Wrapping up unfinished work, two spacewalkers stepped outside the International Space Station early Saturday to complete electrical connections with a European experiment platform, to vent and relocate ammonia coolant jumpers and to install a new wireless camera transceiver.
They also planned to attach a stiffener to the Quest airlock’s flexible thermal hatch cover and to route a pair of ethernet cables near the central Unity module for high definition cameras that will be installed later.
The tasks originally were planned for two spacewalks earlier this month but they were deferred after the assembly of two solar array support fixtures took longer than expected.
As with all NASA spacewalks, or EVAs, today’s excursion officially began when astronauts Victor Glover and Mike Hopkins switched their spacesuits to battery power at 8:14 a.m. ET while still inside the airlock.
For identification, Glover, call sign EV-1, is wearing a spacesuit with red stripes and using helmet camera No. 20. Hopkins, EV-2, is wearing an unmarked suit and using helmetcam No. 22. He also is equipped with a new high-definition helmet camera.
This is the 237th spacewalk devoted to station assembly and maintenance since construction began in 1998 and the fifth so far this year. It is also the fourth for Glover and the fifth for Hopkins.
The first task on the agenda is to safely vent two hoses, or jumpers, used for loading ammonia coolant in the station’s thermal control system and for helping track down leaks. The jumpers are located on the far left end of the lab’s solar power truss, a segment known as port 6, or P6.
Spacewalk flight director Chris Edelen said one of the jumpers will be left in place on the P6 segment for any future troubleshooting that might be needed on that side of the station while the other will be stowed outside the airlock for use if needed later on the right side.
“Of course, when dealing with ammonia, extra vigilance is necessary because of the concern that if we got ammonia contamination on the suits, and then brought that inside station, that could represent a potential toxic atmosphere situation for the crew and station,” Edelen said.
“So again, we’ll be paying extra close attention to make sure that the suits don’t get any contamination with ammonia or if they do, we have contingency procedures available and the teams are trained to execute those to make sure that the crews stay safe.”
With the jumper venting and relocation complete, Glover planned to install a replacement wireless camera transceiver near the central Unity module while Hopkins worked at the forward end of the station where the European Space Agency’s Columbus laboratory module is attached.
An external experiment platform known as Bartolomeo was attached to the forward side of Columbus earlier, but spacewalkers had problems completing electrical connections during an earlier outing. Hopkins will attempt to finish that work.
The wireless video system external transceiver assembly, or WETA, that Glover planned to install is one of three mounted around the station’s exterior. The unit in question failed late last year.
“This is essentially an antenna that receives the transmissions from the crew members’ helmetcams,” Edelen said. “We … really appreciate having this is mission control during EVAs (spacewalks) to be able to have the crew members’ perspective to see exactly what they’re working on. So we definitely want to … get this replaced so that we have good coverage.”
The astronauts also planned to install a stiffener on a thermal cover that protects the airlock’s outer hatch and to route two ethernet cables on the back side of the P1 truss segment.
“This will be used to for a future wireless access point upgrade on the outside of the station to accommodate payloads as well as future high-def TV, wireless video,” Edelen said.
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