Launch Vehicle
Mars Express was launched by a Soyuz-Fregat launcher from the Baikonur Cosmodrome in Kazakhstan in June 2003. Soyuz-Fregat rockets are procured through Starsem, a European-Russian company that is marketing Soyuz launchers outside Russia. Starsem has four shareholders - Aerospatiale, Arianespace, the Russian Space Agency and TsSKB Samara, the manufacturer of the Soyuz vehicle. ESA and Starsem signed the contract for launch of Mars Express in June 1999 at Le Bourget.
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Cutaway diagram of Soyuz-Fregat
launch vehicle (image courtesy of
Starsem) |
The Soyuz rocket was first launched in November 1963 and has since flown more than 1 500 times. A manned version carries crews to space stations such as Mir, while an unmanned version is used to launch satellites and Progress cargo craft. It is one of the most reliable launch vehicles in the world, with a 98% success rate. The Soyuz rocket usually comprises three stages:
- stage 1 four conical boosters grouped around the central core stage.
- stage 2 a cylindrical core.
- stage 3 an upper stage with a payload adapter and fairings.
- For very demanding payloads, a fourth stage is added. This is Fregat for Mars Express, but other, smaller stages are also available. For instance, Starsem uses IKAR stages for Globalstar launches.
The four side boosters and the core (first) stage ignite at the same time before lift off but the lateral boosters shut down and separate first. After the first stage has used all its fuel, it separates and the second stage continues to burn. All three stages use liquid oxygen and kerosene fuel.
The main engine on the fourth stage, the Fregat, is ignited twice. The first ignition puts the Fregat into a circular orbit after separation from Soyuz. The second, a few hours later, injected Mars Express into its interplanetary flight trajectory. The Fregat uses UDMH and nitrogen tetroxide as fuel. It is capable of up to 12 restarts. Mars Express requires the Fregat as it can accommodate a larger fairing (3.7 m diameter) than the other fourth stages available for Soyuz. The resultant higher aerodynamic forces during lift off will require the rocket's inter-tank section to be strengthened.
The third stage of Soyuz will also carry a flight control system, which is slightly modified to match the larger Fregat fairing. The separation system will be the standard Ariane version procured from Saab.
Soyuz facts
- lift off weight 304 tonnes
- (of which) propellant weight 279.5 tonnes
- height 43.5 m
- maximum diameter 10.3 m
- thrust (in vacuum)
- 1st stage: 4964 kN
- 2nd stage: 997 kN
- 3rd stage: 298 kN
- 4th stage: (Fregat) 19.6 kN
- payload capability (to 400 km) up to 6 tonnes
Baikonur Cosmodrome
Baikonur Cosmodrome is located at 45.6oN 63.4oE in the flat grasslands of the former Soviet republic of Kazakhstan. The area has a continental climate, with long, cold winters and hot, dry summers. Construction of the secret missile site began in 1955. The first artificial satellite, Sputnik 1, and first human in space, Yuri Gagarin, were launched from Baikonur. All subsequent Russian manned missions have lifted off from there, as well as geostationary, lunar, planetary, and many ocean surveillance missions.
Until recently, the name Baikonur was misleading. The former Soviet Union used the name and co-ordinates of a small mining town, Baikonur, to describe its secret rocket complex. This was done intentionally to hide the true location of the launch complex. In fact, the launch complex is about 230 miles south-west of Baikonur town, near the railway station and village of Tyuratam and close to Leninsk city. However, in 1998, Leninsk city was renamed Baikonur city.
The Mars Express spacecraft was delivered to the cosmodrome by air in March 2003. It was then housed in a clean room and integrated with the Fregat stage inside a modern payload processing facility. The strap-on boosters and stages of the Soyuz booster are assembled horizontally in the large Vehicle Assembly Building. The entire launch vehicle, with its payload, is then transported by rail to the launch pad, where it is vertically erected over a large flame deflector pit.
The Fregat upper stage
Flight qualified in 2000, the Fregat upper stage is an autonomous and flexible upper stage that is designed to operate as an orbital vehicle. It extends the capability of the lower three stages of the Soyuz vehicle to provide access to a full range of orbits (MEO, SSO, GTO, escape). In order to provide the Fregat with high initial reliability and to speed up the development process, several flight-proven subsystems and components from previous spacecraft and rockets are incorporated into the upper stage.
The upper stage consists of 6 spherical tanks (4 for propellant, 2 for avionics) arrayed in a circle, with trusses passing through the tanks to provide structural support. The stage is independent from the lower three stages, having its own guidance, navigation, control, tracking, and telemetry systems.
The stage uses storable propellants (UDMH/NTO) and can be restarted up to 20 times in flight, thus enabling it to carry out complex mission profiles. It can provide the customer with 3-axis stabilization or spin-up of their spacecraft.
- diameter 3.35 m
- height 1.5 m
- lift off weight 6415 kg
- (of which) propellant weight 5350 kg
- propellant
- fuel Unsymmetrical dimethyl-hydrazine (UDMH)
- oxidizer Nitrogen tetroxide
- main engine thrust 19 620 N
- main engine specific impulse 328s
NPO Lavotchkin (Lavotchkin Research and Production Association) was founded in 1937 as an aircraft manufacturer. It later became one of the leading Soviet design bureaux for planetary exploration, participating in the Luna, Venera, Vega and Mars programmes. The centre has extensive experience in building rocket upper stages.
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Last Update: 22 Oct 2003
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