The Russian Aerospace Forces, itself a division of the Armed Forces of the Russian Federation, has launched a Lotos reconnaissance satellite to compliment their next-generation Liana SIGINT (signal intelligence) satellite system. Liftoff took place at around 20:45 UTC (15:45 EST) on Tuesday, 2 February 2021, from Site 43 at the Plesetsk Cosmodrome – located 800 kilometers north of Moscow.
This was the first orbital launch attempt of the year for the Russian Federation, and the first flight of the Soyuz launch vehicle in 2021.
The more powerful Blok-I engine on the Soyuz 2.1b attains a maximum ISP (specific impulse) of 359 seconds, an improvement over the baseline RD-0110 engine on the Soyuz 2.1a – which has a specific impulse of 326 seconds.
Overall, the Soyuz 2 family of launch vehicles – including the Soyuz 2.1a, 2.1b, and 2.1v – have flown 113 times with 106 successes, four outright failures, and three partial failures (one each to the three variants).
A Soyuz 2.1b launches from the Plesetsk Cosmodrome in Russia. (Credit: Ministry of Defence of the Russian Federation)
Of note, some of those failures and partial failures are due to malfunctions of the optional Fregat-M upper stage, not the actual Soyuz 2 rocket itself.
Tuesday’s launch saw the deployment of Lotos-S1 No.805, the fifth satellite in the Russian military’s Liana program. Liana consists of two families of satellites – Lotos and Pion – however, all of the satellites launched to date have been part of the Lotos series.
The Liana program began in the 1990s with the intent of replacing Soviet-era Tselina and US-PM satellites. Specifically, the Tselina series of spacecraft is being succeeded by Lotos, which will be used for electronic surveillance and radio signals interception. Pion will be a more specialized naval reconnaissance platform and will use radio signals and radar to track vessels.
Russia’s KB Arsenal design bureau is the prime contractor for both Lotos and Pion, and is responsible for building and integrating the satellites’ reconnaissance payloads.
The spacecraft themselves are built by TsSKB Progress, based around a platform derived from the Yantar series of reconnaissance satellites. The satellite bus is three-axis stabilized, with two solar arrays providing electrical power while in orbit.
Lotos-S1 is the operational version of Lotos, following on from the Lotos-S prototype configuration that was used for the first two spacecraft which launched in November 2009 and December 2014. Two Lotos-S1 satellites, Nos.803 and 804, were subsequently launched to orbit in December 2017 and October 2018, respectively.
Artistic render of Lotos-S1 and Pion reconnaissance satellites – credit: KB Arsenal
Soyuz has deployed Lotos-S1 No.805 into a low Earth orbit with an apogee of approximately 900 kilometers (560 miles) and an inclination of around 67 degrees. Within a few days of launch, the spacecraft will circularize its orbit by raising its perigee to the same altitude as its apogee using its onboard propulsion systems.
Now that Lotos-S1 No.805 is in orbit, it will be given a new public name in accordance with a system that Russia – and previously, the Soviet Union – have used to obscure the identities of military payloads since the early 1960s.
Lotos-S1 No.805 is expected to be designated Kosmos-2549. However, this is subject to confirmation as Kosmos numbers are occasionally assigned to sub satellites deployed from spacecraft already in orbit, which are not always announced.
About 16 seconds before liftoff on Tuesday, Soyuz ignited its first and second stage engines. After the engines had been throttled to full bore, the swing arms of the launch pad at Plesetsk’s Site 43 opened up and Soyuz began its climb to orbit. The first stage boosters burned for the first 118 seconds of flight before separating simultaneously in a pattern known as the “Korolev Cross”, named in tribute to the Soyuz rocket’s chief designer.
The payload fairings separated roughly three and a half minutes into flight after the Soyuz had climbed out of the dense lower atmosphere were the fairings’ aerodynamic protection was needed.
The core Blok-A stage continued to power Soyuz towards space until 4 minutes 45 seconds into flight. Shortly before the burn’s conclusion, the Blok-I stage ignited its RD-0124 engine while the Blok-A stage engine was still firing. This “hot staging” or “fire-in-the-hole” separation technique is normal for Soyuz launches, using the thrust from the Blok-A stage to keep the BLok-I stage’s propellants properly settled, eliminating the need for additional ullage or separation motors.
The Blok-I stage made a single burn, lasting just under 5 minutes as it injected the Lotos-S1 No.805 satellite into orbit.
Lotos-S1 No.805 separated from the Soyuz rocket shortly after reaching orbit.
After raising its orbit and undergoing checkout, the satellite will begin its mission, joining the fleet of satellites operated by Russia’s Aerospace Forces.