Uzlovoy Module (UM) “Prichal” | Soyuz 2.1b

Featured image credit: Pavel Kassin/ ROSCOSMOS

Lift Off Time (Subject to change)	November 24, 2021 – 13:06:36 UTC | 16:06:36 MSK
Mission Name	Uzlovoy Module (UM) “Prichal”
Launch Provider (What rocket company is launching it?)	ROSCOSMOS
Customer (Who’s paying for this?)	ROSCOSMOS
Rocket	Soyuz 2.1b
Launch Location	Launch Complex 31/6, Baikonur Cosmodrome, Kazakhstan
Payload mass	4,650 kg (10,250 Ib) the UM Prichal 700 kg (1540 Ib) of cargo
Where is the spacecraft going?	It will rendezvous with the ISS, ~400 km low Earth orbit (LEO) at a 51.6° inclination
Will they be attempting to recover the first stage?	No, Soyuz is not capable of recovery
Where will the first stage land?	The boosters will crash into the steppes of Kazakhstan
Will they be attempting to recover the fairings?	No, Soyuz is not capable of recovery
Are these fairings new?	Yes
How’s the weather looking?	TBD
This will be the:	– 7th uncrewed mission to the ISS of 2021 – 68th launch of Soyuz 2.1b – 171st flight of a Progress spacecraft – 118th orbital launch attempt of 2021
Where to watch	Official livestream

What Does All This Mean?

ROSCOSMOS is ready to launch the Uzlovoy Module (UM) Prichal (the Russian word for “pier”) to the International Space Station (ISS). The UM Prichal – aka The Prichal Node Module – will be a new part of the Russian segment of the ISS. This mission will also bring 700 kg of cargo to the station. It will be launched atop a Soyuz 2.1b vehicle using Progress M-UM spacecraft. The rocket will lift off from Launch Complex 31/6, at the Baikonur Cosmodrome in Kazakhstan. This mission will mark the 7th uncrewed mission to the ISS in 2021 and the 68th launch of Soyuz 2.1b.

Uzlovoy Module (UM) “Prichal”

Prichal is a node module designed and developed for the Russian segment of the ISS by S.P. Korolev Rocket and Space Corporation Energia (RKK Energia). It consists of a pressurized spherical compartment with a diameter of 3.3 m and functional components located outside and inside it. The interior of the module is divided into two zones: habitable and instrument with on-board systems. The primary task of this module is to boost the potential of Russia’s spacecraft to dock with the ISS. The first docking of a Soyuz MS spacecraft to Prichal is planned for March 18, 2022.

Initially, the UM Prichal was supposed to launch in 2012. However, the project has been repeatedly postponed due to different reasons and circumstances, particularly, delay in the development of the MLM Nauka module.

The UM Prichal is equipped with six docking ports, one of which will be used to dock to the Nauka research module, which launched on July 21, 2021. The other five will be available for rendezvous with the Soyuz spacecraft and Progress capsules, as well as with other new modules and spacecraft (e.g., Russia’s new-generation crewed spacecraft Oryol). Moreover, the port opposite to the one docked to Nauka will support automated docking of spacecraft using the Kurs-NA system and transfer of propellants between Nauka and docked spacecraft in both directions.

Specifications

Some specifications of the module are listed below:

Mass, kg	4650
Diameter of the spherical part, m	3.3
Number of docking ports	6
Cargo, kg	700
Pressurized volume, m3	19
Electrical consumption of on-board systems as a part of the ISS, average daily, W	500

Mission Profile

Progress M-UM will separate from the third stage of the Soyuz 2.1b at ~9 min after launch. It will autonomously dock to the ISS two days later, on November 26, at 15:25 UTC (18:25 MSK), at the nadir port of the Nauka module. The Progress M-UM spacecraft will spend less than one month at the station before undocking and deorbiting on December 21 at 22:20 UTC (December 22 at 01:20 MSK).

To complete the integration of the UM Prichal into the Russian segment, cosmonauts Anton Shkaplerov and Petr Dubrov will perform a spacewalk to lay cables between Nauka and Prichal. This spacewalk is scheduled on January 19, 2022.

Approximate Timeline

Hrs:Min:Sec From Lift-Off	Events
– 00:00:15	Engine start sequence
00:00:00	Lift-Off
+ 00:01:58	First stage separation
+ 00:03:03	Fairing jettison
+ 00:04:47	Second stage separation
+ 00:04:57	Tail section separation
+ 00:08:45	Third stage main engine cutoff
+ 00:08:49	Progress M-UM separation

What is Soyuz 2.1b?

ROSCOSMOS’s Soyuz is a multi-use, medium-lift launch vehicle that was introduced in 1966 and since then has been the workhorse of the Soviet/Russian space program. It is capable of launching civilian and military satellites, as well as cargo and crewed missions to the ISS. Over the decades, several variants of the Soyuz rocket have been developed. Soyuz 2.1b is one of its latest iterations that belongs to the Soyuz-2 rocket family.

The rocket consists of three stages, all of them are expendable. When launching to the ISS, Soyuz-2 can be flown with either a Progress capsule or a Soyuz spacecraft.

Soyuz 2.1b is about 46.3 meters (152 ft) in height and 2.95 meters (9 feet) in diameter. The vehicle’s total lift-off mass is approximately 312,000 kg (688,000 lb). The rocket’s payload lift capacity to low-Earth orbit (LEO) is between 6,600 and 7,400 kg depending on the launch site.

Stages

	First Stage	Second Stage	Third Stage
Engine	4 RD-107A	RD-108A	RD-0124
Total Thrust	840 kN (188,720 lbf), sea level 1,020 kN (229,290 lbf), vacuum	792 kN (178,140 lbf), sea level 922 kN (207,240 lbf), vacuum	294 kN (66,094 lbf), vacuum
Specific Impulse (ISP)	263 s, sea level 320 s, vacuum	258 s, sea level 321 s, vacuum	359 s, vacuum

Side Boosters

The first stage of the Soyuz 2.1b rocket is composed of 4 side boosters that are powered by RD-107A engines. Each one of the boosters has a conical shape and a dry weight of 3,784 kg. It is approximately 19.6 meters in length, with a diameter of 2.7 meters. Each side booster has two vernier thrusters that are used for flight control.

The RD-107A engine runs on rocket-grade kerosene (RP-1) and liquid oxygen (LOx). The propellants are stored in the pressurized aluminum alloy tanks, the kerosene tank is located in the cylindrical part of the booster, and the LOx one is in the conical section. Each one of those engines have 4 combustion chambers and together they are capable of producing a thrust of 840 kN at sea level and 1,020 kN in a vacuum.

Perhaps, the most spectacular moment of the Soyuz-2 rocket’s launch is the separation of the first stage. It happens approximately 2 minutes after the launch. The boosters perform a pattern, known as the “Korolev cross” (named after Sergei Korolev, a very important figure of the USSR space program and history).

Second and Third Stages

The center core stage is powered by a single RD-108A engine, and the upper stage is fitted with a single RD-0124 engine. Both of these engines run on RP-1 and LOx and have 4 combustion chambers. The second stage is 27.1 meters long, with a diameter of 2.95 meters, and a dry mass of 6,545 kg. It has 4 vernier thrusters for three-axis flight control.

The third stage of a Soyuz-2 rocket has a height of 6.7 meters, a diameter of 2.7 meters, and a dry mass of 2,355 kg. One interesting thing about the RD-0124 engine on this stage is that it starts its ignition sequence prior to stage separation. This process is called “hot fire staging”.

Progress M-UM Spacecraft

The Progress module is a space “truck” for delivering cargo to the ISS. Its design is largely derived from the Soyuz spacecraft that serves for the transportation of astronauts to the ISS. The Progress capsule is 7.9 meters in length and 2.7 meters in diameter. Standard Progress MS space consists of three parts: a pressurized cargo module, a propellant compartment, and a rear service module (like the Soyuz spacecraft).

The MS series is the latest modernized variation of the Progress spacecraft that began flying in December 2015. Among the introduced upgrades are improved orbital debris shielding, a new flight-control and navigation systems, as well as a new external compartment that can be used for satellite deployment.

For this mission, a special version of the Progress spacecraft will be used that is known as Progress M-UM. Its propulsion compartment will be connected to the Prichal module via a newly developed adaptor that will replace the usual cargo compartment.

Unlike Cargo Dragon 2, Progress M-UM spacecraft is not designed to bring cargo back to Earth. This is because the three modules on Progress are not able to split before re-entry. Therefore, after unloading the cargo, the crew progressively fills it only with trash. At the end of its mission, the spaceship separates from the ISS, performs a deorbit burn, and entirely burns up upon re-entry in Earth’s atmosphere.

 

Fairing

On this mission, the Progress M-UM will be launched in a ST-type fairing (4.1 m in diameter), which is wider than standard fairings (3.7 m in diameter) used in Progress cargo resupply missions, due to the large diameter of Prichal.