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Bulletin of the Eastbay Astronomical Society
Founded in 1924 at Chabot Observatory, Oakland, California
Volume 77, Number 2, October 2000


Front Page.

Roberts Rules. President Carter Roberts’ message.
Sky Lore for the Month. Morning Star

The 9½" Refracting Telescope
Mars Weather Report and a Mars Reading List
News from the Beyond.

Other Stuff.


Discovery of Water on Mars

Dr. Jeff Moore
NASA Ames Research Center

Saturday, 14 October, 2000
General Meeting 7:31 p.m.
Lecture 8:20 p.m.
Chabot Observatory, 4917 Mountain Boulevard, Oakland, California



Nirgal Vallis is an ancient valley thought to have been carved, in part, by running water far in the martian past. Today the valley is, like the rest of Mars, quite dry. However, some of the high resolution Mars Global Surveyor images reveal small gullies on the walls of this valley system. As shown here, channels nearly one kilometer long run down the south-facing slope of the Nirgal Vallis wall. Each narrow channel starts at about the same position below the top of the valley wall, indicating that there is a layer along which a liquid—most likely, water—has percolated until it reached the cliff, then ran down hill to form the channels and the fan-shaped aprons at the bottom of the slope. Since some of the apron deposits seem to cover the dunes on the floor of the valley, the channels and aprons must have formed more recently than the dunes. Because neither the dunes nor the aprons and channels have impact craters on them, these features are all geologically young, meaning a few million years at most, a few days or weeks at least. Credit: NASA/JPL/Malin Space Science Systems




Just three months ago, one of the most startling announcements of the space age was made: evidence for very recent liquid water flowing on Mars. This amazing discovery was the result of recent Mars Global Surveyor images. Gullies were seen on the sides of Martian canyons and craters. On Earth, such landforms occur when water suddenly flows across desert-like terrain, leaving a distinctive pattern. What is particularly exciting is that the gullies and washes below them appear to be very recent. Most of them have no cratering and at least one flows over a sand dune area. Sand dunes on Mars are thought to be constantly changing from windstorms whipping the planet. This suggests that these formations are recent, perhaps very recent (a few months or years ago). If this is so, then liquid water may exist on Mars right now!

These gullies are found in over 120 locations on slopes that face away from the Sun between 30 and 70 degrees latitude in both the Northern and Southern Martian hemispheres. It is thought that the colder temperature on these slopes allows ice to seal in the subsurface water at depths ranging from about 300 to 1300 feet (100 to 400 meters) below the surface.

It is still possible that other, more exotic explanations may explain these formations. The leading candidate is clathrates, a fizzing, bubbling mixture of gas and debris that flows like water.

If these formations are from recent liquid water flow, then the implications are enormous. It is now thought that Mars had rivers, lakes, rain and perhaps even an ocean or two on its surface for about one and a half billion years. This is important because, on the Earth, life got started within the first one hundred million years of the existence of such conditions. This implies that life may well have gotten started on Mars during its wet and warm period. As Mars began to freeze, Martian life could have retreated to these subsurface pools where the Martian life would be protected from the intense ultraviolet radiation on the surface. There may be life in those hypothesized pools right now. And the life would have had about four billion years to evolve! Furthermore, we now know that Mars and Earth exchange substantial amounts of material. It is possible that one planet could have biologically “contaminated” the other. In other words, we could be Martians!

There is no better person to discuss these exciting results and the upcoming missions to Mars than Dr. Jeff Moore, a trained geologist who is intimately involved with many of the aspects of the Mars program.

Dr. Jeffrey M. Moore is a Research Scientist with the SETI Institute, and is based at NASA Ames Research Center in Mountain View. Dr. Moore has both a history and a geophysics degree from the University of Oklahoma. He got his Masters and Ph.D. in Geology from Arizona State University. He has spoken several times to EAS, most recently in March, 2000, about the discoveries of the Galileo Mission. In January, 1999, he told us about the popular culture of observations of Mars.

For more information about this exciting discovery check http://www.space.com/scienceastronomy/solarsystem/mars_science_findings_000622 .html.
To view the fascinating images from Mars global surveyor, go to http://mars.jpl.nasa.gov/mgs/msss/camera/images/june2000/index.html.

DINNER WITH THE SPEAKER
5:27 pm, Saturday, 14 October 2000
BLUE NILE RESTAURANT
2525 Telegraph Avenue, Berkeley (510) 540-6777
Please call Betty Neall at 510/533-2394 by Friday, 13 October to confirm your place. Note the time has been advanced to allow everyone to be able to get to the meeting promptly at 7:31 pm.



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