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Soyuz MS-23 replacement ship completes ISS mission

For the first time an empty crew vehicle headed to the International Space Station, ISS, to provide a return ride for two cosmonauts and an astronaut whose original ship suffered a major failure. Soyuz MS-23 lifted off on Feb. 24, 2023, on a mission to replace the Soyuz MS-22 spacecraft, which lost all its coolant fluid on Dec. 15, 2022.

Previous mission: Soyuz MS-22


Soyuz MS-23 mission at a glance:

Spacecraft designation Soyuz MS-23, 11F732-0000A48-0 No. 754, ISS mission 69S
Launch vehicle Soyuz-2-1a 14S53 No. M15000-060
Payload fairing (SZB) 11S517A3.1000A1-0 No. M15000-099
Spacecraft mass ~7,152 kilograms
Launch Site Baikonur, Site 31, Pad No. 6
Launch date and time 2023 Feb. 24, 03:24:29.466 Moscow Time (actual); 03:24:29 (planned)
Docking date and time 2023 Feb. 26, 03:58:00 Moscow Time (actual); 04:01:08 (planned)
Docking destination ISS, Poisk module, MIM2, zenith port; redocked to UM on April 6, 2023
Flight duration 215 days 10 hours 53 minutes (actual)
Landing date and time 2023 Sept. 27, 14:17 Moscow Time (actual)
Crew at launch No crew
Crew at landing Sergei Prokopiev, Dmitry Petelin, Frank Rubio (Launched on Soyuz MS-22)

Initial mission objectives of Soyuz MS-23

According to the original plans, Soyuz MS-23 was expected to launch with a crew of three on March 16, 2023.

On May 19, 2021, Roskosmos announced that Oleg Kononenko, Nikolai Chub and Andrei Fedyaev were assigned to be primary members of Expedition 69 crew on the ISS. Then, after an agreement with NASA on crew exchange in 2022, Fedyaev was replaced in the crew with American astronaut Loral O'Hara. At the same time, the backup crew of Soyuz MS-23 was comprised of Roskosmos cosmonauts Aleksei Ovchinin, Oleg Platonov and NASA astronaut Tracy Caldwell Dyson.

On Nov. 8, 2022, Roskosmos announced that Andrei Fedyaev had been assigned to NASA's 6th commercial crew, USCV-6, then scheduled to launch in mid-February 2023 aboard SpaceX' Dragon vehicle. He would be accompanied by two astronauts from NASA and one from the United Arab Emirates.

The mission of Soyuz MS-23 was expected to last until Fall of 2023, but in June 2022, Roskosmos announced that one of its crew members would remain aboard the station until 2024, to provide a seat for the return to Earth of a cosmonaut from Belarus, who, at the time, was scheduled to make a short visit the station in the Fall of 2023.

The Soyuz MS-23 spacecraft, Factory No. 754, was completed at the ZEM plant in Korolev in September 2022. Following its rail trip to Kazakhstan, Soyuz MS-23 was unloaded at the processing complex at Site 254 in Baikonur on Sept. 28, 2022.

The payload fairing assembly for the mission had arrived at the processing complex in Baikonur from RKTs Progress factory in Samara on Oct. 28, 2022, followed by the Soyuz-2-1a rocket on November 23 of the same year. The rocket's components were unloaded from rail cars inside the vehicle processing building at Site 31.

During the first 10 days of November 2022, specialists from RKK Energia conducted checks of onboard avionics and radio systems, as well as autonomous tests of Kazbek cosmonaut chairs for Soyuz MS-23.

Plan changes during launch campaign


On Dec. 17, 2022, in the aftermath of a coolant leak aboard the Soyuz MS-22 spacecraft docked at the ISS, Roskosmos said that preparations of the Soyuz MS-23 spacecraft in Baikonur could be speeded up, if necessary, for an earlier launch. According to unofficial rumors at the time, the March 16 liftoff of Soyuz MS-23 could be advanced to as early as Feb. 19, 2023. The most critical items in the accelerated pre-launch processing were reported to be the ship's Emergency Escape System, SAS, and the payload fairing.

On Jan. 11, 2023, Roskosmos announced the decision to launch Soyuz MS-23 on Feb. 20, 2023, at 04:57:53 Moscow Time, without crew, in order to provide a return ride for the three crew members of the damaged Soyuz MS-22.

The replacement vehicle was scheduled to dock at the ISS on Feb. 22, 2023, at 05:36 Moscow Time, after a two-day, 34-orbit autonomous flight. To free its destination docking port on the Poisk module, MIM2, the Progress MS-21 cargo ship was to be undocked from the same location and deorbited on Feb. 18, 2023.

Instead of a crew, Soyuz MS-23 was slated to deliver around 430 kilograms of cargo to the ISS, including life-support materiel and food, Roskosmos said. According to the Head of the Russian piloted space program Vladimir Soloviev, the payload aboard Soyuz MS-23 would also include new remote-sensing instruments, intended for installation on the ISS, radiation-monitoring sensors and equipment for communications with the ground via Luch relay satellites.

On January 20, Roskosmos announced that the emergency escape rocket for the Soyuz MS-23 mission had been delivered to the Krainy airfield in Baikonur by an Antonov-12 transport plane. It was then transferred to Site 112 for processing and integration.

The vacuum testing of Soyuz MS-23 was conducted in Baikonur from January 18 to 24, 2023, and on Feb. 4, 2023, the meeting of the technical management cleared the spacecraft for fueling. Fueling operations started at Site 31 on Feb. 8, 2023, and were completed on the following day. Soyuz MS-23 was then returned to the spacecraft processing building at Site 254, where it was integrated with the launch vehicle adapter, PKhO, serving as an interface with the Soyuz-2-1a rocket on Feb. 10, 2023. Right before the integration, specialists weighted the spacecraft and completed preparations for loading of cargo into its pressurized compartments.

On Feb. 13, 2023, two days after another coolant leak hit a Russian transport ship at the ISS, this time the Progress MS-21 cargo ship, Roskosmos announced that the launch of Soyuz MS-23 had been postponed until the first 10 days of March 2023, at the earliest to give investigators time to rule out similar issues in the upcoming mission. According to unofficial sources, the interrupted processing of the spacecraft for launch was then authorized to resume around February 16 or 17, after an exterior inspection had not found any visible damage to the ship's radiator. The campaign re-scheduled the rollout to the launch pad to February 18 and the liftoff was targeted for February 21. However, by February 16, the launch was rescheduled for February 24 at 03:34:00 Moscow Time (7:34 p.m. EST on February 23).

Following an ISS orbit correction on February 19, the launch time shifted to 03:24:29 Moscow Time on February 24. The docking was then scheduled for February 26, at 04:01:08 Moscow Time.

On February 18, the Chief Designer Council met at RKK Energia in Korolev to review the status of the Soyuz MS-23 preparations. The group formally approved the launch of the mission on February 24, based on the evaluation of the latest data from the Progress MS-21 coolant leak incident and the additional inspection of the radiator system on Soyuz MS-23, which found no damage, according to Roskosmos. On the same day, the encapsulated payload section with Soyuz MS-23 was transferred from the spacecraft processing building at Site 254 to the vehicle assembly building at Site 31 for integration with the Soyuz-2-1a rocket, which was completed on February 20.


The rollout of the launch vehicle with the spacecraft to Pad 6 in Baikonur took place on the morning of February 21.

According to the Russian mission control, key operations on the launch pad on from Feb. 21 to Feb. 24, 2023, had the following timeline:

  • 51:24:29 - 03:24:29 hours to launch: Thermal conditioning of the spacecraft;
  • 07:00:00 - 03:44:00 hours to launch: Fueling of the launch vehicle;
  • 01:30:00 - 00:30:00 hours to launch: Testing of equipment and of onboard systems;
  • 00:45:00 - 00:33:00 hours to launch: Retraction of the access gantry.

Soyuz MS-23 launches


Cargo visible inside the Descent Module of the Soyuz MS-23 spacecraft at launch.

A Soyuz-2 rocket carrying the Soyuz MS-23 spacecraft lifted off from Pad 6 at Site 31 in Baikonur on Feb. 24, 2023, at 03:24:29.466 Moscow Time (7:24 p.m. EST on February 23).

Propelled by the simultaneous thrust of the four engines of the first stage and the single engine of the second stage, the rocket headed almost exactly east to align its ascent trajectory with an orbital plane inclined 51.6 degrees toward the Equator. Slightly less than two minutes into the flight, at an altitude of around 45 kilometers and a velocity of 1.75 kilometers per second, the ship's main emergency escape rocket was jettisoned at L+113.45 seconds, immediately followed by the separation of the four boosters of the first stage at 03:26:27 Moscow Time.

Around 35 seconds later, as the vehicle exited the dense atmosphere at an altitude of 79 kilometers and a velocity of 2.2 kilometers per second, the payload fairing protecting the spacecraft split into two halves and fell away at L+153.70 seconds into the flight, at 03:27:03 Moscow Time.

The second (core) stage of the rocket continued firing until 4.8 minutes into the flight (L+287.70 seconds, 03:28:17 Moscow Time). Moments before the second stage completed its work, the four-chamber engine of the third stage ignited, firing through the lattice structure connecting the two stages. Moments after the separation of the core booster at an altitude of 157 kilometers and a velocity of 3.8 kilometers per second, the tail section of the third stage split into three segments and separated as well.

Following the 8-minute 49-second climb to orbit, the third stage of the rocket was cut off at L+525.77 seconds into the flight and at L+531.76 seconds, it released Soyuz MS-23 into an initial orbit with an inclination 51.6 degrees toward the Equator and an altititude of around 200 kilometers at 03:33:18 Moscow Time.

Immediately after the separation of the spacecraft from the third stage, a camera aboard Soyuz MS-23 showed the deployment of its solar panel, while NASA confirmed that all the ship's antennas had deployed.

Rendezvous and docking


According to the Russian mission control in Korolev, the autonomous rendezvous of Soyuz MS-23 on Feb. 26, 2023, had the following timeline:

  • 01:37:09 Moscow Time: Beginning of autonomous rendezvous with the ISS;
  • 02:26:09 Moscow Time: Activation of the Kurs rendezvous system aboard the Zvezda Service Module, SM;
  • 02:27:09 Moscow Time: Activation of the Kurs rendezvous system aboard Soyuz MS-23;
  • 03:37 — 03:46 Moscow Time: Fly-around of the station;
  • 03:46 — 03:50 Moscow Time: Station-keeping of the spacecraft near ISS before final approach;
  • 03:50 – 04:00 Moscow Time: Final approach to the Poisk module, MIM2;
  • 04:00:58 Moscow Time: Contact.

The Russian mission control in Korolev planned a total of six maneuvers with the transport ship's engines during the autonomous rendezvous with the station:

No. Moscow Time Distance from ISS Delta V Burn duration Engines used
1 02:02:57 400.24 kilometers 15.32 meters per second 40.0 seconds SKD
2 02:20:56 197.13 kilometers 1.21 meters per second 30.4 seconds DPO
3 02:45:16 79.63 kilometers 33.88 meters per second 84.4 seconds SKD
4 03:27:14 2.15 kilometers 5.63 meters per second 16.8 seconds SKD
5 03:31:37 1.04 kilometer 5.87 meters per second 72.8 seconds DPO
6 03:34:25 0.62 kilometers 1.48 meters per second 12.8 seconds DPO

These orbital corrections were expected to put the spacecraft into a 384.645 by 427.005-kilometer orbit during its 32nd revolution around the planet. At the time, the station was forecasted to be in a 414.869 by 438.508-kilometer orbit, close enough for the transport ship to perform a fully autonomous rendezvous.

The automated docking of the Soyuz MS-23 spacecraft with the ISS was scheduled for Feb. 26, 2023, at 04:01:08 Moscow Time (8:01 p.m. EST on February 25) after two days in the autonomous flight. As often, the actual docking took place around three minutes earlier, at 7:58 p.m. EST, accroding to NASA. The Russian mission control confirmed that the first contact between the the spacecraft and the station had taken place at 03:58:00 Moscow Time.

On April 6, the Soyuz MS-23 was scheduled to re-dock from the Poisk module, MIM2, to the Prichal node module, UM, on the Russian Segment of the ISS. The move was probably designed to make Poisk available for spacewalks (INSIDER CONTENT) without the need to isolate members of the Soyuz MS-23 crew in their vehicle in case of problems during the re-pressurization of the airlock after the spacewalk, which would otherwise block the transfer into the transport vehicle in the short-sleeve environment.

As of February 2023, the spacecraft was expected to remain at the station until its landing in Kazakhstan on Sept. 27, 2023.

In the first week of March 2023, ISS crew members removed delivered cargo from the seat locations in the Descent Module of the Soyuz MS-23 spacecraft and installed seat liners from Soyuz MS-22 and Crew Dragon into Soyuz MS-23. They also conducted successful tests the Motion Control and Navigation System, SUDN, of the newly arrived vehicle and rehearsed landing operations.

Early return mulled for Soyuz MS-23

On March 9, 2023, the Izvestiya daily quoted unnamed sources within the Russian industry as saying that RKK Energia was considering advancing the launch date of the Soyuz MS-24 spacecraft from Sept. 15, 2023, to June 7 of the same year in order to accelerate the return of the Soyuz MS-23 crew. The existence of such plans indicated that specialists were still concerned about the possibility of a critical leak in the thermal control system (INSIDER CONTENT) of the fresh crew vehicle similar to those that hit two previous transport ships. Such a change in the schedule would also debunk the official explanation of both accidents by Roskosmos and NASA as have been caused by meteors rather than production defects.

The coolant leaks aboard Soyuz MS-22 and Progress MS-21 transport ships took place roughly three months into their respective missions, while the decision to return Soyuz MS-23 in June rather than in September would cut its flight from six to around 3.5 months.

On March 11, Sergei Krikalev, Head of Piloted Space Flight at Roskosmos, confirmed to the Interfax news agency, that an earlier launch for the Soyuz MS-24 was under consideration among several other scenarios.

Soyuz MS-23 moves to a new location on ISS


In March, NASA confirmed that the re-docking of Soyuz MS-23 was set for April 6, 2023, as originally planned before the mission. The transport ship with Frank Rubio, Sergei Prokopiev and Dmitry Petelin onboard was scheduled to undock from the Poisk module, MIM2, at 4:42 a.m. EDT, and after a 38-minute autonomous flight under manual control by Petelin, the Soyuz commander, the vehicle was to redock to the Prichal Node Module, UM, at 5:21 a.m. EDT.

By April 4, the time of undocking from Poisk was adjusted to 4:45 a.m. EDT (11:45 Moscow Time) and docking at Prichal was re-set for 5:23 a.m. EDT (12:23 Moscow Time). The transport ship was expected to back away to a distance of between 40 and 60 meters from the ISS before making a half a circle around the outpost to reach Prichal.

The operation would free the docking port on Poisk for the arrival of the Progress MS-23 cargo ship, then scheduled for launch on May 24, 2023, and set the stage for the Russian space walks to outfit the Nauka module, on April 18, 25, and May 4, 2023.

In the preparation for redocking, the three crew members of the Soyuz spacecraft boarded the vehicle around two hours before the scheduled trip. Also, the ISS was put into an optimal orientation for the maneuver and the hooks of the docking mechanism on the Poisk module were commanded to open more than an hour ahead of the planned undocking.

According to the Russian mission control in Korolev, the redocking operation had the following timeline:

  • 08:45 - 09:05 Moscow Time: Closing of transfer hatches between Soyuz MS-23 and the ISS;
  • 09:05 - 10:05 Moscow Time: Pressure checks in the closed hatches between Soyuz MS-23 and MIM2;
  • 10:05 - 11:43 Moscow Time: Preparation of the crew for undocking;
  • 11:43 - 11:45 Moscow Time: Undocking;
  • 11:45 - 11:54 Moscow Time: Backing away of Soyuz MS-23 from the station,
  • 11:54 - 12:00 Moscow Time: Station-keeping;
  • 12:00 - 12:23 Moscow Time: Flyaround, station-keeping, berthing;
  • 12:23:00 Moscow Time: Contact.

The command to Soyuz MS-23 to undock from Poisk was issued as planned at 04:43:30 a.m. EDT and the physical separation took place around 1.5 minute later at 4:45 a.m. EDT, NASA confirmed. In the meantime, the Prichal's docking port was powered up in preparation for the Soyuz MS-23 arrival.

After backing away from Poisk Soyuz MS-23 entered station keeping, before performing a 180-degree roll maneuver and extending its docking probe. The Soyuz then flew from the point above the station to a point in front of the station at a range of around 40 meters to align with the aft port of the Zvezda Service Module, SM. The vehicle then continued on to a point below the station to align with Prichal at a distance of around 50 meters. By that time, the operation was going around five minutes ahead of schedule, as the two vehicles flew over Northern Kazakhstan and into the Northern Mongolia.

After a short period of station-keeping and precise alignment of the vehicles, Soyuz MS-23 initiated its final approach to Prichal and docked as planned after 37 minutes in the autonomous flight, as the two spacecraft flew off the East Coast of Japan, shortly before the orbital sunset. According to NASA, the docking took place at 5:22 a.m. EDT, however live data from the Russian mission control in Korolev showed the first contact at 12:21:44 Moscow Time and the mechanical capture a second later. The docking probe retraction was registered at 12:24:25 Moscow Time. At the time, the station was orbiting the Earth in a 437.4 by 413.5-kilometer orbit.

After a series of leak checks, the hatches between the spacecraft and the station were scheduled to be opened according to the following schedule:

  • 12:21:45 Moscow Time: Contact;
  • 12:22 - 12:40 Moscow Time: The docking operations between Soyuz MS-23 and ISS;
  • 12:40 - 13:45 Moscow Time: Pressure checks aboard Soyuz MS-23, drying of pressure safety suits;
  • 13:45 - 15:00 Moscow Time: Docking port air leak checks between Soyuz MS-23 and UM MLM;
  • 15:00 - 15:20 Moscow Time: Opening of the transfer hatches.

According to Roskosmos, it was the 51st redocking of the Soyuz spacecraft since 1978, including 21 re-dockings in the ISS project.

Soyuz MS-23 returns to Earth


Following the traditional change of command ceremony aboard the ISS on Sept. 26, 2023, to symbolize the transition from Expedition 69 to 70, the Soyuz MS-23 spacecraft with three members of the station crew headed for landing on September 27. The hatch closing between the crew vehicle and the ISS took place at 12:41 a.m. EDT (07:41 Moscow Time).

According to Russian mission control, the Soyuz MS-23 landing had the following timeline:

  • 10:53 - 10:55 Moscow Time: Undocking;
  • 13:24:09 Moscow Time: Braking engine firing begins at an altitude of 442.1 kilometers;
  • 13:28:48 Moscow Time: Braking engine cutoff at an altitude of 432.1 kilometers;
  • 13:51:58 Moscow Time: Separation of the spacecraft into the Descent, Habitation and Instrument modules at an altitude of 140.0 kilometers;
  • 13:54:51 Moscow Time: Descent Module atmospheric reentry at an altitude of 99.7 kilometers;
  • 14:03:13 Moscow Time: Activation of the parachute system at an altitude of 10.8 kilometers;
  • 14:17:33 Moscow Time: Touchdown at 47 degrees 21 minutes North latitude, 69 degrees 34 minutes East longitude.

Soyuz MS-23 undocked from the Prichal module, UM, at 3:54:30 a.m. EDT on September 27 (10:54 Moscow Time), officially marking the end of Expedition 69 and the start of Expedition 70 aboard the ISS. At the time, the ISS was in a 438.7 by 414.6-kilometer orbit.

Reentry and landing

After a couple of hours in autonomous flight, Soyuz MS-23 initiated a deorbiting maneuver at 6:24:09 a.m. on September 27 (13:24 Moscow Time). The engine firing lasted four minutes and 39 seconds and reduced the spacecraft velocity by 128 meters per second, ensuring the reentry of the spacecraft into the Earth's atmosphere around 22 minutes later. Around three minutes before the entry interface, the Descent Module, carrying the crew, separated from the Habitation and Instrument modules.

According to Russian mission control, the cover of the parachute container on the Descent Module was jettisoned at an altitude of 10.5 kilometers, followed by the release of the braking parachute at an altitude of 9.5 kilometers and initiating the deployment of the main parachute. Upon completing its job, the braking parachute separated at an altitude of 8.5 kilometers.

The capsule then dropped its main heat shield at an altitude of 5.5 kilometers, revealing soft-landing engines, set to fire less than a meter from the surface. Immediately thereafter, at an altitude of 5.3 kilometers, the lines holding the main parachute system were switched to a touchdown configuration.

Following the nominal aerodynamic reentry, the Descent Module of the Soyuz MS-23 spacecraft touched down around 90 miles southeast of Dzhezkazgan in Kazakhstan, at 7:17 a.m. EDT on September 27 (14:17 Moscow Time, 17:17 local time). The Descent Module was found on its side after landing. Russian mission control reported actual landing point coordinates as 47 degrees 16 minutes North latitude and 69 degrees 40 minutes East longitude.

The on-time landing on Sept. 27, 2023, marked the end of the 371-day flight for all three crew members, who returned to Earth aboard Soyuz MS-23, but launched on Soyuz MS-22. According to NASA, it was the longest space flight for a US astronaut and the third longest space flight ever.

Following their extraction from the Descent Module after landing, the entire crew was scheduled to ride helicopters to the airfield near the city of Karaganda in Kazakhstan, where Rubio was to board a NASA plane heading to Houston, while Russian cosmonauts were to travel to the Gagarin Cosmonaut Training Center.


Soyuz MS-23 crew members (landing only):

Primary crew
Soyuz commander
Sergei Prokopiev (Roskosmos)
Flight engineer 1
Dmitry Petelin (Roskosmos)
Flight engineer 2
Frank Rubio (NASA)


Next mission: Soyuz MS-24


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This page is maintained by Anatoly Zak; Last update: October 11, 2023

Page editor: Alain Chabot; Edits: February 23, March 11, April 6, September 27, 2023

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Original logo of the Soyuz MS-23 mission.


An official logo of the Soyuz MS-23 mission.


Oleg Kononenko practicing controls of the spacecraft inside a Soyuz simulator. Click to enlarge. Credit: Roskosmos

Soyuz MS-23 shortly after integration with a launch vehicle adapter. Click to enlarge. Credit: Roskosmos


The upper composite with the Soyuz MS-23 spacecraft is being prepared for integration with booster stages of the Soyuz-2-1a rocket. Click to enlarge. Credit: Roskosmos


Soyuz-2-1a rocket with Soyuz MS-23 departs the vehicle assembly building at Site 31 on its way to the launch pad in Baikonur. Click to enlarge. Credit: Roskosmos


Soyuz-2-1a rocket with Soyuz MS-23 arrives at launch pad at Site 31 in Baikonur. Click to enlarge. Credit: Roskosmos


Soyuz-2-1a rocket with Soyuz MS-23 is installed on the launch pad at Site 31 in Baikonur. Click to enlarge. Credit: Roskosmos


Soyuz MS-23 enters orbit as seen by a camera aboard the third stage of the launch vehicle. Credit: Roskosmos


A deployed solar panel aboard Soyuz MS-23 as seen by an onboard camera moments after separation from the third stage of the launch vehicle. Credit: NASA


Soyuz MS-23 shortly after redocking to the Prichal Node Module, UM, on April 6, 2023. Click to enlarge. Credit: Roskosmos