Mars Had 'Recent' Volcanic Activity

[zavvy]

<b>Red Planet had 'recent' volcanism</b><br /><br />http://news.bbc.co.uk/2/hi/science/nature/3535498.stm<br /><br /><br />Mars appears to have been volcanically active more recently than previously supposed, according to growing evidence from Europe's Mars Express orbiter. <br /><br />New estimates suggest volcanoes could have been active between one million years ago and 20 million years ago, but more work is needed to refine the dates <br /><br />Previous spacecraft data suggested that volcanism on Mars ceased some time around 600-500 million years ago. <br /><br />Some researchers even speculate Mars could be volcanically active today. <br /><br />Mars Express project scientist Agustin Chicarro said some volcanoes were "extremely young" based on current data. <br /><br />"For volcanic phenomena, we may be talking about a few million years, meaning in the order of one to 20 million years. But this depends very much on the data we have and in a few months we may have much better data," he told BBC News Online. <br /><br />Crater counting <br /><br />The ages were estimated by counting the number of impact craters associated with volcanoes in images from the High-Resolution Stereo Camera (HRSC) aboard Mars Express. <br /><br />This is a method widely used by planetary scientists to estimate the ages of planetary surfaces. However, these estimates are relative, Dr Chicarro cautioned, and involve a certain amount of guesswork. <br /><br />More cratered surfaces are deemed older, while smoother surfaces are considered younger. This assumes a constant cratering rate since the heavy bombardment that terrestrial planets underwent about four billion years ago. <br /><br />But there are complications on Mars, according to Dr John Murray of the Open University, a co-investigator on the HRSC. <br /><br />"You can get dust storms and ice near the poles, so you find that the smaller craters are gone and the larger ones are