Mission

Mars Express in orbit around Mars

Mars Express is Europe’s first spacecraft to the Red Planet. It carries seven instruments and a lander. The orbiter instruments are remotely investigating the Martian atmosphere, surface and subsurface. Beagle 2, the lander, was expected to perform on-the-spot measurements and also search for signs of past life.

Mars has always been a source of intrigue and fascination. It is currently the only planet in the Solar System on which there is a strong possibility of finding life - past, or perhaps present. It is a prime candidate for future manned exploration, and even colonisation.

Mars Express, together with its lander, is an important element of the international flotilla of spacecraft destined to explore Mars. The ESA project is also the start of an innovative way of developing building blocks for cheaper assembly of future European space missions. The spacecraft has been built and launched in record time and at a much lower cost than previous, similar missions into outer space.

What's special?

Mars Express comprises a number of essential components - the spacecraft, its instruments, the lander, the ground segment, and the launcher. An experienced team of engineers in ESA and industry and hundreds of international scientists are combining these elements into a space mission.

One of the main objectives is to search for traces of water in the subsurface, through the atmosphere, and all the way up to free space. The lander was designed to perform on-the-spot analyses on the Martian surface. Seven scientific instruments on board the orbiting spacecraft will perform a series of remote sensing experiments designed to shed new light on the Martian atmosphere, the atmospheric structure, and geology.

The Beagle 2 lander, named after the ship in which Charles Darwin set sail to explore uncharted areas of the Earth in 1831, provided an exciting opportunity for Europe to contribute to the search for life on Mars. After coming to rest on the surface, Beagle 2 was expected to perform environmental, exobiological, and geochemical research.

As well as its science objectives, Mars Express will also provide relay communication services between the Earth and the NASA rovers on the surface, so forming a centrepiece of the international effort in Mars exploration.

Scientists hope that the instruments on board Mars Express will detect the presence of water below the surface. This could exist in the form of underground rivers, pools, aquifiers, or permafrost.

Spacecraft

Mars Express is designed to take a payload of seven state-of-the-art scientific instruments and one lander to the Red Planet and allow them to record data for at least one Martian year, or 687 Earth days. The spacecraft will also carry a data relay system for communicating with Earth.

The mission is a test case for new working methods to speed up spacecraft production and minimise mission costs. This novel approach is, among other things, also based on reuse of technology developed for the Rosetta mission to a comet.

Most of the velocity needed for the journey of Mars Express from Earth to Mars is provided by the fourth stage of the Soyuz launcher. This stage is called Fregat and separated from the spacecraft after placing it on a Mars-bound trajectory. The spacecraft uses its on-board means of propulsion mainly for Mars orbit injection and for orbit corrections.

The main engine, an off-the-shelf item, uses a mixture of two propellants which are contained in two tanks each with a capacity of 267 litres. The fuel is fed into the engine using pressurised helium from a 35-litre tank.

Electrical power is provided by the spacecraft’s solar panels which are folded against its body during launch and deployed shortly after separation from Fregat. The panels are mounted on a rotating drive mechanism, which tilts them forwards and backwards to catch most sunlight.

When the spacecraft's view of the Sun is obscured during a solar eclipse, an innovative lithium-ion battery, previously charged up by the solar panels, will take over the power supply. Over 1400 eclipses, each lasting up to 90 minutes, are expected during the nominal mission's lifetime. They occur when Mars obscures the spacecraft’s view of the Sun. The solar panels will be capable of delivering 650 Watts which is more than enough to meet the mission's maximum requirement of 500 Watts, just half that of a standard household electric fire.

Journey

Mars Express travelled to the Red Planet in seven months arriving in in Mars orbit on 25 December 2003. It set off on its journey from the Baikonur launch pad in Kazakhstan on a Soyuz-Fregat launcher on 2 June 2003. After reaching an altitude of about 200 kilometres, the Fregat upper stage (which carries the spacecraft) fired its own motors to circularise the orbit 200 kilometres above the Earth. Just before completing the first orbit, it fired again to send itself and its cargo into an escape orbit, en-route for Mars.

After separation from Fregat, the spacecraft's first task was to steady itself by locking onto the Sun using a sun sensor and to unfurl its solar arrays.

Two days and 600 000 kilometres later, ground control sent a message to Mars Express to adjust its trajectory onto what put it on a collision course with Mars. A few minutes burn of the small thrusters produced the desired effect. Mars Express was then hurtling through interplanetary space with an absolute velocity of 116 800 kilometres per hour and a velocity relative to Earth of 10 800 kilometres per hour.

One month before arrival, preparations began for the separation of the Beagle 2 lander. Once more, the small thrusters fired to put Mars Express onto a trajectory that would allow Beagle 2, which had no propulsion of its own, to enter the Martian atmosphere and endure a bumpy ride through the Martian atmosphere down to the correct landing site on the surface.

Beagle 2 was released as late as possible, just six days before Mars Express went into orbit around the Red Planet, to increase the precision of landing sequence. The friction caused by Beagle 2 entering the thin Martian atmosphere would cause it to slow down considerably and then parachutes would have deployed; then approximately one kilometre above the surface, large gas-filled airbags would deploy around the lander to cocoon it as it bounced to rest on the surface.

The rocky ride through the Martian atmosphere to the surface should have taken no longer than ten minutes. Contact with Beagle 2 was attempted by the NASA Mars Odyssey orbiter, several Earth-based telescopes and the Mars Express orbiter itself, however no signal was received from the Beagle 2 lander. The Beagle 2 Management Board met in London on 6 February 2004 and, following an assessment of the situation, declared Beagle 2 lost.

History

Europe's Mars Express is the lowest-cost mission to Mars so far and is seen as a pilot project for new methods of funding and working. The experience gained on Mars Express will provide a good basis to further lower the costs of future ESA missions.

After a 12-month competitive study, proposal and evaluation phase, concluded at the end of 1998, ESA recommended Astrium SAS of Toulouse, France, as prime contractor. The contract for the design and development of this first European spacecraft to visit the planet Mars was signed formally on 30 March 1999.

The relatively low cost of the mission was achieved through new and innovative approaches in the working relationship between ESA, industry, national agencies and the scientific community, and through the reuse of equipment developed for ESA’s Rosetta mission. Some of the scientific instruments have a heritage from the Russian Mars 1996 mission.

Partnerships

ESA believes that the scientific community and European industry have gained sufficient experience during past scientific projects for industry to take on more responsibility for the management of interfaces, in particular with the scientific payload.

For this reason, Astrium SAS is taking on tasks that previously would have been done by the project team at ESTEC. These include interacting directly with the Principal Investigators for the scientific payload and with the launch services supplier, Starsem, to ensure that technical interfaces are compatible. As a consequence of this shift in responsibility, the ESA project team is only ten-strong compared with at least 20 for earlier comparable missions.

The Soyuz-Fregat launcher was provided by Starsem, which is jointly owned by Arianespace, Aerospatiale, the Russian Aviation and Space Agency and the Samara Space Centre.