NASA Approves Sunday's Spacewalk-Water in Helmet "Feature" of Spacesuit

NASA International Space Station (ISS) program managers decided today that Wednesday’s “water in the helmet” episode is not an impediment to proceeding with another spacewalk on Sunday.   The ISS Mission Management Team (IMMT) gave approval for the spacewalk to proceed this morning.

NASA astronauts Terry Virts and Barry “Butch” Wilmore are conducting a trio of spacewalks to get docking ports ready to accept commercial crew spacecraft when they begin flying in 2017.   The first two on February 21 and February 25 went fine, but after Virts reentered the airlock on February 25 and it began repressurizing, he noticed water inside his helmet.

Virts was wearing spacesuit 3005 and NASA immediately explained that the same suit had a similar problem after a December 2013 spacewalk.  NASA is very sensitive to water incursion after a very serious incident in July 2013 when ESA astronaut Luca Parmitano’s helmet filled with water during a spacewalk while he was still outside the ISS.

This time was entirely different, according to NASA officials.  The lead EVA spacewalk officer, Alex Kanelakos, said on NASA’s Space Station Live program after the IMMT decision that it was only a small amount of water, 15 milliliters (ml), and it has happened seven times previously with this spacesuit.  He explained that a small amount of “carryover water” can develop inside the helmet during repressurization.  NASA considers up to 57 ml to be permissable.  Kanelakos did not say exactly how much water filled Parmitano’s helmet in July 2013, but indicated it was many times more.

Because this has happened with suit 3005 several times, Kanelakos said that although NASA does not “expect” it to happen, it is a “known feature” of that suit.

NASA posted an explanation later in the day saying the suit “has a history of what is called ‘sublimator water carryover’, a small amount of residual water in the sublimator cooling component that can condense once the environment around the suit is repressurized following its exposure to vacuum during a spacewalk….”

Why Virts and his ISS crewmates were surprised and concerned about the water is unclear if it is a known feature and has happened seven times in the past with this suit.

In any case, the spacewalk was given the go-ahead to proceed on Sunday, March 1, beginning at about 7:10 am ET.  NASA TV coverage will begin at 6:00 am ET.  The spacewalk is expected to last 6 hours 45 minutes.