An X-ray observatory dedicated to investigating neutron stars is “back in the black” and a cosmic ray detector is primed for potential future enhancements following the completion of a spacewalk by two astronauts outside the International Space Station (ISS).
Nick Hague focused on repairing the Neutron star Interior Composition Explorer, or NICER, which is affixed to the exterior of the space station, prior to he and Expedition 72 commander Suni Williams examining the Alpha Magnetic Spectrometer (AMS) during a six-hour EVA (extravehicular activity) on Thursday (Jan. 16).
They commenced their spacewalk at 8:01 a.m. EST (1301 GMT) and efficiently handled their primary task: replacing a rate gyro assembly that assists in maintaining the station’s orientation. Operating near and within the complex’s structural framework, the two astronauts employed power tools to detach the defective unit and secure the new one into its designated spot.
Following that, they split their focus, with Hague attending to NICER while Williams concentrated on substituting a reflector utilized by spacecraft when approaching a docking with the space station. That task led Williams to the Harmony module and international docking adapter, situated just next to her and Hague’s vehicle home in March, SpaceX’s Crew Dragon spacecraft “Freedom.”
Related: Spacewalks: How they operate and significant milestones
Meanwhile, Hague applied pre-made patches to cover areas where optical light was infiltrating the NICER observatory. First detected in May 2023, the leakage through one or more of the instrument’s light-blocking filters greatly affected NICER’s functionality and data collection. With the patches now applied, NICER is anticipated to resume its X-ray observations of deep space phenomena.
Hague and Williams subsequently collaborated on a different astrophysics instrument. The duo inspected access points and connector devices that could be utilized for maintenance tasks on the AMS during future spacewalks.
Installed during the second-to-last flight of the space shuttle in May 2011, the AMS is a particle physics project aimed at measuring antimatter in cosmic rays as part of efforts to understand more about enigmatic dark matter. Although not initially scheduled for servicing, the AMS has undergone repairs during previous spacewalks, and the inspections carried out by Hague and Williams might open the door for further maintenance, including potentially adding a new radiator.
With all scheduled tasks accomplished and still some time left, Hague assessed the condition of a movable portable foot restraint while Williams documented the insulation on an ammonia coolant line, before they both made their way back to the airlock, concluding their spacewalk at 2:01 p.m. EST (1901 GMT).
“We’re about two months shy of the 60th anniversary of the first spacewalk, and it’s just really amazing to be part of that legacy and contribute our little bit,” Hague remarked just before concluding the EVA.
Thursday’s spacewalk marked the 91st U.S. EVA utilizing the Quest airlock, and the 237th in total supporting the construction, upkeep, and enhancement of the International Space Station since 1998.
This was the second spacewalk during Expedition 72 and the first successful American EVA following more than a year. Two prior attempts to exit the space station in 2024 were hindered by equipment and spacesuit issues that impeded task completion.
Hague has now completed four spacewalks, amassing a total of 25 hours and 56 minutes. Williams has performed eight EVAs, dedicating 56 hours and 40 minutes working outside the space station.
Williams, along with Butch Wilmore, is scheduled to conduct the next spacewalk on Jan. 23. The two will remove a radio frequency group antenna assembly from the station’s truss; gather samples of surface material for analysis to determine whether microorganisms might be present on the external surface of the orbital complex; and prepare a spare elbow joint for the Canadarm2 robotic arm should it be necessary for replacement.