Calculating iron contents of lunar highland materials surrounding Tycho crater from integrated Clementine UV-visible and near-infrared data

Research areas:
Year:
2002
Authors:
Journal:
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
Volume:
107
Number:
E10
Month:
October
ISSN:
0148-0227
BibTex:
Abstract:
Optical properties of lunar surface materials are modified by exposure
to the space environment, including bombardment by solar wind particles
and micrometeorites. One of the main problems in the interpretation of
lunar spectral observations is to separate the effects of exposure
({''}space weathering'') and those due to the composition of the soils
(mainly iron and titanium content). Here we use Clementine near-infrared
(NIR) data to investigate this problem for highland-type soils in the
Tycho crater area. Our approach is based on the methods developed for an
analysis of a mare region near Aristarchus Plateau {[}Le Mouelic et al.,
2000]. We show that the systematic relationships between spectral
parameters (1-mum band depth and continuum slope), which were previously
observed in a mare area with varying maturity degree, are also valid for
highland-type soils. This technique aimed at evaluating the iron content
of the surface materials from Clementine UV-visible (UVVIS) and
near-infrared data can therefore be applied globally. This approach
complements the widely used method of Lucey and coworkers, which relies
on the UV-visible bands only. The proposed method relies mostly on band
ratios. The iron map produced from this method is therefore less
dependent on topography than the iron estimates obtained with UV-visible
data alone, where brightness is one of the controlling parameters.
Therefore the proposed approach should be particularly useful at middle
to high latitudes, where local topography generates large variations in
brightness and therefore hampers the interpretation of iron maps
produced from UV-visible bands only.