July 15 (UPI) — Two NASA astronauts plan to walk in space again Thursday to replace aging batteries on the International Space Station as part of an extended SpaceX mission.
The spacewalk is to begin about 7:35 a.m. EDT and last up to seven hours, according to NASA, which will provide live-stream video coverage.
Astronauts Bob Behnken and Chris Cassidy will brave the extreme conditions of outer space for the third time in a month. Four spacewalks have been planned to replace batteries on the exterior of the space station.
Behnken and astronaut Doug Hurley arrived at the space station May 31 as part of the historic return to human spaceflight from U.S. soil. The mission also marked the first time SpaceX carried people into space.
NASA extended the historic trip to space — originally planned as a five-day demonstration — to several months because the batteries needed replacement.
Those replacements will “put the station in a much better configuration long-term,” Kenneth Todd, the space station’s manager for integration and operations, said during a press conference in June.
Behnken and Cassidy spent just over six hours in space during each previous walk on July 16 and 21. The space station is powered largely by solar power stored in batteries that are accessible only from space.
On Thursday, the astronauts plan to remove five older nickel-hydrogen batteries and replace them with three new lithium-ion batteries, as well as accompanying hardware.
They will replace one last aging battery Tuesday, when Behnken and Cassidy venture out on the 300th spacewalk involving U.S. astronauts since Ed White stepped out of his Gemini 4 capsule on June 3, 1965.
After replacing all the batteries, the astronauts are to perform other maintenance Tuesday, including preparing for the arrival of a new airlock built by Houston-based NanoRacks designed to release experiments into space. SpaceX plans to send the new airlock aloft later this year.
Hurley will remain inside the spacecraft to help spacewalkers in and out their spacesuits and monitor the excursion.
As they plan and execute spacewalks, the astronauts also continue to evaluate the Dragon capsule that brought them to the space station.
Hurley and Behnken could return to Earth in a final test of SpaceX’s Crew Dragon capsule as early as Aug. 2, according to NASA officials.
Behnken and Cassidy reviewed spacewalk procedures step-by-step through computer simulation for two hours Monday while Hurley charged their spacesuit batteries.
Astronauts return to space from U.S. soil