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Abstract
Water probably flowed across ancient Mars, but whether it ever exists as a liquid on the surface today remains debatable. Recurring slope lineae (RSL) are narrow (0.5 to 5 meters), relatively dark markings on steep (25° to 40°) slopes; repeat images from the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment show them to appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in some rare locations. RSL appear and lengthen in the late southern spring and summer from 48°S to 32°S latitudes favoring equator-facing slopes, which are times and places with peak surface temperatures from ~250 to 300 kelvin. Liquid brines near the surface might explain this activity, but the exact mechanism and source of water are not understood.
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Published In
Science
Volume 333 | Issue 6043
5 August 2011
5 August 2011
Copyright
Copyright ? 2011, American Association for the Advancement of Science.
Submission history
Received: 25 February 2011
Accepted: 17 June 2011
Published in print: 5 August 2011
Acknowledgments
Acknowledgments: This research was supported by NASA’s MRO project; we thank them along with the reviewers. All original data reported in this paper are tabulated in the SOM and archived by NASA’s Planetary Data System.
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