The SEIS InSight VBB Experiment

Introduction: The SEIS experiment is the primary payload of the Interior Structure Investigation using Seismology and Heat Transport (InSight) mission selected by NASA in August 2012 to be the next Mars mission. The objective of the InSight SEIS experiment is the determination of the deep internal structure of Mars. In particular, geophysical parameters of first importance, such as the state (liquid/solid) and size of the core, structure of the mantle, shape of discontinui-ties and thickness of the crust will be determined by the experiment. It will measure seismic activity over a very broad frequency band, from tidal frequencies (0.05 mHz) up to high frequencies (50 Hz), to address a wide range of scientific questions, from the state of the core to the meteoritic impact rate, marsquake rate and the response of the planet to the Phobos tide. Description of the instrument: The instrument includes notably a Very Broad Band (VBB) 3 axis seis-mometer which is developed by the ';Institut du Globe de Paris' (IPGP) under the funding of CNES. The sensor assembly, which also contains a MEMS short-period seismometer, will be deployed on the Martian ground by a robotic arm from a Phoenix-type lander platform and will be protected by a wind and thermal shield. The wind and thermal shield,together with a vacuum sphere and a passive compensation system will achieve a very high protection of the VBB against temperature and pressure variations, allowing the sensor to operate in the rough Martian thermal environment while reaching a detection threshold below 10-9 ms-2 Hz-1/2 in the VBB bandwidth. Conclusion: Performance has been demonstrated with previous prototypes and the SEIS experiment of the InSight mission will therefore provide high-quality seismic signal acquisition and associated seismic information during one martian year. The delivery of the payload is planned for the end of 2014 and the launch is in March 2016 SEIS deployed on the ground next to the lander

Single-axis VBB-prototype with proximity electronics