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L unar U niversity N etwork for A strophysics R esearch Jack Burns, Director

A LUNAR LASER RANGING RETRO-REFLECTOR ARRAY for the 21 st CENTURY Professor Douglas Currie University of Maryland, College Park, MD, USA NASA Lunar Science Institute, Moffett Field, CA INFN – LNF, Laboratori Nazionali di Frascati, Italy

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L unar U niversity N etwork for A strophysics R esearch Jack Burns, Director

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  1. A LUNAR LASER RANGING RETRO-REFLECTOR ARRAYfor the 21st CENTURY Professor Douglas Currie University of Maryland, College Park, MD, USA NASA Lunar Science Institute, Moffett Field, CA INFN – LNF, Laboratori Nazionali di Frascati, Italy & The LLRRA-21 Teams with the Lunar University Network for Astrophysics Research Jack Burns, Director

  2. OUTLINE • Outline of Talk • Brief History of Lunar Laser Ranging • Original Science Objectives of Our LLR Project • Concept > Apollo 11, 14, 15 • Improvement • Kilometers -> 30 cm • Not one by Time Series of Measurements • Limiting Accuracy • Continuing Science Due to 40 year Baseline • Lunar Physics from Apollo Arrays • Lunar Core • Discovery • Size and Shape • Confirmed • Other • Relativity Physics from Apollo Arrays • Inertial Properties of Gravitational Energy • Temporal Change of G • Spatial Change of G • General Review • Apollo Array Problem Due to Librations • Ground Station Improvement • Factor of 100 • Illustration • Decadal Remarks w.r.t. Lunar Laser Ranging • Planetary - Astronomy Panel • Discovery Mission • Astronomical - LLRRA-21 Proposal • New Interest in the Moon • LLRRA-21 Concept • Why is a Single CCR a Solution • Design of LLRRA-21 • Challenges • Signal Performance • Emplacement Issues • Advantages • Higher Accuracy • More Stations • Accuracies for Various Deployment Methods • Lander • Surface • Anchored • Expected Science Results • Lunar Physics • Relativity Science • Possible Flight Opportunities • Google Lunar X Prize • Lunette ILN • LGN – Lunar Geophysical Network • Discovery Mission • Thank You & Acknowledgements • NASA • LSSO • Lunar Science Institute > LUNAR Team at UC • INFN-LNF

  3. To be done • Simulation Results • More pictures • Find Charts of Accuracy • Lunar with periods • Relativity • Statement about Heritage • Science • Technology American Geophysical Union 5 December 2011

  4. OUTLINE • Brief History of Lunar Laser Ranging • Lunar Physics from the Apollo Arrays • Relativity Physics from the Apollo Arrays • Apollo Array Problem Due to Librations • Decadal Remarks w.r.t. Lunar Laser Ranging • LLRRA-21 Proposal • Accuracies for Various Robotic Deployment Methods • Expected Science Results • Possible Flight Opportunities • Acknowledgements American Geophysical Union 5 December 2011

  5. Brief History of Lunar Laser Ranging • Operational Procedure • Transmit Narrow Laser Pulse from Earth • Pulse is Reflected from a Fixed Point on the Moon • Measure the Light Travel Time • Analyze Time Series of Measurements for Frequencies • Range Improvement due to Apollo LLR • Kilometers (Radar) would go to ~300 mm • Continue Measurements for Long Time Series • Originally 3 Measurements per Day American Geophysical Union 5 December 2011

  6. Lunar Physics from the Apollo Arrays • Discovery of Liquid Core • Ten years Ago • Confirmed This Year by Seismometer • Properties of Liquid Core • Size, • Shape • Moment of Inertia American Geophysical Union 5 December 2011

  7. LLR LUNAR SCIENCEOVERVIEW • Elastic Tides of the Moon • Tidal Dissipation • Size and Oblateness of Liquid Core • Dissipation at Liquid-Core/Solid-Mantle Interface • Lunar Moment of Inertia • Fluid Core Moment of Inertia • Evolution and Heating • Existence of a Smaller Solid Inner Core • Selenodetic Site Positions American Geophysical Union 5 December 2011

  8. Relativity Physics from the Apollo Arrays • Inertial Properties of Gravitational Energy • Does Gravitational Energy Resist Acceleration • Earth and Moon have Different Gravitational Energy • Do They Fall to the Sun at the Same Rate? • Measurement of Temporal Change in G • Addresses Alternative MOND Theories of Gravitation • Measurement of Spatial Change in G • Fundamental Inconsistency of • General Relativity and Quantum Mechanics American Geophysical Union 5 December 2011

  9. What have the Apollo Arrays DoneRelativity Science • The Earth-Moon System Provides an Ideal System • To Evaluate Relativity and Einstein’s Theory • Moon is Massive enough to Resist Drag/Pressure • Moon is Far Enough to be in a Solar Orbit (Weakly Bound) • LLR Currently Provides our Tests of: • The Weak Equivalence Principle (WEP)*:  a / a < 1.310-13 • The Strong Equivalence Principle (SEP):  < 4104 • Time-Rate-of-Change of G to < 710  13 per year • Inverse Square Law to 3 10 11 at 10 8 m scales • Geodetic Precession to 0.6 % • Gravitomagnetism to 0.1 % American Geophysical Union 5 December 2011

  10. Apollo Array Problem Due to Librations • Apollo Arrays Consisted of 100 CCR • Arranged in a10 by 10 flat panel • Accuracy of Ground Stations • Improved by a Factor of 200 w.r.t. 1969 • Lunar Librations • Rotation of Moon w.r.t. Earth-Moon Axis • +/- 8 degrees in Latitude and Longitude • We Cannot Distinguish between Near & Far CCRs • A Very Short Laser Pulse is Spread • Return Pulse is ~20 mm • Therefore Limiting Accuracy American Geophysical Union 5 December 2011

  11. Decadal Remarks w.r.t. Lunar Laser Ranging • 2010 Planetary Decadal Survey • Recommended NGL as Discovery Mission • Including Lunar Laser Retroreflectors • Astro2010 Gravitational and Astrophysics Panel • Specifically Recommended LLRs • “improvements in Lunar Laser Ranging promise to advance this area” • “G (< 10-12/yr) from lunar laser ranging” • “So far, LLR has provided the most accurate tests of the weak equivalence principle, the strong equivalence principle and the constancy in time of Newton’s gravitational constant” • “recommendation below in the context of a recommendation to augment the Explorer program” American Geophysical Union 5 December 2011

  12. LLRRA-21 Proposal • NASA Revives Interest in Moon – 2006 • LSSO Proposal for Improved Lunar Retroreflector • “Lunar Laser Ranging Retroreflector Array for the 21st Century” • Large Single Solid Cube Corner Reflector • Accuracy to be Improved by Factor of 10 to 100 • Great Reduction in Weight w.r.t. Apollo Arrays • No Power or Communication Required • Very Long Operational Lifetime - Centuries • Great Heritage to Assure Risk Reduction • Same Design on the Moon has Provided Excellent Science for 40 years • Thousands of Smaller Solid CCRs Operating in Earth Orbit for over 40 years American Geophysical Union 5 December 2011

  13. Why Consider a Single CCR • No Spreading of Laser Return Pulse • 20 mm Uncertainty due to Librations Goes to ~0 • Larger Return Signal Level – • Similar to Apollo 15 • Available to More Laser Ranging Ground Stations

  14. CHALLENGES for SOLID CCR • Fabrication of the CCR to Required Tolerances • Sufficient Return for Reasonable Operation • Ideal Case for Link Equation • Thermal Distortion of Optical Performance • Absorption of Solar Radiation within the CCR • Mount Conductance - Between Housing and CCR Tab • Pocket Radiation - IR Heat Exchange with Housing • Solar Breakthrough - Due to Failure of TIR • Stability of Lunar Surface Emplacement • Problem of Regolith Heating and Expansion • Drilling to Stable Layer for CCR Support • Thermal Blanket to Isolate Support • Housing Design to Minimize Thermal Expansion LUNAR Workshop 6 October 2010

  15. Thermal Simulation Results 4th Allahabad Science Conclave 28 November 2011

  16. 4th Allahabad Science Conclave 28 November 2011

  17. ROBOTIC DEPLOYMENT • Alterative Deployment Methods • Lander Mounting • Few Millimeters Motion Due to Thermal Cycling • Thermal Expansion of Lander during Lunation • Surface Deployment • Sub-Millimeter Motion Due to Thermal Cycling • Regolith Expansion • Requires an Arm • Anchored Deployment • Tens of Microns American Geophysical Union 5 December 2011

  18. Regolith Drilling in Apollo

  19. KrizZacny at HoneyBee American Geophysical Union 5 December 2011

  20. CURRENT STATUS • Preliminary Definition of Overall Package • Completed Preliminary Simulations • LSSO – Lunar Science Surface Opportunities • Thermal (CCR, Regolith, Housing), Optical • Completed Phase I Thermal Vacuum Tests • Solar Absorption Effects on CCR • CCR Time Constants – • IR Camera – Front Face • Thermocouples – Volume • Preliminary Optical FFDP

  21. LLRRA-21 PACKAGE American Geophysical Union 5 December 2011

  22. LUNAR Science • Fluid Core Moment of Inertia • LLR Detection of Liquid Inner Core has very Recently been Confirmed by Seismometry • Whole Moon Moment of Inertia • Core Oblateness: • LLR detects fluid-core/solid-mantle boundary (CMB) • Inner Core: • A solid inner core apparently exists and can be confirmed by LLRRA-21 • Elastic Tides: • Solid-body tidal displacements depend on the Moon’s elastic properties. • Typical monthly variations are ±9 cm. • Lunar Tidal Dissipation: • The tidal specific dissipation Q depends on the radial distribution of the material Qs. • Core/Mantle Boundary Dissipation: • LLR first demonstrated that the Moon has a fluid core by Free Physical Librations • Selenodetic Site Positions: • The Moon-centered locations of four retroreflectors are known with submeter accuracy • Tidal Acceleration and Orbit Evolution: • LLR is very sensitive to the tidal acceleration of the lunar orbit.

  23. Detailed Lunar Science Results 1 • Fluid Core Moment of Inertia: • LLR is sensitive to the fluid core moment of inertia, which depends on core density and radius. This is a new LLR lunar science result for the core. The solution for the ratio of fluid moment to total moment gives Cf/C = (12±4)x10–4, where the subscript f indicates the fluid core (Williams et al., 2009). For a uniform liquid iron core without an inner core this value would correspond to a radius of 390±30 km. Lower fluid densities or presence of A Planetary Science Decadal Survey White Paper: “Lunar Science and Lunar Laser Ranging” Page 2 of 7 • Retroreflector arrays on the Moon. • an inner core would give larger outer radii for the fluid. Weakly determined at present, an accurate determination of core moment depends on a long time span of high accuracy range data. There is very little information on the core and it is very important to improve this determination. • Whole Moon Moment of Inertia: • The whole Moon moments of inertia A<B<C come from combining LLR results for relative moment differences (C-A)/B and (BA)/C with orbiting spacecraft determined J2 and C22. The most recent published total value (Konopliv et al., 1998) predates the more recent LLR fluid core moment determination, and is limited by the uncertainty of the earlier adopted fluid core moment. As the fluid core momentimproves, so will the whole Moon moment. The lunar moment of inertia constrains model profiles of density vs. radius. American Geophysical Union 5 December 2011

  24. Detailed Lunar Science Results 2 • Core Oblateness: • LLR detects fluid-core/solid-mantle boundary (CMB) flattening. Currently the product of CMB oblatenessand fluid core moment of inertia is determined more strongly than either factor separately. That product is f Cf/C = (Cf–Af)/C =(3±1)x10-7 (Williams et al., 2009). The detection of CMB flattening is one of the demonstrations that there is a fluid core. • Inner Core: • A solid inner core might exist inside the fluid core, but it has not yet been detected by any technique. Gravitational interaction between an inner core and the mantle would affect the mantle’s three-axis orientation. A future detection would be possible if the effect on mantle rotation is large enough. A detection of the inner core would reveal the frequency of one or more of the three possible resonances plus associated strength parameters. These quantities depend on multiple unknown parameters that describe the inner core gravity and moment of inertia and its gravitational interaction with the mantle. • Elastic Tides: • Solid-body tidal displacements depend on the Moon’s elastic properties. Typical monthly variations are ±9 cm. The solution parameters are the second-degree Love numbers h2 and l2 that scale the global tidal displacements. The existing distribution of LLR sites is weak for determining displacement Love numbers. Future sites with a wider geographic distribution would strongly improve the determination. The physical librations are also sensitive to the Love number k2 that describes the second-degree tidal variations in potential and moments of inertia. LLR is potentially very sensitive to the Love number k2, but k2 correlates with core oblateness, which weakens the determination.

  25. Detailed Lunar Science Results 3 • Lunar Tidal Dissipation: • The tidal specific dissipation Q depends on the radial distribution of the material Qs. LLR detects tidal dissipation and infers a weak dependence of tidal Q on frequency. The tidal Qs determined from the orientation are surprisingly low, ~30 at a one month period and ~35 at one year. LLR does not distinguish the location of the low-Q material, but at seismic frequencies low-Q material, suspected of being a partial melt, was found for the deep zone above the core. Future LLR sites and very accurate ranges could help increase the frequency span. They could also detect the few mm dissipation effects in the tidal displacements. • Core/Mantle Boundary Dissipation: • LLR first demonstrated that the Moon has a fluid core by detecting the energy dissipated by the flow of the fluid along the boundary (Williams et al., A Planetary Science Decadal Survey White Paper: “Lunar Science and Lunar Laser Ranging” Page 3 of 7 2001). The CMB dissipation remains strong in LLR solutions (Williams et al., 2009) and is determined in addition to, but correlated with, the tidal dissipation. The CMB dissipation depends on fluid core size, fluid viscosity and CMB roughness. American Geophysical Union 5 December 2011

  26. Detailed Lunar Science Results 4 • Free Physical Librations: • Normal modes of the rotation may be stimulated by internal or external mechanisms, but they are subject to damping which is short compared to the age of the Moon. Two of the free libration amplitudes are observed by LLR to be large (>10 m) which implies active or geologically recent stimulation (Newhall and Williams, 1997; Chapront et al., 1999; Rambaux and Williams, 2009). The 2.9 yr longitude mode with an 11 m amplitude is stimulated, at least in part, by resonance passage (Eckhardt, 1993). The wobble mode, analogous to the Earth’s Chandler wobble, is a large elliptical (28x69 m) 74.6 yr motion of the pole direction. If wobble is stimulated by eddies at the CMB as suggested by Yoder (1981), then ongoing activity might be revealed by future LLR measurements as irregularities in the path of polar wobble. The third mantle mode, a free precession in space, and the liquid core free core nutations are small (<1 m). The former may be detected, but it appears to be sensitive to the interior model. • Site Positions: • The Moon-centered locations of four retroreflectors are known with submeter accuracy (Williams et al., 1996, 2008). Positions for existing and new LLR sites can be used as control points for lunar cartographic networks, as was done by Davies et al. (1987, 1994, 2000). The four site radii are a valuable check on altimetry from orbit (Fok et al., 2009). American Geophysical Union 5 December 2011

  27. Detailed Lunar Science Results 5 • Tidal Acceleration and Orbit Evolution: • LLR is very sensitive to tidal acceleration of the lunar orbit. Tides on Earth dominate the energy and angular momentum transfer to the orbit and the Moon’s evolution outward. Tidal effects on the Moon are separable from Earth tide effects in the LLR solutions (Chapront et al., 2002; Williams et al., 2009). The total tidal acceleration in orbital mean longitude from Earth and Moon tides is –25.85 arcsec/century2, which corresponds to a 3.81 cm/yr recession of the Moon (Williams et al., 2009). Eccentricity rate is also detected. Evolving the lunar orbit backward in time is an important and surprisingly difficult goal. LLR provides numerical values for two sources of dissipation on Earth and two for the Moon. American Geophysical Union 5 December 2011

  28. Projected Relativity Results • Science TimescaleCurrent (cm) 1 mm 0.1 mm • Weak Equivalence Principle Few years |Δa/a|< 1.3×10−13 10‐14 10‐15 • Strong Equivalence Principle Few years |η| < 4.4×10−4 3×10‐5 3×10‐6 • Time variation of G ~10 years yr‐1 9×10−13 5×10‐14 5×10‐15 • Inverse Square Law ~10 years |α|< 3×10‐11 10‐12 10‐13 • PPN β Few years |β−1|< 1.1×10‐4 10‐5 10‐6 American Geophysical Union 5 December 2011

  29. MISSION OPPORTUNITES • Mission Possibilities for LLRRA-21 • Google Lunar X Prize – Most Exciting • Flight in Next Two Years • Astrobotics • Moon Express • Next Giant Leap • 2013 - 2014 • Post-Lunette Discovery Program • Explicitly Recommended in Planetary 2010 Decadal Report • International Lunar Network • Recommend by Planetary 2010 Decadal Report • Being Invistigated by NASA for a Launch in 2018 • Italian Space Agency & INFN-LNF • MAGIA – ASI & INFN • Proposed ASI Lunar Orbiter to Carry a 100 mm Solid CCR • Italian Investigation of the LLRA-21 Retroreflector Instrument • MoonLIGHT-ILN INFN Experiment American Geophysical Union 5 December 2011

  30. Thank You!anyQuestions? orComments?. with Special AcknowledgementstoNASA Lunar Science Sorties Opportunities NASA Lunar Science InstituteItalian Space AgencyLUNAR TeamINFN-LNF, Frascati .currie@umd.edu American Geophysical Union 5 December 2011

  31. Backup Viewgraphs American Geophysical Union 5 December 2011

  32. LLRRA-21 Teams • LSSO Team – NASA • Douglas Currie Principal Investigator • University of Maryland, College Park, College Park m MD, USA • NLSI, Moffett Field, CA, USA & • INFN-LNF Frascati, Italy • Bradford Behr • University of Maryland, College Park, MD, USA • Tom Murphy • University of California at San Diego, San Diego, CA , USA • Simone Dell’Agnello • INFN/LNF Frascati, Italy • Giovanni Delle Monache • INFN/LNF Frascati, Italy • W. David Carrier • Lunar Geotechnical Institute, Lakeland, FL, USA • Roberto Vittori • Italian Air Force, ESA Astronaut Corps • Ken Nordtveldt • Northwest Analysis, Bozeman, MT, USA • Gia Dvali • New York University, New York, NY and CERN, Geneva, CH • David Rubincam • GSFC/NASA, Greenbelt, MD, USA • Arsen Hajian • University of Waterloo, ON, Canada • INFN-LNF Frascati Team • Simone Dell’Agnello PI INFN-LNF, Frascati, Italy • Giovanni Delle Monache INFN-LNF, Frascati, Italy • Douglas Currie U. of Maryland, College Park, MD, USA • NLSI, Moffett Field, CA, USA & • INFN-LNF, Frascati, Italy • Roberto Vittori Italian Air Force & ESA Astronaut Corps • Claudio Cantone INFN-LNF, Frascati, Italy • Marco Garattini INFN-LNF, Frascati, Italy • Alessandro Boni INFN-LNF, Frascati, Italy • Manuele Martini INFN-LNF, Frascati, Italy • Nicola Intaglietta INFN-LNF, Frascati, Italy • Caterina Lops INFN-LNF, Frascati, Italy • Riccardo March CNR-IAC & INFN-LNF, Rome, Italy • Roberto Tauraso U. of Rome Tor Vergata & INFN-LNF • Giovanni Bellettini U. of Rome Tor Vergata& INFN-LNF • Mauro Maiello INFN-LNF, Frascati, Italy • Simone Berardi INFN-LNF, Frascati, Italy • Luca Porcelli INFN-LNF, Frascati, Italy • Giuseppe Bianco ASI Centro di Geodesia Spaziale • “G. Colombo”, Matera, American Geophysical Union 5 December 2011

  33. ASTRO2010 DECADAL SURVEYGravitational and Particle Physics Panel Much is unknown about fundamental theory: Modifications of general relativity on accessible scales are not ruled out by today’s fundamental theories and observations. It makes sense to look for them by testing general relativity as accurately as possible. Cost-effective experiments that increase the precision of measurement of PPN parameters, and test the strong and weak equivalence principles, should be carried out. For example, improvements in Lunar Laser Ranging promise to advance this area. American Geophysical Union 5 December 2011

  34. ASTRO2010 DECADAL SURVEYGravitational and Particle Physics Panel • The direct detection of gravitomagnetic effects (the Lense-Thirring precession) from Lageos/Grace, Gravity Probe B, and lunar laser ranging. • The lunar laser ranging verification of the strong equivalence principle to 10-4, meaning that the triple graviton vertex is now known to a better accuracy than the triple gluon vertex. • Limits on the fractional rate of change of the gravitational constant • G (< 10-12) Limits on the fractional rate of change of the gravitational constant G (< 10-12/yr) from lunar laser ranging. Atomic experiments limiting time variation of the fine structure constant to 10-16/yr over periods of several years. • Experiments that are in progress include the Microscope equivalence principle experiment, the APOLLO lunar laser ranging observations, and tests of general relativity using torsion balances and atom interferometry. • Improved strong and weak equivalence principle limits. Better determination of PPN parameters and and Ġ/G from next generationLunar laser ranging American Geophysical Union 5 December 2011

  35. ASTRO2010 DECADAL SURVEYGravitational and Particle Physics Panel • A new Lunar Laser Ranging (LLR) program, if conducted as a low cost robotic mission or an add-on to a manned mission to the Moon, offers a promising and cost-effective way to test general relativity and other theories of gravity (Figure 8.12). So far, LLR has provided the most accurate tests of the weak equivalence principle, the strong equivalence principle and the constancy in time of Newton’s gravitational constant. These are tests of the core foundational principles of general relativity. Any detected violation would require a major revision of current theoretical understanding. As of yet, there are no reliable predictions of violations. However, because of their importance, the panel favors pushing the limits on these principles when it can be done at a reasonable cost. The installation of new LLR retroreflectors to replace the 40 year old ones might provide such an opportunity. The panel emphasizes again that its opinion that experiments improving the measurements of basic parameters of gravitation theory are justified only if they are of moderate cost. Therefore, it recommends that NASA’s existing program of small- and medium-scale astrophysics missions address this science area by considering, through peer review, experiments to test general relativity and other theories of gravity. The panel notes that a robotic placement of improved reflectors for LLR is likely to be consistent with the constraints of such a program. It returns to this recommendation below in the context of a recommendation to augment the Explorer program. American Geophysical Union 5 December 2011

  36. ASTRO2010 DECADAL SURVEY Cosmology and Fundamental Physics Panel These complex spin-induced orbital effects are the consequences of “frame dragging,” a fundamental prediction of Einstein’s theory that has been probed in the Solar System using Gravity Probe B, LAGEOS satellites, andLunar laser ranging, and has been hinted at in observations of accretion onto neutron stars and black holes. American Geophysical Union 5 December 2011

  37. APOLLO Data from Tom Murphy American Geophysical Union 5 December 2011

  38. CCR FABRICATION CHALLENGE • CCR Fabrication Using SupraSil 1 Completed • Specifications / Actual • Clear Aperture Diameter - 100 mm / 100 mm • Mechanical Configuration - Expansion of Our APOLLO • Wave Front Error - 0.25 / 0.15 [ l/6.7 ] • Offset Angles • Specification • 0.00”, 0.00”, 0.00” +/-0.20” • Fabricated • 0.18”, 0.15”, 0.07” • Flight Qualified • with Certification American Geophysical Union 5 December 2011

  39. THERMAL ANALYSIS – THEORETICALSolar Absorption within CCR • Solar Heat Deposition in Fused Silica • Solar Spectrum – AMO-2 • Absorption Data for SupraSil 1/311 • Compute Decay Distance for Each Wavelength • Compute Heat Deposition at Each Point • Beer’s Law • Thermal Modeling Addresses: • Internal Heat Transport and Fluxes • Radiation from CCR to Space • Radiation Exchange with Internal Pocket Surroundings • Mount Conduction into the Support Tabs American Geophysical Union 5 December 2011

  40. MOUNT CONDUCTANCE • Challenge: • Heat flow from Housing to CCR at Tabs • Optical Distortion due to Heat Flux • Support of CCR with KEL-F “Rings” • Intrinsic Low Conductivity • Use of Wire Inserts - Only Line Contacts • Line Contact of Support Reduces Heat Flow • For Support in Launch Environment • KEL-F Wire Compresses and • Launch Support Comes from Flush on Tab • Estimated (to be Validated in SCF) 1 Milli-W/oK American Geophysical Union 5 December 2011

  41. POCKET RADIATION EXCHANGE • Challenge: • IR Radiation Between CCR & Housing • SiO2 Has High IR Absorptivity/Emissivity • Heat Flux Causes Optical Distortion • Isolation Between CCR and Housing • Low Emissivity Coatings – 2% Emissivity • Successive Cans or Multiple Layers • Simulations Show Isolation is Effective • Thermal Vacuum Chamber Validation • In April 2009 at SCF at INFN/LNF at Frascati American Geophysical Union 5 December 2011

  42. INNER & OUTER THERMAL SHIELDS American Geophysical Union 5 December 2011

  43. THERMAL & SUNSHADE • Role of Sun Shade • Thermal Control and Sun Blocking • Dust Protection • UltraViolet Light Protection • External Surface • Highly Reflective in Visible • High Emissivity in the Infrared • Internal Surface • Black in the Visible • Low Emissivity in the Infrared American Geophysical Union 5 December 2011

  44. LLRRA-21 PACKAGE American Geophysical Union 5 December 2011

  45. ORBITAL THERMAL EVOLUTION • Simulation Performed with • Thermal Desktop • C&R Technologies • IDL • Code V • Initial Analysis • “Steady State” Behavior • Fixed Elevation of Sun • But During Lunar Month • Changing Illumination • Both Intensity and Angle • For CCR/Housing/Thermal Blanket/Regolith • Some Time Constants are Longer than a Month • Analysis of Behavior of Face to Tip Temperature Difference American Geophysical Union 5 December 2011

  46. Simulation Procedure • AutoCad Drawing of Total Package • CCR, Housing, Internal and External Support and Regolith • 4-D Heat Deposition in CCR – UMd IDL Program • Through a Lunation, 1 Nanometer Wavelength Bands, • Many Thousands of Nodes, Reflection Effects of SunShade • Thermal Desktop • Computes Temperature at Each Node • PhaseMap – UMd IDL Program • Converts 3D Temperatures to 2D PhaseMap at Each of 400 Sun Angles • Code V Optical Analysis Program • Adds Optical Errors (Reflection Phases, Offset Angles to Thermal Errors • Analysis Program – UMd IDL Program • Evaluates Laser Return Intensity - Addressing • Velocity Aberrations and Station Latitude • Polarization Effects American Geophysical Union 5 December 2011

  47. FULL Thermal SimulationAnchored Emplacement Regolith from Apollo HFE, Thermal Blanket Current Design Housing Temperature Distribution in CCR and Tip to Face Temperature Difference American Geophysical Union 5 December 2011

  48. SCF Thermal Vacuum TestInfrared Imager Full Dynamic Range Heat Flow Due to Tab Supports American Geophysical Union 5 December 2011

  49. Dust AcceleratorUniversity of Colorado Fused Silica Witness Plates American Geophysical Union 5 December 2011

  50. LLRRA-21 SIGNAL STRENGTH • 88% of the Current Apollo 15 Signal Level • At End of First Decade still about the same as Apollo 15 and • 2.64 Stronger than Apollo 11 • Simulated Pattern with Offset Angles to Correct for Velocity Aberration • Relative to Current A11 • On Axis Return is 49% of Apollo 11 • At Velocity Aberrated Latitude , the Return is ~55% of Apollo 11 • But No Dust so Stronger by a Factor of 9.6 • Overall – Stronger Than Apollo 11 by a factor of 2.64 • Overall – 90% of the return of Apollo 15 • If Dust on the Apollo Array is due LEM Launch – LLRRA-21 has a Cover for Landing Dust • If Dust on the Apollo Arrays is due to Steady Deposit of Dust or High Velocity Impacts • There would be at Least a Decade of Good Returns • But LLRRA-21 Should Expect Better Performance • Sun Shade • Dust Mitigator • APOLLO Station gets Many Thousands of Returns in 5 Minutes on Apollo 15 Almost Every Night • 3.6 meter Therefore Smaller Telescopes can Work • At 1,000 Returns on 3.6 Meter, • One Should get 80 Returns on 1 Meter and 25 Returns on 0.6 meter Telescope NLSI Commerce Virtual Lecture 23 February 2011 American Geophysical Union 5 December 2011

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