Mars Express is a European Space Agency mission and contains an orbiter and a lander. The orbiter carries seven instruments, including a high-resolution stereo-imaging camera as well as ultraviolet and infrared atmospheric spectrometers. The orbiter will complement the British-built lander - called Beagle 2 - that will land in the Isidis Planitia Basin, 10 degrees north of the Martian equator. Beagle 2, which is the brainchild of Colin Pillinger of the Open University, weighs less than 30kg and contains six different instruments. These include a set of ovens for heating rock and soil samples, environmental sensors, and instruments mounted on the end of a robotic arm – such as stereo cameras and spectrometers.

NASA will also launch its own mission this month called Mars Exploration, which consists of two rovers that will land on different sites on the red planet. Rover-A, scheduled for launch atop a Delta II rocket on 5 June, will land at Gusev Crater in early January next year. This crater, 15 degrees south of the equator, is thought to have once been a lake. Rover-B, meanwhile, will launch on 25 June and head for Meridiani Planum, which is 2 degrees south of the equator. Meridiani has deposits of grey hematite, an iron oxide usually produced where there is liquid water.

The two missions follow on from NASA’s Mars Odyssey orbiter and both have very complementary objectives. “The payloads on Beagle 2 and the rovers are very different to each other,” said Steve Squyres, an astronomer at Cornell University in New York and principal investigator of the NASA mission. “You’re going to have this really rich array of sensors and landers all exploring the planet at once.”

Both missions take advantage of an alignment of the Earth and Mars that minimizes the amount of fuel needed to make the trip. Such advantageous alignments occur for just a few weeks every 26 months.