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Progress MS-18 docks at Zvezda

Launched in the early hours of October 28, 2021, the Progress MS-18 cargo ship embarked on a two-day trip to the International Space Station, ISS, concluding with a docking at the aft port of the Zvezda Service Module. That particular docking mechanism was unoccupied for half a year, because it is connected to the rest of the outpost via the PrK transfer compartment which had been leaking air despite all efforts to seal tiny cracks in its walls. (INSIDER CONTENT) Progress MS-18 should confirm that the PrK chamber could be used safely.

Progress MS-18 mission at a glance:

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Progress MS-18 mission

According to Roskosmos, Progress MS-18 will deliver around 1,490 kilograms of supplies to the ISS, including 560 kilograms of propellant for refueling the station, 420 liters of water in the tanks of the Rodnik system and 43 kilograms of compressed air in the tanks of the oxygen supply system. In its pressurized cargo section, the spacecraft will carry dry cargo for the crew and equipment for ongoing scientific studies including experiments Matreshka-R, Biomag-M, Aseptik, Struktura and Fotobioreaktor.

During the early planning of the ISS flight manifest in 2014, the second Russian cargo mission of 2021 was planned for April 16, 2021, however in the provisional schedule prepared by Roskosmos at the end of August 2020, the launch of Progress MS-18 (ISS mission 79P, Production No. 447) was planned for August 18, 2021. By November 2020, the start of the mission slipped to October 28, 2021.

At the time, the vehicle was expected to dock at the aft port of the Zvezda Service Module, SM, and remain in orbit for 215 days, supporting the 66th long-duration expeditions aboard the ISS. That schedule remained unchanged until the launch.

Progress MS-18 launch campaign

The Soyuz-2-1a rocket for the Progress MS-18 mission arrived at Baikonur in the middle of August 2021. On September 1, Roskosmos announced that the cargo ship had been taken out of storage inside processing complex at Site 254 and installed in its testing rig, where specialists conducted visual inspection of the spacecraft in preparation for electric checks scheduled to begin on September 2.

The autonomous tests of the spacecraft's radio systems in the anechoic chamber were completed on September 23 and on September 28, the spacecraft was transported into the vacuum chamber for air leak checks, which were completed by October 4, when the spacecraft was returned to its processing facility at Site 254.

Progress MS-18 (top center) returns to its processing facility on October 4, 2021, after the completion of vacuum tests.

The mechanical assembly of the first and second stages of the Soyuz-2-1a launch vehicle for the mission was performed at Site 31 by October 8. On the same day, specialists conducted routine tests of the cargo ship's solar panels, tested the lines of the ship's Rodnik water-supply system. On October 15, a meeting of technical management cleared Progress MS-18 for fueling of its propulsion unit and of the re-fueling section. Prior to its departure to the fueling station, the spacecraft undewent balancing and weighting at Site 254. Also, on October 15, specialists at the vehicle assembly building at Site 31 completed the four-day process of pneumatic tests on the three stages of the Soyuz-2-1a rocket and transitioned to autonomous tests of the rocket's systems.

The fueling operations with Progress were completed by October 19, after which, the cargo ship was returned to its processing stand at Site 254. On October 20, the spacecraft was integrated with an adapter section serving as an interface with the launch vehicle. The stack was then lowered in horizontal position, rolled inside its payload fairing and, on October 22, the assembled payload section was loaded into a rail transporter and shipped to the vehicle assembly building for integration with its rocket which was completed on October 23.

The launch vehicle was rolled out to the launch pad on the morning of Oct. 25, 2021.

Progress MS-18 launch profile

A Soyuz-2-1a rocket carrying the Progress MS-18 cargo ship lifted off from Site 31 in Baikonur on Oct. 28, 2021, at 03:00:32.525 Moscow Time (8 p.m. EDT on October 27).

Following 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 headed 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 separated nearly two minutes into the flight, followed by the split and drop of the two halves of the payload fairing slightly more than a minute later. In the meantime, the second stage continued firing until 4.7 minutes into the flight.

The third stage ignited 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 after the boosters of the second and third stage parted ways, the aft cylindrical section of the third stage split into three segments and dropped off, ensuring the fall of the second stage and the aft section into the same drop zone.

The spacecraft was expected to separate from the third stage of the launch vehicle 8 minutes and 49 seconds after liftoff into a 193 by 240-kilometer orbit with an inclination 51.67 degrees toward the Equator.

Rendezvous and docking

The Progress MS-18 mission followed a two-day rendezvous profile with the ISS. Its docking at the aft port of the Zvezda Service Module was scheduled for Oct. 30, 2021, at 04:33 Moscow Time (9:33 p.m. EDT on October 29) with three-minute accuracy. The actual physical contact between the cargo ship and the station was registered at 04:31:19 Moscow Time on October 30 (9:31 p.m. EDT on October 29).

It was the first spacecraft docking at the aft port of the Zvezda Service Module since the departure of Progress MS-14 on April 28, 2021. During that period, the PrK transfer chamber connecting the port to the Zvezda's interior, remained closed off to mitigate an air leak in its walls (INSIDER CONTENT).

Progress MS-18 helps ISS to avoid space junk

On November 10, Roskosmos announced that Progress MS-18 cargo ship was scheduled to fire its engine for 361 seconds starting at 23:15 Moscow Time (3:15 p.m. EST), increasing the station's velocity by 0.7 meters per second and boosting its average altitude by 1,240 meters to 420.72 kilometers. According to the State Corporation, the maneuver, designed to avoid space junk, went as scheduled.

Several hours earlier, Roskosmos said that the ISS had been predicted to pass close to a fragment of the Fengyun-1C satellite around 04:00 Moscow Time on November 12 (8 p.m. EST on November 11). Fengyun-1C satellite was destroyed in 2007 in a test of a Chinese anti-satellite missile.

Previously, an orbit correction using Progress MS-18's propulsion system was planned to be initiated on Nov. 16, 2021, at 20:40 Moscow Time. The maneuver was scheduled to last 478 seconds, Roskosmos said on November 8. However, on November 11, Roskosmos announced that the orbit correction originally planned on November 16 had been cancelled, because the space-junk-avoidance manuever conducted on November 10 was designed to provide necessary orbital parameters for the station.

Another maneuver with Progress MS-18's engines was conducted on Dec. 3, 2021, this time to avoid a fragment of the US Pegasus rocket launched in 1994. On December 1, the piece was predicted to pass as far as 5.4 kilometers from the ISS at 13:33 Moscow Time on December 3, but the estimate was later updated to around three kilometes. As a result, at 10:58 Moscow Time, Progress MS-18 was commanded to fire its propulsion system for 160.9 seconds slowing the ISS' velocity by 0.3 meters per second and lowering its overall altitude by 310 meters. According to the Russian mission control, after the maneuver, the station was in orbit with the following parameters:

• Orbital period: 92.91 minutes;
• Orbital inclination: 51.66 degrees;
• Minimal altitude: 420.30 kilometers;
• Maximum altitude: 434.84 killometers,
• Average altitude: 419.65 kilometers.

On December 19, Roskosmos announced that another ISS orbit correction had been scheduled for December 24, with the goal of forming orbital parameters necessary for the launch of the Soyuz MS-21 crew vehicle and landing of the Soyuz MS-19 in 2022. The maneuver was to be conducted with the propulsion system of the Progress MS-18 cargo ship. The engine firing was scheduled to start at 04:18 Moscow Time (8:18 p.m. EST on December 23) and last 561.2 seconds. The maneuver was expected to reduce the station's velocity by 1.06 meters per second and reduce its altitude by 1.8 kilometers to an average altitude of 417.50 kilometers.

As of December 19, the station's orbit was expected to have the following parameters after the maneuver:

• Orbital period: 92.86 minutes;
• Orbital inclination: 51.66 degrees;
• Minimal altitude: 415.88 kilometers;
• Maximum altitude: 433.40 kilometers.

On December 24, Roskosmos confirmed that the maneuver had been started at scheduled time and lasted 544 seconds, delivering 1.02 meters per second in velocity change and reducing the station's average altitude by 1.89 kilometers. According to post-maneuver measurements, the station's orbit had the following parameters:

• Orbital period: 92.86 minutes;
• Orbital inclination: 51.66 degrees;
• Minimal altitude: 415.63 kilometers;
• Maximum altitude: 433.15 kilometers.

January 2022 orbit correction

On Jan. 1, 2022, Roskosmos announced that yet another ISS orbit correction had been scheduled for Jan. 12, 2022, with the goal of forming orbital parameters necessary for the launch of the Soyuz MS-21 crew vehicle and landing of the Soyuz MS-19 in 2022. Once again, the maneuver was to be conducted with the propulsion system of the Progress MS-18 cargo ship. The engine firing was scheduled to start at 21:09 Moscow Time (1:09 p.m. EST) and last 292.5 seconds. The maneuver was expected to add to the station's velocity 0.54 meters per second and increase its altitude by 850 meters to an average altitude of 417.73 kilometers.

As of January 1, the station's orbit was expected to have the following parameters after the maneuver:

• Orbital period: 92.87 minutes;
• Orbital inclination: 51.66 degrees;
• Minimal altitude: 414.69 kilometers;
• Maximum altitude: 436.87 kilometers.

Correction on Feb. 8, 2022

On Feb. 2, 2022, Roskosmos announced that next ISS orbit correction had been scheduled for Feb. 6, 2022, with the goal of forming orbital parameters necessary for the launch of the Soyuz MS-21 crew vehicle and landing of the Soyuz MS-19. Once again, the maneuver was to be conducted with the propulsion system of the Progress MS-18 cargo ship. The engine firing was scheduled to start at 12:30 Moscow Time (4:30 a.m. EST) and last 109.4 seconds. The maneuver was expected to add to the station's velocity 0.2 meters per second and increase its altitude by 400 meters to an average altitude of 417.6 kilometers.

As of January 1, the station's orbit was expected to have the following parameters after the maneuver:

• Orbital period: 92.86 minutes;
• Orbital inclination: 51.66 degrees;
• Minimal altitude: 415.67 kilometers;
• Maximum altitude: 439.62 kilometers.

By February 6, the maneuver was re-scheduled for February 8, at 10:56 Moscow Time (2:56 a.m. EST). According to Roskosmos, the propulsion system aboard Progress MS-18 fired for for 142.3 seconds and added 0.26 meters per second to the station's velocity. The State Corporation said the average altitude of the outpost was increased by 0.45 kilometers and reached 417.6 kilometers above the Earth's surface.

Orbit correction on Feb. 28, 2022

On February 16, Roskosmos announced that next ISS orbit correction had been scheduled for Feb. 26, 2022, with the goal of forming orbital parameters necessary for the launch of the Soyuz MS-21 crew vehicle on March 18 and landing of the Soyuz MS-19 on March 30. Once again, the maneuver was to be conducted with the propulsion system of the Progress MS-18 cargo ship. The engine firing was scheduled to start at 04:37 Moscow Time (8:30 p.m. EST on February 25) and last 372.5 seconds. The maneuver was expected to add to the station's velocity 0.54 meters per second and increase its altitude by 1.1 kilometer to an average altitude of 417.94 kilometers.

As of January 1, the station's orbit was expected to have the following parameters after the maneuver:

• Orbital period: 92.87 minutes;
• Orbital inclination: 51.66 degrees;
• Minimal altitude: 415.40 kilometers;
• Maximum altitude: 435.97 kilometers.

ISS orbit adjusted for planned resupply

In preparation for the launch of the Progress MS-20 cargo mission to the International Space Station, ISS, on June 3, 2022, the outpost's orbit was increased by 1.9 kilometers to an average altitude of 418.22 kilometers on May 14, 2022, Roskosmos said.

As before, the maneuver was conducted with the propulsion unit of the Progress MS-18 spacecraft docked at the aft port of the Zvezda Service Module, SM.

The engine firing started at 21:05 Moscow Time and lasted 659 seconds, adding 1.1 meters per second to the station's velocity.

According to Roskosmos, during its entire mission, Progress MS-18 performed a total of nine ISS orbit corrections, incuding six planned and three to avoid "space junk."

Progress MS-18 ends its mission

On May 19, 2022, Roskosmos said that the undocking of the Progress MS-18 from the ISS had been scheduled for 11:02:30 Moscow Time (4:02 a.m. EDT) on June 1, 2022, as originally planned. Around the time of the announcement, cosmonauts aboard the ISS closed the hatches into the cargo ship, which was loaded with around 1.3 tons of trash.

Following the deorbiting maneuver and the reentry of vehicle, its surviving debris were expected to impact the Pacific Ocean around 2,000 kilometers west of Wellington, New Zealand, at 14:48:52 Moscow Time (7:48 a.m. EDT).

On June 1, 2022, the undocking was reported taking place at 11:02:51 Moscow Time (6:02 a.m. EDT) and the deorbiting maneuver was scheduled from 14:11:19 to 14:15:21 Moscow Time. The engine firing was expected to slow down the ship's orbital velocity by 123.0 meters per second, enough for the destructive reentry into the dense atmosphere.

At 14:43:11 Moscow Time (7:43 a.m. EDT), the vehicle was to hit the dense atmosphere and begin desintegrating at 14:45:41 Moscow Time.

The remnants of the vehicle were now predicted to impact the Pacific at 14:51:10 Moscow Time (7:51 a.m. EDT) around 2,700 kilometers from Wellington, New Zealand, and 7,250 kilometers from Santiago, Chile.

(To be continued)

This page is maintained by Anatoly Zak; Last update: June 17, 2022

Page editor: Alain Chabot; Last edit: October 27, 2021

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Two components of the core stage appearing in the foreground of the photo released on May 4, 2021, likely belong to the Soyuz-2-1b rocket assigned to launch the Progress MS-17. The vehicle for the ninth OneWeb mission is in the background. Click to enlarge. Credit: Roskosmos

Progress MS-18 is undergoing tests in anechoic chamber on Sept. 23, 2021. Click to enlarge. Credit: Roskosmos

Click to enlarge. Credit: Roskosmos

Progress MS-18 is integrated with a payload fairing on Oct. 22, 2021. Click to enlarge. Credit: Roskosmos

Progress MS-18 lifts off on Oct. 28, 2021. Click to enlarge. Credit: Roskosmos