Tuesday, September 1, 1998 Published at 14:03 GMT 15:03 UK
Small is beautiful on Mars
Walk around it in an hour
Scientists are learning about Mars's volcanic past by studying the smallest volcanoes on the planet. Our science editor Dr David Whitehouse reports.
Textbooks say that Mars is a world of wonders. Beneath its peach-coloured sky it has grand mountain ranges, deserts with shifting sand dunes, vast canyons that dwarf anything found on Earth and huge extinct volcanoes three times the height of Mt Everest.
But recently the orbiting Mars Global Surveyor spacecraft has shunned these wonders in favour of a small volcano that you could walk across in 20 minutes.
It is a small "shield" volcano and MGS has obtained the first close-up images of this type of structure. Planetary geologists believe that it may hold important clues about Mars's more active geological past.
But the Martian shield volcano appears to be different from its Earth cousins. It lacks the lava flows seen on Earth and has peculiar ridges.
Expert opinion is that the ridges are volcanic cinders from some past eruption that have been blown into ridges by the wind.