NASA Logo, National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive Header

Seismic Experiment for Interior Structure (SEIS)

NSSDCA ID: 2018-042A-01

Mission Name: InSight
Principal Investigator:Dr. Philippe Lognonne

Description

The Seismic Experiment for Interior Structure (SEIS) consists of two seismometer subsystems: a 3-axis very-broadband (VBB) instrument and a 3-axis short period (SP) instrument. The primary goal of the instrument is to provide the first unambiguous seismic records of Mars. This will help elucidate the structure of the martian interior, the rate of internal seismic activity, and the rate of meteoritic bombardment.

The VBB subsystem comprises three oblique 0.5 Hz seismometers with measurement capabilities of 10^-9 m / s^2 Hz^1/2 from 0.01 to 2 Hz, and the ability to measure at better than 10^-7 m / s^2 Hz^1/2 over the range 0.0001 to 10 Hz. The VBB is held in an insulated, spherically-shaped housing under vacuum. The three instruments are pendulum seismometers with displacement transducers.

The SB subsystem consists of three short-period 7 Hz seismometers with displacement transducers. One seismometer is vertical and two are horizontal, the sensitivity is better than 10^-8 m / s^2 Hz^1/2 from 0.1 - 10 Hz and better than 5 x 10^-8 m / s^2 Hz^1/2 over the range 0.01 to 100 Hz.

The experiment also has inclinometers to measure the tilt of the instrument and temperature sensors for calibration. The entire deployment package is covered with a hemispherical wind and thermal shield, and is connected to the lander by an electronic tether. An acquisition electronics system collects the 24-bit signals from the sensors for transmission to Earth. The instrument, including electronics, has a mass of 29.5 kg and uses up to 8.5 W power.

After landing, the seismometers will be emplaced 1 to 2 meters from the lander by the robotic deployment arm. A leveling system will bring the sensors into their ideal dynamic range. The pendulums can be adjusted after deployment by ground command. The instruments will return 38 megabits of data per day.

Background noise is expected from a few sources, including thermal, thermo-elastic, magnetic, and electric effects, surface deformation due to the lander mass, movement of the surface due to winds, and the background "hum" due to resonances at fundamental mode frequencies. These effects have been modeled to allow better estimates of their effects, and also to help in the use of complementary sensors on the lander to reduce the effects on interpretation of the signal.

Alternate Names

  • INSIGHT/SeismicExperimentforInteriorStructure(SEIS)
  • urn:nasa:pds:context:instrument:seis.insight

Facts in Brief

Mass: 29.5 kg

Discipline

  • Planetary Science: Geology and Geophysics

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Philippe LognonnePrincipal Investigatorlognonne@ipgp.jussieu.fr

Selected References

  • Lognonné, P., et al., SEIS: InSight’s seismic experiment for internal structure of Mars, Space Sci. Rev., 215, 12, doi:10.1007/s11214-018-0574-6, 2019.
[USA.gov] NASA Logo - nasa.gov