New evidence for an ancient Mars ocean

[Mallignamius]

Wow. Maybe Mars was teeming with life.

Evidence seen backing ancient Mars ocean shoreline

WASHINGTON (Reuters) - Long, undulating features on the northern plains of Mars probably are remnants of shorelines of an ocean that covered a third of the planet's surface at least 2 billion years ago, scientists said on Wednesday.

The geological features, stretching thousands of miles (kilometers), were first revealed in the 1980s in Viking spacecraft images. But topographical data collected by NASA's Mars Global Surveyor in the 1990s cast doubt on whether the features truly marked a long-gone sea coast.

The Global Surveyor found big, mountain-sized variations in elevation along the suspected shorelines, whereas a shoreline should be a constant elevation matching sea level.

But scientists writing in the journal Nature said the movement of the Martian poles and also the planet's spin axis by roughly 2,000 miles in the past 2 billion to 3 billion years would have triggered deformation of surface features just like that seen in the suspected coastlines.

"The pole moves and it warps the shorelines," planetary scientist Taylor Perron of Harvard University, the study's lead author, said in a telephone interview.

"We have don't have direct confirmation that there were oceans because, of course, the water isn't there any more. But what we've done is to eliminate one of the main reasons to doubt that they were ever there."

http://news.yahoo.com/s/nm/20070613/sc_nm/mars_oceans_dc

This is very exciting. I can see that when we do get to Mars, there will be a lot more to study and look for than was once thought. A paleozoologist's dream.

-Or a paleomicrobiologist's can of worms. 

[Mallignamius]

Some more coverage, with the article stating a confirmation.

Mystery Solved: Mars Had Large Oceans

http://news.yahoo.com/s/space/20070613/sc_space/mysterysolvedmarshadlargeoceans

[Astronuc]

But must it have been water, as opposed to very fine dust?  Powders will flow like liquid.  Blow sand or dust can cause erosion just as rain or water.

So where did this water go?  Or, how long did water survive on Mars?  Could Mars have had an Ice Age like the Earth - and when the ice melted, most of it evaporated from the planet?

[Orstio]

My opinion on the matter is that too many resources are extended to trying to prove whether or not there was water on Mars.

If there was water on Mars, the atmosphere needed to be thicker.  6-13 mB is just not enough pressure to keep a glass of liquid water, nevermind ponds, lakes, and oceans.  Liquid water instantly vaporizes at that low pressure.

I think what we really need to understand was whether or not the Martian atmosphere was ever any thicker, and even that is not the root.  What we really need to know is what would have enabled Mars to hold a thick atmosphere in the past, but not now.

To summarize:  Without a means to hold a thick atmosphere, there is no thick atmosphere.  Without a thick atmosphere, there is no liquid water. 

http://www-mgcm.arc.nasa.gov/mgcm/HTML/FAQS/liquid.html

Let's also consider the fact that the entire Martian atmosphere contains only 1-2 km³ of water ice.  This comes nowhere near the 13,000 km³ of the Earth's atmospheric water vapour.  If there were oceans, and they vaporized, one would expect the quantity of vapour in the atmosphere to be disproportionately high, and yet it is just the opposite.

[Mallignamius]

If particles/microparticles caused the erosion, would that suggest a stronger atmosphere than 6 millibars?

[Astronuc]

If not density, then it would have to be wind/gas velocity.

Think about dust devils or dust storms - they are certainly possible on Mars.

http://marsrover.nasa.gov/gallery/press/spirit/20050819a.html

http://science.nasa.gov/headlines/y2005/14jul_dustdevils.htm

http://mars.jpl.nasa.gov/gallery/duststorms/

http://news.bbc.co.uk/1/hi/sci/tech/4474675.stm

[Orstio]

No, it just suggests a wind speed fast enough to pick up particles, and particles small enough to be picked up.



As you can see from the graph, the Viking landers independently confirmed the low atmospheric pressure, which reached a high of 9-10 mB during the duration of their readings, and correlated well with the seasonal dust storms.