Progress MS-17 is set to temporarily depart the International Space Station tomorrow in order to relocate its docking position to the station’s newest module, MLM Nauka.
Relocation is scheduled to begin at 23:42 UTC (7:42 PM EDT) on Wednesday, whereby the Russian resupply spacecraft will autonomously undock from the Russian Poisk module and back away from the station to a distance of approximately 180-190 kilometers. In doing so, Progress will perform station-keeping maneuvers in order to remain in the correct proximity to the space station and will hold position for over 24 hours.
The spacecraft will then begin to approach the Nauka multipurpose laboratory, which became a new addition to the station in July, for a scheduled docking at 04:23 UTC (12:23 AM EDT) on Friday. The Progress spacecraft will occupy the nadir port, one of two on the Nauka module.
Russian cosmonauts Pyotr Dubrov and Anton Shkaplerov will be responsible for overseeing the relocation. However, the entire process should be automatically controlled by Progress. Both cosmonauts have been trained to take over the redocking operation should an issue arise, but nominally, the Kurs automated docking system will be used.
Having been at the space station since July 2, Progress MS-17 will remain docked to the station until its permanent departure in late November. As with all Progress spacecraft, after their cargo has been used and their purpose no longer needed, the crew aboard the station will load the vehicle with spent and unwanted supplies which, once de-orbited, will burn up in the Earth’s atmosphere along with the entire spacecraft itself.
Unlike the crewed Soyuz, Progress is designed to be a disposable resupply craft.
Significantly, Progress MS-17 will undock from Nauka with its HDA-to-SSVP (Hybrid Drogue Adapter to Probe and Drogue) docking adapter ring. Currently, the nadir port’s adapter is compatible with both Soyuz and Progress vehicles. However, the port will no longer service these vehicles, and instead will be the attachment point for Russia’s Prichal module.
By Progress removing the HDA-to-SSVP ring, it will revert the docking infrastructure to HDA, an adapter that gives a wider passageway and is thus particularly useful for permanent modules. Nauka was not launched in HDA configuration in the event that Prichal did not make it to the space station, which would render the sought-after port inaccessible for Soyuz and Progress vehicles.
NM (Node Module) Prichal is an addition to the Russian MLM Nauka and will provide four HDA-type docking ports to the Russian segment of the space station. The addition of docking ports would provide Russia and Roscosmos the opportunity to expand their segment.
This prospect may not come to fruition in response to Russia looking at other opportunities away from the ISS this decade. Regardless, it is expected that Prichal will share servicing Soyuz vehicles with the Rassvet module, whilst Progress vehicles will dock to the Zvezda and Poisk modules.
On Wednesday, after “go” is given for undocking, Progress will release a series of hooks and latches followed by the spacecraft performing thruster firings to back away from the Poisk module. Unlike typical relocations, such as the recent Soyuz MS-18, Progress will distance itself from the station well beyond the “keep out sphere” to a distance of 180-190 kilometers.
After backing away from the station, the spacecraft will ensure it maintains a precise position in space, known as station-keeping, in order to efficiently use its onboard propellant without excessive adjustments. It will station keep for over 24 hours.
On Friday, Progress will begin to close in on the station once again, lining up with the nadir port of MLM Nauka until it eventually has contact and capture with the docking port. The docking probe will be captured by the docking cone, and by retracting the probe, Nauka will draw the spacecraft in toward the docking system to allow for the various hooks and latches to form a tight seal.
This is expected to occur at 04:23 UTC (12:23 AM EDT) on Friday, should the relocation be on time and without issues. Once MS-17 is re-docked, the crew will be able to resume using the spacecraft.
Progress’ departure will be carefully timed around the launch of Prichal due to the significance of the APAS-to-SSPV adapter currently on Nauka’s nadir port. If this was removed and Prichal failed during launch, the Russian segment would lose an important docking port for the common visitors of Soyuz and Progress. Thus, MS-17 will return when Prichal is ready to take its place.
In the meantime, Progress MS-18 will launch on October 28 at 00:00 UTC (October 27 at 8:00 PM EDT) aboard a Soyuz 2.1b from the Baikonur Cosmodrome in Kazakhstan. The spacecraft will dock to the aft port of the Zvezda module, a prime location for Progress spacecraft in order to perform ISS orbital reboosts using their main engines.
It will deliver approximately three tonnes of food, fuel, and supplies to the ISS crew. Docking is expected at 01:34 UTC on Friday, October 29 (9:34 PM EDT on Thursday, October 28).
It is currently expected that Prichal will be launched on November 24, also aboard a Soyuz 2.1b from Baikonur. Prichal will be launched with the Progress M-UM, an upgraded type of Progress specifically designed to carry Prichal to the station. After docking the new Russian segment to Nauka, Progress M-UM’s propulsion section will undock after 30 days and re-enter the atmosphere, leaving Prichal’s nadir port free.
Spacewalks are planned in 2021 and 2022 in order to fully integrate Prichal to Nauka and complete the Russian segment’s newest additions.
(Lead image: Progress MS-17 approaching to dock to the Poisk module in July – via NASA)
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