Progress MS-35 Launches From Baikonur, Docks Saturday
The Russian cargo ship lifted off on a Soyuz-2.1b rocket a week after the launch was delayed by a third-stage fault. Sources disagree on the exact mass of the cargo.
The Russian cargo ship Progress MS-35 lifted off today, September 16, from the Baikonur Cosmodrome in Kazakhstan, a week after its launch was postponed over a fault in the rocket’s third stage. The Soyuz-2.1b rocket launched from Site 31, Pad 6, according to NASA, which lists liftoff at 9:33 a.m. Eastern, or 6:33 p.m. Baikonur time, which is 3:33 p.m. Central European Summer Time. Russian media give the launch time as 4:34 p.m. Moscow time, the same moment converted to a different time zone. The ship, designated Progress 96 in NASA’s system, is carrying supplies for the International Space Station and is due to dock automatically on Saturday, September 19.
NASA and Roscosmos say the ship’s orbital insertion, separation from the rocket’s third stage, and the deployment of its antennas and solar panels all went smoothly. The launch had originally been set for September 9, but was delayed after a fault was found in the Soyuz-2.1b’s third stage. The rocket was rolled back to the assembly building for repairs before being returned to the launch pad. According to the outlet www1.ru, this was the sixth flight of a Soyuz-2.1b rocket in 2026 and the 105th in the rocket’s entire history. The same source gives the rocket’s technical specifications: it stands 46.3 meters tall, produces 4,550 kilonewtons of thrust at liftoff, and can carry up to 8,670 kilograms to low Earth orbit.
The trip to the station takes 72 hours and 13 minutes and includes 49 orbits of Earth before the ship docks automatically at the upper port of the Poisk module. NASA lists the docking time as 9:46 a.m. Eastern on Saturday, while Russian sources give it as 4:47 p.m. Moscow time, roughly 3:46 p.m. Central European Summer Time.
Why the cargo figures don’t match
Sources disagree on the exact makeup and mass of the cargo, and neither side has published a single, agreed figure so far. NASA gives a rough estimate of about three tons of food, fuel and supplies, without a detailed breakdown by category. The Russian outlet Bes.media, citing Roscosmos, puts the total mass at 2,489 kilograms: 1,177 kilograms of dry cargo for the crew and the station’s systems, 842 kilograms of fuel to replenish the station, 420 kilograms of drinking water and 50 kilograms of oxygen. Other Russian reports cite about 2.4 tons of cargo, but with a different breakdown, 1,275 kilograms of food, 357 kilograms of sanitary equipment and hygiene supplies, and 20 kilograms of medicine. The outlet www1.ru, for its part, says the ship is carrying up to 2,600 kilograms of goods. The discrepancies most likely come from each source grouping cargo categories differently, rather than from conflicting measurements.
The dry cargo includes equipment for the Biopolymer, Vampire, Virtual, FS gas analyzer, Teledroid and Uragan science experiments. Along with the equipment for the Teledroid experiment, the station is also receiving an exoskeleton that cosmonauts will use to remotely operate a humanoid robot, which is expected to arrive on a future cargo flight.
Progress MS-35 is 7.4 meters long and 2.7 meters in diameter, with solar panels spanning 10.7 meters, according to Russian media. Its launch mass is 7,280 kilograms. It will remain at the station for roughly five months, after which it will be loaded with waste and deorbited over the Pacific Ocean, where it will burn up with no consequences. The previous cargo ship, Progress 94, undocked from the station on September 7 at 11:18 a.m. Eastern, freeing up the port the new ship is now taking. The International Space Station, according to NASA, has had a crew aboard continuously for more than 25 years, and regular resupply runs by cargo ships like Progress are part of that ongoing supply chain.
Progress MS-35’s docking had not yet taken place as of this writing, it is scheduled for Saturday, and only then will it be clear whether the automatic maneuver went off without any deviation, as well as how it affects the schedule for the arrival of the humanoid robot for which the control exoskeleton was sent. Neither Roscosmos nor NASA has so far published an agreed, single figure for the total cargo mass, so the breakdown in this article is given according to whichever source reported it, not as a confirmed official value.
