Soyuz launches an ear in the sky
The Russian military personnel in Plesetsk performed the country's first orbital launch of 2021 in the late hours of February 2. A Soyuz-2-1b rocket delivered a semi-classified satellite known as Lotos-S1 or 14F145. It was the fifth addition to the Liana constellation performing electronic intelligence from space for the Russian armed forces.
The fifth Lotos-S1 mission at a glance:
Preparations for launch
First introduced in 2009, the Lotos-S1 satellite had to wait for five years before being joined by the second spacecraft. The interval then fell to three years between the second and third launch in 2014 and 2017. After that the launches were expected annually, but after the fourth launch in 2018, the next mission previously rumored in 2019 and 2020, did not materialize until early 2021.
According to industry sources, the Soyuz-2 launch vehicle was ready for rollout from the vehicle assembly building to the launch pad on the morning of January 31 for final countdown and launch on February 2, 2021. By the time, Lotos-S1 No. 805 reached the launch pad in 2021, the two original satellites in the constellation appeared be no longer maintaining their orbits, according to Western tracking data. Moreover, a Russian industry source said that only Lotos-S1 No. 804 satellite had been operational at the time when the fifth satellite had gone into orbit.
At the end of January 2021, the local environmental ministry in the Komi Republic issued an advisory about the launch of a Soyuz-2 rocket with a military payload on February 2, with a backup opportunity on the following day. The agency warned about falling debris in the Ust-Tsilimsk and Izhem Districts of the republic and said that its officials would inspect the area between January 28 and February 1.
Orbital ascent scenario
A Soyuz-2-1b rocket carrying a Lotos-S1 No. 805 satellite lifted off as scheduled at 23:45:28.079 Moscow Time (20:45 UTC; 3:45 p.m. EST) from Site 43 in Plesetsk on February 2, 2021. Several minutes after the planned liftoff, the Russian Ministry of Defense confirmed that the mission had been underway. Ground assets of the Titov Chief Test Space Center began tracking the vehicle at 23:47 Moscow Time, a statement distribued by the official Russian media said.
Available information from the previous launches into the Liana constellation and recent advisories to air traffic over Northern Russia allow projecting the flight scenario for this latest mission. After a few seconds in vertical ascent, the rocket headed northeast to align its ground track with an orbit inclined around 67.1 degrees toward the Equator. The four boosters of the first stage separated after around two minutes into the flight and fell at the S15 drop zone around 350 kilometers from the launch site. The payload fairing protecting the payload was dropped next, likely targeting the S16 drop zone in the Komi Republic.
Less than five minutes into the flight, the core booster of the rocket completed its firing and separated as well.
Moments before the second stage separation, the RD-0124 engine of the third stage ignited and fired through the interstage lattice structure, which separated moments later along with the second stage. Around five seconds after that, the tail section on the third stage was dropped splitting into three segments. Both, the second-stage booster and the segments of the tail section were expected to fall at the S18 drop zone in the Yamalo-Nenetsk Autonomous Region. The third stage then continued firing until around nine minutes into the flight, before releasing its payload into an initial orbit.
Russian military had confirmed successful separation of the satellite shortly after the fact and its good communications with ground control. The satellite was officially designated as Kosmos-2549.
In previous launches of Lotos satellites, the spacecraft and its empty third stage first entered a 200 by 900-kilometer elliptical orbit, but the satellite fired its engine in apogee to circularize its orbit at a safe altitude of around 900 kilometers a couple of days later. The satellite would then be ready for operation.
Shortly after launch on February 2, 2021, the US military cataloged the fresh satellite under No. 47546 (International designation 2021-008A) in the expected 240 by 899-kilometer initial orbit. By February 7, Kosmos-2549 had already been tracked in the expected 907.8 by 917.3-kilometer orbit with an inclination 67.1 degrees toward the Equator.
A complete list of launches in the Liana constellation:
Lotos-S electronic intelligence spacecraft. Credit: Arsenal
The fueling of the Soyuz rocket on the evening of February 2, 2021. Click to enlarge. Credit: Russian Ministry of Defense
A Soyuz rocket moments after ignition on the evening of February 2, 2021. Click to enlarge. Credit: Russian Ministry of Defense
A Soyuz-2-1b rocket lifts off on February 2, 2021. Click to enlarge. Credit: Russian Ministry of Defense