By IANS
London : Mars has undergone massive volcanic upheavals that alternatively spewed lava and water onto its surface, giving the red planet its current contours.
German scientists have come to this conclusion after viewing the latest images of those contours – captured by the high-resolution stereo camera (HRSC) of Mars Express, the European Space Agency’s (ESA) spacecraft circling the planet, reports Scincedaily.
“We can now determine the ages of large regions and resurfacing events on the planet,” said Gerhard Neukum of Berlin’s Freie Universität. And he attributed those to volcanic eruptions spreading lava across Mars’ surface.
Neukum, who led a study of the images, believes that the sculpting of the Martian surface has not proceeded steadily.
Rather, Mars has been wracked by violent volcanic activity five times in the past, after the early supposedly warmer and wetter phase, more than 3.8 billion years ago. In between these episodes, the planet has been relatively calm.
The five volcanic episodes stretch throughout Martian history, occurring around 3.5 billion years ago, 1.5 billion years ago, 400-800 million years ago, 200 million years ago and 100 million years ago.
The ages have been estimated by counting the number of small craters that appear on the landscape. The idea is simple: the older the surface, the more craters it will have accumulated as meteorites of all sizes have struck over the ages.
There has been a debate recently about the validity of this method. However American researchers, analysing seven years’ worth of images from the Mars Orbiter Camera (MOC) on NASA’s Mars Global Surveyor, have found new craters appearing on the surface during that time.
“The present day cratering rate can be calculated from their observations,” says Neukum. It fits very closely with the cratering rate he established from the Mars Express data with Bill Hartmann, Planetary Science Institute, Tucson, Arizona.
Far from revealing a geologically dead world, Mars Express is exposing a place of subtle activity that could still erupt into something more spectacular.