Curiosity at Gale Crater, Mars

Tuesday 17th October, 2017

Our speaker was Dr Susanne Schwenzer who is a lecturer in Earth Science at The Open University. She came to talk to us about NASA's robotic rover on Mars, called "Curiosity" and her talk was entitled "Curiosity at Gale Crater, Mars". She is part of NASA's Mars Science Laboratory mission team who study the data returned by NASA's Curiosity rover on Mars. She began by giving a short overview of the mission.

Curiosity left Earth aboard an Atlas V rocket on November 26th 2011 and reached the Martian surface in Gale Crater on August 6th 2012. It used a rather unorthodox method of slowing its descent in its last few metres before landing, as the rover hung underneath a cradle suspended by wires rather like a puppet on strings. To ensure a soft touchdown the cradle was fitted with rockets that would bring everything to a halt before the rover's wheels finally made contact with the Martian surface. Once the rover was safely on the surface the tethers were cut and the cradle flew off to a safe distance before it, in turn, hit the surface.

Dr Schwenzer then explained that the rover is much larger than previous rovers sent there. It is about the size of a small car and weighs roughly a metric tonne. Unlike the previous rovers that relied on solar power, it has a radioactive power source that could, in theory, last for 14 Earth years, which is well outside the primary mission timeline of two years. However, it may be mechanical components that end the mission. For its aluminium wheels now have tears in them due to Mars' hard pointed rocks and there are problems with the drill in its robotic arm.

Despite the wear and tear in such a harsh environment and the rover drivers coping with a significant time lag, Curiosity has covered around 11 miles by using a combination of human driving instructions sent from Earth along with some clever autonomous driving software. Its landing site in Gale Crater is not far from the Martian equator and is a large impact crater with a 5.5 km-high mountain at its centre. This landing site was chosen as the bottom of the central mountain has layers made up of clays and sulphates which suggest that at one time in Mars' past water was present in the crater.

Dr Schwenzer continued by saying that Curiosity had answered the question whether Mars had at one time been suitable for life in some form. She commented, though, that although the environment had been suitable it had yet to be proven that life had taken hold on Mars. By studying the rocks, the rover had found carbon hydrogen, oxygen, phosphorous and sulphur, which are key building blocks of life. Not only had it found these elements but also organic carbon and a short increase in methane levels in the atmosphere over a couple of months. Also, apart from the clay minerals it found, it had also taken pictures of smooth and rounded pebbles that were evidence of a small stream of water that would have been about knee-deep.

She said that she would be involved in the next Martian rover, the European Space Agency's "ExoMars", which will be launching in 2020. Its primary mission is also concerned with the search for past life on Mars.