Optimism Experiment and Development of Space-qualified Seismometers in France

The OPTIMISM experiment will put two magnetometers and two seismometers on the Martian floor in 1995, within the framework of the Mars '94 mission. The seismometers are put within the two small surface stations. The seismometer sensitivity will be better than 10 exp -9 g at 1 Hz, 2 orders of magnitude higher than the Viking seismometer sensitivity. A priori waveform modeling for seismic signals on Mars shows that it will be sufficient to detect quakes with a seismic moment greater than 10 exp 15 Nm everywhere on Mars. Such events, according to the hypothesis of a thermoelastic cooling of the Martian lithosphere, are expected to occur at a rate close to one per week and may therefore be observed within the l-year lifetime of the experiment. Other aspects of the experiment are discussed.