their useful life. Changing the suits has long been a concern for ASAP and others, including the agency’s inspector general. NASA has focused on a new spacesuit called the xEMU for Artemis lunar missions, and has proposed measures to extend the lifespan of current space station suits through 2028.

“The current plan is to extend the current use of EMU to 2028; however, it is becoming increasingly clear that the useful life of current EVA suits is limited,” the panel noted in its annual report published in January. “New suits are needed not only for future space exploration, but also for current space activities. NASA cannot maintain necessary, ongoing operations in low Earth orbit without fully functional EVA suits.”

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