HP3: An integrated sensor package to explore the regolith layers of planets and moons

Citation

Hagermann A (2006) HP3: An integrated sensor package to explore the regolith layers of planets and moons. In: AIAA 57th International Astronautical Congress, IAC 2006. 2. 57th International Astronautical Congress (IAC 2006), 02.10.2006-06.10.2006. Valenica, Spain: International Astronautical Federation, pp. 1350-1355. https://www.scopus.com/inward/record.uri?eid=2-s2.0-40549144581&partnerID=40&md5=650a37e5dfe6f21e0842bf45943052e6

Abstract
Most of the planets and rocky moons in the solar system have surfaces covered by a regolith layer, storing in its physical properties a record of the processes that have taken place during and after its deposition. The study of these properties below the immediate surface allows a glimpse in the recent and remote past of these bodies. Unfortunately, access to depths up to a few meters still remains to be accomplished; of the many planetary missions flown and planned, just a very few propose investigations of the subsurface (i.e. Rosetta). In the last decade a new class of tools to explore the regolith in depth has been developed: the Moles (i.e. PLUTO, the sampling system on board Beagle 2). With funding from ESA, our team has built and tested a functioning prototype of a novel instrument concept, where a sensor package is attached to a Mole, deployed inside the regolith to depths of up to 5 meters and operated to take in-situ measurement of the regolith status and processes during and after the penetration. HP3, the Heat flow and Physical Properties Package, and has thermometers and heaters to measure the thermal status and the thermal properties of the soil; accelerometers to derive the mechanical characteristics and the precise position of the tool, and a -ray Compton backscattering densitometer to measure the density. By combining the data, HP3 can derive the planetary heat flow, providing data on the internal structure and thermal evolution of the target body (Mercury for this study). In the chosen configuration, HP3 is housed in a trailed compartment, connected to the deployment Mole and, by a flat Copper-Kapton tether, to the surface element.