SEIS seis­mome­ter

The three sensors that are sensitive to low frequencies are housed in an evacuated container, as the air resistance of even the thin Martian atmosphere would dampen the movement of the sensors too much. This container rests on a levelling system (LVL) with three telescopic legs to ensure that the casing is precisely horizontally aligned, as the VBB sensors would not work otherwise. The three sensors for the higher frequency range are mounted on the outside of the LVL. In order to protect the seismometer against wind and strong temperature fluctuations, a protective dome (Wind and Thermal Shield, WTS) will be placed over it.

In the first two weeks after arrival, the lander’s immediate surroundings will be precisely mapped and surveyed to find the ideal location for the two instruments – SEIS and HP³. The robotic arm will then lift out and install the seismometer, with the location checked and recorded once more before the WTS is placed on top of it. Work on the assembly of the seismometer should be complete by 5 January 2019.

Institutions from several countries have provided the SEIS components. The low-frequency VBB sensors are from the Institute du Physique du Globe in France, the high-frequency SP sensors are from Imperial College in the United Kingdom, and the control electronics were made at the Swiss Federal Institute of Technology in Zurich (Eidgenössische Technische Hochschule; ETH). The vacuum container, the WTS and the connecting cable, with almost 300 wires for electrical supply and data transmission to the lander, come from the NASA Jet Propulsion Laboratory (JPL) in the USA. Finally, the levelling system was developed and built by the Max Planck Institute for Solar System Research in Göttingen, Germany.