Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more.
European Space Agency astronaut Thomas Pesquet and Japan Aerospace Exploration Agency astronaut Akihiko Hoshide are back inside the International Space Station after completing a successful spacewalk Sunday to prepare for more solar array upgrades.
The spacewalk started around 8:15 a.m. ET and lasted six hours and 54 minutes, according to NASA tweets and footage. Live coverage has been airing on NASA’s TV channel and website.
During the walk, Hoshide and Pesquet installed a modification kit, or support bracket, to prepare the outside of the station for future Roll-Out Solar Array installation work.
In its spacewalk commentary, NASA said the astronauts had completed all their primary tasks for the day as well as “one get ahead task,” which was replacing a part in the station’s airlock.
The two astronauts worked on the inward port side of the station’s backbone truss structure called P4. This is close to the space station’s living space.
When new solar arrays are sent to the space station, the modification kit will allow astronauts on a future spacewalk to install the third new Roll-Out Solar Array (which arrive rolled up like carpet).
The solar array upgrades will help upgrade the station’s power channels.
Sunday’s spacewalk was the first conducted out of the orbiting laboratory’s Quest airlock by two international partner astronauts at the space station, according to NASA.
A 360-degree virtual reality camera filmed Hoshide and Pesquet during their spacewalk.
During the spacewalk, Hoshide was extravehicular crew member one, wearing the spacesuit with red stripes, and Pesquet was extravehicular crew member two in a white unmarked suit.
It was the fourth career spacewalk for Hoshide and the sixth spacewalk for Pesquet. It was the 244th spacewalk to help assemble, maintain and upgrade the station.
Upgrading solar power
While the current solar arrays on the space station are still functioning, they have been supplying power there for more than 20 years and are showing some signs of wear after long-term exposure to the space environment. The arrays were originally designed to last 15 years.
Erosion can be caused by thruster plumes, which come from both the station’s thrusters as well as the crew and cargo vehicles that come and go from the station, said Dana Weigel, deputy manager of the International Space Station Program.
“The other factor that affects our solar arrays is micrometeorite debris. The arrays are made of a lot of small power strings, and over time those power strings can degrade if they’re hit by debris,” she said.
The new solar arrays will be placed in front of the current ones. This will increase the space station’s total available power from 160 kilowatts to 215 kilowatts. It’s also a good test for the new solar arrays because this same design will power parts of the Gateway lunar outpost, which will help humans return to the moon through NASA’s Artemis program in 2024.
“The exposed portion of the old arrays will still be generating power in parallel with the new arrays, but those new Iris arrays have solar cells on them that are more efficient than our original cells,” Weigel said.
“They have a higher energy density and together in combination may generate more power than what our original array, when it was new, did on its own.”
The new arrays will have a similar 15-year expected life span. However, since the degradation on the original arrays was expected to be worse, the team will monitor the new arrays to test their true longevity because they may last longer.
Rescheduling a spacewalk
Sunday’s spacewalk was rescheduled from August 24, with some changes. The original spacewalk plan included NASA astronaut Mark Vande Hei working alongside Hoshide.
The August spacewalk was postponed a day before it was set to occur due to what NASA described as a “minor medical issue” experienced by Vande Hei. He later revealed he had a pinched nerve in his neck on Twitter.
During the spacewalk, Vande Hei provided support from inside the space station as he continues to recover.
The agency also provided an update on the detection of smoke on the space station earlier this week.
A Russian spacewalk continued as scheduled on Thursday despite the fact that the space station crew was awakened by a fire alarm around 10 p.m. ET Wednesday night.
The alarm sounded for a minute after sensors detected smoke in the Russian Zvezda module. The smoke and burning plastic smell was also present in the US parts of the space station.
The crew reacted quickly, replaced air filters, scrubbed the atmosphere, and all signs of smoke dissipated, according to NASA. However, the source of the smoke was not identified at the time.
The Russian cosmonauts have been investigating the issue, and believe they have discovered a connection. They had a piece of equipment running in the module that has since been turned off. After that, the smell dissipated.
“Everything is returned back to normal, and they haven’t had any recurrence of any issues,” Weigel said. “So everything is stable and great onboard.”