STORY WRITTEN FOR CBS NEWS & USED WITH PERMISSION
Two astronauts labored outdoors the International Space Station Wednesday to assist reposition two spare photo voltaic array ammonia coolant pump assemblies, placing a failed unit, dubbed “Leaky,” into long-term storage and attaching one other, generally known as “Frosty,” to an appendage of the lab’s robotic arm.
After the spacewalk is over, arm operators on the Johnson Space Center in Houston deliberate to transfer Frosty to the P6 photo voltaic array section on the far left finish of the station’s energy truss the place it may be plugged in for diagnostics. It will be a part of yet one more spare pump movement management sub-assembly, or PFCS, generally known as “Motley,” that’s already in place on P6.
The models are designed to assist push coolant by photo voltaic array batteries to maintain them from overheating. The appropriately named Frosty has been saved outdoors the station for almost 20 years however it as soon as was with out heater energy for an prolonged interval and engineers should not certain if it’s nonetheless a viable spare.
Motley was delivered to the lab advanced by a SpaceX Dragon cargo ship earlier this yr. As its identify would possibly recommend, it’s made up of spare components however it’s totally operational and available if one of many eight operational PFCS models, one for every photo voltaic array set, fails.
But as a result of the station makes use of eight PFCSs to cool all the photo voltaic array batteries, NASA needs two operational spares obtainable always and engineers need to discover out whether or not Frosty is, in reality, operational.
Station commander Drew Feustel and Ricky Arnold, floating within the station’s Quest airlock, switched their spacesuits to battery energy at 7:39 a.m. EDT (GMT-Four), formally kicking off a deliberate 6.5-hour spacewalk.
For identification, Feustel, name signal EV-1, is carrying a swimsuit with purple stripes and is utilizing helmet digicam 17. This is his eighth spacewalk after six throughout two shuttle missions and one outdoors the station earlier this yr. Arnold, EV-2, is carrying an unmarked swimsuit and is utilizing helmet cam 18. This is his fourth EVA after two on a shuttle flight and one with Feustel on the station.
Going into the EVA, Frosty was mounted on External Storage Platform No. 1 whereas Leaky was earlier hooked up to an appendage of the station’s particular function dexterous manipulator, or DEXTRE, a multi-joint hand-like becoming utilized by the lab’s robotic arm.
Leaky will take Frosty’s place on ESP-1 the place it’ll stay in long-term storage and Frosty will likely be hooked up to DEXTRE. After the spacewalk is over, flight controllers will use the arm to transfer Frosty out to the P6 photo voltaic array truss section the place it may be plugged in for energy and telemetry.
“The purpose of a PFCS, a pump flow control sub-assembly, is all about the cooling of the batteries the space station holds its electrical power in,” stated Anthony Vareha, the spacewalk flight director on the Johnson Space Center in Houston.
“We’ve got the eight big solar arrays you’ve seen on space station, each of those has some batteries, we need to keep the batteries cool just like in your cell phone. We do that with an ammonia cooling loop. We pump the ammonia through a radiator and out through the batteries, cools them off.”
More than 15 years in the past, Frosty misplaced heater energy due to an unrelated drawback elsewhere within the station.
“As a result, the worry is that pump got a little bit cold and henceforth, it was named ‘Frosty.’ We are going to swap Frosty out to the shelf on P6 so we can plug it in, we can actually get data from it and make sure it is, indeed, a healthy pump. That tells us do we have a good spare there or not.”
Feustel and Arnold additionally plan to exchange an ordinary definition digicam, its gentle and its pan-and-tilt mechanism.
With the spacewalk out of the best way, the station crew will flip its consideration the launch Sunday of an Orbital ATK Cygnus cargo ship from the Mid-Atlantic Regional Spaceport at NASA’s Wallops Island, Va., facility. The cargo ship is predicted to arrive on the station on May 24.
The astronauts will assist with preliminary unloading earlier than Soyuz MS-07/53S commander Anton Shkaplerov, Scott Tingle and Norishige Kanai pack up for re-entry and touchdown June three to shut out a 168-day mission. Feustel, Arnold and Soyuz MS-08/54S commander Oleg Artemyev could have the station to themselves till three recent crew members arrive June eight.
After the brand new crew — Soyuz MS-09/55S commander Sergey Prokopyev, veteran European Space Agency astronaut Alexander Gerst and NASA flight surgeon Serena Aūnón-Chancellor — arrives, one other spacewalk is deliberate by Feustel and Arnold on June 14 to set up cameras on the entrance of the station to monitor arrivals and departures of business crew ships being constructed by Boeing and SpaceX.