Physics – Optics
Scientific paper
Dec 2010
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010agufm.p51c1467c&link_type=abstract
American Geophysical Union, Fall Meeting 2010, abstract #P51C-1467
Physics
Optics
[0649] Electromagnetics / Optics, [1221] Geodesy And Gravity / Lunar And Planetary Geodesy And Gravity, [2194] Interplanetary Physics / Instruments And Techniques, [5450] Planetary Sciences: Solid Surface Planets / Orbital And Rotational Dynamics
Scientific paper
The Lunar Laser Ranging Program using the Apollo Cube Corner Retroreflector (CCR) Arrays [1] has operated as the only active experiment on the lunar surface for the past 4 decades. During this time it has provided control points for the lunar coordinate system, contributed to the determination of the physical properties of the moon and provided some of the best tests of General Relativity [2]. In terms of the physical properties of the moon, Lunar Laser Ranging (LLR) has detected, evaluated the shape and the frictional behavior of the boundaries of the liquid core. This and other areas will be addressed. The LLR Program has evaluated the PPN parameters, addressed the possible changes in the gravitational constant and the properties of the self-energy of the gravitational field. Initially the Apollo CCRs contributed a negligible fraction of the ranging error. Over the decades, the ground stations have improved by more than a factor of 200. Now, the existing Apollo retroreflector arrays contribute a significant fraction of the limiting errors in the range measurements due to the lunar librations tilting of the array of CCRs and thus contribution to the spreading of the return laser pulse. The University of Maryland, as the Principal Investigator for the original Apollo arrays, is now proposing a new approach to the Lunar Laser Array technology [3]. The investigation of this new technology, by two teams with Professor Currie as PI, is currently being supported by two NASA programs, the LSSO and LUNAR. The LUNAR program at the University of Colorado the is funded through the NLSI. Both LSSO and the LUNAR programs are in collaboration with the INFN-LNF in Frascati, Italy. After the proposed installation during the next lunar landing, the new arrays will support ranging observations that are a factor 100 more accurate than the current Apollo Cube Corner Retroreflector (CCR) Arrays. The new fundamental selenodetic, cosmological physics and the lunar physics [3] that this new LLRRA-21 can provide will be described. In the initial design of the new array, there are three major challenges: 1) Validate the ability to fabricate the required CCR; 2) Address the thermal and optical effects of the absorption of solar radiation within the CCR; 3) Validate an emplacement technique for the CCR package on the lunar surface to remain stable over the lunar day/night cycle and the long term. References: [1] C. O. Alley 1, R. F. Chang 1, D. G. Currie 1, Apollo 11 Laser Ranging Retro-Reflector: Initial Measurements from the McDonald Observatory Science 23 January 1970: Vol. 167. no. 3917, pp. 368 - 370 [2] P. L. Bender, D. G. Currie, S. K. Poultney The Lunar Laser Ranging Experiment Science 19 October 1973: Vol. 182. no. 4109, pp. 229 - 238 [3] D. G. Currie; S. Dell-Agnello; G. Delle Monache. A LUNAR LASER REFLECTOR FOR THE 21ST CENTURY Acta Astronatica to be published
Currie Douglas G.
Dell'Agnello Simone
Delle Monache Giovanni
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