Astronauts Shane Kimbrough of NASA and Thomas Pesquet of the European Space Agency will conduct their third spacewalk in just over a week to install a second new solar array outside the space station on Friday.
Pesquet is wearing red stripes on his spacesuit as extravehicular crew member 1, and Kimbrough is wearing the suit without stripes as extravehicular crew member 2.
During the spacewalk, Pesquet will be attached to the end of the robotic Canadarm2, which he’ll use to grab the solar array. Inside the space station, astronaut Megan McArthur will maneuver the robotic arm and Pesquet to the location where the array will be installed.
It’s Pesquet’s fifth and Kimbrough’s ninth spacewalk overall, and their fifth together as a team. And this is the 241st spacewalk to support the assembly, maintenance and upgrading of the space station.
The duo attempted to install the first solar array last Wednesday and ran into technical issues before finishing the job. But on Sunday? They successfully installed the first Roll-Out Solar Array, called iROSA, bolted it into place and connected cables to the station’s power supply.
The solar arrays arrived at the space station on June 5 after launching on the 22nd SpaceX Dragon cargo resupply mission. The arrays were rolled up like carpet and are 750 pounds (340 kilograms) and 10 feet (3 meters) wide.
Once the array is unfurled and bolted into place by the astronauts, it will be about 63 feet (19 meters) long and 20 feet (6 meters) wide. This unfurling process takes about six minutes.
While the original 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 exposed portion of the old arrays will still be generating power in parallel with the new arrays, but those new 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.