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Progress MS-15 completes ISS mission

Russia launched its second unpiloted mission of 2020 to deliver cargo to the International Space Station, ISS. The liftoff of a Soyuz-2-1a rocket with the Progress MS-15 cargo ship took place as scheduled on July 23, 2020, at 17:26 Moscow Time (10:26 a.m. EDT). The spacecraft linked up with the station less than 3.5 hours after launch. It was the 76th Progress mission to resupply the international outpost which lasted until February 2021.

Previous mission: Progress MS-14

Progress MS-15 mission at a glance:

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Mission of Progress MS-15

According to information from Roskosmos released in July 2020, Progress MS-15 was expected to deliver around 2,600 kilograms of supplies to the ISS. The cargo included water-carrying tanks with a total mass of around 420 kilograms, oxygen tanks weighing around 46 kilograms, propellant for refueling worth of 621 kilograms and a variety of dry cargo, including food, clothing and medical supplies with a total mass of 1,520 kilograms placed in the pressurized compartment of the vehicle. The spacecraft also had 880 kilograms of propellant in its KDU propulsion system.

Before October 2019, the Progress MS-15 mission was expected to begin on July 15, 2020. By October 2019, Progress MS-15 was charged at the end of what was then expected to be a 132-day flight to deorbit the Pirs Docking Compartment, SO1, a part of the Russian Segment since 2001. The operation would free the nadir (Earth-facing) docking port on the Zvezda Service Module, SM, for the arrival of the MLM Nauka module in December 2020. However, after the early-2020 delay of the Nauka's launch to 2021, Roskosmos considered transferring that task to a follow-on cargo vehicle and deorbiting Progress MS-15 on December 4, 2020. However, another revision of the ISS flight manifest drafted in early Summer 2020 penciled the extension of the Progress MS-15 mission to 274 days, apparently for the purpose of still using this ship to perform the originally planned deorbiting of the Pirs module on or around April 23, 2021.

On the launch day of the Progress MS-15 mission, NASA TV reported that the cargo ship would remain at the station until December 2020, meaning that the task of discarding Pirs was transferred to the Progress MS-16 mission. Perhaps, NASA referred to the old version of the flight manifest targeting the launch of MLM Nauka module in December 2020 and the respective deorbiting of Progress MS-15 with the Pirs module shortly thereafter. The preliminary version of the ISS flight manifest drafted by Roskosmos at the end of August 2020, still assigned the task of discarding Pirs to Progress MS-15 at the end of April 2021. If the timeline goes as planned, Progress MS-15 will log 274 days in space.

Cargo delivered in pressurized compartment of the Progress MS-15 spacecraft:

Preparing for flight

The Soyuz-2-1a rocket with Progress MS-15 is being erected on the launch pad on July 20, 2020.

On April 28, 2020, Roskosmos announced that its specialists had begun unloading boosters for the Soyuz-2-1a rocket assigned to launch Progress MS-15 from railway carriers and that they planned to begin assembling cabling network for the electric testing of the vehicle in the near future. The cargo ship itself was in storage mode at the time, Roskosmos said. The Progress MS-15 launch campaign resumed on June 10, 2020, with preparations for electrical checks, the inspection of solar panels, tests of pyrotechnic lines and the recording of the default status of all systems.

According to NASA information made public in the middle of June 2020, the launch of Progress MS-15 was scheduled for 17:26 Moscow Decree Time on July 23 and its docking at the Pirs module was planned at 20:47 Moscow Decree Time on the same day.

On June 23, RKK Energia announced that the tests of the Progress MS-15's radio systems in the anechoic chamber at Site 254 in Baikonur Cosmodrome had been completed. The subsequent vacuum tests were finished on June 30, 2020.

On July 3, specialists at the Yuzhny (Southern) branch of the TsENKI ground infrastructure center and RKTs Progress, the manufacturer of the Soyuz rocket family, completed the assembly of the second (core) stage of the Soyuz-2-1a launch vehicle inside the processing building at Site 31. On July 6, Roskosmos announced that specialists from RKK Energia and the Yuzhny branch had completed testing of solar panels aboard Progress MS-15. In addition, engineers checked the seals of the Rodnik water supply system inside the spacecraft and performed routine disinfection of the vehicle, Roskosmos said.

The technical management met on July 9 and cleared the vehicle for loading of propellant components into its integrated propulsion section, KDU, and the refueling tanks. The meeting was preceded by the weighing and balancing of the vehicle and balancing inside the processing building at Site 254.

On July 13, Roskosmos announced that the fueling operations with the Progress MS-15 had been completed and that it had been returned to its processing stand for the final pre-launch operations and loading of cargo and onboard documentation into its pressurized cargo section. The photos released with the announcement and dated July 12 showed the transfer of the spacecraft from the fueling station back to the processing facility, while the July 13 images documented loading of cargo items through the main docking port of the spacecraft. The next day, the spacecraft was integrated with an adapter ring designed to connect it to the launch vehicle.

On July 16, specialists from RKK Energia and Roskosmos conducted the traditional visual inspection of the Progress MS-15, after which it was rotated in horizontal position and rolled inside its payload fairing. The payload section with the spacecraft was then placed back into its vertical test stand for the integrated launch readiness test. On July 17, the vehicle was loaded into a rail container and transferred from the spacecraft assembly building at Site 254 to the vehicle assembly building at Site 31 for integration with its Soyuz-2-1a rocket. The next day, the payload section was connected to the third stage of the rocket which in turn was integrated with the assembled first and second stages.

The launch vehicle with the spacecraft began the trip to the launch pad at Site 31 on July 20, 2020, at 05:30 Moscow Time. According to the official Russian media, quoting Roskosmos officials, specialists found a problem in one of the systems within the launch facility, but it was resolved in the first day of the operations on the pad and the preparations for launch remained on schedule, the TASS news agency reported. According to reports from TsENKI ground infrastructure division at Roskosmos, the specialists at the organization's Yuzhny (southern) branch, based in Baikonur, had to replace the failed electric motor of a mechanical jack in the second level of the load-bearing structure in the launch facility. The work was complicated by +40C-degree temperatures at the spaceport.

The State Commission overseeing the operations met on the morning of July 23 and cleared the launch vehicle for fueling. The fueling of the rocket's third stage with liquid oxygen started at 13:50 Moscow Time on July 23, 2020. The fueling of booster stages started at 14:35 Moscow Time.

Pre-launch operations of the Progress MS-15 mission:

Progress MS-15 launch profile

A Soyuz-2-1a rocket carrying the Progress MS-15 cargo ship lifted off on July 23, 2020, at 17:26:21.374 Moscow Time (10:26 a.m. EDT) from Site 31 in Baikonur.

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 the continuous thrust during the separation process. A fraction of a second after the boosters parted, 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 Progress MS-15 separated from the third stage of the launch vehicle at 17:35:11 Moscow Time, or 8 minutes 49 seconds after liftoff, completing its ride to orbit without problems. All external elements of the vehicle had deployed as planned, according to NASA.

Progress MS-15 launch timeline:

Glitch during a rendezvous with the ISS

The Progress MS-15 launch was targeting an initial parking orbit with the following parameters and allowable deviations:

At the time of the launch, the station was in orbit with an average altitude of around 419 kilometers. It passed over Baikonur 41 seconds after the liftoff of Progress MS-15, but by the time the cargo ship entered orbit, the outpost was around 11,000 statute miles ahead, as both vehicles flew over Eastern Mongolia, according to NASA.

If launched on time and delivered into the correct orbit within a required 15-degree corridor, the Progress MS-15 would be on track for an automated rendezvous with the ISS after just two revolutions around the Earth, or 3 hours and 21 minutes after its liftoff from Baikonur.

After Progress MS-15 had reached orbit, NASA said that the vehicle was on track for a two-orbit rendezvous profile.

According to mission control in Korolev, the autonomous rendezvous of the vehicle with the station was scheduled to begin at 18:27:54 Moscow Time or around an hour after launch. Progress MS-15 was scheduled to perform a total of six orbit correction maneuvers according to the following timeline:

At 19:16:06 Moscow Time, shortly before the second maneuver, the passive rendezvous equipment on the Zvezda Service Module of the Russian Segment would be activated to respond to signals from the active Progress vehicle. The active part of the Kurs system on the Progress MS-15 was to be activated two minutes later.

After catching up with the station, the cargo ship was scheduled to begin the fly-around process and station-keeping, lasting from 20:27 to 20:37 Moscow Time. According to NASA, Progress MS-15 was to begin flying around the station at a distance of 400 meters from the ISS to make a 57-degree turn of the trajectory to align with the nadir (Earth-facing) port of the Pirs Docking Compartment, SO1, a part of the Russian Segment. By the time of the station-keeping period, the spacecraft was expected to be at a distance of 215 meters from the outpost.

The final approach was expected to last from 20:37 Moscow Time to 20:44 Moscow Time. The docking of Progress MS-15 with the Pirs module, was scheduled at 20:47 Moscow Time (1:47 p.m. EDT, 17:47 UTC) with a projected accuracy of three minutes either way. The earliest time for the contact was 20:44:52 Moscow Time. The docking process was projected to last until 21:02 Moscow Time.

In preparation for docking, Russian cosmonauts aboard the ISS activated the TORU remote-control system at 20:19 Moscow Time in the unlikely event the fully automated control would fail. In fact, during the final approach to the ISS, the cross hairs of the ship's navigation camera were not perfectly aligned with the docking target on the Pirs module. Moreover, at a distance of around 15 meters from the station, the spacecraft also began an unexpected roll by a few degrees from its planned orientation. "I honestly don't like this movement," one of the cosmonauts was heard saying. The cosmonauts proposed mission control to switch to the TORU mode, but when the cargo ship was just meters away from the station, Vladimir Soloviev, the head of flight operations in Korolev, advised the crew not to interrupt the automated process. "Everything is nominal, Anatoly, don't do anything," he told Anatoly Ivanishin, who was at the TORU control console inside the Zvezda Service Module.

Moments later, a seemingly normal contact took place at 20:44:52 Moscow Time, followed by a capture by a couple of seconds later, as the two spacecraft were flying over Eastern China. The docking probe then started moving at 20:48:17 Moscow Time, pulling the two objects together, and the closure of the hooks in the ports, completing the docking process, was reported to take place at 20:49 Moscow Time.

Still, even after the seemingly smooth docking, the cosmonauts reported a signal on their monitors "Uvod TGK", which can be translated as the "the spacecraft back away." The command is usually associated with an abort in the berthing attempt. Fortunately, in this case, the UVD TGK mode was apparently triggered by a premature deactivation of the TORU remote-control system by the crew after the successful docking and it had no effect.

On July 24, 2020, Roskosmos publicly admitted that the anomaly during docking had been under investigation, but did not say whether any safety guideliness had been violated during the final approach of Progress MS-15 to the ISS. According to unofficial sources, protective elements of the Kurs antenna were damaged by the separating payload fairing during the ascent of the vehicle to orbit.

Progress MS-15 deorbits

Reentry of Progress MS-15 as seen from the ISS.

Near the completion of the 201-day flight, the hatches from the Progress MS-15 cargo ship and the Pirs module were closed on Feb. 8, 2021, at 13:40 Moscow Time. Then, on February 9, at 08:20 Moscow Time, the mission control issued a command to undock the cargo ship from the station. The physical separation between Progress MS-15 and the Pirs module took place at 08:21:30 Moscow Time on Feb. 9, 2021. According to a pre-programmed sequence, Progress MS-16 ignited its propulsion system on the same day, at 11:30:11 Moscow Time. The deorbiting maneuver, lasting 3 minutes and 30 seconds, reduced the ship's velocity by 116 meters per second and initiated its reentry into the Earth's atmosphere.

According to calculations of the mission control in Korolev, the surviving debris of the vehicle impacted the remote area of the Pacific Ocean 1,680 kilometers from Wellington, New Zealand, at 12:13:18 Moscow Time on Feb. 9, 2021.

Next cargo mission: Progress MS-16

This page is maintained by Anatoly Zak; Last update: February 13, 2021

Page editor: Alain Chabot; Edit: July 22, July 24, 2020

All rights reserved

The core stage of the Soyuz-2-1a rocket is unloaded in Baikonur at the end of April 2020. Click to enlarge. Credit: Roskosmos

Specialists check solar panels of the Progress MS-15 spacecraft on June 10, 2020. Click to enlarge. Credit: Roskosmos

Progress MS-15 undergoes work in the anechoic chamber on June 22, 2020. Click to enlarge. Credit: Roskosmos

Progress MS-15 returns from vacuum tests on June 30, 2020. Click to enlarge. Credit: Roskosmos

Loading of cargo aboard Progress MS-15 spacecraft on July 13, 2020. Click to enlarge. Credit: Roskosmos

Progress MS-15 was integrated with its launch vehicle adapter on July 14, 2020. Click to enlarge. Credit: Roskosmos

Progress MS-15 is being lowered in horizontal position for integration with its payload fairing on July 16, 2020. Click to enlarge. Credit: Roskosmos

Progress MS-15 travels to the vehicle assembly building on July 17, 2020. Click to enlarge. Credit: Roskosmos

The upper composite containing the Progress MS-15 spacecraft is being integrated with the Soyuz-2-1a launch vehicle on July 18, 2020. Click to enlarge. Credit: Roskosmos

Soyuz-2-1a with Progress MS-15 rolls out to the launch pad on July 20, 2020. Click to enlarge. Credit: Roskosmos

Progress MS-15 shortly before lift off on July 23, 2020. Click to enlarge. Credit: Roskosmos

Click to enlarge. Credit: Roskosmos

Progress MS-15 lifts off on July 23, 2020. Click to enlarge. Credit: Roskosmos

Launch of the Progress MS-15 photographed from the ISS by the Russian cosmoanut Ivan Vagner. Click to enlarge. Credit: Roskosmos

Click to enlarge. Credit: Roskosmos

Progress MS-15 begins ascent to orbit. Click to enlarge. Credit: Roskosmos

First stage separation photographed from the ISS by Ivan Vagner. Click to enlarge. Credit: Roskosmos

Progress MS-15 approaches the ISS on July 23, 2020. Click to enlarge. Credit: Roskosmos

Progress MS-15 was slightly off-target during its final approach and made an unexpected roll maneuver just meters from docking. Click to enlarge. Credit: Roskosmos