Space Debris Delays U.S. Spacewalk

Space Debris Delays U.S. Spacewalk

Two NASA astronauts were suited up and getting ready to begin a 7 hour spacewalk this morning when it was suddenly cancelled because a piece of space debris was closing in on the International Space Station. The spacewalk has been rescheduled for tomorrow, but the incident is another illustration of the growing problem of debris in low Earth orbit.

Josh Cassada and Frank Rubio were supposed to exit the ISS at 7:45 am ET and install a new ISS Roll Out Solar Array (iROSA). They installed one already on December 3, part of an effort to increase electricity production on the ISS.

iss068e026403 (Dec. 3, 2022) — NASA astronaut and Expedition 68 Flight Engineer Josh Cassada holds a roll-out solar array as he rides the Canadarm2 robotic arm toward the Starboard-4 truss segment installation site.

But Mission Control called it off when they became aware that a piece of debris from a Russian rocket upper stage would come within a quarter of a mile of the ISS and they needed to move the ISS away to avoid a potential collision.

Engines on Russia’s Service Module (also called Zvezda) and Russian Progress cargo ships are used both to periodically reboost the ISS orbit to compensate for atmospheric drag and to make Pre-Determined Debris Avoidance Maneuvers or PDAMs like this.

Two Progress spacecraft are docked to ISS right now. In this case, thrusters on Progress MS-20 were fired at 8:42 am ET for 10 minutes 21 seconds.

NASA illustration of the International Space Station showing the location of visiting vehicles as of December 3, 2022. Progress MS-20 is labeled here as Progress 81, NASA’s designation because it is the 81st Progress to resupply the ISS, but there were dozens of Progress spacecraft that serviced earlier Soviet/Russian space stations. Progress MS-20 is docked to Russia’s Zvezda module.

Astrophysicst Jonathan McDowell of Jonathan’s Space Report identifed the debris as coming from a July 18, 2011 launch of a Zenit rocket with the Fregat upper stage, which placed Russia’s Spektr-R space telescope into orbit. McDowell emphasized that the debris is not from the Fregat upper stage itself, but a propellant tank that was jettisoned at the time and disintegrated on May 8, 2020.

NASA tweeted this is the third collision avoidance maneuver the ISS has had to make this year.

NASA rescheduled the spacewalk for tomorrow at 8:30 am ET. NASA TV coverage begins at 7:00 am ET.

Just last week, a planned Russian spacewalk was abruptly terminated when Russia’s Soyuz MS-22 spacecraft dramatically began to leak coolant just outside the airlock two cosmonauts were about to open. They remained safely inside. Roscosmos is still trying to definitively determine what happened, but among the top theories is that the coolant line was ruptured by a piece of debris or a micrometeorite.

NASA ISS Program Manager Joel Montalbano and Roscosmos’s head of human spaceflight Sergei Krikalev, one of Russia’s most experienced cosmonauts, will hold a media briefing tomorrow to discuss the Soyuz MS-22 situation. As it turns out, that briefing will take place while Cassada and Rubio are on their spacewalk.

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