Soyuz rocket successfully launches fourth O3b quartet

On March 9, 2018, a Soyuz rocket successfulled delivered the fourth quartet of O3b satellites, to be operated by SES networks and designed to provide low-cost Internet access around the world, after lifting off from its Amazon region launch pad in French Guiana. The European Arianespace consortium, which operates commercial Soyuz launches from the South-American launch site, designated the mission as VS18, which denotes the 18th launch of the Russian-built rocket from the site.

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Soyuz VS18 mission at a glance:

Spacecraft designation O3b (four satellites: FM13, FM14, FM15, FM16)
Spacecraft developer Thales Alenia Space
Spacecraft operator Société Européenne des Satellites, SES (Luxembourg)
Total mission payload mass 3,198 kilograms
Single spacecraft liftoff mass 700 kilograms (2,800 kilograms for four satellites)
Launch vehicle Soyuz-ST-B / Fregat-MT 133-06 / ST payload fairing
Launch site French Guiana, ELS
Launch date 2018 March 9
Orbital insertion duration 2 hours 22 minutes 51 seconds
Target orbit 7,830 kilometers, inclination 0.04 degrees (Medium Earth Orbit, MEO)


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Preparing fourth O3b launch

An Arianespace's contract for the fourth O3b mission was announced on Dec 14, 2015, and it also included a "firm option" for the fifth Soyuz launch in 2018 or later. The fourth delivery of the satellite quartet during the VS18 mission was to increase the number of the spacecraft in the O3b constellation from 12 to 16. The O3b network has been officially operational since 2014.

According to SES Networks, four additional satellites delivered during the VS18 mission were expected to allow more capacity, enhanced coverage, increased efficiencies and greater reliability for the O3b system, while delivering carrier-grade services including MEF Carrier Ethernet 2.0 certified services to telecommunications operators, mobile network operations, MNOs, enterprises, Internet service providers, ISPs and government services.

At the time of the VS18 mission, Arianespace said that another launch with a quartet of O3b satellites had been set for 2019.

On Dec. 29, 2017, Roskosmos announced that the launch had been scheduled for March 1, 2018.

The satellites arrived to Kourou in two pairs in the second half of January 2018.

On Feb. 7, 2018, specialists from Roskosmos' TsENKI center, responsible for ground infrastructure, began processing of cryogenic fueling systems in French Guiana.

On February 15, the Roskosmos team in Kourou conducted autonomous tests of the measurement system for the Soyuz-ST-B rocket and installed the European safety kit, designed for the emergency situations aboard the vehicle during launches from Kourou. On February 16, engineers began autonomous tests of the flight control system for the Soyuz-ST-B rocket and continued fueling operations on the Fregat upper stage for the mission. They were also preparing the launch pad for receiving the rocket and its payload section. By that time, the launch was scheduled for March 6, Roskosmos said. By March 5, the mission was postponed until March 9, to conduct additional checks in the wake of the Ariane-5 launch anomaly on Jan. 25, 2018.

On March 6 and 7, the launch vehicle was rolled out to the launch pad followed by its payload section, which was then hoisted on top of the rocket. Processing personnel then integrated all mechanic, electric and pneumatic interfaces of the two components.

The launch readiness review for the VS18 mission took place on May 8, 2018, and cleared the Soyuz rocket for liftoff, Arianespace said.


A Soyuz-ST-B rocket for the fourth O3b mission is rolled out to the launch pad in French Guiana.

Countdown milestones for the VS18 mission on March 9, 2018:

Time (h:min:sec)
Local time (h:min:sec)
Beginning of the State Commission meeting for launcher fueling authorization (BTR)
Beginning of Launch Vehicle fueling with propellant components
Launch Vehicle is fueled with all propellant components
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

Launch and orbital deployment


Initial powered flight profile during the fourth launch of O3b satellites on March 9, 2018.

A Soyuz-ST-B rocket carrying a quartet of O3b satellites (FM13, FM14, FM15, FM16) from the Soyuz launch facility near Kourou, French Guiana was scheduled to liftoff during a 33-minute window beginning at 1:37:06 p.m. French Guiana time (11:37 a.m. EST, 19:37 Moscow Time) on March 9, 2018. However, around 11 minutes before the originally scheduled liftoff time, concerns over the weater situation at the site forced mission managers to push the launch to the end of the window at 05:10:06 GMT. Strong winds at an altitude of around 10 kilometers were cited to be a culprit.


After a 33-minute delay by weather, the Soyuz-ST-B lifted off and its three booster stages performed as planned.

According to the official flight scenario of the VS18 mission, following liftoff from the Guiana Space Center, the first, second and third stages of the Soyuz rocket were to operate for a total of nine minutes and 23 seconds.

As expected, the third stage of the launcher then separated from the upper composite, comprising the Fregat upper stage and the four O3b satellites. The three lower stages fell back into the sea.

The Fregat upper stage then carried out three main engine firings:

  • First burn, lasting about 4 minutes, followed by a ballistic phase lasting about 8 minutes and 27 seconds;
  • Second burn, lasting about 8 minutes and 36 seconds, followed by a second ballistic phase, lasting one hour and 21 minutes;
  • Third burn, lasting about 5 minutes and 6 seconds to be followed by a third ballistic phase lasting 4 minutes and 20 seconds.

The satellites were released two by two, with the first pair being released two hours and one minute after liftoff.

One additional burn was carried out with the Attitude Control System, ACS, to form the release orbit for the second pair of satellites.

The third and fourth satellites were released about 21 minutes later or 2 hours 22 minutes 51 seconds after the liftoff.

Two successive firings of the Fregat engine were scheduled later to place Fregat into an orbit underneath that of the O3b constellation.

Upon the completion of the satellite release, SES Networks that the newest quartet would enter service by May 17, 2018.

Mission timeline for the Soyuz-ST-B rocket with Fregat-MT upper stage and four O3b satellites on March 9, 2018:

Time (h:min:sec)
Separation between Stage I and Stage II
Payload fairing separation
Core stage separation
Separation of the tail section of the third stage
Stage III engine cutoff
Separation between Stage III and a payload section (Fregat upper stage and four satellites)
First burn of Fregat upper stage starts to form initial parking orbit
First burn of Fregat upper stage ends
Second burn of Fregat upper stage starts to form a transfer orbit
Second burn of Fregat upper stage ends
Third burn of Fregat upper stage starts to form release orbit for the first O3b pair
Third burn of Fregat upper stage ends
Separation of spacecraft No. 2 and No. 4
Fourth burn of Fregat upper stage starts to form release orbit for the second O3b pair
Fourth burn of Fregat upper stage ends
Separation of spacecraft No. 1 and No. 3
Fifth burn of Fregat upper stage starts to enter burial transfer orbit
Fifth burn of Fregat upper stage ends
Sixth burn of Fregat upper stage starts to enter burial orbit
Sixth burn of Fregat upper stage ends


Mission scenario for the fourth O3b mission on March 9, 2018. Credit: Arianespace.

O3b satellites


03b satellites are built by a European company Thales Alenia Space for the 03B Networks Ltd, a global, high-speed, satellite-based Internet network for telecommunications operators and ISPs. It was designed to provide high-speed, ultra-low-latency Internet Protocol (IP) connectivity between emerging and developed markets worldwide, thus bringing online most remote and disconnected regions of our planet.

More than 3 billion people in Asia, Africa, South America and the Middle East were reported to benefit from O3B’s new broadband internet infrastructure, whose name stands for "Other 3 billion." The system was promised to fundamentally change the way IP, 3G Cellular and WiMAX networks interconnect. It was expected to reduce the costs of backhaul for Mobile Operators and Internet Service Providers, enabling them to provide more cost-effective services in underserved and emerging markets. O3b Networks Ltd., based in Jersey (Channel Islands) had investors including SES (a major communications satellite operator), Google Inc. (a search engine giant), Liberty Global Inc. (a cable company) and investment banks HSBC, Allen & Company, North Bridge Venture Partners, Satya Capital, and the Development Bank of South Africa. Combined these companies had reportedly invested $1.18 billion into the new venture since its foundation in 2008. (656) The idea for the project was reportedly conceived in the jungle of Rwanda in 2007.

O3B satellites built by Thales Alenia Space had a mass of 700 kilograms and a design life of 10 years. The satellites were to operate in Ka-band and provide greater than 10 Gbps of capacity.

Specifications of O3b satellites:

Manufacturer Thales Alenia Space
Application Telecommunications and internet
Orbit 8,063 kilometers
Orbital inclination toward the Equator 0.04 degrees
Orbital period 288 minutes (4.8 hours)
Satellites angular distribution in orbit 45 degrees from each other
The satellite's visibility time for users on the ground approximately 45 minutes
Payload 12 Ka-band transponders with 12 steerable antennas
Coverage area Asia, Africa, South America, Australia, Middle East
Onboard power supply 2,482 Watts
Mass of each individual satellite at launch 700 kilograms
The spacecraft life span Approximately 10 years
Satellite dimensions 7.72 meters by 3.2 meters by 1.7 meters


Next chapter: Fifth Soyuz rocket mission with O3b satellites


This page is maintained by Anatoly Zak

Last update: April 3, 2019





Payload section of the Soyuz-ST-B rocket with O3b satellites. Credit: Alenia



Artist rendering of O3b satellites launch during the second-stage phase of the mission. Credit: CNES/Arianespace


Artist rendering of O3b satellites separating from Fregat upper stage. Credit: CNES/Arianespace



An artist rendering of O3b satellites in orbit. Credit: Alenia