Three International Space Station (ISS) crew members took a short ride in their Soyuz MS-13 spacecraft Sunday night (EDT) to move it from one docking port to another. The maneuver was needed because an automated rendezvous and docking system at one of the ports malfunctioned during Saturday morning’s attempt to dock Soyuz MS-14. That is a test flight and no one is aboard so it needs the automated system. Soyuz MS-13 does not because the crew can dock it manually. With the orbital do-si-do complete, Roscosmos will try again to dock Soyuz MS-14 Monday night EDT (Tuesday morning Moscow Time). [UPDATE, August 26, 11:14 pm EDT: Soyuz MS-14 successfully docked at the Zvezda port at 11:08 pm EDT].

Russia’s Alexander Skvortsov, NASA’s Drew Morgan, and ESA’s Luca Parmitano arrived at ISS on Soyuz MS-13 on July 20, docking at the Zvezda port.

Soyuz MS-14 was scheduled to dock at the Poisk port, but that attempt was aborted when the KURS automated system at that port failed. Among other things, Soyuz MS-14 is testing new navigation and propulsion systems for docking, but the problem was not with the Soyuz MS-14 systems. Instead, the KURS failure was traced to a bad power amplifier on the ISS.

Soyuz MS-14 was commanded to a safe position above and behind the ISS to await further instructions. Russian flight controllers determined that the best option was to bring it in to a port where KURS was working and the Soyuz MS-13 crew (“Expedition 60”) got the news that they would need to move their spacecraft to a different port. Such an operation is not unprecedented.

At 11:35 pm EDT Sunday, Soyuz MS-13 undocked from the Zvezda port. All three crewmembers were aboard in the unlikely event that something went awry with the docking and they had to return to Earth. The other three ISS crew members (Russia’s Aleksey Ovchinin and NASA’s Christina Koch and Nick Hague) have Soyuz MS-12 as their ride home.

It was a short 24-minute ride. They redocked at the Poisk port at 11:59 pm EDT.

Three Exp 60 crewmembers successfully relocated their Soyuz MS-13 spacecraft when they docked to the Poisk module today at 11:59pm ET. https://t.co/hAfKDEfFXb pic.twitter.com/Nfg35aCBdc — Intl. Space Station (@Space_Station) August 26, 2019

With the Zvezda port now free, Roscosmos will attempt to dock Soyuz MS-14 there Monday night at 11:12 pm EDT (Tuesday morning, 6:12 am Moscow Time). NASA TV coverage of the docking begins at 10:30 pm EDT.