Lotos-S1 n05 | Soyuz 2.1b

Lift Off Time
February 02, 2021 – 20:45 UTC | 23:45 MSK
Mission Name
Lotos-S1 n°05, the fifth overall Lotos-S satellite
Launch Provider
(What rocket company launched it?)
Russian Federal Space Agency
(Who paid for this?)
Russian Space Forces
Soyuz 2.1b
Launch Location
Site 43/4, Plesetsk Cosmodrome, Russia
Payload mass
6,000 kg (~13,000 lbs)
Where did the satellite go?
~900 km circular Sun-Synchronous Orbit
Did they recover the first stage?
No, this is not a capability of Soyuz
Did they recover the fairings?
No, this is not a capability of Soyuz
Were the fairings new?
This was the:
– 58th launch of Soyuz 2.1b
9th orbital launch of 2021
Where to watch
Unfortunately, there was no stream of this launch

How did it go?

The Russian Federal Space Agency successfully launched the Lotos-S1 electronic intelligence (ELINT) satellite on a Soyuz 2.1b rocket into a 900 km Sun-Synchronous orbit. On February 2, 2021 at 20:45 UTC, the rocket took off from the Plesetsk Cosmodrome, in Russia. The Lotos satellite was the fourth non-development satellite in the Lotos ELINT constellation.

What is Liana?

Liana is Russia’s second generation space-based surveillance system, replacing the current Tseliuna-2 and Pion-NKS constellations. So far, the constellation consists of a singular Lotos-S development satellite, which has been used as a tech demonstrator for the operational satellites, and the 3 operational satellites. Russia plans on having 8 operational satellites in this constellation, which likely won’t be complete until near the end of the decade.

The Liana constellation is an ELINT (electronic intelligence) constellation of satellites that are used alongside optical and radar spacecraft. ELINT satellites are able to detect and analyze radio signals from ground based and mobile assets. The radio signals that the satellite intercepts will be used to locate, characterize, and target buildings, vehicles, and boats. The satellites are also likely equipped with radio jammers, which can be used to prevent communication between Russia’s enemies.

Lotos-S1 satellite

Due to the classified nature of this satellite very little specific information about Lotos-S1 satellites is known. The Russian military contracted TsSKB-Progress to build the satellite bus and KB Arsenal to build the payload. The satellite has two deployable solar arrays, some batteries, and a mass of ~6,000 kg.

What is Soyuz 2.1b?

Introduced in 1966, the Soyuz rocket (also known as R7) has been the workhorse of the Soviet/Russian space program. The first launch of the Soyuz 2.1a, on November 8, 2004 from the Plesetsk Cosmodrome, represented a major step in the Soyuz launch vehicle’s development program.

Evolution of the R7 / Soyuz rocket family (Credit: NASA / Peter Gorin / Emmanuel Dissais)

The Soyuz version currently being used for most satellite launches is a four-stage launch vehicle, that consists of:

  • four side boosters
  • a central core booster
  • an upper (central) stage which is common to all Soyuz rockets regardless of payload
  • an optional Fregat upper stage (not being used on this mission)

Side Boosters

Each side booster has a singular RD-107A engine, which runs on liquid oxygen and RP1. The RP-1 tanks are located in the cylindrical part of the booster, and the liquid oxygen tanks are in the conical section. Each engine has four combustion chambers and four nozzles, which is common in older Russian engines as the USSR could not solve the problem of combustion instability in large nozzles.

During side booster separation, the boosters perform a well-known pattern, in which they peel off and cartwheel outwards. This is known as the “Korolev cross,” named after Sergei Korolev, the Chief Design Engineer of the USSR space program in the 1960s.

Korolev cross during side booster stage separation on a Soyuz launch
“Korolev cross” seen during side booster stage separation on a Soyuz launch.

Soyuz Center Core

The center core is fitted with an RD-108A engine, which also has four combustion chambers and four nozzles. The engine contains four attitude thrusters, used for three-axis flight control once the side boosters have separated. The center core also runs on RP1 and LOx.

Second Stage

The third stage uses an RD-0124 engine on the ST-B (2.1b) version. This closed cycle engine once again runs on LOx and RP1, producing 294 kN of thrust, and having an ISP of 359 seconds.

RD-0124 motor at Salon-du-Bourget 2013. (Credit: Pline)
Rocket section adapted from Andy Law

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