EPITHERMAL FLUX DEPRESION

AND PSR IN SHOEMAKER CRATER

V.V.Shevchenko1, I.G.Mitrofanov2, E.A.Kozlova1, A.A. Shangaraev1, and the LEND Science Team

1Sternberg State Astronomical Institute, Moscow University2Space Research Institute, RAS

THE SECOND MOSCOW SOLAR SYSTEM SYMPOSIUMMOONS OF PLANETS

MOSCOW 2011IKI RAS

Unique capability of LEND to measure epithermal neutron albedo with high spatial resolution allow to create maps with resolution up to 10 km for circumpolar areas

(Mitrofanov et al., 2011).

Well-seen NSR with area about 1500 km2 was detected within crater

Shoemaker. Its boundary coincides very well with the contour of PSR in the bottom of

this crater. In this case the surface of NSR is permanently cold, and there are perfect conditions for permanent

storage of frozen water in the regolith

TEMHERATURE MODEL OF CRATER SHOEMAKER

Temperature, K

T < 70 K

At speed of formation of a layer of regolith equal 1 cm (Killen et al., 1997)

or 15 cm (Morris, 1978) for 50 million years for formation of a shielding

layer by thickness of 0,2 – 0,5 m it is necessary on the average 1 billion years.

Using similar Clementine data for other lunar regions of mare and highland types, we obtained a scale of conformity

between OMAT, spectropolarimetric maturity indexes

and exposure age of surface soil (Shevchenko et al., 2003).

The maturity index values ranging from 0,15 to 0,20 correspond to exposure age from 0,2 to 0.4 billion years.

SUMMARY:

It’s possible that a shielding layer in crater Shoemaker has a thickness up to

0.5 – 1.0 meter

shielding layer

frozen waterlayer?

THANK YOU