The Mars Express spacecraft has been 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 also carries a data relay system for communicating with Earth.

Exploded Diagram of Mars Express

The mission is a test case for new working methods to speed up spacecraft production and minimise mission costs. These new methods have had two major impacts on spacecraft design. Weight was kept to an absolute minimum: 116 kg was allowed for the seven instruments and 60 kg for the lander. And off-the-shelf technology, or technology developed for the Rosetta mission to a comet, was used wherever possible.

The instruments sit inside the spacecraft bus which is a honeycomb aluminium box just 1.5 m long by 1.8 m wide by 1.4 m high. The lander, Beagle 2, was attached to the outside of the bus. Payload, lander, spacecraft and on-board fuel weighed 1223 kg at launch.