Astronauts Kayla Barron and Raja Chari floated out of the International Space Station airlock for a spacewalk Tuesday, installing brackets and struts to support new solar arrays to upgrade the research lab’s power system on the same day that crewmate Mark Vande Hei marked his 341st day in orbit, a U.S. record for a single spaceflight.

Barron and Chari put on their NASA spacesuits early Tuesday, depressurized the station’s Quest airlock, and opened the hatch to venture outside the complex. The spacewalk officially began at 8:11 a.m. EDT (1211 GMT), when the astronauts switched their suits to battery power.

The astronauts gathered equipment and tools before heading out to the space station’s starboard, or right-side, truss for their work.

Barron was the lead spacewalker, designated EV1, and wore a suit marked with red stripes. Chari, designated EV2, wore a spacesuit with no stripes.

After making their way to the work site, the astronauts assembled and installed brackets and struts to accommodate new solar arrays to be delivered to the space station on a future SpaceX Dragon cargo mission. The spacewalkers constructed the triangular fixture, called a modification kit and made of individual struts, to provide a mounting location for one of six new roll-out solar array wings to enhance the station’s power generation capability.

Two of the station’s new roll-out solar arrays, or iROSAs, were delivered on a SpaceX resupply mission last June and installed on the outboard port-side, or left-hand, truss . The next two are scheduled to arrive on a SpaceX flight in October, and another pair will be hauled up to the station later.

The new arrays are designed to cover up portions of the space station’s older solar arrays, which have degraded over time.

The work by Barron and Chari on Tuesday focused on the solar array modification kit for the inboard starboard truss.

The astronauts finished up the work with the solar array struts ahead of schedule, allowing them to move out to the end of the port truss on the opposite side of the space station. At that location, they opened insulation covering a battery charge/discharge unit and reduced torque on bolts holding similar units into place in preparation for a possible future swap out using the station’s robotics systems.

The spacewalkers also inspected an electrical panel on the Alpha Magnetic Spectrometer particle physics experiment to check how easy it would be to access the component, if necessary during future upgrades or repairs to the instrument.

Barron and Chari, both on their first flights to space, arrived at the space station in November on SpaceX’s Crew Dragon Endurance spacecraft. The spacewalk Tuesday was the second of Barron’s career, following an excursion in December. It was the first for Chari.

The spacewalk was the 247th in support of International Space Station assembly and maintenance.

Barron, Chari, and crewmates Tom Marshburn and Matthias Maurer are slated to return to Earth on their Crew Dragon spacecraft around April 26, 11 days after the launch of a replacement team of four astronauts on another SpaceX Dragon capsule.

The spacewalk Tuesday came the same day that Mark Vande Hei, who launched to the station last April on a Russian Soyuz spacecraft, broke the U.S. record for the longest duration human spaceflight. Vande Hei marked his 341st day in space Tuesday, surpassing the length of former NASA astronaut Scott Kelly’s nearly year-long mission in 2015 and 2016.

Vande Hei is scheduled to return to Earth on March 30 with two Russian cosmonauts, ending a planned 355-day flight in low Earth orbit.

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