Astronauts Steve Bowen and Woody Hoburgh donned overalls outside the International Space Station Friday for a space walk to install and open an upgraded solar array wing delivered to the complex earlier this week by a SpaceX Cargo Dragon supply vessel.
The astronauts switched their spacesuits to internal battery power at 9:25 a.m. EDT (1325 UTC) Friday. After depressurizing and leaving the Quest airlock, Bowen and Hoburgh headed to the starboard, or right-hand side of the space station’s football field-long electric truss to begin work installing the new solar array into a fixed arc, then deploying the solar blanket.
The SpaceX Cargo Dragon spacecraft delivered two new ISS Roll-Out Solar Arrays, or iROSA modules, to the space station earlier this week. The uncrewed cargo capsule launched Monday from NASA’s Kennedy Space Center in Florida and docked at the space station Tuesday, then the lab’s Canadian-made robotic arm removed the solar arrays from the Dragon spacecraft’s aft cargo bay and placed them in a temporary storage location on the station’s gears.
Bowen and Hoburgh began spacewalks on Friday.
The astronauts fired the restraint screws on one of the two new solar arrays, and Hoburg stepped up a foot restraint on the station’s robotic arm. Once the solar array was freed from its mount, Hoburg grabbed the rolled blankets — folded together and roughly the size of a refrigerator — as he rode the robotic arm to the new solar array’s permanent home in truss section S4, just on the inside of the right end of the space station’s backbone.
The astronauts there affixed the wrapped solar array to a mounting bracket installed on a previous spacewalk, then opened the hinge to open the two blankets that make up the iROSA module, like opening the cover of a book. Bowen torqued eight screws with a power tool to securely mount the iROSA to its mounting bracket.
A stabilization bracket connects the new arrays to the station’s power channels and rotating joints, which keep the solar wings pointed toward the sun while the spacecraft races around Earth at more than 17,000 miles per hour.
The International Space Station has eight power channels, each of which is fed by electrical energy generated from a single solar array wing that extends from the station’s backbone. Deployed Friday, a new solar array will produce electricity for the space station’s 1A power channel.
Bowen and Hoburg then mated four electrical connectors to the newly introduced solar array, which was positioned to partially cover one of the space station’s original solar panels that was delivered by the space shuttle mission during the lab’s construction 16 years ago this week. The eight old solar arrays had deteriorated over time, as expected, and NASA purchased six discarded solar panels to boost the space station’s power generation capacity back above its original capacity.
NASA plans to order one last pair of rolled-up solar arrays to complete the space station’s electrical upgrade, ensuring that the lab will have enough power to support research through the station’s planned retirement date in 2030.
The astronauts connected a “Y” cable to allow power to flow from both the original solar array and the new iROSA to the station’s power grid, then Hoburg released the screws that kept the iROSA blankets rolled up for the launch.
The blankets took about 10 minutes to spread out 63 feet (19 m) long. Each upgraded solar array is about 20 feet (6 meters) wide, about half the length and width of the station’s original solar arrays.
Despite their small size, each of the new arrays generates about the same amount of electricity as one of the station’s existing solar panels. The deployment mechanism design eliminates the need for motors to drive the solar array open.
Once the blanket was opened, the astronauts adjusted tension screws to secure the iROSA blanket in place.
Bowen and Hoburg then went back inside on the space station’s truss to prepare another iROSA module that will be installed at the far right end of the truss structure during the June 15 spacewalk.
After their tasks were completed, the astronauts returned to the Quest airlock and sealed the hatch. NASA determined that the spacewalk was officially complete when the astronauts began repressurizing the airlock at 3:28 PM EST (1928 UTC). The duration of the spacewalk was 6 hours 3 minutes.
Friday’s spacewalk was the ninth of Bowen’s career as an astronaut, and the first for the city of Hoburg. It was the 264th spacewalk since 1998 in support of the assembly and maintenance of the International Space Station, and the seventh spacewalk outside of a research site this year.
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