Soyuz launches military payload
Russian military personnel in Plesetsk launched a classified payload. A Soyuz-2-1b rocket lifted off on Oct. 27, 2023, likely carrying a semi-classified payload known as Lotos-S1 or 14F145. It is the eighth addition to the Liana constellation performing electronic intelligence from space for the Russian armed forces.
The eighth Lotos-S1 mission at a glance:
Preparations for launch
The preparations for the eighth Lotos mission were hinted at in mid October 2023, with the advisory issued by the authorities of the Russia's Yamal Region warning of the rocket boosters impacts between Yar Sale and Ports Yakha settlements and Panaevsk - Khadaty-Yakha sites, which were previously employed for discarding the second stage and the three panels of the aft skirt from the third stage of the Soyuz rocket during missions known to be delivering Lotos and and Neitron satellites into orbits with an inclination of 67 degrees toward the Equator.
This time, the launch window was expected to last from October 27 until Nov. 15, 2023.
The sixth and seventh Lotos-S satellites were launched in 2022, while the fifth satellite flew in 2021. Before that, there was a nearly 2.5 three-year gap in launches, probably indicating some problems with the program.
Orbital ascent scenario
A Soyuz-2-1b rocket, likely carrying a Lotos-S1 No. 808 satellite, lifted off from Pad 3 at Site 43 in Plesetsk on Oct. 27, 2023. The launch was estimated to take place around 09:00 Moscow Time (2 a.m. EDT).
Available information from the previous launches into the Liana constellation and advisories to air traffic allowed projecting the flight scenario for this 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.
The Russian Ministry of Defense confirmed the launch soon after the fact, and reported the delivery of more than one spacecraft into orbit.
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.
The first set of orbital parameters released by the US Space Force for the Oct. 27, 2023, launch, showed two objects typical for Lotos missions, likely representing the third stage of the Soyuz rocket and the main payload:
By Oct. 29, 2023, there was the first sign that the Lotos spacecraft tested its propulsion system, slightly boosting its perigee, likely in preparation for maneuvering to a higher circular orbit near the latitude of the apogee:
As expected, on Oct. 30, 2023, the US Space Force cataloged the third object associated with the launch in the 893 by 914-kilometer orbit with an inclination 67.1 degrees toward the Equator:
It confirmed that the spacecraft circularized its orbit and released a sub-satellite. According to radar observations performed by LeoLabs, Object C, which separated from Kosmos-2570 on Oct. 30, 2023, then likely released its own sub-satellite, Object D, possibly on Nov. 23, 2023, at 14:00 UTC.
A complete list of launches in the Liana constellation:
Lotos-S electronic intelligence spacecraft. Credit: Arsenal
Soyuz-2-1b with Lotos-S1 No. 808 on the launch pad in Plesestk. Click to enlarge. Credit: Roskosmos
Soyuz-2-1b rocket lifts off from Plesetsk on Oct. 27, 2023. Click to enlarge. Credit: Roskosmos