Geophysical observations of Phobos transits by InSight
- Simon C. Stähler,
- Rudolf Widmer-Schnidrig,
- John-Robert Scholz,
- Martin van Driel,
- Anna Magdalena Mittelholz,
- Kenneth Hurst,
- Catherine L. Johnson,
- Mark T Lemmon,
- Ralph D. Lorenz,
- Philippe Henri Lognonné,
- Nils T Mueller,
- Laurent Pou,
- Aymeric Spiga,
- Donald Banfield,
- Savas Ceylan,
- Constantinos Charalambous,
- Domenico Giardini,
- Francis Nimmo,
- Mark Paul Panning,
- Walter Zürn,
- William Bruce Banerdt
Rudolf Widmer-Schnidrig
Black Forest Observatory, Institute of Geodesy, Stuttgart University, Heubach 206, D-77709 Wolfach, Germany
Author ProfileJohn-Robert Scholz
Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
Author ProfileAnna Magdalena Mittelholz
The University of British Columbia
Author ProfileKenneth Hurst
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
Author ProfileRalph D. Lorenz
Johns Hopkins University Applied Physics Lab
Author ProfilePhilippe Henri Lognonné
Institut de Physique du Globe de Paris et Université de Paris Diderot
Author ProfileNils T Mueller
German Aerospace Center (DLR), Institute of Planetary Research
Author ProfileLaurent Pou
Dept. of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, USA
Author ProfileMark Paul Panning
Jet Propulsion Laboratory, California Institute of Technology
Author ProfileWalter Zürn
Black Forest Observatory (Schiltach), Universities Karlsruhe/Stuttgart
Author ProfileAbstract
Since landing on Mars, the NASA InSight lander has witnessed 8 Phobos
and one Deimos transit. All transits could be observed by a drop in the
solar array current and the surface temperature, but more surprisingly,
for several ones, a clear signature was recorded with the seismic
sensors and the magnetometer. We present a preliminary interpretation of
the seismometer data as temperature induced local deformation of the
ground, supported by terrestrial analog experiments and finite-element
modelling. The magnetic signature is most likely induced by changing
currents from the solar arrays. While the observations are not fully
understood yet, the recording of transit-related phenomena with high
sampling rate will allow more precise measurements of the transit times,
thus providing additional constraints for the orbital parameters of
Phobos. The response of the seismometer can potentially also be used to
constrain the thermo-elastic properties of the shallow regolith at the
landing site.