Progress MS-35 to resupply ISS

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Progress MS-35 to re-supply ISS

After a week-long delay caused by a technical problem, the third Russian cargo mission to the ISS in 2026 is slated to lift off from Baikonur on September 16 to support Expedition 75 aboard the outpost. The Progress MS-35 supply vehicle will follow a two-day rendezvous profile with the station and remain at the ISS until February 2027.

Previous cargo mission: Progress MS-34

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Progress MS-35 mission at a glance:

Spacecraft designation(s)	Progress MS-35, 11F615 No. 465, ISS mission 96P
Launch vehicle	Soyuz-2-1b
Payload fairing	SZB: 11S517A2.1000A1-0
Launch site	Baikonur, Site 31, Pad 6
Mission	Cargo delivery to the ISS Expedition 75
Launch date and time	2026 Sept. 16, 16:33:53 Moscow Time
Docking date and time	2026 Sept. 19, 16:46:00 Moscow Time
Docking destination	ISS, Russian Segment, Poisk module (MIM2), zenith port
Deliverable payload mass	~2,500 kilograms
Mission duration	~5 months
End of mission	2027 February

Progress MS-35 mission

As usual, the Progress MS-35 will carry around 2.5 tons of supplies to the International Space Station, ISS. The refueling section (INSIDER CONTENT) will also contain propellant and water for the station.

The mission was initially planned for November 2026, but by 2025, it was advanced to April 28, 2026. By October 2025, the launch slipped to June 17, 2026. Following the service platform collapse at Site 31 in November 2025, and the resulting domino effect of delays, the Progress MS-35 mission was re-scheduled for Sept. 9, 2026.

Progress MS-35 launch campaign

Progress MS-35 is being prepared for shipment to Baikonur.

After a series of factory checks, Progress MS-35 was shipped from its production plant in Korolev around April 1, 2026, and reached Baikonur around five days later. The initial inspection of the spacecraft ahead of an active launch campaign started at Site 254 on June 30, 2026. Between Aug. 3 and 11, 2026, RKK Energia reported testing the spacecraft for air leaks in the vacuum chamber at Site 254, after which, the vehicle was returned to its processing stand.

On Aug. 21, 2026, the ship's solar panels went through a routine test with the exposure to an array of artificial lights.

On Aug. 25, 2026, the assembly of the booster stages of the Soyuz rocket for the Progress MS-35 mission was reported completed. On Aug. 28, 2026, RKK Energia reported that a meeting of the technical management in Baikonur had cleared Progress MS-35 for irreversible operations, including fueling of its Integrated Propulsion System (INSIDER CONTENT) and of the Refueling System (INSIDER CONTENT). Before the transfer to the fueling facility, the vehicle went through the weighting and balancing process at Site 254. The fueling operations were reported completed on August 29.

The spacecraft was then returned to its processing facility at Site 254, where it was integrated with the launch vehicle adapter and a payload fairing, after which the resulting payload section was transferred to the vehicle assembly building at Site 31, where it was integrated with the rocket.

Launch delay

The completed launch vehicle with the cargo ship was rolled out to the launch pad at Site 31 on the morning of Sept. 6, 2026. The liftoff was planned for Sept. 9, 2026, at 19:15:03 Moscow Time, allowing the docking with the ISS on Sept. 11, 2026, at 21:37 Moscow Time (2:37 p.m. EDT).

However soon after the installation of the rocket on the launch pad on September 6, Russian and Kazakh sources reported a problem with the third stage, which was serious enough to require the return of the rocket to the vehicle assembly building. According to the KazTAG news agency, the Soyuz-2-1b vehicle was expected to be removed from the pad and rolled back to the processing building at Site 31 on Sept. 7, 2026, following a decision of a State Commission overseeing the launch campaign.

According to an unofficial source, the rocket had an issue with a hydraulic system. The launch was re-scheduled for Sept. 16, 2026, at 16:33:53 Moscow Time, shifting the ship's arrival at the ISS to Sept. 19, 2026, at around 16:46 Moscow Time.

For the second launch attempt, the rocket was rolled out to the launch pad on the morning of Sept. 13, 2026.

Progress MS-35 launch profile

A Soyuz-2-1b rocket, carrying the Progress MS-35 cargo ship, is scheduled to lift off from Pad 6 at Site 31 in Baikonur on Sept. 16, 2026, at 16:33:53 Moscow Time: (9:33 a.m. EDT).

Following a vertical liftoff under the combined thrust of the four RD-107 engines on the first stage and the single RD-108 of the second (core) stage, the launch vehicle will head eastward from Baikonur matching its ground track to an orbit inclined 51.67 degrees to the plane of the Equator.

The four first-stage boosters should separate 1 minute 58 seconds after liftoff, at an altitude of around 43 kilometers, followed by the split and drop of the two halves of the payload fairing slightly more than a minute later, at an altitude of around 91 kilometers, just above the dense atmosphere and around 200 kilometers downrange. In the meantime, the second stage should continue firing until 4 minutes and 47 seconds into the flight, bringing the vehicle to around 143 kilometers above the planet and a speed of around four kilometers per second, some 500 kilometers downrange from the launch site.

The third stage will then ignite moments before the separation of the second stage, firing its RD-0110 engine through a lattice structure connecting the two boosters and ensuring a continuous thrust during the separation process. A fraction of a second later, the boosters of the second and third stage should part ways and the aft cylindrical section of the third stage will split into three segments and dropped off, ensuring the fall of the second stage and the aft section into the same area on the ground.

The third stage should complete firing its engine and release the cargo ship into an initial parking orbit at around 8 minutes 49 seconds after liftoff, at an altitude of around 193 kilometers.

Progress MS-35 docking profile

After a three-day autonomous flight, Progress MS-35 is scheduled to perform an automated docking at the zenith (sky-facing) port of the Poisk (MIM2) module, a part of the Russian ISS Segment on Sept. 19, 2026, at 16:46 Moscow Time.

The cargo ship was expected to remain at the ISS for around five months, before undocking and performing destructive reentry into the Earth's atmosphere in February 2027.

This page is maintained by Anatoly Zak; last update: September 14, 2026

Page editor: Alain Chabot; last edit: September 14, 2026

Progress MS-35 is lowered in horizontal position at RKK Energia for loading into a railway container ahead of its trip to Baikonur. Click to enlarge. Credit: Roskosmos

Progress MS-35 at the fueling facility at the start of irreversible operations in late August 2026. Click to enlarge. Credit: Roskosmos

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Assembly of the Soyuz-2-1b rocket for the Progress MS-35 mission in late August 2026. Credit: Roskosmos