Space Forum / Space Science / September 2005

8 Years at Mars #1: New Dune Gullies
MGS MOC Release No. MOC2-1220, 20 September 2005
http://www.msss.com/mars_images/moc/2005/09/20/dunegullies/index.html

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 et.al. 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/050824_mars_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_query?2005DPS....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_query?2005LPI....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_query?2005JGRE..11005004H

The researchers argue that the present low pressure conditions on Mars
actually support the morphological characteristics of the gullies.

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/images/E13/E1300738.html

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

  Bob Clark