Publication Date:
1998-12-16
Description:
Elevations from the Mars Orbiter Laser Altimeter (MOLA) have been used to construct a precise topographic map of the martian north polar region. The northern ice cap has a maximum elevation of 3 kilometers above its surroundings but lies within a 5-kilometer-deep hemispheric depression that is contiguous with the area into which most outflow channels emptied. Polar cap topography displays evidence of modification by ablation, flow, and wind and is consistent with a primarily H2O composition. Correlation of topography with images suggests that the cap was more spatially extensive in the past. The cap volume of 1.2 x 10(6) to 1.7 x 10(6) cubic kilometers is about half that of the Greenland ice cap. Clouds observed over the polar cap are likely composed of CO2 that condensed out of the atmosphere during northern hemisphere winter. Many clouds exhibit dynamical structure likely caused by the interaction of propagating wave fronts with surface topography.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zuber, M T -- Smith, D E -- Solomon, S C -- Abshire, J B -- Afzal, R S -- Aharonson, O -- Fishbaugh, K -- Ford, P G -- Frey, H V -- Garvin, J B -- Head, J W -- Ivanov, A B -- Johnson, C L -- Muhleman, D O -- Neumann, G A -- Pettengill, G H -- Phillips, R J -- Sun, X -- Zwally, H J -- Banerdt, W B -- Duxbury, T C -- New York, N.Y. -- Science. 1998 Dec 11;282(5396):2053-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. zuber@tharsis.gsfc.nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9851922" target="_blank"〉PubMed〈/a〉
Keywords:
*Carbon Dioxide
;
Extraterrestrial Environment
;
*Ice
;
*Mars
;
*Water
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
