Water on Mars

Mars is a cold desert planet with no liquid water on its surface, but discoveries announced in 2000 by Malin Space Science Systems (MSSS) using cameras aboard Mars Global Surveyor and discoveries by Mars Odyssey Orbiter researchers in 2002 showed the presence of water ice just below ground level. In 2005, while re-imaging certain areas MSSS discovered this recent flow:

This 2005 reconstructed image from the European Space Agency's (ESA) Mars Express spacecraft shows vertical cliffs nearly 2 kilometers high bordering a volcanic caldera near the north pole of Mars. Also visible are reddish areas of rock and sand, white areas of ice, and dark areas that are probably volcanic ash. No, the greenish tinge isn't shrubbery.

The MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding) radar on the Mars Express spacecraft studied the structure of the layered deposits of this region to a depth of 3.7 km. In March of this year JPL reported in Science magazine that the data indicated a giant underground dome about 1000 km in diameter composed of water ice and a little (10%) dust.

The total volume of ice in the region is calculated to be about 1.6 million cubic kilometers. Melted, that much ice would cover the entire planet with water 11 meters (36 feet) deep, according to JPL, ignoring topography. But Michael Malin and Ken Edgett at MSSS estimate the volume of the 7 km deep, 5000 km long Valles Marineris canyon alone at about 3 million cubic kilometers.

Still, if you use both the JPL and Malin-Edgett figures, the water would only fill the canyon half full—except for the fact that much of the huge chasm's volume is well above what would be 'mean sea level'. And Olympus Mons would be an island continent displacing a lot of the water. So maybe the JPL 11 meter estimate is close even if it does ignore topography?

Probably not. James Head at Brown University published a report in 1999 that included an image showing it would take water almost 1500 m deep to flood more than the northern basin.

I played around with a Mars Orbiter Laser Altimeter (MOLA) flat projection map in Photoshop, cooked up some greenhouse warming, filled in the lowlands with melted ice water, grew some plants, created some clouds, wrapped it around a sphere and produced this pure fantasy. Looks a lot like home.

A couple of weeks ago ESA announced that the Mars Express orbiter found an amazing surface feature in Deuteronilus Mensae, also up north. From every indication it's a glacier.

Signs of old glaciers have been found on Mars, but this one may be only thousands of years old and it seems to still have ice on the characteristic ridges, so it may be active even today.

The interesting question, of course, is where is the water ice coming from? Maybe from underground, maybe from snow? The Phoenix lander due to arrive in May 0f 2008 will use a robotic arm to dig through the protective top soil layer to the water ice below and ultimately, to bring both soil and water ice to the lander platform for sophisticated scientific analysis that may answer the question.

UPDATE: Yup It's Ice!

And that may take us closer to answering the ultimate question if there's water on Mars is there life too? There always is here on Earth, whether the water is frozen solid at the poles or boiling hot in volcanic vents.

The next few years of exploration on Mars may be the most exciting yet.


jackholt said…
The 11 meters of global water reported by JPL assumes a smooth topography. It is a common way to express the water volume of ice masses in order to compare them. If one took into account topography, then if you started melting ice masses, the effective "sea level rise" of each would depend on the existing topography which would change as other ice masses melt. So a smooth surface at the mean planetary radius is used.

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