The lower rock layers of the Gale Crater mound, a record of Martian climate.
14th February 2010.
The array of Nasa spacecraft and rovers, or rover (sadly, Spirit is in it’s final resting place) just carry on giving us great pictures and science from the red planet. The razor sharp images we now routinely get from Nasa’s Mars Reconnaissance Orbiter are breathtaking, and this time they show Mars giving up yet more of it’s secrets.
A lot of astronomy resides in the imagination, the surface of Europa, a star that shines 2,000 times brighter than the Sun, the strange life forms that could inhabit that barely detectable galaxy you can see in your telescope. Imagine a huge Martian crater the size of Connecticut, with a mountain near the centre as tall as the Rockies, containing hundreds of exposed rock layers. There you have Gale Crater, a place showing dramatic environmental changes in it’s many layers of rock, from billions of years ago. Scientists have discovered how the layers go from the oldest rock at the bottom, laid down in wet conditions, gradually drying out as you go up the layers, to the youngest rock at the top formed when Mars had drier conditions. The clay is the key, clay minerals were found to be present at the bottom of the Gale Crater rock peak, laid down in a wet environment.
Back in Mars’ distant past, there was plenty of water. Could there have been life? If you want to find life you should first look for water. Whatever, if anything, is inside the ancient “wet” rocks of Mars will have to wait for future missions to find out.
