Russian cosmonauts manually docked an unmanned Progress cargo spaceship at the International Space Station (ISS) on Sunday after its automatic docking system unexpectedly failed.
Launch and Initial Approach Goes Smoothly
The Progress MS-25 spacecraft, also known as Progress 86P, lifted off atop a Soyuz 2.1a rocket at 9:24 p.m. EST Friday (8:24 a.m. Saturday local time) from the Baikonur Cosmodrome in Kazakhstan. The launch and early phases of the flight went smoothly as Progress made its way toward the space station.
On Sunday morning, the cargo ship began its automated final approach and rendezvous procedures to autonomously link up to the aft port of the station’s Zvezda service module. However, at a distance of about 100 feet (30 meters) from the station, Progress’ Kurs automated docking system encountered an unknown issue and aborted the procedure.
Cosmonauts Take Manual Control
With the automated docking attempt unsuccessful, Russian cosmonauts Sergey Prokopyev and Dmitri Petelin aboard the ISS took over manual control of the Progress vehicle using a remote command panel on the space station. After stabilizing the spaceship’s position, they carefully guided it in and made contact with the docking port.
Hook latches were then closed to create a firm connection between Progress and the ISS at 1:13 p.m. EST, over 25 hours after the cargo ship’s launch.
While infrequent, manual control takeovers have occurred during past Russian vehicle dockings when the automated system has failed or had issues. According to Anatoly Zak, publisher of RussianSpaceWeb.com:
"Manual docking is part of standard contingency procedures practiced by Russian cosmonauts. However, the last time it was required in real life was in 2018, during the approach of Progress MS-08."
Bringing Vital Cargo to Station
Now securely attached to the ISS, Progress 86P is delivering over 3,000 pounds of food, fuel, and supplies for the Expedition 68 crew. Highlights of its cargo manifest include:
- 1,170 pounds of propellant to refuel the Zvezda service module’s tanks
- 926 pounds of water
- 107 pounds of oxygen and air
- 2,982 pounds of dry cargo such as spare parts, experiment hardware, crew provisions, and personal packages for the astronauts
This vital replenishment will support ongoing science activities and the day-to-day needs of the seven-person crew. Over the next six months, Progress will be docked to help reboost the station’s orbital altitude when required using its own engines.
Cause of Automated Failure Still Unknown
Russian engineers are currently reviewing telemetry from the Progress spacecraft to try and determine why the Kurs rendezvous system aborted Sunday’s automated approach. So far though, the reason is still unclear according to officials:
"It is too early to tell precisely what happened. We need time to look deeply at the telemetry and figure it out," says Sergei Krikalev, Executive Director for Human Space Flight Programs at Roscosmos. "But the main thing is that docking occurred successfully in manual mode."
While a technical anomaly, the smooth changeover to manual control and subsequent safe docking shows an element of redundancy and flexibility built into these rendezvous procedures. Cosmonauts train often to be able to take over ISS vehicle piloting if needed, which proved useful in this case.
Background on Progress Cargo Flights
| Craft Name | Launch Date | Docking Location | Notes |
|---|---|---|---|
| Progress 86P | Dec 1, 2023 | Zvezda Aft Port | Delivery of propellant & supplies. Will stay docked for ~6 months |
| Progress 85P | Oct 16, 2022 | Nauka Module | Recently undocked after reboost/cargo duties |
| Progress 84P | Feb 11, 2022 | Pirs Module | Undocked in August 2022 |
The Russian Progress spacecraft is an automated, unpiloted version of the Soyuz crew ship that has been transporting fuel, equipment, experiments and other goods to the ISS since 2000.
Its unique capability to refuel the propulsion system on the Russian segment makes Progress flights vital at regular intervals. The vehicles stay docked anywhere from five to eight months before being loaded with trash and undocking to burn up in Earth’s atmosphere.
Looking Ahead After Docking
With Progress 86P now linked to the station’s Zvezda module, the Expedition 68 crew can soon get to work unloading its precious cargo. Access to the new supplies and provisions will help enable ongoing science activities, maintenance tasks, and daily life onboard the orbiting laboratory.
Meanwhile, analysis into Sunday’s aborted automatic docking attempt will continue. Engineers hope the telemetry review will uncover the fault that triggered the system’s halt so that any fixes or adjustments can be implemented ahead of the next Progress vehicle launch.
And coming up on December 14th, a SpaceX Dragon cargo craft is also scheduled to visit the ISS, delivering hardware, crew supplies, and science investigations including cardiac research and an oven for baking food in microgravity. Its arrival will further stock the station’s coffers helping sustain operations through next year and beyond.
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