Heat Flow and Physical Properties Package

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Heat Flow and Physical Properties Package (HP3)
HP3 on the deck of InSight on Sol 10 on Mars (Dec '18)
ManufacturerGerman Aerospace Center (DLR)
Instrument typeinfrared radiometer
FunctionGeophysics of Mars
Mission duration2 years on Mars
Began operationsLanding: 26 November 2018
Mass3 kg (6.6 lb)
Power consumption2 watts
Host spacecraft
SpacecraftInSight Mars lander
Launch date5 May 2018, 11:05 (2018-05-05UTC11:05) UTC
RocketAtlas V 401[1]
Launch siteVandenberg SLC-3E[1]
COSPAR ID2018-042A

The Heat Flow and Physical Properties Package (HP3) is a science instrument onboard the InSight lander that features a self-penetrating probe to determine how heat flows inside Mars. InSight landed on Mars on 26 November, 2018.

Referred to as a "self-hammering nail"[2] and nicknamed "the mole", it was designed to burrow as deep as 5 m (16 ft) below the Martian surface while trailing a tether with embedded heat sensors to measure how efficiently heat flows through Mars' core, and thus reveal unique information about the planet's interior and how it has evolved over time.

The Principal Investigator is Tilman Spohn from the German Aerospace Center (DLR).


The mission aims to understand the origin and diversity of terrestrial planets.[3] Information from the HP3 heat flow package is expected to reveal whether Mars and Earth formed from the same material, and determine how active the interior of Mars is today.[3][4][5][6][7] Together with the seismometer, the mission will estimate the size of Mars' core and whether the core is liquid or solid.[8]

In addition to the mole, there is also an infrared radiometer (HP3-RAD) mounted to the main saucer, also contributed by DLR.[9][10][11]


HP3 was conceived by Gromov V. V. et al. in 1997,[2][12] and first flown as the PLUTO instrument on the failed 2003 Beagle 2 Mars lander mission.[2] HP3 evolved further and it was proposed in 2001 for a mission to Mercury,[13] in 2009 to the European Space Agency as part of the Humboldt payload onboard the ExoMars lander,[14][13] in 2010 for a mission to the Moon,[15] and in 2011 it was proposed to NASA's Discovery Program as a payload for InSight Mars lander, known back then as GEMS (Geophysical Monitoring Station).[6] InSight was launched on 5 May 2018 and landed on 26 November 2018.

The version flown to Mars is nicknamed "the mole", and was designed to burrow as deep as 5 m (16 ft) below the Martian surface to measure how efficiently heat flows through Mars' core, and thus reveal unique information about the planet's interior and how it has evolved over time.[3][5][6][7] HP3 was provided by the German Aerospace Center (DLR), and the tractor mole portion of the instrument was perfected by the Polish company Astronika and the Space Research Centre of the Polish Academy of Sciences under contract and in close cooperation with DLR.[2][16]

The Principal Investigator is Tilman Spohn from the German Aerospace Center.[3][4]


For displacement, the mole uses a motor/gearbox (provided by maxon motor ag) and a roller that periodically loads a spring connected to a rod that functions as a hammer; after release from the cam, the hammer accelerates downwards eventually hitting the outer casing and causing its penetration through the regolith, whereas a suppressor mass travels upwards and its kinetic energy is compensated by gravitational potential and compression of a brake spring and wire helix on the opposite side of the mole.[2] The burrowing mole is a pointed cylinder with a smooth outer surface approximately 35 cm (13.8 in) in length and 3.5 cm (1.38 in) in diameter. It contains a heater to determine thermal conductivity during descent, and it trails a tether equipped with precise heat sensors placed at 10 cm (3.9 in) intervals to measure the temperature profile of the subsurface.[3][17] In principle, every 50 cm (1.5 ft) the probe puts out a pulse of heat and its sensors measure how the heat pulse changes with time. If the crust material is a thermal conductor, like metal, the pulse will decay quickly.[4] Together, these measurements yield the rate of heat flowing from the interior.

The total mass of the system is approximately 3 kg (6.6 lb) and it consumes a maximum of 2 watts while the mole is active.[4]

HP3-RAD Infrared Radiometer[edit]

The HP3 instrument is supported by an infrared radiometer measuring surface temperatures, contributed by DLR and based on the MARA radiometer for the Hayabusa2 mission.[9][10][11] HP3-RAD uses thermopile detectors to measure three spectral bands: 8-14 μm, 16-19 μm and 7.8-9.6 μm.[18] HP3-RAD has a mass of 120 grams.[18]

Background about infrared radiometers includes some important Mars science history.[19] They were sent to Mars in 1969 as one of four major instruments on the Mariner 6 and Mariner 7 flyby spacecraft, and the observations helped to trigger a scientific revolution in Mars knowledge.[20][21] The Mariner 6 & 7 infrared radiometer results showed that the atmosphere of Mars is composed mostly of carbon dioxide (CO2), and they were also able to detect trace amounts water on the surface of Mars.[22]

See also[edit]


  1. ^ a b Clark, Stephen (19 December 2013). "Mars lander to launch from California on Atlas 5 in 2016". Spaceflight Now. Retrieved 20 December 2013.
  2. ^ a b c d e Hammering Mechanism for HP3 Experiment (InSight). (PDF) Jerzy Grygorczuk1, Łukasz Wiśniewski1, Bartosz Kędziora1, Maciej Borys, Rafał Przybyła1, Tomasz Kuciński1, Maciej Ossowski, Wojciech Konior,Olaf Krömer, Tilman Spohn, Marta Tokarz and Mateusz Białek. European Space Mechanisms and Tribology Symposium; 2016.
  3. ^ a b c d e Banerdt, W. Bruce (2012). InSight – Geophysical Mission to Mars (PDF). 26th Mars Exploration Program Analysis Group Meeting. 4 October 2012. Monrovia, California.
  4. ^ a b c d HP3 Overview. NASA. Accessed: 15 July 2018.
  5. ^ a b Agle, D. C. (20 August 2012). "New Insight on Mars Expected From new NASA Mission". NASA.
  6. ^ a b c Grott, M.; Spohn, T.; Banerdt, W. B.; Smrekar, S.; Hudson, T. L.; et al. (October 2011). Measuring Heat Flow on Mars: The Heat Flow and Physical Properties Package on GEMS (PDF). EPSC-DPS Joint Meeting 2011. 2–7 October 2011. Nantes, France. Bibcode:2011epsc.conf..379G. EPSC-DPS2011-379-1.
  7. ^ a b Kelly, Tiffany (22 May 2013). "JPL begins work on two new missions to Mars". Glendale News-Press. Retrieved 24 August 2015.
  8. ^ Kremer, Ken (2 March 2012). "NASAs Proposed 'InSight' Lander would Peer to the Center of Mars in 2016". Universe Today. Retrieved 27 March 2012.
  9. ^ a b Banerdt, W. Bruce (7 March 2013). InSight: A Geophysical Mission to a Terrestrial Planet Interior (PDF). Committee on Astrobiology and Planetary Science. 6–8 March 2013. Washington, D.C.
  10. ^ a b "InSight: In Depth". Solar System Exploration. NASA. Retrieved 2 February 2018.
  11. ^ a b Grott, M.; et al. (July 2017). "The MASCOT Radiometer MARA for the Hayabusa 2 Mission". Space Science Reviews. 208 (1–4): 413–431. Bibcode:2017SSRv..208..413G. doi:10.1007/s11214-016-0272-1.
  12. ^ Gromov V.V. et al.: The mobile penetrometer, a "mole" for sub-surface soil investigation. In Proc. of 7th European Space Mechanisms and Tribology Symposium. 1997.
  13. ^ a b A heat flow and physical properties package for the surface of Mercury. Tilman Spohn, Karsten Seiferlin. Planetary and Space Science 49(14-15):1571-1577 December 2001. doi:10.1016/S0032-0633(01)00094-0
  14. ^ HP3 on ExoMars. Krause, C.; Izzo, M.; Re, E.; Mehls, C.; Richter, L.; Coste, P. EGU General Assembly 2009, held 19-24 April 2009 in Vienna, Austria.
  15. ^ Measuring heat flow on the Moon — The Heat Flow and Physical Properties Package HP3. (PDF) T. Spohn, M. Grott L. Richter, J. Knollenberg, S.E. Smrekar, and the HP3 instrument team. Ground-based Geophysics on the Moon (2010). Lunar and Planetary Institute, conference 2010.
  16. ^ "Polish Kret will fly to Mars". Science in Poland. Retrieved 2018-05-05.
  17. ^ "HP3 (Heat Flow and Physical Properties Probe)". NASA. Retrieved 24 August 2015.
  18. ^ a b Kopp, et all - HP3-RAD: A compact radiometer design with on-site calibration for in-situ exploration
  19. ^ [1]
  20. ^ [2]
  21. ^ Chdse, S. C. (1969-03-01). "Infrared radiometer for the 1969 mariner mission to Mars". Applied Optics. 8 (3): 639. doi:10.1364/AO.8.000639. ISSN 1559-128X. PMID 20072273.
  22. ^ [3]

External links[edit]