Volume 630, October 2019
|Number of page(s)||7|
|Section||Letters to the Editor|
|Published online||02 October 2019|
Letter to the Editor
Detection of an excessively strong 3-μm absorption near the lunar highland crater Dufay
Image Analysis Group, TU Dortmund University, Otto-Hahn-Str. 4, 44227 Dortmund, Germany
2 Physical Research Laboratory, Ahmedabad 380009, India
3 Sternberg Astronomical Institute, Moscow State University, Universitetskij Pr., 13, 119234 Moscow, Russia
Accepted: 6 September 2019
Using the near-infrared spectral reflectance data of the Chandrayaan-1 Moon Mineralogy Mapper (M3) instrument, we report an unusually bright structure of 30 × 60 km2 on the lunar equatorial farside near crater Dufay. At this location, the 3-μm absorption band feature, which is commonly ascribed to hydroxyl (OH) and/or water (H2O), at local midday is significantly (∼30%) stronger than on the surrounding surface and, surprisingly, stronger than in the illuminated polar highlands. We did not find a similar area of excessively strong 3-μm absorption anywhere else on the Moon. A possible explanation for this structure is the recent infall of meteoritic or cometary material of high OH/H2O content forming a thin layer detectable by its pronounced 3-μm band, where a small amount of the OH/H2O is adsorbed by the surface material into binding states of relatively high activation energy. Detailed analysis of this structure with next-generation spacecraft instrumentation will provide further insight into the processes that lead to the accumulation of OH/H2O in the lunar regolith surface.
Key words: Moon / planets and satellites: surfaces / planets and satellites: composition / infrared: planetary systems / solid state: volatile
© ESO 2019
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