A commercial Cygnus supply ship from Northrop Grumman is set to depart the International Space Station Tuesday, completing a four-month stay after delivering more than 8,000 pounds of cargo and boosting the research lab into a slightly higher orbit.
The Cygnus spacecraft is scheduled for release from the space station’s Canadian-built robotic arm at 7:05 a.m. EDT (1105 GMT) Tuesday. Mission control delayed the release by an hour Tuesday to adjust the Cygnus spacecraft’s post-departure trajectory to be clear of space debris, and allow for improved communications with the cargo ship on its course away from the space station.
Ground teams will command the robotic arm to release the Cygnus spacecraft. Mission control unberthed the Cygnus cargo ship from the station’s Unity module early Tuesday, then moved the robotic arm to position the departing spacecraft in the proper position for release below the orbiting research lab.
The Northrop Grumman supply freighter arrived at the space station Feb. 21, two days after launching from NASA’s Wallops Flight Facility in Virginia aboard an Antares rocket.
The mission is the 17th Cygnus resupply flight to the space station since 2013 under a series of commercial cargo transportation contracts with NASA. The supply delivery capability was originally developed by Orbital Sciences, now part of Northrop Grumman after a corporate acquisition in 2018.
Northrop Grumman named the Cygnus spacecraft for the NG-17 mission the “S.S. Piers Sellers” ini honor of a space shuttle astronaut and NASA climate scientist who died from cancer in 2016.
The pressurized cabin of the Cygnus spacecraft is packed with several tons of trash and other equipment no longer needed at the space station. After moving a safe distance from the complex, the Cygnus freighter will perform a de-orbit burn Wednesday to fall back into the atmosphere. Most of the spacecraft, and its contents, will burn up over the Pacific Ocean.
The NG-17 mission delivered more than 8,300 pounds (about 3,800 kilograms) of cargo to the space station in February, including experiments, equipment to support new power-generating solar arrays, and a trash disposal system that will allow garbage to be jettisoned out of the station’s Nanoracks commercial airlock.
Using its gimbaled main engine, the Cygnus spacecraft also nudged the International Space Station into a slightly higher orbit Saturday, in one of the mission’s final tasks before leaving the complex. The maneuver lasted 5 minutes, 1 second, and raised the station’s altitude by 0.1 miles at apogee, or its highest point, and 0.5 miles at perigee, or its lowest point.
An attempt to reboost the station’s orbit June 21 was aborted after five seconds. NASA said the June 21 reboost attempt was terminated early as a “conservative measure due to system parameters that differed from Cygnus flight operations.”
Engineers determined the parameters were acceptable, and adjusted the limits for the next reboost try Saturday.
The space station’s orbit reboost capability has been exclusively provided by Russia since the retirement of the space shuttle in 2011. A Cygnus mission in 2018 tested the spacecraft’s ability to raise the station’s altitude, but the NG-17 mission was the first to employ the capability as an operational service.
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