Acidalia Planitia mud volcanoes
Date: 05 October 2011
Copyright: NASA/JPL-Caltech/University of Arizona
This image of a site in Acidalia Planitia on Mars depicts densely situated mounds, which are thought to be mud volcanoes.
Mud volcanoes are geological structures formed when a mixture of gas, liquid and fine-grained rock (or mud) is forced to the surface from a distance of several metres to kilometres underground. Scientists are interested in the mud volcanoes because the sediments brought up from below could contain organic materials that might provide evidence for possible past or present microbial life below the Martian surface. Mud volcanoes on Earth (for example, those found in Italy and Romania) vent methane, a chemical species that will be searched for by the two spectrometers that will be carried on the ExoMars Trace Gas Orbiter.
Acidalia Planitia is located in a region in the Northern Plains on Mars that was the focal point for deposition of sediments transported through outflow channels. For this reason it could be an interesting target for the orbiter's investigations.
Candidate mud volcanoes have been reported since the 1970s. However, it was only in 2010 that they were positively identified and a map including more than 18,000 of these circular mounds was published for the first time.
This image covers an area about 6 kilometres wide and is centred at 44.5°N / 317.2°E. It was produced from a HiRISE (High Resolution Imaging Science Experiment) observation on 2 October 2010. HiRISE is a high-resolution camera on the Mars Reconnaissance Orbiter.
