How to watch NASA’s milestone 300th spacewalk

Two NASA astronauts have finished a spacewalk that saw the completion of three and a half years’ work to upgrade the International Space Station’s (ISS) power system.

The spacewalk on Tuesday, July 21, was notable for being the 300th such outing performed by U.S. astronauts since the first one in 1965 when Ed White exited his Gemini 4 capsule and floated for around 20 minutes while tethered to the spacecraft (check out this stunning collection of spacewalk images from over the years).

American astronauts Chris Cassidy, commander of the current Expedition 63, and flight engineer Bob Behnken, who arrived at the ISS at the end of May 2020 with Doug Hurley aboard SpaceX’s Crew Dragon in the spacecraft’s first crewed flight, finished off work that’s mainly involved swapping old nickel-hydrogen batteries with new lithium-ion batteries on the space station’s Starboard-6 truss structure. The batteries store power collected by the ISS’s main solar arrays, which is then used by the orbiting laboratory.

The entire operation to upgrade the station’s power supply took 12 spacewalks in all, with the task started by other ISS astronauts in January 2017.

The space station, which orbits Earth at an altitude of about 250 miles, hosts a revolving team of international space travelers who carry out ongoing research in microgravity conditions, so keeping it in tip-top condition is vitally important work.

“For almost 20 years, humans have lived and worked continuously aboard the International Space Station, advancing scientific knowledge and demonstrating new technologies, making research breakthroughs not possible on Earth that will enable long-duration human and robotic exploration into deep space,” NASA says on its website. “As a global endeavor, 239 people from 19 countries have visited the unique microgravity laboratory that has hosted more than 2,800 research investigations from researchers in 108 countries and areas.”

How to watch the 300th spacewalk

A stream of the spacewalk, which lasted 5 hours and 29 minutes, can still be viewed on NASA’s YouTube channel.

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