Spacewalkers carry out space station power system upgrades
Three days after a Russian spacewalk, Japanese space station commander Akihiko Hoshide and Frenchman Thomas Pesquet floated outside for their own excursion Sunday, building a support fixture for a roll-out solar array blanket that will be attached later.
The astronauts also replaced a device that measures the strength of the electrical environment around the International Space Station as it interacts with charged particles in the extreme upper atmosphere.
Looking on throughout was a 3D camera mounted on the space station's robot arm that was expected to capture high-definition shots of the spacewalk for use in a commercial documentary series, "The ISS Experience." The movie is intended to give viewers an immersive look at life in orbit.
"The procedures are developed in a way where the camera will be completely out of the path of the spacewalkers," said flight director Ali Boudous. "We made sure that the camera gets some amazing views, however it doesn't interfere at all with our spacewalk tasks themselves."
Floating in the Quest airlock compartment, Hoshide, making his fourth spacewalk, and Pesquet, making his sixth, switched their spacesuits to battery power at 8:15 a.m. EDT, officially kicking off the 12th spacewalk so far this year.
NASA is in the process of installing six new roll-out solar array blankets — iROSAs — to augment the space station's eight original wings, which have degraded over the years and no longer generate the power they did when they were new.
The iROSA blankets are designed to be mounted on triangular frames made up of multiple struts assembled in Tinkertoy fashion.
Two iROSA blankets were installed on the left outboard set of arrays in June. During Sunday's spacewalk, Hoshide and Pesquet assembled the support bracket for a left-side inboard iROSA array, which will be installed next year or in 2023. The remaining three iROSA's will be installed on the right side of the power truss.
With the iROSA support frame in place, Hoshide and Pesquet replaced a device called a floating potential measurement unit, or FPMU, that had a failed power supply. The device, located just inboard of the left-side solar arrays, measures charges on the station from its interaction with the space plasma environment.
After retrieving tools and configuring their safety tethers, Hoshide and Pesquet returned to the Quest airlock, sealed the hatch and began repressurization at 3:09 p.m. ET. Duration was six hours and 54 minutes, pushing total space station EVA time to 1,541 hours and 54 minutes over 244 spacewalks since assembly began in 1998.
Astronaut Mark Vande Hei originally planned to join Hoshide for Sunday's spacewalk, then scheduled for early September, but the outing was delayed after Vande Hei developed a pinched nerve in his neck.
To get the spacewalk video back to Earth aboard a SpaceX Dragon cargo ship at the end of September as originally planned, NASA managers decided to replace Vande Hei with Pesquet because they wear the same size suit and because Pesquet carried out three similar spacewalks in June.