The SEIS experiment on INSIGHT Discovery mission to Mars IPPW-10, June 18th 2013, San José Rene Perez, SEIS instrument manager, CNES Ph. Lognonné, S. Deraucourt, IPGP D. Mimoun, ISAE K. Hurst, JPL and the SEIS Team

1 1 A fundamental contribution to understanding the early evolution of the terrestrial planets through investigations of the Mars interior 1

2 Why bother about planetary interiors ? The interior of a planet retains the signature of its origin and subsequent evolution. The interior structure provides the boundary conditions that can constraint our understanding of both accretion composition and conditions The interior structure reveals the signature of early differentiation processes Crust Mantle Core Crust Mantle

3 3 Seismology on Mars: a long story : Viking 3 months of (accumulated) seismic data 1996: Mars 96 Failed at launch 2016: Insight Will provide 1 martian year of data (or more?)

4 Scientific objectives: Understand the formation and evolution of terrestrial planets through investigation of the interior structure and processes of Mars Determine the present level of tectonic activity and impact flux on Mars Objectives translated in Threshold Science Requirements for SEIS: -Rayleigh wave group velocity dispersion -P and S arrival times -Phobos tide amplitude 4 Regional Global to regional Global a few/yr ~ 10/yr ~100/yr M~5.5 M~4.5 M~ Magnitudes 2.6

5 The InSight Payload: Use or disclosure of information contained on this sheet is subject to the restriction on the title page of this document. SEISRISEHP3

6 6 3 VBBs-Long period axis (IPGP) The SEIS experiment overview: 3 SP sensors (IC) short period LVL: Leveling system (MPS) E-Box (ETHZ) WTS: Wind and Thermal shield (JPL) Tether / Tether box (JPL) On Lander Mars surface APSS: Wind sensors (CAB) Pressure sensors (JPL) and Magnetometer (UCLA) Earth Ground segment SEIS operational (CNES) and data center (IPGP) SEIS Management (CNES)

7 SEIS Operation Concept The instrument is always ON and keeps on acquiring raw data SW (and C&DH) wakes up ~every TBD hours during about ten of minutes In routine one daily DSN pass for data downlink 7 C&DH t Wake-up TBD hrs SEIS communication session E-Box NVmemory usage

8 8 The Sphere VBB (long period sensors)

9 Sphere VBB development history: 16 years old...

10 Performance Validation Plan: Phobos tide calibration : –end-to-end performance test done on Earth SP performances –end-to-end performance test done on Earth VBB performances (S/N): end-to-end test not doable on Earth: –VBBs performance cannot be measured on Earth without a compensation mass (so, not in Mars configuration) –Only reduced functional tests can be performed on flight VBBs (due to the difference in gravity) –Planning will be incompatible in long term (e.g. ~month) tests in low noise sites with temperature comparable to Martian condition (e.g. Antarctica) Final performance is demonstrated by Tests and Modeling: –Early model (VBB5) extensively tested for performance, providing elements for last tuning of flight models –Measure the instrument self noise, and correct with the Performance Model –Measure sensitivity to external environment parameters –Test in Martian environment when possible (e.g. temperature, pressure capsule noise) –Simulate, when tests are not possible, to derive SEIS performance in Martian environment (Magnetic field, Pressure)

11 SEIS success tree (example) WTS Th constant Preliminary- STM Test - QM Sphere Th. Constant Preliminary- STM Test - QM VBB thermal Sensitivity Test – EM Test - QM SEIS Thermal Noise Simulation QM performance plus temperature profile Performance Test Simulation + Tests Simulation Validation of Thermal noise allocation Mars Temperature Model + Sci. Temp. performance (CNES) (IPGP) (CNES) SP thermal Sensitivity Test – EM Test - QM (Oxford) SP Th. Constant Preliminary- STM Test - QM (Oxford) Ground Inside/payload skin Exterior skin Convection Model

12 Performances budget: VBB noise budget (Velocity output):

13 VBB5 first results … Thermal environment tests done (and to be continued): Thermal sensitivity Behavior under cold environment (recentering, transfer function …) Full cold Performance Validation: Early model, but highly representative design under tests. Ambient Maur des Fossés (0.1-1Hz) 2013/05/21 M7.4 Earthquake Tonga Maur des Fossés (0.1-1Hz)

14 Seismic Vault VBB (one axis) + reference seismometer installed on the same pillar. Axes in vacuum chamber + µ-metal shielding Recombine reference seismometer axes to fit VBB’s sensitivity axis, then compare measurements both in time and frequency domain

15 Low noise test in low noise site? Unique way to detect noise issues at ng/Hz 1/2 on fully integrated instrument This test has been done last summer (BFO) with a previous instrument configuration (significant gain on the results!) It’s worth to be repeated with VBB5, but challenging for planning –Could be attempted in // with ATLO ( )? BFO or Antartica?...

16 Thanks for your attention!