Spacewalk ends early after water found in Kopra’s helmet
After two spacewalkers completed the primary task of replacing a voltage regulator and restoring full power to the International Space Station (ISS), water build-up inside NASA astronaut Timothy Kopra’s spacesuit helmet caused flight controllers to terminate the walk after 4 hours and 43 minutes on Friday, Jan 15.
Just before 11 a.m. CST (17:00 GMT), Kopra noticed a small water bubble inside of his helmet. Timothy Peake, Kopra’s spacewalking partner, also saw the bubbles in Kopra’s helmet. Kopra was asked by flight controllers to taste the water: he noted it was cold. The event was reminiscent of an issue back in July 2013 when ESA astronaut Luca Parmitano’s helmet started filling with water.
“As soon as you can tell if it’s cold water there’s something going on where that’s coming from a source in your backpack, which is a significant concern to us,” said astronaut Chris Cassidy, chief of the astronaut office, during an interview on NASA TV. Cassidy was the other spacewalker during the July 2013 incident.
Friday’s issue was not an emergency, but rules put in place due to the 2013 event prompted Flight Director Royce Renfrew to order both astronauts back inside in an orderly fashion. There was no rush and the crew was never in any danger. The hatch was closed with re-pressurization beginning at 11:31 a.m. CST (17:31 GMT).
“We had a [carbon dioxide] sensor that went fritzy on us,” Renfrew said of an event early in the spacewalk. “Then, a little bit later in the EVA [extravehicular activity], Tim Kopra started seeing some water on his visor.”
Once inside, Commander Scott Kelly and crew helped Kopra remove his helmet and collected the water in a syringe. Both the water as well as an absorption pad will be kept and sent back to Earth later for analysis. Kelly noted that he collected about 15 cubic centimeters of liquid.
The EVA started at 6:48 a.m. CST (12:48 GMT) with the suits being switched to battery power. Kopra exited first followed by Peake, who is the first British astronaut to go on a spacewalk. It was Kopra’s third EVA of his astronaut career.
“It looks great to see that Union Jack going outside,” Kelly said while holding a camera up towards the airlock window. “It’s explored all over the world, now it’s explored space.”
“Thank you, Scott, it’s great to be wearing it,” Peake said. “A huge privilege, proud moment.”
Once outside, the space station happened to be going into orbital night, something that happens once every hour and a half. “Beautiful sunset,” Peake said.
The first task was for the crew to head over to the S6 Truss on the far starboard side of the space station to replace the 1B channel Sequential Shunt Unit (SSU), which failed on Nov. 13, 2015. This unit regulates output voltage that the solar arrays produce to around 160 volts, although it can vary between 130 and 180 volts.
Kopra first went to the starboard Crew and Equipment Translation Aid (CETA) cart to get a foot restraint before continuing down the truss. After that, Peake took the spare SSU and headed toward the work site.
Once Kopra arrived at the work site, he installed the foot restraint to give him good access to the SSU. Peake got himself into a good position to help Kopra. The task required the two astronauts to work during the orbital night, to ensure that no electrical arcing would occur.
Kopra used the Pistol Grip Tool, a high-tech space screwdriver, to remove the sole bolt holding the failed SSU in place. He then stowed it into a bag in preparation to take it back to the airlock. Then, with the help of Peake, Kopra placed the spare SSU and began to blot it down.
Once that was complete, Peake took the failed SSU to the airlock. Kopra followed, returning the foot restraint to the CETA cart along the way. By this time, the two were already about 10 to 15 minutes ahead of the EVA timeline and would continue to breeze through their tasks.
After gathering some more tools at the airlock, Kopra then made his way to the Harmony module to begin reinstalling a non-propulsive vent (NPV), which was removed to allow for proper clearance when the Permanent Multipurpose Module was relocated early last year.
Meanwhile, Peake began his task of routing cables from the lab to the Unity node. This was a holdover from a previous EVAs due to time constraints. The ultimate goal is to route power and data cables from Unity over to Harmony where the International Docking Adapters (IDAs) will be attached. This task required him to translate across what is called the “rat’s nest”, a large collection of cables on the Z1 and S0 truss segments.
This was was around the time Kopra noticed his helmet had a small amount of water in it and where the spacewalk was terminated.
It took Kopra and Peake about 30 minutes to get back to the airlock. The crew wasn’t in any immediate danger, but per flight rules, the walk was done.
“Prior to any EVA, we look at all the tasks and say ‘these are the tasks that we really have to get done, these other ones we can break off at any time’; for instance, laying cable with wire ties,” Cassidy said in an interview with NASA PAO Robert Navias.
Cassidy said that the whole reason the SSU replacement was put in the timeline first was so that it was most likely to get finished in case an issue cropped up. Because that task was finished, the space station is back to full power.
Tasks leftover on this spacewalk includes finishing the cable routing for IDAs, releasing a launch latch on Pressurized Mating Adapter 3 and retrieving a luminaire in addition to a few get-ahead items.
“In several of the meetings that I attended, the common phrase was ‘anything after the SSU was all gravy anyways’,” Cassidy said. “We got a little bit of the gravy, but the meat was consumed.”
Video courtesy of NASA
Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a blog about the International Space Station, called Orbital Velocity.