HR: 16:00h
AN: P24A-01 INVITED    [Abstracts]
TI: Seasonal Changes in the Martian North Polar Region from CRISM, MARCI and CTX
AU: * Calvin, W M
EM: wcalvin@unr.edu
AF: University of Nevada - Reno, Geological Sciences, MS172, Reno, NV 89557, United States
AU: Pocock, J M
EM: jill.pocock@gmail.com
AF: University of Nevada - Reno, Geological Sciences, MS172, Reno, NV 89557, United States
AU: Seelos, F P
EM: Frank.Seelos@jhuapl.edu
AF: Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723,
AU: Lee, S W
EM: slee@dmns.org
AF: Denver Museum of Nature & Science, 2001 Colorado Blvd., Denver, CO 80205,
AU: James, P B
EM: pjames@cableone.net
AF: Space Science Institute, 4750 Walnut Street Suite 205, Boulder, CO 80301,
AU: Thomas, P C
EM: pthomas@astro.cornell.edu
AF: Cornell University, 422 Space Sciences Building, Ithaca, NY 14853,
AU: Murchie, S L
EM: scott.murchie@jhuapl.edu
AF: Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723,
AB: Significant mobility and spatial variation in high albedo patches are noted in the summer northern ice cap. These patches are shown to be fine-grained water frost and their motions may provide information on winds or local accumulation and ablation occurring both on seasonal and inter-annual timeframes in the permanent ice deposits. The Mars Reconnaissance Orbiter instruments provide complementary views of the processes involved. MARCI covers the entire northern residual ice and surrounding Polar Layered Deposits (PLD) multiple times per day at spatial resolutions of a few kilometers. CTX has been targeted on one of the largest bright deposits with repeated coverage in the first northern summer. The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) observes the polar deposits in the wavelength range where multiple, diagnostic features can separate H₂O and CO₂ ices and allow the determination of effective grain size of ice and level of dust contamination. Several full-resolution and approximately 80 multi-spectral observations were targeted during the first northern summer on a known sustained bright anomaly. Previous work by the OMEGA team has demonstrated the evolution of water frost grain size over the summer season and suggests that the late northern seasonal frost is dominated by water rather than CO₂ ice. This late water ice lag in the seasonal cap may also drive the appearance and mobility of residual fine grained ice patches. Spectral properties in exposed layers are more complicated, and even dark lanes within the reentrant troughs still show features associated with water ice. However, within the larger PLD areas that appear as transparent ice to MARSIS and SHARAD have no infrared spectral absorption features of ice. The modern view shows that both seasonal and permanent ice deposits are highly active with complex temporal patterns and understanding these dynamic phenomena are critical to understanding martian climate history. We will report the latest synthesis of these observations.
DE: 5422 Ices
DE: 5462 Polar regions
DE: 5464 Remote sensing
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting