UNDOCKING OF PROGRESS MS-16 AND PIRS DOCKING COMPARTMENT FROM ISS, July 26, 2021, Earth orbit, 6:56 am ET

Update, July 25, 2:45 pm ET:  The head of Russia’s space agency, Dmitri Rogozin, tweeted that the undocking now is scheduled for tomorrow, July 26, at 13:56 Moscow time, which is 6:56 am EDT.

Update July 24, 3:45 pm ET:  A knowledgeable person on Twitter reports the docking has been delayed another day, until July 26, but it has not been officially announced.

Update, July 24:  Nauka continues to make slow progress towards the ISS, but its propulsion system appears to still be experiencing difficulties.  NASA TV no longer lists the departure of Progress MS-16/Pirs on its schedule for July 25, but whether that simply means it will not be televised, or if undocking will be being further delayed until Nauka’s status is confirmed, is unknown. If Nauka is unable to dock, Russia would need Pirs to remain, which is why the undocking is linked to Nauka’s fate. We will post any new information here when we get it.

Update, July 23:  The undocking has been delayed another day, to Sunday, July 25, as Russia continues to troubleshoot the problems with Nauka’s engines.

Update, July 22:  Nauka launched on time on July 21, but problems with its propulsion system after it reached orbit  altered Russia’s plans. Everything appears to be resolved at the moment, but Roscosmos announced that the deorbiting of Progress MS-16 and Pirs has been pushed back a day to July 24. NASA’s TV schedule shows undocking now is at 8:28 am ET and NASA TV coverage begins at 8:00 am ET.

After analyzing telemetry received from the #Nauka module, rocket and space industry specialists decided to schedule the #Pirs module deorbit for Saturday, July 24. https://t.co/5EdoOjAeAs

— РОСКОСМОС (@roscosmos) July 22, 2021

Original Entry: Russia will undock its Progress MS-16 cargo spacecraft (which NASA calls Progress 77) from the International Space Station (ISS) on July 23, 2021 at 9:17 am ET.

Progress undockings are routine, but this one is different because it will be taking the Pirs docking compartment with it.  That will free this docking port for Russia’s new 20-metric ton Nauka (Science) module that is scheduled for launch on July 21.  It will dock at that port on July 29 if the current schedule holds.

NASA TV coverage of the Progress MS-16/Pirs undocking begins at 8:45 am ET.