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Spohn T, Hudson TL, Marteau E, Golombek M, Grott M, Wippermann T, Ali KS, Schmelzbach C, Kedar S, Hurst K, Trebi-Ollennu A, Ansan V, Garvin J, Knollenberg J, Müller N, Piqueux S, Lichtenheldt R, Krause C, Fantinati C, Brinkman N, Sollberger D, Delage P, Vrettos C, Reershemius S, Wisniewski L, Grygorczuk J, Robertsson J, Edme P, Andersson F, Krömer O, Lognonné P, Giardini D, Smrekar SE, Banerdt WB. The InSight HP 3 Penetrator (Mole) on Mars: Soil Properties Derived from the Penetration Attempts and Related Activities. Space Sci Rev 2022; 218:72. [PMID: 36514324 PMCID: PMC9734249 DOI: 10.1007/s11214-022-00941-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 11/26/2022] [Indexed: 06/17/2023]
Abstract
UNLABELLED 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. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s11214-022-00941-z.
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Affiliation(s)
- T. Spohn
- International Space Science Institute, Hallerstrasse 6, 3012 Bern, Switzerland
- DLR Institute of Planetary Research, Rutherfordstr. 2, 12489 Berlin, Germany
| | - T. L. Hudson
- Jet Propulsion Laboratory, California Institute of Technology, Oak Grove Drive, Pasadena, CA 91109 USA
| | - E. Marteau
- Jet Propulsion Laboratory, California Institute of Technology, Oak Grove Drive, Pasadena, CA 91109 USA
| | - M. Golombek
- Jet Propulsion Laboratory, California Institute of Technology, Oak Grove Drive, Pasadena, CA 91109 USA
| | - M. Grott
- DLR Institute of Planetary Research, Rutherfordstr. 2, 12489 Berlin, Germany
| | - T. Wippermann
- DLR Institute of Space Systems, Robert-Hooke-Str. 7, 28359 Bremen, Germany
| | - K. S. Ali
- Jet Propulsion Laboratory, California Institute of Technology, Oak Grove Drive, Pasadena, CA 91109 USA
| | - C. Schmelzbach
- Department of Earth Sciences, ETH Zürich, Institute of Geophysics, CH-8092 Zürich, Switzerland
| | - S. Kedar
- Jet Propulsion Laboratory, California Institute of Technology, Oak Grove Drive, Pasadena, CA 91109 USA
| | - K. Hurst
- Jet Propulsion Laboratory, California Institute of Technology, Oak Grove Drive, Pasadena, CA 91109 USA
| | - A. Trebi-Ollennu
- Jet Propulsion Laboratory, California Institute of Technology, Oak Grove Drive, Pasadena, CA 91109 USA
| | - V. Ansan
- Laboratoire de Planétologie et Géodynamique de Nantes, Université de Nantes, 44322 Nantes, France
| | - J. Garvin
- NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 USA
| | - J. Knollenberg
- DLR Institute of Planetary Research, Rutherfordstr. 2, 12489 Berlin, Germany
| | - N. Müller
- DLR Institute of Planetary Research, Rutherfordstr. 2, 12489 Berlin, Germany
| | - S. Piqueux
- Jet Propulsion Laboratory, California Institute of Technology, Oak Grove Drive, Pasadena, CA 91109 USA
| | - R. Lichtenheldt
- DLR Institute of System Dynamics and Control, Münchener Strasse 20, 82234 Wessling, Germany
| | - C. Krause
- DLR MUSC Space Operations and Astronaut Training, Linder Höhe, 51147 Köln, Germany
| | - C. Fantinati
- DLR MUSC Space Operations and Astronaut Training, Linder Höhe, 51147 Köln, Germany
| | - N. Brinkman
- Department of Earth Sciences, ETH Zürich, Institute of Geophysics, CH-8092 Zürich, Switzerland
| | - D. Sollberger
- Department of Earth Sciences, ETH Zürich, Institute of Geophysics, CH-8092 Zürich, Switzerland
| | - P. Delage
- École nationale des ponts et chaussées, Laboratoire Navier, Paris, France
| | - C. Vrettos
- Department of Civil Engineering, University of Kaiserslautern, Kaiserslautern, Germany
| | - S. Reershemius
- DLR Institute of Space Systems, Robert-Hooke-Str. 7, 28359 Bremen, Germany
| | - L. Wisniewski
- Astronika Sp. z o.o., ul. Bartycka 18, 00-716 Warszawa, Poland
| | - J. Grygorczuk
- Astronika Sp. z o.o., ul. Bartycka 18, 00-716 Warszawa, Poland
| | - J. Robertsson
- Department of Earth Sciences, ETH Zürich, Institute of Geophysics, CH-8092 Zürich, Switzerland
| | - P. Edme
- Department of Earth Sciences, ETH Zürich, Institute of Geophysics, CH-8092 Zürich, Switzerland
| | - F. Andersson
- Department of Earth Sciences, ETH Zürich, Institute of Geophysics, CH-8092 Zürich, Switzerland
| | | | - P. Lognonné
- Institut du Physique du Globe Paris, CNRS, Université Paris Cité, Paris, France
| | - D. Giardini
- Department of Earth Sciences, ETH Zürich, Institute of Geophysics, CH-8092 Zürich, Switzerland
| | - S. E. Smrekar
- Jet Propulsion Laboratory, California Institute of Technology, Oak Grove Drive, Pasadena, CA 91109 USA
| | - W. B. Banerdt
- Jet Propulsion Laboratory, California Institute of Technology, Oak Grove Drive, Pasadena, CA 91109 USA
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