Poles of the Moon

Robert Citron Lunar Seminar 4/6/10 Outline

• Previous Observaons – Clemenne, Lunar Prospector • Science at the Poles • Recent Observaons – LRO, LCROSS, Chandrayaan-1 • Exploraon

1 Previous Observaons Dark Sides of the Moon

3 4 Permanently Shadowed Craters

Images extend to 78 degrees North/South 5 South Pole Darkness

6 Poles of Mercury

7 Why is ice radar-bright? • Coherent Backscaer Opposion Effect – Radar magnitude – Rao of outgoing to returned polarizaon – Angular dependence of these properes

8 Clemenne Observaons

9 Neutron Measurments Fast neutrons – energy Epithermal neutrons – intermediate energy Thermal neutrons – low energy (thermalized)

H20  Depleon in epithermal neutron flux

10 Lunar Prospector

Depleon in epithermal neutron flux  H2O

11 Results and Controversy

• Results: 1.5 wt % H2O from Radar and Neutron measurements • Radar observaons – High CPR in sunlit and dark regions – Surface roughness or water ice? • Neutron Measurements – Hydrogen could be implanted by solar wind – No thermal neutron excess • Explained by 10cm layer overlying the water rich soil

12 Science at the Poles Sources of Volales at the Poles

Lucey 2001 14 15 A Natural Laboratory

• Organic synthesis of trapped volales • Temperature cycling • Clathrates promote retenon of methane and CO2 • Monolayers of ice form hydrated minerals • Hydrothermal systems in hot ejecta blankets

16 Lunar Atmosphere

• Cold traps at poles interact with lunar exosphere • Equilibrium between cold trapping and escape • Lifeme of gases depends on flux of volales in and out of poles – Probably different than on Mercury • Observaonal Evidence: Na column density decreases at the poles

17 New Observaons Chandrayaan-1

19 Chandrayaan-1 M3 (Moon Minerology Mapper)

Blue – hydroxyl Red – pyroxene Green – brightness

20 LRO

NASA

21 LRO

22 LRO

23 LRO

24 LCROSS

25 LCROSS

26 LCROSS

27 LCROSS

28 Poles and Exploraon

• Ideal lunar outpost site • Areas of constant illuminaon/darkness • Ice is a valuable resource, hard to extract • Interesng science

Spudis Lunar Resources 29 References

• Paul G. Lucey, The Poles of the Moon, ELEMENTS, 2009 • Paul D. Spudis, Ice on the Bone Dry Moon • Linda Martel, The Moon's Dark, Icy Poles, 2003 • Paul D. Spudis, Ice on the Moon, The Space Review, 2006 • Paul G. Lucey, Potenal for pre-bioc chemistry at the poles of the Moon, 2000 • hp://planetary.org/blog/arcle/00002100 • www.nasa.gov/mission_pages • www.spudislunarresources.com

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