Five of the instruments on Mars Express (HRSC, OMEGA, PFS, ASPERA and SPICAM) were descendants of instruments originally built for the Russian Mars ’96 mission. Each of the seven orbiter instrument teams on Mars Express had Russian coinvestigators who contributed their intellectual expertise to the project.
The Japanese spacecraft Nozomi was intended to go into near equatorial orbit around Mars shortly after Mars Express entered polar orbit. Nozomi had been due to reach the Red Planet in October 1999, but was delayed by a problem with the propulsion system, so the two missions took the opportunity to collaborate.
They shared a common interest in the Martian atmosphere – Nozomi even carried a close relative of ASPERA, the instrument on Mars Express to study interactions between the upper atmosphere and the solar wind.
Measurements recorded simultaneously by both spacecraft from their different vantage points would provide an unprecedented opportunity to study such interactions, so the two missions agreed to a programme of joint investigations and to the exchange of coinvestigators between the instrument teams.
ESA’s Beagle 2 landed on Mars at about thesametime as NASA’s Mars Rover mission. The two space agencies made arrangements to use each other’s orbiters as back-up for relaying data and other communications from the landers to Earth.
Mars Express also intended to use NASA’s Deep Space Network for communications with Earth during parts of the mission. US scientists played a major role in one of Mars Express’s payload instruments, MARSIS, and participated as co-investigators in most other instruments.
Mars Express and Beagle 2 marked the beginning of a major European involvement in an international programme to explore Mars over the next two decades. Europe, the US and Japan are planning to send missions, but many more countries will be contributing experiments, hardware and expertise.