Mgs News Briefing On September 20, 2005, interesting changes observed... Options

[Bob Shaw]

Nobody has seen this cool gif animation?
Is it Ice under the ground?



http://photojournal.jpl.nasa.gov/archive/PIA04295.gif

No. It's CO2 subliming and creating pits. There's an optical illusion at work here - it's not sticky-out features which are growing, but holes!

[Guest_RGClark_*]

You should be disappointed only if the proffered explanation is the correct one. The gullies seen on sand dunes prior to this were believed also to be due to liquid water. It is only when they are seen to be produced currently that the suggestion is made by Malin that they are due to gas release.
However, there has been published research that the gullies can be produced under current conditions:

Water Flowed Recently on Mars, NASA Scientists Say.
By Robert Roy Britt
posted: 24 August 2005
"If liquid water pops out onto Mars' surface, it can create short gullies about 550-yards (500-meters) long," Heldmann said in a statement. "We find that the short length of the gully features implies they did form under conditions similar to those on present-day Mars, with simultaneous freezing and rapid evaporation of nearly pure liquid water."
http://www.space.com/scienceastronomy/0508...rs_gullies.html

Formation of Martian Gullies by the Action of Liquid Water Flowing under Current Martian Environmental Conditions.
American Astronomical Society, DPS meeting #37, #32.10
"We find that, contrary to popular belief, the fluvially-carved Martian gullies are consistent with formation conditions such as now occur on Mars, outside of the temperature-pressure stability regime of liquid water.
... our model indicates that these fluvially-carved gullies formed in the low temperature and low pressure conditions of present day Mars by the action of relatively pure liquid water.
http://adsabs.harvard.edu/cgi-bin/bib_quer...DPS....37.3210H

Formation of Martian Gullies by the Action of Liquid Water Flowing Under Current Martian Environmental Conditions.
36th Annual Lunar and Planetary Science Conference, March 14-18, 2005, in League City, Texas, abstract no.1270.
http://adsabs.harvard.edu/cgi-bin/bib_quer...LPI....36.1270H

Formation of Martian gullies by the action of liquid water flowing under current Martian environmental conditions.
Journal of Geophysical Research, Volume 110, Issue E5, CiteID E05004.
http://adsabs.harvard.edu/cgi-bin/bib_quer...JGRE..11005004H

  Bob Clark

Note that another researcher has suggested a different dune field shows both signs of current high ice content and gullied flow:

Martian dunes hide water secret.
Scientists have found evidence that large amounts of water-ice hide within massive sand dunes on Mars.
"If you're looking for a source of water for any future landers," said Dr Bourke, "I am advocating that you march up to your nearest sand dune."
Monday, 5 September 2005, 19:31 GMT 20:31 UK
http://news.bbc.co.uk/1/hi/sci/tech/4217528.stm

This is of a different dune field in Kaiser crater than the one proven to have currently forming gullies. However, Dr. Bourke noted that dunes in the vicinity of Kaiser have high water content from GRS readings - and the dunes with the currently forming gullies are indeed nearby to Kaiser.
A dramatic image of Kaiser gives the impression the gullies here formed *very* recently (also within a few Mars years?):

MOC narrow-angle image E13-00738.
Traverse across crater and dunes on floor of Kaiser Crater.
http://www.msss.com/moc_gallery/e13_e18/im...3/E1300738.html

It may be worthwhile to also search the Kaiser dune field for currently forming gullies.



Bob Clark