Soyuz rocket resumed flights after accident
The Russian military personnel in Plesetsk launched an operational spacecraft for electronic intelligence, known as Lotos-S1 or 14F145. A part of the Liana constellation, the mission lifted off on a Soyuz-2-1b rocket on Oct. 25, 2018, at 03:15 Moscow Time (8:15 p.m. EDT on October 24) or just two weeks after the failed launch of the Soyuz MS-10 spacecraft on a Soyuz-FG rocket.
The fourth Lotos-S1 mission at a glance:
Preparations for launch
The launch of the fourth Lotos-S1 satellite was initially planned for Aug. 26, 2018, but on August 17, the decision was made to postpone the flight, even though all preparations at the launch site were proceeding as planned, indicating a possible issue with a previous spacecraft in orbit. At the beginning of October, the launch was planned for October 18, but by the middle of the month, the mission was re-scheduled for October 25, in the wake of the launch accident with the Soyuz MS-10 spacecraft on October 11. Despite the ongoing investigation into the assembly process and the performance of the separation system between the first and second stage of the Soyuz-FG rocket during the October 11 accident, officials in Plesetsk were confident enough to proceed with the launch of a Soyuz-2-1b rocket.
In preparation for liftoff, the rocket with the spacecraft was rolled out to the launch pad on October 22 and underwent integrated testing during the day of October 23.
The fueling of the rocket began at 23:40 Moscow Time (4:40 p.m EDT) on October 24.
How Lotos was launched
After a few seconds in vertical ascent, the rocket headed northeast to align its ascent trajectory with an orbit inclined around 67.1 degrees toward the Equator. The four boosters of the first stage separated after around two minutes in flight and fell at the S15 drop zone around 350 kilometers from the launch site. The payload fairing protecting the payload probably 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.
Around five seconds later, the tail section on the third stage dropped splitting into three segments. Both, the second-stage booster and the segments of the tail section aimed 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.
According to the official statement from the Russian Ministry of Defense issued after the launch, Col. General Aleksandr Golovko, the commander of the Russian space forces, oversaw launch operations in Plesetsk and the rocket's ascent and the insertion of the spacecraft into orbit had proceeded in a nominal mode. The ground assets of the Titov Chief Test Center of the Airspace Forces began tracking the launch vehicle at 03:18 Moscow Time, a Ministry of Defense communique quoted by the official Russian media said around a quarter of an hour after the liftoff.
After entering orbit, the military satellite recieved an official designation Kosmos-2528, the Ministry of Defense said.
Lotos-S1-4 in orbit
In previous launches of Lotos satellites, the spacecraft and its empty third stage would first enter a 200 by 900 kilometer elliptical orbit, but the satellite would then fire its engine in apogee to circularize its orbit at a safe altitude of around 900 kilometers. The satellite would then be ready for operation.
As before, NORAD listed two objects associated with the mission – spacecraft itself and the third stage of the Soyuz rocket that had delivered it into orbit:
By Oct. 29, 2018, the satelllite, now identified as Kosmos-2528, maneuvered to its expected nearly circular orbit. According to NORAD radar, the spacecraft entered a 903 by 910-kilometers orbit with an inclination 67.149 degrees toward the Equator.
By Jan. 21, 2020, independent orbital observers in the West noticed that NORAD added two pieces of debris associated with the Kosmos-2528 launch. Because the pair had similar brightness and produced regular flashing, Cees Bassa, and his colleague observer, suggested that the objects could be some sort of covers that the main spacecraft had ejected later in flight. However, no such objects have been seen in other Lotos missions, until the seventh spacecraft in a series deployed some kind of object shortly after its launch in 2022.
Lotos-S electronic intelligence spacecraft. Credit: Arsenal
Launch personnel oversees preparations of the rocket inside the firing bunker. Click to enlarge.
The fueling of the Soyuz rocket began at 23:40 Moscow Time on Oct. 24, 2018. Click to enlarge.