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Image Credit: NASA TV.

Pirs and Progress wave farewell to the International Space Station

The Russian Pirs Docking Compartment located at the Russian segment of the International Space Station (ISS), earlier today, July 26, 2021, departed the space station prior to its fiery return to planet Earth. The module was undocked from the Earth-facing docking port of the ISS’ Zvezda module at 10:55 UTC, by the uncrewed Russian Progress MS-16 resupply freighter. Both the Progress and Pirs will burn up in Earth’s atmosphere over the Pacific Ocean in a few hours from now. Prior to this, the Progress will perform a 17 min 37 s long deorbit burn, beginning at 14:01 UTC. This will slow down Progress MS-16 and Pirs to allow them to re-entre the atmosphere at about 14:45 UTC. Most parts of the two spacecraft will burn up, while some larger pieces may harmlessly fall into the Pacific.

Pirs and Progress MS-16 depart the ISS. Image Credit: NASA TV.
Pirs and Progress MS-16 depart the ISS. Image Credit: NASA TV.

The removal of Pirs from the orbiting laboratory was performed to free the docking port for the new Russian Nauka laboratory module, which is scheduled to rendezvous and dock with the ISS on July 29.

Ground controllers will now conduct a detailed video survey of the vacated docking port with the space station’s Canadarm2 robotic arm, to search for any debris caused by the undocking of Pirs. In the unlikely case of a damage to Zvezda’s nadir port, the two Russian cosmonauts Pyotr Dubrov and Oleg Novitsky will perform a spacewalk later this week, to clean and repair the port ahead of Nauka’s arrival.

Pirs departure was originally scheduled to occur on Friday, July 23, but was postponed several times to allow the Russian ground controllers perform additional tests of the Nauka module’s propulsion and navigation systems.

The Pirs module

The Pirs Docking Compartment, also known as DC-1, was a Russian module docked to the Zvezda module’s nadir port at the Russian segment of the ISS for almost 20 years. Pirs was launched to the ISS on September 14, 2001 atop a Soyuz rocket from the Baikonur Cosmodrome in Kazakhstan. The module, which was attached to a modified Progress freighter, arrived at the space station about three days later on September 17, 2001 and automatically docked to the station at 01:05 UTC. Pirs was 4.91 m in length, 2.55 m in diameter and served as one of the International Space Station’s airlocks for spacewalks. It also provided a docking port for the arriving Russian Soyuz and Progress spacecraft and was able to transfer propellant between docked visiting vehicles and the Zvezda and Zarya modules.

The Pirs module and a docked Progress space freigher. Image Credit: NASA.

The Progress MS-16 freighter

Progress MS-16, also known as Progress 77, was an uncrewed Russian resupply freighter launched to the International Space Station on February 15, 2021, atop a Soyuz rocket from the Baikonur Cosmodrome in Kazakhstan. The spacecraft rendezvoused and docked with the space station’s Pirs module around two days later, on February 17 at 06:27 UTC. It delivered about 2 1/2 tonnes of water, air, propellant and other cargo to the orbiting laboratory. The freighter, together with the Pirs module, undocked from the ISS earlier today to return to planet Earth. Both Progress MS-16 and Pirs will burn up in the atmosphere a few hours after their departure.

Soyuz MS-18 (foreground) and Progress MS-16 (background) attached to the space station's Rassvet and Pirs modules. Image Credit: NASA.
Soyuz MS-18 (foreground) and Progress MS-16 (background) attached
to the space station’s Rassvet and Pirs modules. Image Credit: NASA.

The Nauka module

The Multipurpose Laboratory Module (MLM), also known as Nauka, is a Russian laboratory module to arrive at the ISS in a couple of days. Development and construction of Nauka already began in the mid-1990s, however the module was originally designed as a backup for the Russian Zarya module and not as a dedicated research facility. Nauka had a launch mass of over 20 tonnes, is equipped with a docking port for arriving Soyuz and Progress spacecraft and is able to transfer propellants between spacecraft and other modules. The module provides space for up to three tonnes of research equipment and experiments and has its own onboard propulsion system, with which Nauka will help raise the ISS’ orbit from time to time. The MLM also includes space for another crew member, another toilet and is equipped with the European Robotic Arm (ERA).

The module blasted off into space atop a Russian Proton-M rocket from Site 200 at the Baikonur Cosmodrome in Kazakhstan on July 21, 2021 at 14:58 UTC / 19:58 QYZT (local time). Nauka’s launch to the ISS was the first launch of a large Russian module since the launch of Zvezda in Juli 2000.

The Nauka module seen during final preparations ahead of its launch. Image Credit: Roscosmos.

Sources:

https://blogs.nasa.gov/spacestation/2021/07/26/progress-77-and-pirs-undocked-from-station/

https://www.nasa.gov/mission_pages/station/structure/elements/pirs-docking-compartment

https://www.nasa.gov/centers/johnson/news/station/2001/iss01-29.html

https://www.nasa.gov/centers/johnson/news/station/2001/iss01-30.html

https://blogs.nasa.gov/spacestation/2021/02/14/russian-cargo-craft-in-orbit-to-station/

https://blogs.nasa.gov/spacestation/2021/07/21/liftoff-multipurpose-laboratory-module-nauka-launches-to-space-station/

https://tass.com/science/1017479

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