The SEIS seismometer has now landed on Mars
NASA has just successfully landed the InSight probe's SEIS seismometer on Mars. This is the first time in the history of the conquest of space that an instrument has been deployed by a robotic arm on the surface of another planet. The success of this critical stage in the mission is the result of years of incessant technical effort by American, French and European teams.
Publication date: 19/12/2018
General public, Observatories, Press, Research
Related observatories : InSight Observatory
Related themes : Earth and Planetary Interiors
The complex sequence of instructions commanding the deployment had been sent on December 18th 2018 (at 5.11pm California time) towards the Red Planet. On December 19th 2018 at 6.40pm local (Martian) time, InSight’s arm moved into action to deposit the 9.5kg SEIS seismometer on the ground. For this high-risk operation, the instrument had been completely switched off and numerous tests had been carried out beforehand on Earth to validate the controls, the landing site having been faithfully reproduced for the occasion.
To place SEIS on the ground, the robotic arm performed a fairly complex series of movements. But the deployment sequence itself lasted only 10 minutes. However, the need to acquire images via the probe’s cameras extended the duration of the operation to around 20 minutes, spread over 45 minutes. The time at which the SEIS seismometer planted its three feet in the sand is estimated at 7:05 (California time), or 18:54 Martian time.
The spot on which SEIS now rests is directly in front of the robotic arm (to ensure that the umbilical cord linking the instrument to the lander lies flat on the ground), and as far away as possible (1.65 metres) from the probe, to minimise disturbance.
However, operations are far from over for SEIS. First of all, the engineers will have to align the seismometer with the horizontal, using the motorised levelling cradle. Once this stage has been completed, the Very Broadband (VBB) sensors, which are currently inactive unlike the short-period SP sensors, will be refocused and calibrated. All the data transmitted by the six seismic sensors will then be used to characterise the noise level at the landing site, as well as the level of disturbance induced by the cable linking the instrument to the lander.
When the performance is deemed acceptable, the cable still in the TSB reel will be completely unwound, which will then allow the final placement of the imposing WTS thermal and wind protection shield on top of the instrument.
So there’s still a lot of work to be done before the first Martian geophysics station is fully operational, but the installation of the first seismometer on Mars is already a great success, and the team members will be celebrating in style by probably taking a few days off for the Christmas holidays!
