IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2021A025 PROGRAM_TITLE Chemistry and transport of water on the Moon PROGRAM_INV1 Paul Lucey PROGRAM_INV2 Casey Honniball PROGRAM_INV3 Abigail Flom PROGRAM_INV4 Chiara Ferrari-Wong PROGRAM_INV5 PROGRAM_SCICAT solar system PROGRAM_ABSTRACT_BEG Infrared spectrometers carried by the Deep Impact, Chaandryaan-1 and Cassini spacecraft detected broad, asymmetric absorption features across the lunar surface near 3.0 um attributed to either hydroxyl [OH] or molecular water [H2O]. This absorption feature shows strong variability with latitude and temperature. At the equator, the depth of the band is extremely weak while at high latitudes it can be up to 30% deep; lunar time of day and temperature variations are superimposed on the latitude trend. However, correction for thermal emission problematic and making detection of diurnal absorption controversial. Our removal of thermal emission from lunar spectra uses the methods commonly used to correct asteroid spectra for thermal emission in the 3 um region. However, the lunar surface can be 100K hotter than typical asteroids, so there is concern that the asteroid methodology may break down at high temperatures. We exploit lunar eclipses to test this hypothesis. During portions of lunar eclipses the Sun is partially obscured by the Earth from a vantage point on the Moon. This drastically drops the solar illumination and surface temperatures to values equivalent to those of Main Belt asteroids, making the methods used for asteroid 3 um thermal correction directly applicable. PROGRAM_ABSTRACT_END