Watch live: Astronauts begin spacewalk to prep for station power system upgrades

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Two astronauts floated outside the International Space Station early Sunday for the first in a series of spacewalks needed to upgrade the lab’s aging solar power system, working to install one and possibly two support fixtures that eventually will hold new solar blankets.

Floating in the Quest airlock, Kate Rubins and Victor Glover switched their spacesuits to battery power at 6:12 a.m. EST to officially kick off the 235th station spacewalk since assembly began in 1998, the third so far this year and the third overall for both astronauts.

For identification, Rubins, call sign EV-1, is wearing a suit with red stripes and using helmet camera No. 22, along with a new high-definition camera that provides razor-sharp views. Glover, EV-2, is wearing an unmarked suit and using helmet cam 20.

The goal of the excursion is to begin work to install struts at the far left end of the station’s power truss to support new roll-out solar array blankets scheduled for delivery later this year and next. Additional spacewalks will be needed to installed additional support fixtures and, eventually, new solar array blankets.

The space station is equipped with four huge solar array wings, two on each side of the lab’s power truss. Each wing is made up of two 39-foot-wide blankets extending 112 feet in opposite directions. The first two-blanket wing was launched in December 2000 with additional pairs delivered in 2006, 2007 and 2009.

The arrays feed power into eight electrical circuits, two per wing. When the station is in daylight, the arrays charge batteries and deliver power to the lab’s myriad systems. During night passes, the batteries feed stored power to the station.

Solar cells degrade over time and NASA is adding six new blankets, at a cost of $103 million, to the existing power system. Each one of the new ISS roll-out solar arrays, or IROSA, blankets measure 20 feet wide by 63 feet long when fully extended, generating more than 20 kilowatts.

Combined with the 95 kilowatt output of the original eight panels, the station’s upgraded system will provide about 215,000 kilowatts of power.

“Commercial users are coming on board that are looking for power that that we didn’t even dream of back in the mid 90s,” said Kenny Todd, deputy manager of the station program at the Johnson Space Center.

“The technology really has gotten to the point that we can do something like these roll out solar arrays. They’re not as big as the ones that we previous deployed, and yet we can we can get even more power out of them.”

Six of the space station’s eight large solar arrays will be augmented with new solar panels. Credit: NASA TV/Spaceflight Now

Rubins and Glover planned to spend the day Sunday working at the base of the far left, or port six, set of solar arrays, which provide power to electrical channels 2B and 4B.

Exiting the airlock, the astronauts carried out two eight-foot-long bags containing struts what will be assembled into triangular support fixtures at the bases of the P6 arrays.

Depending on how easily the first fixture go together for the 2B array, Rubins and Glover will either complete the second support structure or defer some of the task to another spacewalk next Friday. That spacewalk will be carried out by Rubins and Japanese astronaut Soichi Noguchi.

“We’ll start with the 2-Bravo side, complete the installation of that structure, and then we’ll pick up with the 4-Bravo side and get as far as we can on that one,” said spacewalk officer Art Thomason.

Additional spacewalks will be needed later to install the four additional solar blanket supports and the blankets themselves. The new arrays will be delivered aboard three SpaceX Dragon cargo ships staring later this year. Two spacewalks will be required to install each new blanket.

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