ESA's first mission to the Red Planet, Mars Express, was launched in June 2003. It comprised an orbiter carrying seven scientific instruments to probe the planet's atmosphere, structure and geology, including a search for evidence of hidden water. The main spacecraft released the UK's small Beagle 2 lander to gather and test rock and soil samples on the surface. As well as its science objectives, Mars Express also provides relay communication services between Earth and landers deployed on the surface by other nations, thus forming a centrepiece of the international effort in Mars exploration.

Mars Express is a pilot project for new methods of funding and managing ESA space missions, built more quickly and launched at a much lower cost than any previous mission of a similar nature.