Two astronauts floated outside the International Space Station on Wednesday. They installed the first of six rolled-up solar arrays that would restore the lab's power to factory-fresh levels. However, they could not extend the new panel as intended due to time wasted due to a spacesuit malfunction and an interference issue with the array mechanism.
Another spacewalk was planned on Sunday by European Space Agency astronaut Thomas Pesquet and NASA crewmate Shane Kimbrough to install a second roll-out solar array. Still, it's unclear how the unfinished work on Wednesday would fit into that timeframe.
How Astronauts Installed New Solar Panels
Space.com said Pesquet and Kimbrough, floating in the station's Quest airlock, switched their suits to battery power at 8:11 a.m. EDT to formally start the year's seventh spacewalk. That is for the 239th devoted to station assembly and maintenance since the building began in 1998.
The EVA was the first of two required to install a pair of ISS roll-out solar arrays (iROSAs) on the space station's primary power truss on the far left end.
The iROSA blankets were delivered to the station earlier this month aboard a SpaceX cargo ship and were planned to be mounted on fixtures that were built like Tinker Toys and affixed to the base of the existing port 6, or P6, solar wings during two spacewalks by other astronauts in March.
The space station has eight solar wings in total, four on each side of the truss, with each circuit receiving up to 120 kilowatts of power. The two P6 arrays, constructed in 2000 and supplying electricity to power channels 2B and 4B, are the station's oldest.
The first iROSA wing was attached to the current P6/2B array during Wednesday's spacewalk, followed by a spacewalk on Sunday to install the P6/4B blanket. Each of the iROSA panels will produce more than 20 kilowatts of energy.
The first half of Wednesday's game was set aside for carrying the first 750-pound iROSA out to the far left end of the power truss. This process required Pesquet and Kimbrough to manually hand the rolled-up array back and forth as they moved near the left-most P6 truss section.
Challenges Astronomers Face While Installing The Arrays
CNN said Kimbrough reported a problem with his suit's data display unit, which displays the status of several internal systems before the iROSA was removed from its mounting bracket. He went back into the airlock, hooked the suit to an umbilical, and reset the unit, which seemed to fix the problem.
A pressure surge in the suit's temperature management system was also observed. He was cleared to rejoin Pesquet and continue the spacewalk after an analysis on the ground. For the rest of the mission, the spacesuit worked usually.
The astronauts then carefully relocated the first iROSA to its installation place on the P6/2B solar wing base, despite delays. However, they could not separate the two portions of the array so that the panel could be stretched due to an interference issue.
Flight controllers opted to call it a day at that moment. Pesquet and Kimbrough were instructed to return to the airlock after completing a seven-hour 15-minute EVA, leaving the iROSA folded and not yet connected to station circuitry.
What Are iROSA Panels?
When fully unfurled, the iROSA panels will span 63 feet in front of an existing 112-foot-long P6 array, slanted around 10 degrees away from the old arrays.
The iROSA blankets include carbon composite struts on either side that are rolled up and secured in place for launch, unlike the station's original solar wings, which were deployed using sophisticated motor-driven self-assembling trusses. The pent-up "strain energy" is enough to unroll the blankets to their full length once the locks are released.
Dana Weigel, deputy manager of the space station program at the Johnson Space Center in Houston, told SpaceFlightNow the new panels are placed on top, over in front of the existing solar arrays. Weigel added the exposed portion of the old arrays will continue to generate power in parallel with the new displays.
Those new iROSA arrays have solar cells that are more efficient than our original cells, have a higher energy density, and create more electricity when combined than our original array did when it was new.
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