On June 24, the National Aeronautics and Space Administration’s Mars rover, Curiosity, which soft-landed on the floor of the Gale Crater on a never-before-used contraption called sky crane, successfully completed one Martian year — 687 Earth days. The rover, a car-sized mini- laboratory on six wheels, has so far travelled nearly 8 km since touchdown. What makes the completion of one Martian year all the more significant is the rover’s ability to not only survive the harsh environment of the red planet but also fulfil its primary objective — providing much sought after information on whether past environmental conditions there were favourable for microbial life. The most important parameter that can prove that such a condition existed, is the presence of liquid water at some point in the planet’s history. The rover returned abundant and invaluable information that unequivocally confirmed that Mars once had liquid water that was suitable for drinking. Though there are micro-organisms on Earth that thrive in highly acidic and alkaline conditions, such water bodies, in general, are very unsuitable and challenging for microbial existence.
The bonanza was indeed the detection of well-rounded pebbles in the rock layers on a dry river bed. Sharp-edged stones can become well-rounded only when transported over a long distance and above a particular speed by surface running water. On Earth, rounded pebbles are seen only in the lower reaches of a river. Also, the deposition of alternate layers of pebbles aligned at a particular angle is strongly suggestive of a paleoriver. The presence of clay minerals inside a drilled rock suggests that water was present for extended periods of time. The detection of mineral orthoclase, abundantly seen in Earth’s crust but never before detected on Mars, in the Windjana sandstone sample is yet another surprise find. The biggest question now is whether Curiosity can reconfirm on the ground the latest find of glacial, periglacial and fluvial (including glacio-fluvial) activity within the Gale Crater some 3,500 million years ago. The potential evidence of paleoglaciers was gathered by cameras on board NASA’s Mars Reconnaissance Orbiter and the European Space Agency’s Mars Express. Despite the presence of liquid water, the lack of atmospheric methane greatly reduces the possibility of any extant or extinct microbial life on Mars. Several other unique features detected by Curiosity confirm that our understanding of the red planet is very limited. There is hence every possibility that India’s Mars Orbiter Mission, which will be inserted into the Martian Orbit on September 24 this year, may unearth some unknown facets of the red planet.