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Prichal arrives at ISS The Prichal Node Module, UM, Russia's latest permanent addition to the International Space Station, ISS, lifted off from Kazakhstan on Nov. 24, 2021. The spacecraft followed a two-day rendezvous profile with the outpost, docking at the nadir (Earth-facing) port of the Nauka module on Nov. 26, 2021.
Prichal launch at a glance:
Prichal's launch profile
A Soyuz-2-1 rocket, carrying a stack of the Prichal module and its Progress M-UM space tug, lifted off as scheduled from Pad 6 at Site 31 in Baikonur Cosmodrome on Nov. 24, 2021, at 16:06:35.042 Moscow Time (8:06 a.m. EST, 13:06 UTC). 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 (at L+117.8 seconds) at an altitude of around 40 kilometers, while the core booster of the second stage continued firing until 4.7 minutes into the flight (L+287.7 seconds). The third stage ignited moments before the separation of the second stage, firing its four-chamber RD-0124 engine through a lattice structure connecting the two boosters and ensuring a continuous thrust during the separation process. Nearly 10 seconds after the second and the third stages parted ways at an altitude of around 150 kilometers, the aft section of the third stage split into three segments and fell off (at L+296.9 seconds), followed half a second later by the splitting of the payload fairing into two halves (at L+297.3 seconds). All five fragments were expected to fall in the same general area downrange from the launch site. The third stage continued operating until 559.94 seconds into the flight, releasing its payload into an initial parking orbit well within specifications at 16:15:58 Moscow Time (L+563.24 seconds):
According to Roskosmos and NASA, the ascent and orbital insertion of Prichal went flawlessly, with all its antennas and solar arrays confirmed as successfully deployed immediately after the separation of the module from the third stage of the launch vehicle, according to the following timeline:
According to the Russian mission control, testing of the ship's Kurs rendezvous equipment was scheduled to take place from 16:17 to 16:27 Moscow Time. Next, between 17:43 and 17:52 Moscow Time, a drogue probe on the module's active docking mechanism was scheduled to extend in operational position for docking.
At the time of Prichal's launch, the ISS was in a 419.832 by 435.969-kilometer orbit over the Southern Atlantic. For its ride from the initial parking orbit, where it was released by the launch vehicle, to the ISS, the Prichal Node Module will be integrated with a custom version (Insider Content) of the Progress cargo ship. The Progress will use its own propulsion and flight control system to deliver and then permanently attach the Node Module to the nadir (Earth-facing) docking port of the MLM module on the Russian Segment of the ISS. According to Roskosmos, the first two orbit maneuvers using the propulsion system of the Progress M-UM space tug were performed flawlessly starting at 19:45:19 and 20:35:35 Moscow Time on November 24. The third maneuver was scheduled at 17:31:45 Moscow Time on November 25. After Prichal reached its orbit as planned, the undocking of the Progress MS-17 spacecraft to free the nadir port of the Nauka module took place on Nov. 25, 2021, at 14:22:30 Moscow Time. The stage was then set for the fully automated docking of Prichal to Nauka on Nov. 26, 2021, within three minutes from 18:25:28 Moscow Time (10:25 a.m. EST), following the standard two-day rendezvous profile with the station practiced during routine Progress resupply missions. Like for the rendezvous with the Nauka module in July 2021 (Insider Content), the ISS was turned 180 degrees with the Russian Segment oriented forward relative to the station's velocity vector on the eve of the encounter with the Prichal module. The station was then pitched 90 degrees, so that the main axis of the Nauka module (and the direction of Prichal's final approach) would be aligned with the orbital motion. The autonomous rendezvous process on Nov. 26, 2021, between the module and the station was planned according to the following timeline:
According to the mission control in Korolev, during the autonomous rendezvous, Progress M-UM was scheduled to perform six impulse burns using its main SKD engine and DPO attitude-control thrusters:
Progress M-UM was projected to intercept the station during its 33rd orbit, which was projected to have a perigee of 384.171 kilometers and an apogee of 428.521 kilometer. At the same time, the station was expected to be in 420.109 by 435.623-kilometer orbit. As usual, at the time of a final approach, cosmonauts Anton Shkaplerov and Petr Dubrov activated the TORU manual control rendezvous system in a stand-by mode in case of any problems with the Kurs-NA automated system. The propellant supplies aboard the Progress M-UM spacecraft enabled a second rendezvous attempt with the station, if needed, while reserving a cache for the subsequent deorbiting of Progress M-UM's aggregate module. However, according to NASA and Roskosmos, Prichal's first rendezvous attempt with the ISS went flawlessly followed by a 45-degree flyaround of the station starting from a distance of around 400 meters, during Prichal's 34th orbit. At that point, the module was projected to be in a 402.498 by 429.866-kilometer orbit, while the station was in a 420.162 by 435.585-kilometer orbit. Prichal then initiated the automated final approach achieving contact at 09:19 Houston Time (10:19 EST, 18:19 Moscow Time, 15:19 UTC) or six minutes ahead of schedule, according to NASA. Immediately after the mechanical capture of the docking ports, live TV images showed a considerable motion of the newly arrived spacecraft relative to the station, but soon data from the Russian mission control in Korolev confirmed that all electric interfaces and a hard mate between the two vehicles had been successfully achieved by 18:23:09 Moscow Time. According to the telemetry data displayed by the mission control in Korolev, the docking process was performed along the following timeline:
Mission control also registered the completion of the following milestones during docking:
On the same day, at 22:39 Moscow Time, Russian cosmonauts Anton Shkaplerov and Petr Dubrov opened hatches into the new module and entered its interior, Roskosmos said.
During its trip to the station, the Prichal delivered around 0.5 ton of cargo to the station:
Prichal jettisoned its space tug
Artist rendering of the Prichal's space tug separation from the ISS. With the Prichal Node Module firmly in place at the International Space Station, ISS, it was time to discard the aggregate section, PAO, of the Progress-UM space tug that delivered the new component to the outpost's Russian Segment. As of November 2021, the separation was scheduled for Dec. 22, 2021, at 01:20:30 Moscow Time (5:20 p.m. EST on December 21). The PAO module would be deorbited over the Pacific Ocean three orbits after its departure from the station. The undocking of the space tug would open the access to the passive docking port along the Prichal's +X axis. On December 18, Roskosmos said that the undocking of the PAO section was re-scheduled for Dec. 23, 2021, at 02:03 Moscow Time (6:03 p.m. EST on December 22). The actual separation of the component appeared to take place on schedule and without incident. The deorbiting engine firing, intended to reduce the vehicle's velocity by 125.0 meters per second, was scheduled to begin at 06:45:25 Moscow Time on December 23 (10:45 p.m. EST on December 22) and fire for around 13 minutes. The maneuver would push the vehicle on a destructive path into the Earth's atmosphere. The impact of the surviving debris of the ship in the Pacific was now projected for 07:30 Moscow Time on December 23 (11:30 p.m. EST on December 22) around 2,460 kilometers from Wellington, New Zealand and 7,030 kilometers from Santiago, Chile. Roskosmos confirmed that the deorbiting of the component had taken place exactly as planned.
Planned timeline for the deorbiting of the PAO compartment from the Prichal Node Module on Dec. 23, 2021, according to Roskosmos:
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