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The InSight HP3 Penetrator (Mole) on Mars: Soil Properties Derived from the Penetration Attempts and Related Activities

Spohn, Tilman and Hudson, T.L. and Marteau, E. and Golombek, M. and Grott, Matthias and Wippermann, Torben and Ali, K. and Schmelzbach, C. and Kedar, S. and Hurst, K. and Trebi-Ollennu, A. and Ansan, V. and Garvin, J. and Knollenberg, Jörg and Müller, Nils and Piqueux, S. and Lichtenheldt, Roy and Krause, Christian and Fantinati, C. and Brinkman, Nienke and Sollberger, D. and Delage, P. and Vrettos, C. and Reershemius, Siebo and Wisniewski, Lukasz and Grygorczuk, J. and Robertsson, J. and Edme, P. and Andersson, F. and Krömer, Olaf and Lognonne, A.P. and Giardini, D. and Smrekar, S. and Banerdt, B. (2022) The InSight HP3 Penetrator (Mole) on Mars: Soil Properties Derived from the Penetration Attempts and Related Activities. Space Science Reviews, 218 (72). Springer. doi: 10.1007/s11214-022-00941-z. ISSN 0038-6308.

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Official URL: https://link.springer.com/article/10.1007/s11214-022-00941-z


The NASA InSight Lander on Mars includes the Heat Flow and Physical Properties Package HP3 to measure the surface heat flow of the planet. The package uses temperature sensors that would have been brought to the target depth of 3–5 m by a small penetrator, nicknamed the mole. The mole requiring friction on its hull to balance remaining recoil from its hammer mechanism did not penetrate to the targeted depth. Instead, by precessing about a point midway along its hull, it carved a 7 cm deep and 5–6 cm wide pit and reached a depth of initially 31 cm. The root cause of the failure – as was determined through an extensive, almost two years long campaign – was a lack of friction in an unexpectedly thick cohesive duricrust. During the campaign – described in detail in this paper – the mole penetrated further aided by friction applied using the scoop at the end of the robotic Instrument Deployment Arm and by direct support by the latter. The mole tip finally reached a depth of about 37 cm, bringing the mole back-end 1–2 cm below the surface. It reversed its downward motion twice during attempts to provide friction through pressure on the regolith instead of directly with the scoop to the mole hull. The penetration record of the mole was used to infer mechanical soil parameters such as the penetration resistance of the duricrust of 0.3–0.7 MPa and a penetration resistance of a deeper layer (> 30 cm depth) of 4.9±0.4 MPa. Using the mole’s thermal sensors, thermal conductivity and diffusivity were measured. Applying cone penetration theory, the resistance of the duricrust was used to estimate a cohesion of the latter of 2–15 kPa depending on the internal friction angle of the duricrust. Pushing the scoop with its blade into the surface and chopping off a piece of duricrust provided another estimate of the cohesion of 5.8 kPa. The hammerings of the mole were recorded by the seismometer SEIS and the signals were used to derive P-wave and S-wave velocities representative of the topmost tens of cm of the regolith. Together with the density provided by a thermal conductivity and diffusivity measurement using the mole’s thermal sensors, the elastic moduli were calculated from the seismic velocities. Using empirical correlations from terrestrial soil studies between the shear modulus and cohesion, the previous cohesion estimates were found to be consistent with the elastic moduli. The combined data were used to derive a model of the regolith that has an about 20 cm thick duricrust underneath a 1 cm thick unconsolidated layer of sand mixed with dust and above another 10 cm of unconsolidated sand. Underneath the latter, a layer more resistant to penetration and possibly containing debris from a small impact crater is inferred. The thermal conductivity increases from 14 mW/m K to 34 mW/m K through the 1 cm sand/dust layer, keeps the latter value in the duricrust and the sand layer underneath and then increases to 64 mW/m K in the sand/gravel layer below.

Item URL in elib:https://elib.dlr.de/191936/
Document Type:Article
Title:The InSight HP3 Penetrator (Mole) on Mars: Soil Properties Derived from the Penetration Attempts and Related Activities
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Hudson, T.L.Jet Propulsion Laboratory, Caltech, Pasadena, CA, USAUNSPECIFIEDUNSPECIFIED
Marteau, E.Jet Propulsion Laboratory, Pasadena, CA, USAUNSPECIFIEDUNSPECIFIED
Golombek, M.Jet Propulsion Laboratory, Pasadena, CA, USAUNSPECIFIEDUNSPECIFIED
Grott, MatthiasUNSPECIFIEDhttps://orcid.org/0000-0002-8613-7096UNSPECIFIED
Wippermann, TorbenUNSPECIFIEDhttps://orcid.org/0000-0002-0354-6557UNSPECIFIED
Ali, K.Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USAUNSPECIFIEDUNSPECIFIED
Schmelzbach, C.ETH Swiss Federal Institute of Technology, Zurich, SwitzerlandUNSPECIFIEDUNSPECIFIED
Kedar, S.jet propulsion laboratory, pasadena, ca, usaUNSPECIFIEDUNSPECIFIED
Hurst, K.JPL, California Institute of Technology, Pasadena, CA, USAUNSPECIFIEDUNSPECIFIED
Trebi-Ollennu, A.Jet Propulsion Laboratory, Pasadena, CA, USAUNSPECIFIEDUNSPECIFIED
Ansan, V.Laboratoire Planétologie et Géodynamique de Nantes, LPGN/CNRS, Université NantesUNSPECIFIEDUNSPECIFIED
Garvin, J.NASA Goddard Space Flight Center, Greenbelt, MD, United StatesUNSPECIFIEDUNSPECIFIED
Müller, NilsUNSPECIFIEDhttps://orcid.org/0000-0001-9229-8921UNSPECIFIED
Piqueux, S.Jet Propulsion Laboratory, California Institute of Technology (Pasadena, CA, 91109)UNSPECIFIEDUNSPECIFIED
Lichtenheldt, RoyUNSPECIFIEDhttps://orcid.org/0000-0002-2539-4910UNSPECIFIED
Sollberger, D.ETH Swiss Federal Institute of Technology, Zurich, SwitzerlandUNSPECIFIEDUNSPECIFIED
Delage, P.Ecole des Ponts ParisTech, Navier-CERMES, Paris, FranceUNSPECIFIEDUNSPECIFIED
Vrettos, C.Division of Soil Mechanics and Foundation Engineering, Technical University of Kaiserslautern, Kaiserslautern, GermanyUNSPECIFIEDUNSPECIFIED
Robertsson, J.ETH Swiss Federal Institute of Technology, Zurich, SwitzerlandUNSPECIFIEDUNSPECIFIED
Edme, P.Institute of Geophyisics, ETH ZürichUNSPECIFIEDUNSPECIFIED
Andersson, F.Institute of Geophyisics, ETH ZürichUNSPECIFIEDUNSPECIFIED
Lognonne, A.P.Institut de Physique du Globe de ParisUNSPECIFIEDUNSPECIFIED
Giardini, D.Institute of Geophysics/Swiss Seismological Service, Swiss Federal Institute of Technology, (ETHZ), Honggerberg, CH-3093 Zurich, SwitzerlandUNSPECIFIEDUNSPECIFIED
Smrekar, S.Jet Propulsion Laboratory, California Institute of Technology, PasadenaUNSPECIFIEDUNSPECIFIED
Banerdt, B.Jet Propulsion Laboratory, Pasadena, CA, USAUNSPECIFIEDUNSPECIFIED
Date:December 2022
Journal or Publication Title:Space Science Reviews
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
Keywords:InSight Mars Heat Flow Geophysics Soil Mechanics
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Space Exploration
DLR - Research theme (Project):R - Project InSight - HP3
Location: Berlin-Adlershof , Bremen , Köln-Porz , Oberpfaffenhofen
Institutes and Institutions:Institute of Planetary Research > Planetary Sensor Systems
Institute of Planetary Research > Planetary Physics
Space Operations and Astronaut Training > User center for space experiments (MUSC)
Institute of Space Systems > Land and Exploration Technology
Institute of System Dynamics and Control > Space System Dynamics
Deposited By: Grott, Dr.rer.nat. Matthias
Deposited On:12 Dec 2022 09:05
Last Modified:28 Jun 2023 13:01

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