The seismic OPTIMISM experiment

International audienceThe study of the deep interior of Mars suffers from the very limited amount of data available, particularly seismological data. The objective of the OPTIMISM seismic experiment, lost with the failure of the Mars 96 mission, was to perform a seismic reconnaissance of Mars, to constrain the level of martian seismic noise and its level of seismicity. The seismometer was expected to operate during one year, with a sensitivity one hundred times higher than the Viking seismometer.Observation of relatively frequent low magnitude marsquakes, as well as a few large magnitude quakes might then be probably achieved. The OPTIMISM experiment might then, as a seismic ‘path-finder’, open a new field in Mars exploration and a new era in our present knowledge of the interior of Mars. A seismic experiment on Mars, especially performed by a network of stations, remains as the necessary experiment for the determination of the internal structure of the planet