Geysers on Mars
Martian geysers (or CO2 jets) are putative sites of small gas and dust eruptions that occur in the south polar region of Mars during the spring thaw.
These features are unique to the south polar region of Mars in an area informally called the 'cryptic region', at latitudes 60° to 80° south and longitudes 150°W to 310°W;[11][12][13] this 1 meter deep carbon dioxide (CO2) ice transition area—between the scarps of the thick polar ice layer and the permafrost—is where clusters of the apparent geyser systems are located.
[2][3][4][5][6][7][8] This process is rapid, observed happening in the space of a few days, weeks or months, a growth rate rather unusual in geology – especially for Mars.
The geological features informally called dark dune spots and spiders were separately discovered on images acquired by the MOC camera on board the Mars Global Surveyor during 1998–1999.
[9] However, soon after their first detection, they were discovered to be negative topographical features – i.e. radial troughs or channels of what today are thought to be geyser-like vent systems.
[24] Its radial patterns represent shallow channels or ducts in the ice formed by the flow of the sublimation gas toward the vents.
[6] The geyser-like system produce low-albedo spots, fans and blotches, with small radial spider-like channel networks most often associated with their location.
[2] Time-lapsed imagery performed by NASA confirms the apparent ejection of dark material following the radial growth of spider channels in the ice.
[14] A number of geophysical models have been investigated to explain the various colors and shapes' development of these geysers on the southern polar ice cap of Mars.
[7] Some teams propose dry venting of carbon dioxide (CO2) gas and sand, occurring between the ice and the underlying bedrock.
[37] The second part comprises steep slopes known as 'scarps', made almost entirely of water ice, that fall away from the polar cap to the surrounding plains.
This model explores the possibility of active water-driven erosive structures, where soil and water derived from the shallow sub-surface layer is expelled up by CO2 gas through fissures eroding joints to create spider-like radiating tributaries capped with mud-like material and/or ice.
[14][38][39][40] A European team proposes that the features could be a sign that non-solar energy source is responsible of the jets, subsurface heat wave for instance.
[20][34][35] While the European Space Agency (ESA) has not yet formulated a theory or model, they have stated that the process of frost sublimation is not compatible with a few important features observed in the images, and that the location and shape of the spots is at odds with a physical explanation, specifically, because the channels appear to radiate downhill as much as they radiate uphill, defying gravity.
[22][44][45][46] The Hungarian scientists think that even a complex sublimation process is insufficient to explain the formation and evolution of the dark dune spots in space and time.
[19] A multinational European team suggests that if liquid water is present in the spiders' channels during their annual defrost cycle, the structures might provide a niche where certain microscopic life forms could have retreated and adapted while sheltered from UV solar radiation.
[3] British and German teams also consider the possibility that organic matter, microbes, or even simple plants might co-exist with these inorganic formations, especially if the mechanism includes liquid water and a geothermal energy source.
There is no direct data on these features other than images taken in the visible and infrared spectra, and development of the Mars Geyser Hopper lander is under consideration to study the geyser-like systems.
