London, March 16 : A new analysis of impact cratering data, sing images from the High Resolution Stereo Camera (HRSC) on ars Express, has revealed that the Red Planet has undergone a eries of global volcanic upheavals. These violent episodes spewed lava and water onto the surface, culpting the landscape that ESA's Mars Express looked down upon.
According to Gerhard Neukum, Freie Universitdt Berlin, Germany, nd colleagues, who are discovering the history of the Red lanet's geological activity, "We can now determine the ages of arge regions and resurfacing events on the planet."
Resurfacing occurs when volcanic eruptions spread lava across the lanet's surface.
The new analysis has suggested that the sculpting of the Martian urface has not proceeded in a steady fashion, as it does on arth.
Rather, the team has discovered that Mars has been subject to iolent volcanic activity five times in the past, after the early upposedly warmer and wetter phase, more than 3.8 thousand illion years ago. In between these episodes, the planet has been elatively calm.
The five volcanic episodes stretch throughout Martian history, ccurring around 3.5 thousand million years ago, 1.5 thousand illion years ago, 400-800 million years ago, 200 million years go and 100 million years ago.
According to Neukum, the dates of the earlier episodes are orrect to within 100-200 million years and that the later dates re correct to within 20-30 million years.
The ages have been estimated by counting the number of small raters that appear on the landscape. The idea is simple: the lder the surface, the more craters it will have accumulated as eteorites of all sizes have struck over the ages.
American researchers, analysing seven years' worth of images from he Mars Orbiter Camera (MOC) on NASA's Mars Global Surveyor, ave found new craters appearing on the surface during that time.
"The present day cratering rate can be calculated from their bservations," said Neukum.
During these volcanic episodes, eruptions of lava flowed across ars. The internal heat generated by the volcanic activity also aused water to erupt from the interior, causing wide-scale flash looding.
As for why Mars behaves like this, geophysical computer-based odels have suggested that the planet has been trying to stablish a system of plate tectonics, as there is on Earth where he crust is broken into slowly moving plates.
On Mars, the volcanic episodes represent the planet almost chieving, but not actually attaining, plate tectonics - and hese volcanic episodes might not be over.
"The interior of the planet is not cold yet, so this could happen gain," said Neukum.
Far from revealing a geologically dead world, Mars Express is xposing a place of subtle activity that could still erupt into omething more spectacular.