NASA astronaut Ricky Arnold works on May 16, 2018 during a spacewalk with NASA astronaut Drew Feustel to replace a camera assembly at the International Space Station.
Credit: NASA TV
Two NASA astronauts today (May 1
In Extravehicular Mobility Expedition 55 flight engineers Drew Feustel and Ricky Arnold came through the Quest airlock at 8:39 am EDT (1239 GMT) before spending the day working in the vacuum of space Hardware Installation  Your primary goal was to install a failed pump in the station's cooling system, where a liquid ammonia refrigeration cycle is used to protect the station's massive solar cells and batteries from overheating. They also installed new communications equipment to prepare the station for commercial crew vehicles such as the Boeing CST-100 Starliner and the SpaceX Crew Dragon, the latter of which could make its first test flight in August. [Space Station Photos: Expedition 55 Crew in Orbit]
As extraavehicular crewmember 1 (EV1), Feustel wore the suit in red stripes while Arnold wore a simple white suit. This helps NASA's Johnson Space Center's Houston Johnson Space Center ground controllers explain the difference between the two spacewalkers as they watch live video broadcasts from the station's external cameras.
The first task was the faulty Pump Flow Control Subassembly (PFCS) unit, nicknamed "Leaky" by NASA. After ammonia leaked in 2013, the problematic pump was replaced with a replacement pump and stowed near the P6 Truss segment. Today, the Spacewalks have brought Leaky on an external stowage platform (ESP-1) to make room for a more reliable replacement unit called "Frosty". If future spacewalks have to replace the PFCS in case of another leak, Frosty will be in a "strategically advantageous" position on the P6 truss. @Astro_Feustel Reports Failed Pump Flow Control From Subassembly (PFCS) According to @Astro_Ricky before installing a new PFCS to ensure cooling of external station systems. https://t.co/yuOTrZ4Jut pic.twitter.com/JQj5PfZGTs
– Intl. Space Station (@Space_Station) May 16, 2018
After Leaky and Frosty changed places, the Spacewalkers installed a new HD camera at the Destiny Laboratory and replaced a communications receiver on one of the ground antennas in the Z1 Truss segment. For their "get-ahead" tasks, the astronauts installed some new grips outside the station and stored a thermal cover near a particle detector experiment known as an alpha magnetic spectrometer.
Feustel knocked on the door and said, "Who's home, sweet or sour!" Japanese astronaut Norishige Kanai and NASA astronaut Scott Tingle were waiting to greet the spacewalkers at the door, but they did not seem to have any sweets for these off-season tricks.
The spacewalk ended officially as Feustel and Arnold exchanged their space suits from EDT (1810 GMT) at 14:10. It took 6 hours and 31 minutes, just 1 minute longer than NASA had planned.
This was the 210th Spacewalk to support the construction and maintenance of the International Space Station. It was Feustel's eighth spacewalk, and he has now collected 54 hours and 59 minutes of spacewalk. It was the fourth spacewalk of Arnold's career, bringing his entire space walk time to 25 hours and 15 minutes.
Feustel and Arnold have now completed two spacewalks together; her first outing was on March 29th. The duo will gather for the third consecutive spacewalk on June 14, where they will continue the preparations for commercial team vehicles.