Rationale for a Geophysics & Geodesy Payload for Lunar Networks

Transcription

1 N. Schmitz, J. Biele, M. Grott, M. Knapmeyer, J. Oberst, F. Sohl, T. Spohn, S.Ulamec Rationale for a Geophysics & Geodesy Payload for Lunar Networks DLR, Institute of Planetary Research, Berlin, Germany Folie 1 ICEUM9/ILC2007> Nicole Schmitz >

2 Lunar Research Strategy for the Near Term Moon is (again) prime focus of space exploration Selene already operating, Chang e, Chandrayaan, LRO planned for 2007/2008 looking beyond, science goals need to be articulated for early decisions about system design and operations planning NRC report recommends to emplace a geophysical network Folie 2

3 Do we need a Next-Generation ALSEP? Committee on the Scientific Context for Exploration of the Moon Space Studies Board, The Scientific Context for Exploration of the Moon: Final Report, The National Academies Press, Washington D.C., USA, Folie 3

4 Seismology continued seismic monitoring needed, since: deep moonquakes have fixed positions and show periodic activity = > new moonquake data can be inverted together with the old Apollo ALSEP data no broadband seismic observations or long period observations done by Apollo science return depends on number and distribution of simultaneously operating seismic stations 1 station would be able to monitor seismic activity within (known) moonquake nests, resolve tidally-induced deformations and free Moon oscillations locating quakes outside the nests or more precisely locating them inside the nests requires several stations a new seismic network should ideally consist of at least four three-component broadband seismometers covering an aperture much larger than the ALSEP triangle Folie 4

5 Heat Flow Measurements Astronaut Dave Scott inserts the Apollo 15 Heat Flow Experiment probe into the regolith (credit: LPI/USRA). only 2 measurements of lunar heat flux in areas of the Moon with high concentration of heat-producing elements performed so far (likely not representative) new heat flux measurements needed on near-side (including highland and mare) away from the Procellarum KREEP terrain far-side measurements desirable to account for the near side-far side crustal dichotomy single location heat flow measurements provide a value for the internal temperature gradient at that location detecting regional variations of the heat flux within each of the major geological provinces of the Moon requires multiple stations Folie 5

6 Geodesy Locations of Retroreflectors possible new locations at lunar limbs Folie 6

7 Geodesy Apollo and Lunokhod laser reflectors are still used! current limitations: no reflectors at high latitudes -> little resolution for lunar librations in latitude limited range accuracy -> little data on lunar tidal deformation little data on lunar tides and core signals -> more Earth-Moon ranging data needed a combined laser ranging and radio VLBI package would allow measurement precision to approach millimeter-level three packages widely distributed near the limbs would be optimal for high precision ranging and complement the geophysics instrument suite Folie 7

8 Environmental Sensors past magnetometer experiments included surface measurements (Apollo 12,14,15,16) and orbital measurements (Luna 1,2,10, Explorer 35, Apollo 15/16 sub-satellites, Lunar Prospector) open questions: origin of remanent lunar crust magnetization, lunar dynamo, characteristics (size, composition) of lunar core, magnetospheric and solar wind science combined orbital/surface magnetic field observations can be used to detect the core magnetic induced signal multipoint measurements required! Folie 8

9 Conclusions a network configuration of key instruments is highly desirable budgetary constraints and technical complexity may severely limit the realization of network missions but: the scientific need for multiple stations does not necessarily require all instruments to be deployed on a single mission long-lived autonomous packages, placed as payload on several missions planned for the next decade, would allow to create a new lunar network essential: coordination of international mission plans that include lunar landers Folie 9

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