The NetLander very broad band seismometer

The interior of Mars is today poorly known, in contrast to the Earth interi or and, to a lesser extent, to the Moon interior, for which seismic data ha ve been used for the determination of the interior structure. This is one o f the strongest facts motivating the deployment on Mars of a network of ver y broad band seismometers, in the framework of the 2007 CNES-NASA joint mis sion. These seismometers will be carried by the Netlanders, a set of 4 land ers developed by a European consortium, and are expected to land in mid-200 8. Despite a low mass, the seismometers will have a sensitivity comparable to the present Very Broad Band Earth sensors, i.e. better than the past Apo llo Lunar seismometers. They will record the full range of seismic and grav ity signals, from the expected quakes induced by the thermoelastic cooling of the lithosphere, to the possible permanent excitation of the normal mode s and tidal gravity perturbations. All these seismic signals will be able t o constrain the structure of Mars ' mantle and its discontinuities, as well as the state and size of the Martian core, shortly after for the centennia l of the discovery of the Earth core by Oldham (Quart. J. Geol, Sec. 62(190 6) 356-475).(C) 2000 Elsevier Science Ltd. All rights reserved.