1. LRO/LEND LEND 1 LCROSS Site Selection Workshop October 16 th 2006 Lunar Exploration Neutron Detector Evaluation of Potential LCROSS Impact Sites Igor Mitrofanov Space Research Institute imitrofa@space.ru and Richard Starr The Catholic University of America richard.starr@gsfc.nasa.gov

2. LRO/LEND LEND 2 LCROSS Site Selection Workshop October 16 th 2006 Igor MitrofanovPIRussian Institute for Space Research William BoyntonCoIUniversity of Arizona Larry EvansCoIComputer Science Corporation Alexandr KozyrevCoIRussian Institute for Space Research Maxim LitvakCoIRussian Institute for Space Research Roald SagdeevCoIUniversity of Maryland Anton SaninCoIRussian Institute for Space Research Vladislav ShevchenkoCoISternberg Astronomical Institute Valery ShvetsovCoIJoint Institute for Nuclear Research Richard StarrCoICatholic University Vlad Tret’yakovCoIRussian Institute for Space Research Jacob TrombkaCoINASA Goddard Space Flight center LEND Team

3. LRO/LEND LEND 3 LCROSS Site Selection Workshop October 16 th 2006 Lunar Exploration Neutron Detector LEND is one of six science instruments (plus one tech demo) that make up the science payload on NASA’s Lunar Reconnaissance Orbiter (LRO) mission. LEND is a contributed instrument of the Federal Space Agency of Russia. LEND will determine hydrogen distribution in the lunar subsurface to depths of 1-2 meters.

4. LRO/LEND LEND 4 LCROSS Site Selection Workshop October 16 th 2006 Cosmic Ray Induced Neutron flux

5. LRO/LEND LEND 5 LCROSS Site Selection Workshop October 16 th 2006 LRO Spaccraft LOLA LEND Mini-RF ANTENNA LROC NAC (2) LAMP CRaTER Diviner X Z Y

6. LRO/LEND LEND 6 LCROSS Site Selection Workshop October 16 th 2006 General Description of LEND Eight 3 He counters for detection of thermal and epithermal neutrons. –Four of the 3 He counters are collimated with a combination of polyethylene and 10 B powder. –Collimated detectors are also surrounded by Cd shields to filter out thermal neutrons with energies below ~0.4 eV so they are primarily sensitive to epithermal neutrons. One stylbene scintillation spectrometer for detection of fast neutrons. Moon V orb

7. LRO/LEND LEND 7 LCROSS Site Selection Workshop October 16 th 2006 Epithermal Neutrons The first global mapping of neutron emission from the Moon was performed in 1998 by the Neutron Spectrometer on NASA’s Lunar Prospector mission. Epithermal neutron flux decreased in polar regions of the Moon as compared with lower latitudes. These regions of reduced epithermal flux correspond to floors of craters that are permanently shadowed suggesting water ice as a possible source of the signal. Feldman W.C. et al. (1998) Science 281, 1496-1500.

8. LRO/LEND LEND 8 LCROSS Site Selection Workshop October 16 th 2006 LEND Collimators - 1

9. LRO/LEND LEND 9 LCROSS Site Selection Workshop October 16 th 2006 LEND Collimators - 2 LEND sensitivity to hydrogen depends on the collimator length and radius of its opening. These two parameters must be optimized without violating mass constraints.

10. LRO/LEND LEND 10 LCROSS Site Selection Workshop October 16 th 2006 LEND Collimators - 3 Polyethylene collimator 10 B powder collimator 3 He counters Scintillation detector

11. LRO/LEND LEND 11 LCROSS Site Selection Workshop October 16 th 2006 LEND Collimators - 4 Total counting rate:2.1 s -1 Field of view:5.7° N FOV :0.9 s -1 N bgd :1.2 s -1 N bgd / N FOV :1.3 The modeled instrument sensitivity to hydrogen in a polar spot with 10 km diameter is ~70 ppm after 1 year of orbital operations.

12. LRO/LEND LEND 12 LCROSS Site Selection Workshop October 16 th 2006 Minimum Energy Lunar Transfer ~ 4 Days Lunar Orbit Insertion Sequence, 4 Maneuvers, 2-4 Days Commissioning Phase, 30 x 216 km Altitude Quasi-Frozen Orbit, Up to 60 Days Polar Mapping Phase, 50 km Altitude Circular Orbit, At least 1 Year Launch: October 31, 2008 Nominal End of Mission: February 2010 LRO Mission Overview

13. LRO/LEND LEND 13 LCROSS Site Selection Workshop October 16 th 2006 South Pole Candidate Targets - 1

14. LRO/LEND LEND 14 LCROSS Site Selection Workshop October 16 th 2006 South Pole Candidate Targets - 2 #LatitudeLongitude ΔS, km 2 Name of crater Detection limit (3σ) of hydrogen for LEND (in ppm) Average content of hydrogen from LP (in ppm) 1212-89.9111.1380Shackleton30.9 145 10-88.5220400-75.8 136 4-87.638575Shoemaker80.1 154 6-86.875.8257Faustini141.3 159 8-87.4260.2183-151.5 117 3-84.454.8140Nobile264.5 114 1-83.784.7140Amundsen282.3 107 5-87.412.5116-284.8 88 1-85.248.199-294.4 136 2-84.7323100Cabeus309.4 142 9-85.1184.558-403.7 86 7-83.5164.570Vichert426.4 131

15. LRO/LEND LEND 15 LCROSS Site Selection Workshop October 16 th 2006 Shoemaker - 1 LEND sensitivity vs. time for integration over entire are of Shoemaker crater. Bar at 60 days indicates how sensitivity may vary if exposure time increases or decreases by a factor of 2.

16. LRO/LEND LEND 16 LCROSS Site Selection Workshop October 16 th 2006 Shoemaker - 2 Assumptions in Shoemaker Sensitivity Calculation: Used the current model of the 50 km circular science orbit. Used only direct projection criteria for accumulation of exposure time, when nadir direction crosses the target.