HISTORY FOR CBS MESSAGES WRITTEN
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Two astronauts were working in front of the International Space Station on Wednesday to position two replacement cooling units for the ammonia coolant pump and set up a malfunctioning unit called "Leaky" , In the long-term storage and attached another, known as "Frosty", attached to an attachment of the robot arm of the laboratory.
After the spacewalk is over, armbands at the Johnson Space Center in Houston planned to place Frosty in the P6 solar array segment at the extreme left end of the station's energy source where it can be plugged for diagnosis. It is connected to another replacement pump flow control subassembly or PFCS, known as "Motley", which is already installed on P6.
The units are designed to force coolant through solar cell batteries to protect them from overheating. The aptly named Frosty has been stored outside the station for nearly 20 years, but once for a long time it was without heating power and the engineers are not sure if it is still a viable replacement.
Motley was delivered to the laboratory complex by a SpaceX Dragon cargo ship earlier this year. As its name implies, it consists of spare parts, but it is fully functional and readily available when one of the eight operational PFCS units, one for each solar system, fails.
But because the station uses eight PFCS All NAS batteries are cooled, NASA wants to have two ready-to-use replacement parts at all times and engineers want to find out if Frosty is actually up and running.
Station chief Drew Feustel and Ricky Arnold hovering in the station's airlock. At 7.39 EDT (GMT-4) they switched their spacesuits to battery power and officially launched a planned 6.5-hour spacewalk.
For identification, Feustel, call sign EV-1
Entering the EVA, Frosty was mounted on external storage platform # 1, while Leaky was previously attached to an attachment of the station's special spiral manipulator, or DEXTRE, a multi-joint, hand-like fitting used by the lab's robotic arm.
Leaky will take Frosty's seat on ESP. 1, where it will stay in long-term storage and Frosty will be connected to DEXTRE. After the spacewalk is over, the air traffic controllers will use the arm to move Frosty into the P6 solar array truss segment, where it can be plugged in for power and telemetry.
"The Purpose of a PFCS, a Pump Flow Control Assembly is all about cooling the batteries in which the space station keeps its electrical energy," said Anthony Vareha, Spacewalk Flight Director of the Johnson Space Center in Houston.
"We've seen the eight large solar panels on the space station, each of them has some batteries, we need to keep the batteries cool, just like in your cell phone, we do that with an ammonia refrigeration circuit, we pump the ammonia through a radiator and through the batteries, it cools down. "
More than 15 years ago, Frosty lost heating power due to another problem in the station.
The worry is that the pump got a bit cold and henceforth was called "Frosty". We'll put Frosty on P6 on the shelf so we can plug it in, we can actually get data from it and make sure it's, in fact, a healthy pump. That tells us if we have a good reserve there or not.
Feustel and Arnold also plan to replace their standard-definition camera, their light and their pan and tilt mechanism.
With the spacewalk out of the way, the Station Crew will pay attention to the launch Sunday of an orbital ATK Cygnus The cargo ship is expected to arrive at the station on May 24.
The astronauts will help with the first unloading before the Soyuz MS-07 / 53S Commander Anton Shkaplerov, Scott Tingle and Norishige Kanai arrive for June 3 to complete a 168-day mission Feustel, Arnold and Soyuz MS-08 / 54S Commander Oleg Artemyev will have the station to himself until three new crew members arrive at the June 8.
After the new crew – Sergei Prokopyev, MS-09 / 55S commander, veteran of the European Space Agency astronaut Alexander Gerst and the NASA-Flugme Dean Serena Aūnón-Chancellor – another space walk is planned by Feustel and Arnold on June 14 to install cameras at the front of the station to monitor the arrival and departure of Boeing and SpaceX-built commercial crew vessels.