Astronauts Deploy a Second New Solar Array for ISS

Astronauts are making progress on upgrading the power system for the International Space Station (ISS), recently completing a spacewalk to install a second new solar array.

Astronauts Thomas Pesquet of the European Space Agency (ESA) and Shane Kimbrough of NASA stepped outside the space station at 1:45 p.m. ET on Friday, June 25, and deployed the new solar array. With preparations and checks, the spacewalk took 6 hours and 45 minutes in total, but the deployment of the array took only around 10 minutes, and the new array began generating power straight away.

This time-lapse shows the second iROSA, or roll-out solar array, unrolling after installation by @astro_kimbrough and @Thom_astro during their spacewalk. The actual unraveling took just 10 minutes and concluded at 1:55 EDT.

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— NASA's Johnson Space Center (@NASA_Johnson) June 25, 2021

This array, called an ISS Roll-Out Solar Array (iROSA), is one of six to be deployed as part of a long-term project to upgrade the space station’s power system. Some of the current solar arrays in use on the station are up to 20 years old, older than the 15-year life they were originally intended for. These older arrays are still functioning but the amount of power they generate is slowly dropping over time. The new arrays are smaller than the current arrays, but they generate the same amount of power because they are more efficient.

“The new solar array is positioned in front of the current solar array on the same plane and rotary joints, but not directly on top of the primary solar arrays,” NASA writes. “The new arrays are 60 feet long by 20 feet wide (18.2 meters by 6 meters) and will shade a little more than half of the original array, which is 112 feet long by 39 feet wide. Each new iROSA will produce more than 20 kilowatts of electricity, while the current arrays generate, on average, 17 to 23 kilowatts each.”

The same two astronauts performed several other spacewalks recently, including installing the first new solar array last week. The two must be well used to working with each other by now, as they have completed a total of five spacewalks together — three so far on their current mission, and two previous spacewalks during a previous mission in 2017 when they replaced the station’s older nickel-hydrogen batteries with new lithium-ion batteries.

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