Continuing work left over from a spacewalk last month, astronauts Nicole Mann and Koichi Wakata headed outside the International Space Station Thursday to finish installing a mounting bracket for new solar arrays due to arrive at the complex on a SpaceX resupply mission in June.
Mann and Wakata switched their spacesuits to internal battery power at 7:45 a.m. EST (1245 GMT) Thursday, marking the official start of the spacewalk. After exiting the Quest airlock, the two astronauts moved to the right, or starboard, side of the space station’s truss backbone to complete assembling a mounting bracket they started working on during a spacewalk Jan. 20.
The astronauts finished work on the attachment fixture, called a modification kit, associated with Channel 1A of the space station’s electrical network, which consists of eight power channels fed by power from the lab’s large solar arrays. During the previous spacewalk last month, Mann and Wakata competed work on a similar mounting fixture on Channel 1B of the power system.
With the primary goal of the spacewalk complete, the astronauts moved on to secondary objectives, including the relocation of a portable foot restraint for use on a future spacewalk, and cable routing. After finishing their tasks, Mann and Wakata headed back to the Quest airlock and began re-pressurizing the compartment at 2:26 p.m. EST (1926 GMT). The spacewalk’s official duration was 6 hours and 41 minutes.
The 1A and 1B power channels, both on the starboard side of the station’s solar power truss, will be upgraded with new roll-out solar arrays scheduled for launch in June on a SpaceX Dragon cargo freighter. Channel 1B is on the S6 truss section at the far right of the power truss, and Channel 1A is located on the next section inward, called S4.
SpaceX has already launched four of the roll-out solar arrays, called iROSAs, on two previous Dragon resupply missions in June 2021 and in November 2022. The iROSA units are built by Redwire, and are designed to augment the space station’s capability to generate electricity as the efficiency of the lab’s original solar panels declines with age.
When the new solar arrays arrive later this year, astronauts at the space station will go outside on spacewalks to install and unroll the new power generators.
The roll-out solar arrays launch wrapped around a spool to fit inside the Dragon spacecraft’s cargo trunk. Once deployed, they stretch about 63 feet long and 20 feet wide (19-by-6 meters), roughly half the length and half the width of the station’s original solar panels. The solar array blanket deploys at a canted angle relative to the original solar panel on each truss, allowing sunlight to illuminate the new and old arrays.
Despite their smaller size, each of the new arrays generate about the same amount of electricity as each of the station’s existing solar panels.
The original solar panels launched on four space shuttle missions from 2000 to 2009. As expected, the efficiency of the station’s original solar arrays has degraded over time. NASA is upgrading the space station’s power system with the new roll-out solar arrays — at a cost of $103 million — which will partially cover six of the station’s eight original solar panels.
When all six iROSA units are deployed on the station, the power system will be capable of generating 215 kilowatts of electricity to support at least another decade of science operations. That’s a 30% increase in power generation capability. The enhancement will also accommodate new commercial modules planned to launch to the space station.
The spacewalk Friday was the second in the careers of Wakata and Mann, and the 259th spacewalk overall since 1998 in support of space station assembly and maintenance. Mann, a Marine Corps pilot and designated EV1 as the lead spacewalker Thursday, is on her first spaceflight. Wakata, a Japanese astronaut, is a veteran astronaut on his fifth mission to space.
Mann and Wakata launched Oct. 5 on a SpaceX Crew Dragon spacecraft with crewmates Josh Cassada and Russian cosmonaut Anna Kikina. They are scheduled to return to Earth in early March, after the arrival of another team of four astronauts and cosmonauts on SpaceX’s next crew launch scheduled for Feb. 26.
NASA astronaut Frank Rubio and Russian cosmonauts Sergey Prokopyev and Dmitri Petelin round out the seven-person crew on the International Space Station. They arrived at the space station in September on a Russian Soyuz spacecraft, and will return to Earth in September after more than a year in orbit. Their mission was extended after their Soyuz spacecraft was damaged in December by an impact from a small piece of debris, likely a small piece of rock from deep space.
Russia plans to launch a replacement Soyuz spacecraft without a crew on-board Feb. 20 to serve as a lifeboat for Prokopyev, Petelin, and Rubio, and eventually bring them home later this year.
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