Ancient Martian Ocean
The latest issue of The Planetary Report discusses polygons on Mars. These terrain features are in Mare Acidalium, in the planet's northern hemisphere. Measuring 1-12 miles across, the polygons have terrestrial analogs. Buried, undersea polygons have been found on Earth. They support an interpretation of the Martian features as having been formed in an ancient sea. This interpretation is almost certainly correct. Mare Acidalium was the destination for water and sediments from huge outflow channels. These channels are known as circumchrysean because they formed around the Chryse plain, south of Mare Acidalium. They were certainly vast. A single one, Kasei Vallis, dwarfed the Amazon river. Enough water flowed into Mare Acidalium to create an ocean there.
But could an ocean last on Mars? It almost certainly couldn't, especially not in liquid form. Even 2.5 billion years ago, Mars was essentially the same frozen world we know today. The ocean must've immediately acquired a thick ice cover. It probably froze completely, prior to gradual sublimation. After millions of years, the ice was all gone, the bulk of it ending up in the north polar area nearby. Some water, however, seeped into the ground and froze there.
The brevity of the northern ocean argues against it being an abode of life.
posted by starman at 5:19 AM
6 Comments:
I seriously doubt that life existed in Martian seas. The probability of it does not seem great. If intelligent life forms (ones with star going spaceships) ever colonized Mars, they would have left it long ago.
Neal Robbins
I doubt life had enough time to evolve in the ephemeral ocean c 2.5 billion years ago. It froze and sublimated in a relatively brief time. At least it seems safe to assume that.
You know Neal, the author of COSMIC YOYAGE actually claimed, on the basis of "remote viewing," that Mars had an indigenous civilization. A near miss from an asteroid is said to have thinned the Martian atmosphere and made the planet uninhabitable. Absurd.
Interesting. Did they say what caused the liquid water in the first place? Was it geothermal, volcanism? How long could that have lasted? How widespread could it have been? From what I've read the entire surface of Venus was overturned half a billion years ago. Is that one Martian sea the only large body of ancient water on Mars? Have you ever come across any figures on how long it took after the Earth cooled (?) to moderate temperatures and seas formed before life began here? I'm real hazy on the pre-Cambrian.
The great circumchrysean outflow events might've been triggered by volcanic heating/melting of permafrost plugs, or impacts. There are similar channels in other regions like eastern Hellas. They may have lasted only a few days. Earth had cooled somewhat by c 4 billion years ago but the first life might've been extremophile/thermophilic.
ok interesting hope I get a chance to study up more on these things but my impression is still that there's a huge amount that's not known...I had never heard of those giant undersea polygons before, did they have any theories as to their cause?
They may not know the exact way they were formed just that they're associated with an ocean environment.
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