WASHINGTON — NASA is continuing to investigate water that leaked into a spacesuit helmet during a spacewalk earlier this year and is postponing future spacewalks until engineers can resolve the problem.
The leak took place during the most recent spacewalk from the US segment of the station on March 23, involving 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 pooled on his visor, although the thin layer of water, about 8 to 10 inches wide, 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 who is on the panel, said the agency “does not conduct” spacewalks, or EVA, currently because the current investigation.
“Because NASA is thinking about the risk posture for these suits, which are aging, the EMU is currently not accepting planned EVAs pending an investigation into what they discover,” he said. An EMU, or Extravehicular Mobility Unit, is the spacesuit used by NASA for ISS spacewalks.
In a May 17 briefing on the upcoming Boeing CST-100 uncrewed flight test, Dana Weigel, NASA’s ISS deputy program manager, confirmed that NASA is delaying routine spacewalks for the time being. The investigation found no signs of contamination in the suit water that could be related to the helmet leak.
The suit itself, he said, cannot be inspected in detail until it is returned to Earth. NASA plans to bring the suit back on SpaceX’s next cargo Dragon mission, which will launch to the station in early June.
“From an EVA standpoint, until we better understand what the causal factors might have been during the last EVA with our EMU, we’re not going to nominal EVAs,” he said. “We won’t do a planned EVA until we’ve had a chance to really address and rule out the major failure modes of the system.” That will be done through a review process that he likened to a flight readiness review.
Weigel said NASA will consider “contingency” spacewalks by balancing the risk of conducting the spacewalk against the risk posed by the component of the station that requires a spacewalk to repair or replace. “We will have to analyze risk versus risk,” he said, which will include the status of the investigation and any measures to resolve the problem.
The Crew-4 mission delivered several pads designed to be placed inside the helmet to absorb water, he said. Sixteen more pads will be delivered in the Starliner mission.
The “no go” assessment for routine spacewalks has little practical effect on ISS operations, as no spacewalks were planned until later this year to install a second set of new solar arrays. Weigel did not estimate how long the investigation will take.
The March incident was not as serious as the one in 2013, when water leaked into the helmet of another ESA astronaut, Luca Parmitano, shortly after he began his spacewalk. He was able to return to the airlock safely, but only after about a liter and a half of water seeped into his hull, making it difficult for him to breathe.
Water leaks have been an intermittent problem for suits for years. “There are still ongoing problems with evidence of water on spacesuit hulls after the conclusion of an EVA or even, in some cases, during an EVA,” Helms said at the ASAP meeting, with no clear root cause of the problem. . In addition to adding the pads, he said engineers are looking at the “general helmet moisture level” normal for the suit.
The water leak, he suggested, is evidence that decades-old suits are nearing the end of their useful life. Replacing the suits has been a long-standing area of concern for ASAP and others, including the agency’s inspector general. NASA has focused on a new spacesuit, called xEMU, for the Artemis lunar missions, and has proposed measures to extend the lifespan of current space station suits to 2028.
“The current plan is to extend the current use of the EMU until 2028; however, it is becoming increasingly apparent that the service 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 their current space activities. NASA cannot maintain ongoing and necessary low-Earth orbit operations without fully functional EVA suits.”