Roll out of new space station solar arrays hits snag during spacewalk

iROSAs were designed to roll out, begin generating power ASAP, according to Boeing

In this image taken from NASA video, French astronaut Thomas Pesquet, top center, and NASA astronaut Shane Kimbrough venture out on a spacewalk Wednesday, June 16, 2021, to outfit the International Space Station with powerful, new solar panels to handle the growing electrical demands from upcoming visitors. (NASA via AP) (Uncredited, NASA)

Two astronauts conducting a spacewalk Wednesday began the installation of the International Space Station’s new upgraded power source in the form of two solar arrays that roll out like carpets but hit several set backs delaying the deployment of the new power source.

European Space Agency’s Thomas Pesquet and NASA’s Shane Kimbrough suited up and left the space station airlock at 8 a.m., beginning their six-hour long extravehicular activity, or EVA. Pesquet was wearing the spacesuit with the red stripes and Kimbrough was wearing the unmarked suit.

The pair were attempting to install the first of two new ISS Roll-Out Solar Arrays, or iROSAs, that arrived last week via SpaceX cargo delivery. The space station’s robotic Canadarm2 grabbed the rolled-up arrays from the SpaceX Cargo Dragon trunk on June 10 and has been holding them until the pair can be installed.

The two arrays were built by Jacksonville-based Redwire Space with Boeing solar cell technology. The blanket-like arrays are much smaller than the space station’s current arrays --but more powerful with new technology-- and will eventually provide 120 kilowatts, or 120,000 watts, of power during the daylight hours.

Currently, the ISS has eight solar arrays generating about 160 kilowatts of power total but it’s been more than 20 years since the first solar arrays were installed on the ISS and even with upgrades, solar cells degrade over time.

The new solar arrays are essentially large blankets with more than 9,000 solar cells on each one attached to carbon composite boom arms. The massive arrays are rolled up to launch in the Dragon cargo spacecraft and then, through two spacewalks, will be installed outside the ISS.

After about 4 hours into their spacewalk Kimbrough’s spacesuit had some monitoring issues and required him to re-enter the airlock for safety checks, delaying the task at hand for about an hour. Kimbrough’s spacesuit display unit was rebooted and a potential sensor error stabilized before he was cleared to return to the spacewalk.

Next, Pesquet and Kimbrough attempted to secure the first iROSA in front of the current ISS solar arrays but were unable to roll out the solar blanket due to technical hiccups. The pair spent significant time troubleshooting issues with ground control as teams offered suggestions.

The astronauts were able to soft capture the iROSA but ended their spacewalk without rolling out the solar blanket. The array was bolted down and secured until another attempt can be made.

Pesquet and Kimbrough spent more than 6 and a half hours outside the ISS.

Rick Golden, Boeing project manager, explained in a recent interview with News 6 that the way the arrays are rolled up it looks like a big carpet, and the arrays can be deployed in minutes, immediately ready to start turning sunlight into energy.

The astronauts should have pulled out the four flight release bolts in orbit and then the arrays are designed to unfurl in space but that didn’t happen Wednesday quite as planned.

“It just pulls it out, and it is powerless. There’s no telemetry to it, it’s a very simplistic approach. And then once it’s out, the sunlight will hit the PV (solar cells) and they’ll start generating power,” Golden explained.

The astronauts will conduct a second spacewalk Sunday to continue the installation of the two arrays. NASA is assessing how this delay will impact that spacewalk.

The full ISS power upgrade will consist of six iROSAs launching on supply runs to the ISS two at a time. The next pair of iROSAs will launch in spring 2022 and about a year later the final two will go up.

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