HR: 0800h
AN: P51A-0896    [Abstracts]
TI: The MESSENGER Earth Flyby: First Results from the Mercury Atmospheric and Surface Composition Spectrometer
AU: * Holsclaw, G
EM: holsclaw@colorado.edu
AF: University of Colorado / Laboratory for Atmospheric and Space Physics, 1234 Innovation Drive, Boulder, CO 80303 United States
AU: Bradley, T
P51A-0896 AF: University of Colorado / Laboratory for Atmospheric and Space Physics, 1234 Innovation Drive, Boulder, CO 80303 United States
AU: McClintock, W E
P51A-0896 AF: University of Colorado / Laboratory for Atmospheric and Space Physics, 1234 Innovation Drive, Boulder, CO 80303 United States
AU: Izenberg, N
P51A-0896 AF: Johns Hopkins University / Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 United States
AU: Vaughan, R
P51A-0896 AF: Johns Hopkins University / Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 United States
AU: Robinson, M S
P51A-0896 AF: Northwestern University - Center for Planetary Sciences, 1850 Campus Drive, Evanston, IL 60208 United States
AB: The MESSENGER (MErcury Surface, Space Environment, Geochemistry, and Ranging) spacecraft, NASA's first mission to orbit the planet Mercury, was launched on August 3, 2004, from Cape Canaveral Air Force Station. A gravity-assist maneuver brought the spacecraft through the Earth-Moon system with a closest approach on August 2, 2005. This event provided an important opportunity to observe the Moon with several of MESSENGER's remote sensing experiments. The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) instrument, one of seven instruments onboard the spacecraft, consists of a Cassegrain telescope that simultaneously feeds the Visible and Infrared Spectrograph (VIRS) and the Ultraviolet and Visible Spectrometer (UVVS). VIRS is a point spectrometer, covering the wavelength range 320-1450 nm with a field-of-view of 0.023°, while the UVVS is a scanning-grating monochromator covering 115-600 nm with a field-of-view of 0.04° square in surface mode. MASCS observed the Moon on July 31 at 2:24 UTC, when MESSENGER was at a distance of ~950,000 km, at a phase angle of 65°. The spacecraft performed mosaic maneuvers that yielded spectra of the southern hemisphere on both channels. The western portion of the near and far side were seen at a spatial resolution of ~380 km for VIRS and 650 km for UVVS. The mosaic maneuvers were followed by targeted observations of the 930-km-diameter Orientale impact basin (20° S, 95° W). These observations, together with simultaneous images by MESSENGER's Mercury Dual Imaging System, provide a unique data set for validating the MASCS pre-flight radiometric calibration and will allow us to compare directly the spectra of Mercury with those of the Moon. The MASCS-derived spectral reflectance and color ratios of terrain types are being compared with standard near-side measurements to check pre-launch calibration parameters.
DE: 6207 Comparative planetology
DE: 6235 Mercury
DE: 6250 Moon (1221)
DE: 6297 Instruments and techniques
SC: Planetary Sciences [P]
MN: Fall Meeting 2005