Life on Mars: Little Green Men, or Little Grey Bugs? Planet Mars is a close neighbour of the Earth - on average, its orbit is only about 78 million km away and it may come as near as 58 million km. We know much about this planet, from space missions, Earth-based observations and also through study of martian meteorites. There have been over 30 space missions to Mars since 1960. Why is Mars so popular? Why is it thought to be a prime place to search for signs of past or present life? Surface features on Mars indicate that water might once have been present - and where there is water, there may be life! If there has been life on Mars, it is likely only to have been fairly primitive. The coming space mission Mars Express, with its lander Beagle 2, is designed to search for evidence for life on Mars.

This is all of Mars. The picture was reconstructed from over 200 million laser altimeter measurements taken by the Mars Global Surveyor spacecraft. Particularly notable are the volcanoes of the Tharsis province, visible on the left, which are taller than any mountains on Earth. Just to the left of the center is Valles Marineris, a canyon much longer and deeper than Grand Canyon. On the right, south of the center, is the Hellas Planitia, a basin over 2000 kilometers wide that was likely created by a collision with an asteroid.