WASHINGTON — A spacesuit malfunction that nearly drowned Italian astronaut Luca Parmitano during a spacewalk outside the international space station last July was probably caused when aluminum silicate debris clogged a water pipe and forced liquid into the suit’s ventilation system, according to a NASA report released Feb. 26.
“Of all the [spacewalk] issues we’ve encountered to date, this was probably the most serious one,” Chris Hansen, ISS chief engineer and chairman of the Mishap Investigation Board that produced the report, said on a Feb. 26 media teleconference.
Exactly how the suit’s plumbing got clogged is still a mystery, and an ongoing investigation “is expected to continue for many months,” according to the report. It is possible that the aluminum silicate was produced by a sublimator — a component in the suit’s life-support system used for cooling purposes.
The sublimator “may have been producing more silicates than other sublimators,” Michael Suffredini, manager of the ISS Program Office at NASA’s Johnson Space Center in Houston, said on the Feb. 26 call. “It’s pretty common in the suit, and [ordinarily] it doesn’t come out in large parts.”
NASA has never seen a spacesuit fail the way Parmitano’s did about 44 minutes into a July 16 spacewalk outside the ISS, when water flooded the astronaut’s helmet and forced him to navigate blindly back to a nearby airlock, according to NASA’s report on the accident.
NASA has not pinned down the root cause of Parmitano’s close call, but the agency has concluded that the suit he wore actually began leaking on the Italian astronaut’s previous spacewalk, which took place July 9.
Teams on the ground looked into the leak after that spacewalk but misdiagnosed the issue as a leaky drinking bag — a known problem with the type of suit Parmitano wore, and one that teams on the ground would not have found life threatening, Hansen said.
“It’s understandable why the teams would pick up the drink bag as the most likely failure,” William Gerstenmaier, associate administrator for NASA’s Human Exploration and Operations Mission Directorate, said on the call.
“We have a little bit of data from the fan pump separator, and it showed no anomalies at all” after it malfunctioned on the July 9 spacewalk, Hansen said.
Nevertheless, Hansen said the ISS ground team might have been hesitant to call for a deeper probe of the leak, since doing so would oblige astronauts to put off the experiments that NASA insists are the space station’s primary purpose.
Among the mishap investigation board’s recommendations are that flight teams at ISS mission control in Houston never hesitate to consume crew time for critical maintenance tasks, Hansen said. These, and the report’s other top-tier safety recommendations, are to be put in place at NASA before the agency’s next scheduled spacewalk, which is on the slate for late July or early August.
The spacesuit Parmitano was wearing, called an Extravehicular Mobility Unit, is made by Hamilton Sundstrand, which is now UTC Aerospace of Charlotte, N.C. NASA has certified each suit to remain on orbit for six years and perform as many as 25 spacewalks, Suffredini said.