to Space launchers main page



Russian rocket delivers European spy satellite

Revealing a strange geo-political dichotomy, a Russian-built rocket was launched to boost Europe's military reconnaissance capabilities from space. The launch of a Soyuz ST-A/Fregat-M rocket from the ELS facility near Kourou, French Guiana, on Dec. 19, 2018, (after a 24-hour delay due to high-altitude winds), delivered the CSO-1 imaging satellite to serve the needs of the French Ministry of Defense and other European armed forces. The 3.5-ton spacecraft will undoubtedly be used to monitor Russia's military activities.


Soyuz ST-A mission (VS20) with the CSO-1 satellite at a glance:

Spacecraft designation
Launch vehicle
Soyuz ST-A/Fregat-M (Soyuz-2 family) (Mission VS-20)
Launch site
Launch date and time
2018 Dec. 18, 13:37:14 local (11:37 a.m. EST)

CSO spy satellite constellation


Artist rendering of the CSO-1 satellite in deployed position in orbit.

The launch of the CSO-1 satellite was the 20th Soyuz mission from the South-American launch site and procured by the European Arianespace consortium. According to the official description provided by Arianespace, the Composante Spatiale Optique (or "optical space component") spacecraft, CSO, was designed for observations of the Earth's surface at very high resolution in the visual and infra-red parts of spectrum from the 800-kilometer Sun-synchronous orbit with an inclination 98.6 degrees toward the Equator. The satellite was reported to be capable of conducting imaging operations in a variety of imaging modes, including day or night in "fair weather." The CSO spacecraft were also reported to be the first French satellites capable of autonomous orbit control, which allowed them to maneuver and boost their altitude without interaction with ground control during flight over oceans and, thus, avoid interrupting imaging activities.


Optical system of the CSO-1 satellite.

The complete three-spacecraft constellation is expected to work at different altitudes of polar orbit, with CSO-1 and CSO-3 satellites focusing on reconnaissance functions and CSO-2 specializing in the identification of potential targets. As of 2018, the CSO-3 satellite was expected to be launched around 2021 on the Ariane-6 mission.

The CSO satellite were developed by the European consortium Airbus Defense and Space and its main optical imaging instrument was provided by the French division of Thales Alenia Space.

The CSO network will be operated by the French space agency, CNES (Centre National d’Etudes Spatiales) via its mission control center in Toulouse, France, and the French defense procurement agency, DGA (Direction générale de l’armement), on behalf of the nation's ministry of defense.

CNES served as the contracting authority for the CSO program and its mission ground segment, as well as being the overall co-architect of the system. CNES was also responsible for orbital positioning, in-orbit acceptance testing and operation of CSO satellites. In turn, the DGA agency served as contractor for the development and maintenance of the ground control infrastructure of the project, and it was also responsible for the transfer of reconnaissance data from the satellite to its end users on the ground. The headquarters of the French armed forces was the operating authority for CSO, Arianespace said.

Like the two previous French-built military observation systems, Helios-1 and Helios-2, the CSO was made available to other European armed forces. At the time of the CSO-1 launch, Germany, Sweden and Belgium were cited as members of the CSO user team and an agreement with Italy was expected shortly. The CSO network was expected to replace the Helios satellites.

According to Arianespace, CSO addressed France and Europe’s operational needs for global intelligence and strategic surveillance, knowledge of the geographic environment and support for operational deployments. The data from the satellite could be delivered upon request to end users, including military units deployed overseas.

Known specifications of the CSO-1 satellite:

Spacecraft operator
CNES on behalf of DGA
Spacecraft developer
Airbus Defense and Space (formerly EADS Astrium)
Spacecraft platform
Life span
10 years
Liftoff mass
3,565 kilograms
Total payload mass
3,716 kilograms
Orbit type


Preparations for flight


As of 2011, the first CSO-1 satellite was expected to fly on a Soyuz rocket in December 2016, but the launch date eventually slipped to the end of 2018.

The three booster stages of the Soyuz ST-A rocket for the mission were under assembly at the Soyuz facility in Kourou from Sept. 13 to Oct. 4, 2018, and the mission's Fregat upper stage was ready by October 24. The next day, the Fregat was moved to the FCube facility for fueling, which took place place from November 22 until December 5.

The three booster stages of the Soyuz ST-B rocket underwent pneumatic and propulsion tests from November 12 to -15, immediately followed by electric tests completed on November 22.

The CSO-1 spacecraft arrived at French Guiana on November 5 and was placed at the S1A building for pre-launch processing.

On November 28, the spacecraft was transferred from the S1B processing building to the S3B facility in preparation for fueling, which was conducted from December 1 to 3.

On December 11, CSO-1 was integrated with the Fregat upper stage and, on December 13, the payload section was encapsulated into its protective fairing to form the upper composite of the rocket.

The integrated three stages of the Soyuz launcher were rolled out to the launch pad on December 14, and on the same day, the upper composite was delivered to the pad and hoisted on top of the rocket. The final checks of the payload, the final countdown rehearsal and tests of the rocket were conducted on the pad from December 15 to December 17, concluding with the Launch Readiness Review, RAL, which cleared the mission for the liftoff next day.

However, on December 18, Arianespace announced that due to unfavorable high-altitude wind conditions, the launch had to be postponed for 24 hours, until December 19, at 13:37:14 local time in French Guiana (11:37 a.m. EST).

Apparently due to the military nature of the mission, Arianespace did not release any photos of the CSO-1 satellite in processing. A few visuals of the satellite appeared in a video footage from Airbus Defense and Space, but it appeared to avoid showing the complete spacecraft and its imaging system.

Countdown milestones for the VS-20 mission on Dec. 18, 2018:

Time (h:min:sec)
Beginning of the meeting for launcher fueling authorization (BTR)
Beginning of launch vehicle fueling with propellant components
Completion of launch vehicle fueling
Mobile gantry withdrawal
"Key-to-launch" command (beginning of Soyuz synchronized sequence)
Fregat transfer to onboard power supply
Upper Composite umbilical drop off command
Ground-board power transfer
Lower stage mast retraction
Preliminary thrust level
Full thrust level


CSO-1 satellite lifts off


After a 24-hour delay, Soyuz ST-A rocket with the CSO-1 satellite lifted off as scheduled on Dec. 19, 2018, at 13:37:14 local time (11:37 a.m. EST; 16:37 GMT) from the ELS pad in Kourou.

After eight seconds of vertical ascent, the rocket headed north over the Atlantic Ocean. Four strap-on boosters of the first stage finished firing and separated one minute 58 seconds in flight. The payload fairing then split into two halves and separated as well.

The second stage completed its firing and separated four minutes 47 seconds into the flight. Moments earlier, the main engine of the third stage ignited and fired through the lattice structure connecting the two stages until their separation. Around five seconds after the separation of the second stage, the aft adapter ring on the third stage split in three sections and separated.

The powered phase of the ascent for the first three stages of the launch vehicle lasted around nine minutes. The payload section, consisting of the Fregat upper stage and the satellite, then separated from the third stage into a suborbital trajectory just short of orbital velocity. A minute later, Fregat fired its propulsion system for nine minutes to enter a highly elliptical orbit with an apogee close to the planned orbital altitude of the CSO-1 satellite.

The stack then climbed passively toward the apogee for 38 minutes and 43 seconds, before Fregat initiated its second engine firing to make the orbit circular. The maneuver lasted one and a half minute. Another five minutes later, the spacecraft was released into its orbit.

After the separation of its payload, the Fregat upper stage was programmed to make one more engine firing, entering a burial orbit safely below the CSO satellite. According to NPO Lavochkin, the fourth maneuver with Fregat's main engine was to brake the stage for a destructive reentry into the Earth's atmosphere.


The VS-20 mission timeline:

Scheduled elapsed time
Stage I separation
1 minutes 58 seconds
Payload fairing separation
*4 minutes 15 seconds
Stage II separation
4 minutes 47 seconds
Stage III separation
**8 minutes 49 seconds
Fregat engine firing 1 begins
9 minutes 49 seconds
Fregat engine firing 1 ends
18 minutes 41 seconds
Fregat engine firing 2 begins
54 minutes 15 seconds
Fregat engine firing 2 ends
55 minutes 44 seconds
CSO-1 satellite separation
1 hour 00 minutes 44 seconds
Fregat engine firing 3 begins
1 hour 51 minutes 40 seconds
Fregat engine firing 3 ends
1 hour 52 minutes 35 seconds
Mission end
1 hour 53 minutes 05 seconds

*T+215.52 seconds according to NPO Lavochkin;

**T+563.71 seconds according to NPO Lavochkin

Bookmark and Share


Page author: Anatoly Zak; Last update: April 19, 2023

Page editor: Alain Chabot; Last edit: December 17, 2018

All rights reserved


insider content



A 1-to-5 scale model of the CSO-1 satellite displayed at Paris Air and Space Show in Le Bourget in 2009. Copyright © 2009 Anatoly Zak


The payload section of the Soyuz rocket with the CSO satellite. Credit: Arianespace



CSO-1 during tests in echoless chamber. Credit: Airbus


Testing of solar panel deployment aboard CSO-1 satellite. Click to enlarge. Credit: Airbus



Click to enlarge. Credit: Airbus Defense and Space


Due to military nature of the CSO-1 mission, few visuals of the spacecraft in processing had been released and those that were appeared to be avoid showing the aperture area of the imaging system. Click to enlarge. Credit: Airbus Defense and Space


Payload section containing the Fregat upper stage and the CSO-1 satellite is being prepared for integration with the Soyuz rocket. Click to enlarge. Credit: Arianespace


Soyuz-2-1a lifts off with the CSO-1 satellite on Dec. 20, 2018. Click to enlarge. Credit: Arianespace


Artist rendering of the CSO-1 satellite separating from the Fregat upper stage. Credit: Arianespace


Illustration of solar panel deployment aboard CSO-1 satellite. Credit: Airbus




Artist renderings of the CSO satellite in orbit. Credit: CNES


Illustration of engine firing aboard the CSO satellite. Credit: Airbus


Data from CSO satellites is downlinked to a ground station in Kiruna in Sweden and then channeled to the central control center in Creil, France, from where it is distributed to French users and European allies. Click to enlarge. Credit: Airbus