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Soyuz MS-24 delivers crew to ISS

For the first time in a year, a Russian Soyuz crew vehicle is delivering three fresh crew members to the International Space Station on Sept. 15, 2023. The successful docking with the outpost on the day of the launch also relieved the three members of Expedition 69, who stayed in orbit for a year due to a failure of the thermal control system aboard Soyuz MS-22 in December 2022.

Previous mission: Soyuz MS-23


Soyuz MS-24 mission at a glance:

Spacecraft designation Soyuz MS-24 (No. 755), ISS mission 70S
Launch vehicle Soyuz-2-1a 14S53 No. M15000-061
Payload fairing (SZB) 11S517A3.1000A1-0 No. M15000-100
Spacecraft mass ~7,152 kilograms
Launch Site Baikonur, Site 31, Pad No. 6
Launch date and time 2023 Sept. 15, 18:44:35.417 Moscow Time (actual)
Docking date and time 2023 Sept. 15, 21:53:32 Moscow Time (actual)
Docking destination ISS, Rassvet module (MIM1), nadir port
Flight duration (planned) Around 180 days (planned)
Landing date 2024 March 25 (planned)
Crew at launch Oleg Kononenko, Nikolai Chub, Loral O'Hara
Crew at landing Oleg Novitsky, Marina Vasilevskaya, Loral O'Hara

Changing crews and flight plans

One of the three crew members aboard Soyuz MS-24 was initially expected to be a guest cosmonaut from Belarus, who would return to Earth with the crew of Soyuz MS-23 after a short visit to the station. In the meantime, the guest's return seat aboard Soyuz MS-24 in early 2024 would be occupied by one member of the original Soyuz MS-23 crew who would stay on the station for two long-duration shifts lasting around a year.

According to Roskosmos, on June 14, 2022, the National Academy of Belarus submitted 29 candidates to Roskosmos for the guest-cosmonaut selection after screening more than 100 applicants. Two finalists expected to be females serving as a primary candidate and a backup. They were scheduled to be selected early in 2023.

By January 2023, Oleg Kononenko and Nikolai Chub, originally slated to launch aboard Soyuz MS-23, were re-assigned to the Soyuz MS-24 mission, due to the need to use their original spacecraft as a replacement vehicle for Soyuz MS-22, which was damaged by a coolant leak in December 2022. In turn, the flight of a guest cosmonaut from Belarus was shifted from Soyuz MS-24 to the follow-on Soyuz mission in 2024. US astronaut Loral O'Hara joined Kononenko and Chub on the Soyuz MS-24 crew. For Kononenko, it would be the fifth orbital space flight, while Chub and O'Hara would be flying for the first time.

On Aug. 15, 2023, the Chief Medical Commission at the Cosmonaut Training Center recommended the removal of Oleg Platonov from the backup crew of Soyuz MS-24 and Expeditions 70 and 71. As a result, Aleksei Ovchinin was left as a backup to both Russian members of the Soyuz MS-24 crew.

On Feb. 1, 2023, Roskosmos announced that two Soyuz-2-1a rockets for launching Progress MS-23 and Soyuz MS-24 spacecraft had been shipped from the manufacturing site at RKTs Progress in Samara to the Baikonur launch site.

In early March 2023, plans surfaced to advance the launch of Soyuz MS-24 from September 15 to June 7, 2023, probably in order to provide an earlier landing of the Soyuz MS-23 spacecraft, which could be affected by an issue that caused coolant leaks aboard Soyuz MS-22 and Progress MS-21 transport ships.

On March 11, 2023, Sergei Krikalev, Head of Piloted Space Flight at Roskosmos, confirmed to the Interfax news agency, that an earlier launch for the Soyuz MS-24 had been under consideration among several other scenarios. However, the meeting of the State Commission on March 24, 2023, kept the schedule as is for the time being, possibly because it would be impossible to sustain future crew rotations aboard the ISS with earlier launches.

Soyuz MS-24 launch campaign


The first phase of preparation for the Soyuz MS-24 mission started in the processing building at Site 254 on March 17, 2023, with a visual inspection, initial measurements and the connection of the ship to test equipment, RKK Energia said. By March 24, specialists completed autonomous tests of Soyuz' avionics and Kazbek cosmonauts seats on ground-based stands.

In the last week of March 2023, specialists from RKK Energia powered up the onboard computer system, TV and radio equipment aboard Soyuz MS-24 and tested the pressurization of the ship's Thermal Control System, SOTR, (INSIDER CONTENT). The testing of the spacecraft in the anechoic chamber, BEK, at Site 254 was performed on April 14. On April 29, engineers powered up the ship's onboard systems to perform the simulation of launch readiness and integrated tests during various flight modes. The spacecraft was then mothballed at the work site until the start of its active launch campaign, Roskosmos said, indicating that the earlier launch of the Soyuz MS-24 had been ruled out for the time being.

On May 6, Oleg Kononenko and Nikolai Chub were reported conducting final fit checks of Sokol KV-2 safety suits and Kazbek-UM seats at NPP Zvezda enterprise.

On June 3, 2023, Roskosmos announced that Kononenko and Chub had completed several weeks of training in Houston on the US Segment of the station and the joint emergency exercise with NASA's 7th commercial crew simulating fire, depressurization and toxic spill aboard the ISS.

By June 8, 2023, the four boosters of the first stage were attached to the core (second) stage of the Soyuz-2-1a rocket inside the vehicle assembly building at Site 31.

By Aug. 10, 2023, Soyuz MS-24 was placed into a vacuum chamber at Site 254 for pressure tests, which were completed on August 15, when the spacecraft was returned to its processing site. On Aug. 17, 2023, Roskosmos reported that An-12 transport plane had landed at Krainy airport in Baikonur with an Emergency Escape System, SAS, for the Soyuz MS-24 mission. The rocket unit was then transported to Site 112.

On Aug. 25, 2023, the Inter-agency Qualification Commission at the Gagarin Cosmonaut Training Center confirmed the readiness of the Soyuz MS-24 crews for flight.

The primary and backup crews of Expedition 70/71 arrived at Baikonur on Aug. 29, 2023, for the final two-week period of preparation for the Soyuz MS-24 launch. On the same day, both crews conducted "fit checks" inside their flight-ready Soyuz spacecraft. Right after the familiarization training, the spacecraft was transferred to the fueling station at Site 31, where propellant and pressurized gases loading operations commenced on August 31. Fueling operations were completed on September 1, after which the spacecraft was transported back to Site 254.

On Sept. 5, 2023, Soyuz MS-24 was connected to its launch vehicle adapter, after the specialists performed weighing of the spacecraft and loaded around 120 kilograms of cargo intended for delivery to the ISS. They also conducted the final visual inspection of the spacecraft, after which the payload fairing was then installed on September 7. The vehicle was then put back in vertical position for a launch readiness simulation.

On September 10, members of the primary and backup crew conducted another training inside the flight-worthy spacecraft, after which specialists loaded the payload section with the spacecraft on a rail trailer and transported it to the vehicle assembly building at Site 31 for integration with the rocket, which took place on September 11. On the same say, the vehicle was cleared for rollout to the launch pad, which took place on the morning of Sept. 12, 2023.

Soyuz MS-24 enters orbit

A Soyuz-2-1a rocket carrying the Soyuz MS-24 spacecraft lifted off from Baikonur on Sept. 15, 2023, at 18:44:35.417 Moscow Time (11:44 a.m. EDT).

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 (L+113.69 seconds), 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, immediately followed by the separation of the four boosters of the first stage at L+117.85 seconds into the flight.

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+153.92 seconds into the flight.

The second (core) stage of the rocket continued firing until 4.8 minutes into the flight (L+287.70 seconds). 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 at L+296.31 seconds into the flight.

Following the 8-minute 49-second climb to orbit, the third stage of the rocket cut off at L+526.18 seconds into the flight, releasing Soyuz MS-24 into an initial orbit with an inclination 51.6 degrees toward the Equator and an altitude of around 200 kilometers.

Rendezvous and docking operations


Soyuz MS-24 spacecraft was scheduled to rendezvous with the ISS on the day of the launch, after a two-orbit, three-hour 14-minute autonomous flight.

Around 38 minutes after launch, at 19:23:25 Moscow Time, Soyuz MS-24 was scheduled to perform an initial orbit correction with its main SKD engine, which was to last 13 seconds and deliver 4.74 meters per second in velocity change. The maneuver would put the spacecraft in a 404.683 by 431.497-kilometer orbit to begin an autonomous rendezvous with the station during its second revolution around the Earth. At the time, the station was forecasted to be in a 414.750 by 438.183-kilometer orbit, close enough for the transport ship to perform a fully autonomous rendezvous.

As usual, the Russian mission control in Korolev planned additional six maneuvers with the transport ship's SKD and DPO engines during the autonomous rendezvous with the station:

No. Moscow Time Distance from ISS Delta V Burn duration Engines used
SB1 19:53:04 627.47 kilometers 53.40 meters per second 132.2 seconds SKD
bok 20:18:56 185.09 kilometers 0.96 meters per second 24.6 seconds DPO
SB2 20:39:45 96.57 kilometers 55.53 meters per second 137.2 seconds SKD
SB3-1 21:26:25 2.04 kilometers 5.29 meters per second 16.0 seconds SKD
SB3-2 21:30:35 1.02 kilometer 5.93 meters per second 75.4 seconds DPO
SB3-3 21:33:25 0.61 kilometers 1.46 meters per second 12.6 seconds DPO

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

  • 19:33:58 Moscow Time: Beginning of autonomous rendezvous with the ISS;
  • 20:22:58 Moscow Time: Activation of the Kurs rendezvous system aboard the Zvezda Service Module, SM;
  • 20:23:58 Moscow Time: Activation of the Kurs rendezvous system aboard Soyuz MS-24;
  • 21:36 — 21:41 Moscow Time: Fly-around of the station;
  • 21:41 — 21:44 Moscow Time: Station-keeping of the spacecraft near ISS before final approach;
  • 21:44 — 21:56 Moscow Time: Final approach to the Rassvet module, MIM1;
  • 21:56:00 Moscow Time: Contact.

The 54-degree, three-minute flyaround of the station began from a distance of around 400 meters to align the spacecraft with the nadir-facing docking port of the Rassvet module. The spacecraft then started the final approach from a distance of around 200 meters.

The docking of the crew vehicle with the Rassvet module, MIM1, a part of the Russian Segment of the ISS was scheduled for 21:56 Moscow Time (2:56 p.m. EDT) on Sept. 15, 2023, but the contact and capture took place three minutes earlier at 21:53:32 Moscow Time as the two spacecraft were flying over Ukraine. According to data from mission control, peripheral interfaces of the docking port were connected at 21:57:08 Moscow Time, followed by the closure of the main ring two tenths of second later. Hooks on both sides of the port then started driving, closing by 21:58:43 Moscow Time. The docking process was completed with the retraction of the latches on the passive part of the port holding the docking probe of the active mechanism at 22:00:42 Moscow Time (3 p.m EDT).

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

  • 21:53:32 Moscow Time: Contact;
  • 21:54 — 22:55 Moscow Time: The hooks closure on MIM1 (Rassvet), Pressure checks; crew transfer to the Habitation Module, BO;
  • 22:55 — 00:10 Moscow Time: Spacesuits removal, drying of pressure safety suits; docking port pressurization checks;
  • 00:10 — 00:50 Moscow Time: Pressure equalization between the crew vehicle and the station. Hatch opening; TV report.

The hatches between the newly arrived crew vehicle and the station were opened at 00:16 Moscow Time on September 16, (5:16 p.m. EDT on Sept. 15, 2023).


Soyuz MS-24 crew members:

Primary crew at launch
Backup crew
Crew at landing
Soyuz commander
Oleg Kononenko (Roskosmos)
Aleksei Ovchinin (Roskosmos)
Oleg Novitsky (Roskosmos)
Flight engineer 1
Nikolai Chub (Roskosmos)
Marina Vasilevskaya (Belarus)
Flight engineer 2
Loral O'Hara (NASA)
Tracy Caldwell Dyson (NASA)
Loral O'Hara (NASA)


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This page is maintained by Anatoly Zak; Last update: September 17, 2023

Page editor: Alain Chabot; Edit: September 15, 2023

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Initial processing of Soyuz MS-24 in Baikonur. Click to enlarge. Credit: Roskosmos


Encapsulation of the Soyuz MS-24 spacecraft in Baikonur. The payload fairing for the mission had an insignia dedicated to the 105th anniversary since the birth of Sergei Afanasiev, the Minister of General Machine-building, MOM, a Soviet-era predecessor of Roskosmos. Click to enlarge. Credit: Roskosmos


Cosmonauts and astronauts during final training for the Soyuz MS-24 mission (primary crew, front row, left to right): NASA astronaut Loral O'Hara, Soyuz commander Oleg Kononenko and flight engineer Nikolai Chub; (backup crew, second row, left to right): NASA astronaut and flight engineer Tracy Caldwell Dyson, Roskosmos cosmonaut and Soyuz commander Aleksei Ovchinin. Click to enlarge. Credit: Roskosmos


Soyuz MS-24 shortly after its rollout to launch pad at Site 31. Click to enlarge. Credit: Roskosmos


Soyuz MS-24 enters orbit as seen by a camera aboard the third stage of the launch vehicle. Credit: Roskosmos