Back to the time of the Viking program there was the theoretical prediction of water eruptions on Mars in Geyser-like events [1]. This theory was later supported by the discovery of two subsequent Viking Orbiter Images by Leonard Martin of Lowell Observatory in 1980 [2]. What looks like the plume of a water eruption seems at closer investigation to be a large dust devil. Martian dust devils were first identified on Viking Orbiter images in the late 1980s and are better known from pictures taken by Mars Global Surveyor's orbiter camera (MOC).

One indication of near surface liquid water are the so called pseudocraters, rootless cones created by explosive steam vents. They are common in some areas of Mars and a recent study of pseudocraters indicates their creation in present geological time (< 10 million years) through lava / water interaction up to 10 meters below the ground [3]. At least one MGS image (AB103104) seems to show such a venting, but on a rather small and less violent scale. Here the eruption plume is associated with a black streak area. Such black streaks were long suspected in relation with water [4]. The dark color could be the chemical response of the UV activated martian soil to water.

Questions, comments?

All MOC images from Aerobraking-1 (AB1), Science Phasing-1 (SP1) and 2 (SP2) and High-Gain Antenna Images (fha) stored at IDA and MSSS were screened regarding:

1.0 Unusual black streaks

1.1 Unusual albedo situations perhaps related to black streaks

1.2 Black streaks related to possible ponds
Contrary to public opinion, some areas of Mars have today the pressure and temperature range to allow stable liquid water [5]. But no lakes have been observed in these regions. Therefore any pond could only be temporary and should be dark colored according the black streak / water hypothesis.


2. Evaporites
Any water from subsurface Mars is probably very salty. As it evaporates the salt will remain and accumulate over time to evaporite structures. Complex evaporite structures are rather rare on Earth, but seem to be very common on Mars. If the source is a single hole, a cone-like structure will evolve. If the source is a crack line, a ridge evolves. Two crossing cracks like an X will create a four-sided pyramid, and so on. It seems possible that evaporites created most types of geometrical and irregular structure on Mars.

2.1 Evaporites related to flow phenomena and ridges

2.2 Evaporites at crater rims

2.3 Evaporites in crater center

2.4 Evaporites burying craters


3. Additional THEMIS Evidence

3.1 The cloud pillars of Arabia

3.2 A northern Meridiani venting site

3.3 A northern Noachis venting site



References:

0 Phillips, Tony: "Making a Splash on Mars", Science@NASA article, June 29, 2000. Phillips describes the Martian "gullies" and explains the conditions under which liquid water can exist on the surface of Mars.

1 M.H. Carr (1979): "Formation of Martian Flood Features by Release of Water From Confined Aquifers", JGR Vol. 84, No. B6, p. 2995ff

2 "NASA Activities" (Dec. 1980, vol. 11, number 12) and further processed by V. Di Pietro and G. Molenaar: "Unusual Martian Surface Features", Glenn Dale, Maryland 1982

3 Lanagan, McEwen, Keszthelyi1 and Thordarson: "Analysis of rootless eruption model for origins of small cratered cones of Elysium Basin and Amazonis Planitia, Mars." in: Volcano/Ice Interaction on Earth and Mars Conference, August 13-15, 2000, Reykjavik, Iceland

4 Schorghofer, Aharonson, and Khatiwala (2002): "Slope streaks on Mars: Correlations with surface properties and the potential role of water", Geophysical Research Letters, Vol. 29, No. 23, 2126 (PDF)

5 McKay, Christopher P.: "Life on Mars: Past, Present, and Future." Journal of the Mississippi Academy of Sciences, Vol. 48, No. 3, July 2003