Earthlike Mars? Options

[MarsIsImportant]

I suppose it would help to see the images before registering a "definitive" opinion on the subject.

But on its surface, the word definitive is rather strong. Even if the paper does not actually use that word and it is a reporting error, it does say "first direct evidence". As far as "first" is concerned, I doubt it. "Direct evidence" maybe somewhat subjective. I want to see the images in unambiguous HiRise first.

[Marz]

FYI: NOVA's latest Mars show, "Is There Life on Mars", does an excellent job summarizing the latest results & discoveries from MRO, Odyssey, Phoenix, and MER.

http://www.pbs.org/wgbh/nova/mars/

It also briefly describes:
-- the giant-impact theory for the northern basin
-- possible climatic history
-- comparison on how Meridiani was very acidic with evaporite deposits, yet the chemistry of where Phoenix sampled was slightly basic (Calcium carbonate!), lightly salty, with perchlorate present (and how perchlorate may improve the chances for microbial life).

[Dominik]

Too sad, it's only available for the audience in the USA .

I really would love to watch "Is There Life on Mars?".

[SFJCody]

I imagine life could certainly have occurred on Mars in the past and may still be present today provided there is sufficient water underground. We know from the Martian flood channels that there were once vast TORRENTS (hint hint) of water on the surface.

[Juramike]

Well....looking at the morphology of the channel networks, it appears that the channel networks were not formed by rainfall, but rather from subsurface reservoirs.

Check out:
Gulick, V.C. Geomorphology 37 (2001) 241-268. "Origin of the valley networks on Mars: a hydrological perspective." (pay for article, link here)

Fully freely accessible articles (confess I haven't read these yet):
http://www2.ess.ucla.edu/~nimmo/ess250/baker.pdf

Carr and Head, GEOPHYSICAL RESEARCH LETTERS, VOL. 30 (2003) , NO. 24, 2245. "Basal melting of snow on early Mars: A possible origin of some valley networks". doi:10.1029/2003GL018575
(accessible here)


The Gulick (and others) articles give very good evidence that the valley networks were formed from subsurface sources (amphitheatre-headed valleys, very low drainage densities, low-Strahler order networks with high bifurcation ratios, etc.).

The valley networks are also very localized. One example in the Gulick article was of a dense valley system in Warrego Valles that was situated along a topographic break - yet neighboring areas also on the topographic break (same geology, same climate) were totally devoid of channels.

Their hypothesis is that Mars was covered in snowfall and melted in a few places due to magmatic activity and released water catastrophically. Other regions of snowfall that didn't melt quickly simply sublimed away slowly.

[SFJCody]

Well....looking at the morphology of the channel networks, it appears that the channel networks were not formed by rainfall, but rather from subsurface reservoirs.

Well, yes! The word torrent, according to wikipedia "generally signifies a strong flow of something, especially fluids and particles". By using it I was not implying that the channels were caused by precipitation.

[glennwsmith]

Here's an interesting reference (on an interesting site) to Oceanus Borealis (about halfway down the page):

http://oklo.org/2006/12/

[stewjack]

For those who wanted to watch the NOVA show Is There Life on Mars? produced by PBS; the full show is now freely available for streaming in six "chapters." ( 1 Hour show )

QuickTime or Windows Media Player streaming formats are provided.

NOVA: Is There Life on Mars?

You won't get a review from me. No way!

[kohare]

For those who wanted to watch the NOVA show Is There Life on Mars? produced by PBS; the full show is now freely available for streaming in six "chapters." ( 1 Hour show )

But only available within the USA

[RJG]

Quite by chance I found that I could watch it on my laptop - then realised it was because I was running Hotspot Shield (http://anchorfree.com), a freebie on a recent cover disk. As a side effect, Hotspot Shield appears to confuse the server into thinking I'm in the US...

Rob
(UK)

[stewjack]

But only available within the USA

I apologize. I don't see anything about that on the web page. They fail to mention it in the technical help section also.

[glennwsmith]

Just a reminder to participants in this thread (which should really be entitled "Oceanus Borealis") that we are fast approaching the climax of the LCROSS mission to search for water at the lunar south pole, the results of which have a major bearing, it seem to me, on whether we can also expect to find a frozen ocean hidden beneath the dust of the northern plains of Mars.

[Juramike]

Hmmm. Not sure on that. If I got it right, the volatiles on our Moon were delivered by comet impacts long after it's formation, spraying volatiles all over, some of which settled in cold traps (permanently shadowed craters).

The water on Mars presumably was there from it's formation and is residual from it's early days.

(Trying to figure out predicted H/D ratios, here....Mars should be HDO enriched from several cycles of evaporation/sputtering-loss of lighter mass H2O/recondensation. The Moon on the other hand should be closer to the primordial H/D ratio - thes more H2O. If anything ever evaporated it would be a one way trip off Luna....)

[glennwsmith]

Yet another indication of -- dare I say it -- water on Mars:

http://spacefellowship.com/2009/09/15/evid...e-beds-on-mars/

And in reference to Oceanus Borealis, the idea as I understand it is that a meteor impact can melt part of the underlying frozen ice ocean, which in turn dries up to leave the polygonal formations which we see today.

[Fran Ontanaya]

If those cracks are so ancient, why aren't they filled here and there with dust?