Astronauts complete all US EVA-49 tasks despite limited duration
Less than a week after arriving at the International Space Station in Soyuz MS-08 for a five-month stay, two astronauts donned spacesuits to venture outside the complex for a six-hour extravehicular activity (EVA).
Expedition 55 Flight Engineers Drew Feustel and Ricky Arnold of NASA performed the fourth spacewalk of 2018 for the ISS program. The primary tasks involved installing wireless communications antennas on the Tranquility module as well as to replacing a camera system on the port truss, according to the U.S. space agency. While U.S. EVA-49 was limited to around six hours because of a limited consumable in their suits carbon dioxide scrubbers, the duo was still able to accomplish all the primary goals and complete get-ahead tasks.
Between Feustel and Arnold, the two have some 55 hours worth of spacewalking experience with the former conducting six previous excursions—three during the STS-125 Hubble servicing mission in 2009 and three during the STS-134 ISS assembly mission in 2011—and the latter performing two—both during the STS-119 ISS assembly mission.
For this spacewalk, the two began their day with the final preparations for the EVA and suiting up. They were helped by fellow Expedition 55 astronauts Scott Tingle of NASA and Norishige Kanai of the Japan Aerospace Exploration Agency.
During these final checks, Feustel’s suit failed three leak checks. This resulted in him having to remove his helmet and gloves to clean the seals before trying again, which seemed to do the trick as the suit passed on the fourth leak check.
Because of the delay due to the leak checks, the spacewalk schedule was behind the timeline by about 90 minutes. Finally, after getting into the Quest airlock and depressurizing it, the crew was able to start the EVA. The official start time was at 9:33 a.m. EDT (13:33 GMT) March 29, 2018, when the duo switched their suits to battery power.
Once outside, the two split up to perform their first tasks. Feustel, who was wearing the suit with red stripes and was designated EV-1, went to Tranquility to begin installing the wireless communications antennas, while Arnold, wearing the suit with no stripes and designated EV-2, gathered a foot restraint and moved over to the awaiting robotic Canadarm2 to set up to ride atop it to the P1 truss.
At the controls of Canadarm2 was Tingle and Kanai, who were inside the outpost at the Robotics Workstation located in the Cupola module. They moved it with Arnold over to a work site at a heat rejection system radiator on the P1 truss segment. There, he worked to remove several hoses attached to one of six Radiator Beam Valve Modules (RBVMs) that were thought to have had leaks.
The hoses were identified in 2016 as potentially leaking after data began showing a decrease in that general area and after European Space Agency astronaut Thomas Pesquet inspected the hoses in a 2017 spacewalk. After that, Mission Control in Houston worked to remotely re-route the station’s coolant and vented the lines.
Now removed, the hoses will be returned to Earth for inspection so that NASA engineers can better understand why they leaked and to improve future systems.
While Arnold was working on that, Feustel continued to install antennas on Tranquility. In particular, he attached two handrails on the module that had the WiFi antennas attached before connecting power and data lines to the device.
It was around this time, some three hours into the spacewalk, that Mission Control noted that the duo’s suit carbon dioxide scrubbers would be a limiting factor for how long they could stay outside. In order to make the most of that time, the task of replacing failed Camera, Light, Pan/Tilt Assembly (CLPA) was modified.
Instead of removing a high-definition camera before attaching a spare CLPA and then re-installing the camera, Arnold (while attached to the robotic arm) was told to remove the whole CLPA (camera and all), install the spare, and hand the old one to Feustel (who was now completed with his antenna task) to bring it to the airlock. The crew would remove the camera inside the outpost later.
Once Feustel arrived at the airlock with the assembly, about four hours into the spacewalk, it was determined that there would now be enough time left to install the high-definition camera. So, he removed the camera from the CLPA and translated back to the P1 truss segment to hand it to Arnold to install.
With all the primary tasks completed, NASA then instructed Arnold to clean up his work area on Canadarm2 and return to the airlock. Feustel, however, was given the get-ahead task of breaking torque on four bolts on a spare ammonia pump module so a future spacewalk can install it.
With all of that done, three two returned to Quest to conclude their first outing of Expedition 55. The official end time of the spacewalk was at 3:43 p.m. EDT (19:43 GMT) to bring the total time spent outside for U.S. EVA-49 to six hours, 10 minutes.
Feustel’s seven career spacewalks brings his total to 48 hours, 28 minutes, while Arnold’s three bring him to 18 hours, 44 minutes. There are several more spacewalks planned for spring 2018, however NASA has yet to officially schedule them.
This was the 209th spacewalk in support of space station assembly and maintenance, the first one occurring in 1998. Astronauts and cosmonauts have now spent a total of 54 days, 10 hours working outside the ISS, according to NASA.
Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity. You can find him on twitter @TheSpaceWriter.