Saturn's Titan: Surface change, ammonia, and implications for atmospheric and tectonic activity

被引：48

作者：

Nelson, R. M. ^{[1
]}

Kamp, L. W. ^{[1
]}

Matson, D. L. ^{[1
]}

Irwin, P. G. J. ^{[2
]}

Baines, K. H. ^{[1
]}

Boryta, M. D. ^{[3
]}

Leader, F. E. ^{[1
]}

Jaumann, R. ^{[4
]}

Smythe, W. D. ^{[1
]}

Sotin, C. ^{[5
]}

Clark, R. N. ^{[6
]}

Cruikshank, D. P. ^{[7
]}

Drossart, P. ^{[8
]}

Pearl, J. C. ^{[9
]}

Hapke, B. W. ^{[10
]}

Lunine, J. ^{[11
]}

Combes, M. ^{[12
]}

Bellucci, G. ^{[13
]}

Bibring, J. -P. ^{[14
]}

Capaccioni, F. ^{[13
]}

Cerroni, P. ^{[13
]}

Coradini, A. ^{[13
]}

Formisano, V. ^{[13
]}

Filacchione, G. ^{[13
]}

Langevin, R. Y. ^{[14
]}

McCord, T. B. ^{[15
]}

Mennella, V. ^{[16
]}

Nicholson, P. D. ^{[17
]}

Sicardy, B. ^{[8
]}

机构：

[1] NASA, Div Earth & Space Sci, JPL, Pasadena, CA 91109 USA

[2] Univ Oxford, Clarendon Lab, Oxford OX1 3PU, England

[3] Mt San Antonio Coll, Dept Geol, Walnut, CA 91789 USA

[4] DLR, Inst Planetaty Explorat, Berlin, Germany

[5] Univ Nantes, Lab Planetol & Geodynam, Nantes, France

[6] US Geol Survey, Fed Ctr, Lakewood, CO 80225 USA

[7] NASA AMES, Moffett Field, CA 94035 USA

[8] Observ Paris, F-92195 Meudon, France

[9] NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA

[10] Univ Pittsburgh, Pittsburgh, PA 15260 USA

[11] Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA

[12] Observ Paris, Off Director, F-75014 Paris, France

[13] Ist Astrofis Spaziale Fis Cosm, I-00133 Rome, Italy

[14] Univ Paris 11, Fac Sci, F-91405 Orsay, France

[15] Univ Washington, Winthrop, WA 98862 USA

[16] Osserv Astron Capodimonte, I-80131 Naples, Italy

[17] Cornell Univ, Dept Astron, Ithaca, NY 14853 USA

来源：

ICARUS | 2009年 / 199卷 / 02期

基金：

美国国家航空航天局; 英国科学技术设施理事会;

关键词：

Titan; Spectrophotometry; Infrared observations; Ices; Spectroscopy; TROPOSPHERIC CLOUDS; INTERNAL STRUCTURE; 9500 CM(-1); HAZE; ALBEDO; VIMS;

D O I：

10.1016/j.icarus.2008.08.013

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Titan is known to have a Young Surface. Here we present evidence from the Cassini Visual and Infrared Mapping spectrometer that it is currently geologically active. We report that changes in the near-infrared reflectance of a 73,000 km 2 area on Titan (latitude 26 degrees S, longitude 78 degrees W) occurred between July 2004 and March of 2006. The reflectance of the area increased by a factor of two between July 2004 and March-April 2005; it then returned to the July 2004 level by November 2005. By late December 2005 the reflectance had surged upward again, establishing a new maximum. Thereafter, it trended downward for the next three months. Detailed spectrophotometric analyses suggest these changes happen at or very near the surface. The spectral differences between the region and its surroundings rule out changes in the distribution of the ices of reasonably expected materials such as H2O, CO2, and CH4 as possible causes. Remarkably, the change is spectrally consistent with the deposition and removal of NH3 frost over a water ice substrate. NH3 has been proposed as a constituent of Titan's interior and has never been reported on the surface. The detection of NH3 frost on the surface might possibly be explained by episodic effusive events occur which bring juvenile ammonia from the interior to the surface. If so. its decomposition would feed nitrogen to the atmosphere now and in the future. The lateral extent of the region exceeds that of active areas on the Earth (Hawaii) or to (Loki). (c) 2008 Elsevier Inc. All rights reserved.

引用

页码：429 / 441

页数：13

共 42 条

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