Record-Breaking Spacewalk Successfully Upgrades International Space Station’s Power Supply

Two NASA astronauts, Stephen Bowen, and Warren “Woody” Hoburg, have now made history by installing the sixth and last International Space Station (ISS) Roll-Out Solar Array (iROSA), marking an increase in the orbital laboratory’s power supply. The historic spacewalk took place on Thursday, June 15, with the astronauts operating outside the ISS to augment the power of the 1B power channel, located on the opposite side of the station’s starboard truss.

The Noteworthy Spacewalk

The spacewalk began at 8:42 a.m. EDT (1242 GMT) as both astronauts switched their suits to internal battery power. After leaving the U.S. Quest airlock, the astronauts went to work preparing the array for removal from its temporary storage platform. Hoburg, using the station’s Canadarm2 robotic arm, transported the iROSA to its installation point. Meanwhile, Emirati astronaut Sultan AlNeyadi controlled the arm from inside the station, shifting Hoburg and the 720-pound (330 kilograms) array to the S4 truss. Bowen separately navigated to the same location.

Once in position, the duo alternated holding the iROSA while aligning it with its mounting bracket, an attachment point assembled and installed during a previous spacewalk. Once aligned, Hoburg and Bowen drove bolts to secure the array to the station, thus beginning the process of unfolding the iROSA from its launch configuration.

The New Solar Array Installation

With the iROSA securely bolted to the station, the astronauts briefly paused their work on the array’s installation to clean up their worksites, awaiting for the space station to move into Earth’s shadow to ensure the legacy IB solar array wasn’t generating power when the new iROSA was tied into the power channel.

When the station moved into eclipse, the astronauts connected cables to the new array assembly, readying the wing for deployment. Each iROSA, measuring 60 feet long by 20 feet wide (18.2 meters by 6 meters), overlays its corresponding legacy solar array by a little more than a half. Each produces over 20 kilowatts of electricity, contributing to a 30% increase in power production over the station’s legacy arrays alone, with six new arrays installed.

Once out of Earth’s shadow, Hoburg released two bolts allowing the iROSA to unfurl. The potential energy stored by the rolled-up carbon composite booms enabled the array to unroll on its own to its full length, with no motor needed.

A Look to the Future

This successful installation marked the completion of a two-year-long initiative to deploy all six iROSA assemblies, with the first unfurled on June 16, 2021. NASA and Boeing have a plan in place for a fourth set of roll-out arrays further to enhance the International Space Station’s power supply. These arrays, which would be the seventh and eighth installed, are targeted for delivery to the orbiting laboratory around 2025.

Record-Breaking Astronauts

Stephen Bowen, with his 10th spacewalk during this operation, now ties the record for the most extravehicular activities (EVAs) by an American astronaut, alongside former NASA astronauts Michael Lopez-Alegria, Bob Behnken, Peggy Whitson, and Chris Cassidy. This spacewalk also marks