The 114th and final orbital launch of 2020 saw a Soyuz ST-A rocket loft the CSO-2 Earth observation satellite for the French Ministry of Defence.
Liftoff occurred at 16:42:07 UTC (11:42:07 EST) on 29 December from the ELS (Ensemble de Lancement Soyouz) launchpad at the Guiana Space Centre in French Guiana, an overseas department of France.
The only passenger on the 10th and final flight for Arianespace this year — the fifth using the Soyuz — is the Composante Spatiale Optique -2 (CSO-2) satellite for the French Ministry of Defence.
Launched in cooperation with the French (Centre National d’Etudes Spatiales — CNES) space agency and the DGA (Direction générale de l’armement) defense procurement agency, the 25th flight of a Soyuz from French Guiana took the defense- and security-aligned Earth observation satellite toward a Sun-synchronous orbit.
Built by Airbus Defence and Space, with the French arm of Thales Alenia Space providing the optical imaging instrument for the satellite, it will join CSO-1 as the second of three planned CSO satellites that are succeeding the Helios 1 and 2 military observation systems.
CSO-1 was launched on 19 December 2018, likewise on a Soyuz ST-A/Fregat-M rocket. CSO-3 will differ greatly from its predecessors in launch vehicles as it is scheduled to be taken to orbit on the much larger and upcoming Ariane 6 rocket.
The third part of the trio was to launch in October 2021, but with Ariane 6’s debut pushed into at least the second quarter of 2022, CSO-3’s launch date is nebulous at this time.
The CSO program will use two different orbital altitudes for the three satellites, with CSO-1 and -3 in 800 km Sun-synchronous orbits while CSO-2 goes into a much lower 480 km Sun-synchronous orbit.
The different orbital altitudes will allow different mission objectives, with CSO-1 and -3 performing reconnaissance operations while CSO-2 gathers extremely-high-resolution imagery with a primary mission objective of identification.
In so doing, the trio of satellites will meet their mission objectives to:
- gather global intelligence and strategic surveillance,
- acquire knowledge of the geographic environment, and
- support operational deployments.
With a total launch mass of 3,562 kg and a design life of 10 years, CSO-2 will operate in an orbit inclined 97.3 degrees to the equator and will use a variety of imaging techniques, including visual and infrared, to observe Earth’s surface day or night.
While designed, built, and operated by France, access to the CSO systems and information are accessible to European partners, with Germany, Sweden, and Belgium having already joined and an agreement with Italy forthcoming.
Like many other missions, CSO-2 faced delays this year due to COVID-19 and the vital need to keep people safe and unharmed.
After arriving at the launch site on 27 February 2020, all work on the satellite and mission stopped on 17 March and did not resume until 14 September when integration of the Soyuz rocket began.
Work on the satellite did not begin again until 17 November. CSO-2 was integrated on top of the Fregat-M upper stage on 18 December, with the duo then encapsulated inside the payload fairing on 21 and 22 December.
The payload was then moved to the launchpad on 23 December – the same day the Soyuz rocket was transferred to the launch site. The payload was then mated to the top of the rocket later that day.
Launching the CSO-2 satellite into its proper orbit required pinpoint precision and a single second, instantaneous launch window at 16:42:07 UTC.
As part of the interagency agreement, the Soyuz 2.1a was heavily modified with several European upgrades, including a European Safeguard Kit to shut the engines off (a flight termination system) in the event of an anomaly; pyrotechnic engine ignition sources instead of chemical; European payload adapters; increased air conditioning and environmental protective measures to prevent large ice build-ups and moisture intrusion due to the tropical location of the launch site; and vertical payload integration.
For this mission, Soyuz ST-A uses the Fregat-M upper stage, which carries 5,600 kg of dinitrogen tetroxide and unsymmetrical dimethylhydrazine — extremely toxic hypergolic fuels that allow for multiple engine restarts and prolonged coasting ability in orbit between re-ignitions.
With all stations “go” for launch, and the weather within limits, Soyuz’s on-board computers commanded the ignition sequence of the four boosters and the Blok-A core stage at T-16 seconds. Each booster used a single RD-107A engine and two verniers while the Blok-A used a single RD-108A engine and four verniers.
The first part of the two-step ignition process verified proper combustion was occurring within the engines from their pyrotechnic sources, with a preliminary thrust level reached at T-14 seconds.
Just 4 seconds prior to liftoff, the full ignition sequence was commanded, with the Soyuz reaching liftoff thrust one second before it was released from the launchpad.
During the launch sequence, after the boosters were jettisoned and the payload fairings were discarded, the Blok-I stage, sitting atop the Blok-A core, ignited its RD-0110 engine two seconds prior to the Blok-A stage shutting down and separating.
This maneuver is known as hot staging and allows the G forces acting upon the Blok-I stage to keep its propellants pushed back and settled in their tanks, thus allowing a stable RD-0110 ignition.
Using a hot staging technique like this eliminates the added complexity for ullage, or push, motors that would otherwise be needed to perform the same operation if the Blok-A stage were allowed to shut down and separate prior to ignition of the Blok-I.
After successfully delivering the CSO-2 satellite into the proper orbit, the Fregat-M upper stage will continue its mission, performing both a third and fourth sequence of burns to deorbit itself and prevent itself from becoming a derelict piece of space trash/debris.
Lead image: A Soyuz rocket launches from French Guiana. Credit: Arianespace
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