Pion-NKS No. 1 | Soyuz 2.1b

Lift Off Time
June 25, 2021 – 19:50 UTC | 22:50 MSK 
Mission Name
Pion-NKS No. 1, a military satellite for the Liana constellation
Launch Provider
(What rocket company launched it?)
Russian Federal Space Agency
(Who paid for this?)
Russian Space Forces
Soyuz 2.1b
Launch Location
Plesetsk Cosmodrome, Russia
Payload mass
~6,500 kg (14,330 Ib)
Where did the satellite go?
~500 km Sun-Synchronous orbit (SSO), at a 67° inclination
Did they attempt to recover the first stage?
No, this is not a capability of Soyuz
Where did the first stage land?
It crashed on the land of Ust-Tsilemsky District, Komi Republic
Did they attempt to recover the fairings?
No, this is not a capability of Soyuz
Were these fairings new?
This was the:
– 1st launch of the Pion-NKS military satellite
– 2nd launch from the Plesetsk cosmodrome in 2021
– 6th launch of a satellite for the Liana surveillance system
– 63rd launch of Soyuz 2.1b
– 58th orbital launch attempt of 2021 (56th successful)
Where to watch
Unfortunately, there was no livestream of this lauch

How did it go?

The Russian Federal Space Agency successfully launched the Pion-NKS No. 1 (14F139) satellite on a Soyuz 2.1b launch vehicle into a Sun-synchronous orbit. The rocket lifted off from the Plesetsk Cosmodrome, in Russia. This mission marked the first of two launches of the Pion-NKS satellites for the Liana electronic intelligence (ELINT) constellation. The satellite was assigned the serial number “Cosmos-2550”.

Pion-NKS No. 1 Mission

Liana Constellation

Liana is a new Russian military surveillance constellation that will consist of two series of satellites: Lotos-S1 and Pion-NKS. Both of them are intended to gather data on foreign military forces located on the ground, on water, and in the air. However, they work a little bit differently, Lotos-S1 has a passive radar system, whereas Pion-NKS has an active one.

Liana is the successor of the Soviet reconnaissance system Legenda-Tselina that was also used for target designation and guidance of high-precision weapons. One of its components, active satellites US-A, had such a powerful radar that it had to be equipped with a nuclear reactor. Only this type of source could provide the system with enough energy. This caused an international scandal in January 1978, when, during an emergency deorbiting of the satellite, radioactive debris crashed and contaminated over a 124,000 square kilometer area of the Northwest Territories in Canada. As a result, the Liana constellation will not use nuclear energy as a power source.

As of today, only Lotos-S satellites have already been deployed into orbit (1 Lotos-S and 4 Lotos-S1, which is a modernized iteration of Lotos-S). The latest launch of Lotos-S1 took place in February 2021.

Pion-NKS No. 1 satellite

Due to the classified nature of this mission, very little is known about the characteristics of the Pion-NKS satellite, however, its purpose is far from a secret. Pion-NKS is a military reconnaissance satellite. Its model was first presented to the public in 2017, at the naval showcase in Saint-Petersburg. The main aim of this satellite is surveillance of foreign military forces.

Pion-NSK military satellite, a model
A model of the Pion-NSK satellite. (Credit: tvzvezda.ru)

According to Russian media sources, Pion-NKS will be able to detect small objects like cars of potential enemy forces in real-time. By receiving and analyzing radio signals, this satellite will help to understand what type of military equipment was detected and provide its coordinates. In contrast, the Lotos-S1 series of satellites are specialized in the interception of different information, including communications.

What is Soyuz 2.1b?

ROSCOSMOS’s Soyuz is a multi-use medium-lift launch vehicle that was introduced in far 1966 and since then has been the workhorse of the Soviet/Russian space program. It is capable to launch 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.

A Soyuz 2.1b rocket on the launch pad, Arktika-M mission
A Soyuz 2.1b rocket on the launch pad. (Credit: ROSCOSMOS)

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.


First StageSecond StageThird Stage
Engine 4 RD-107ARD-108ARD-0124
Total Thrust 840 kN (188,720 lbf),
sea level
1,020 kN (229,290 lbf),
792 kN (178,140 lbf),
sea level
922 kN (207,240 lbf),
294 kN (66,094 lbf),
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.

"Korolev cross", Progress MS-16 mission
“Korolev cross” seen during Stage I separation on the Progress MS-16 mission. (Credit: ROSCOSMOS’s livestream)

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”.

Rocket-motor-RD-0124б Soyuz 2.1b
RD-0124 motor at Salon-du-Bourget 2013. (Credit: Pline)

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: