[X] My Assistant

[imipak]

Thanks everyone, I thought there'd be some interesting comments here as soon as I saw the story.

On a somewhat related note, I'm indebted to the wonderful IT site The Register for pointing out some amazing HiRISE pics of avalanches "caught in the act". Not terribly relevant to this discussion, but great images!

http://www.nasa.gov/mission_pages/MRO/mult...o20080303a.html
http://www.nasa.gov/images/content/214808m..._2640_hires.jpg

[jamescanvin]

On a somewhat related note, I'm indebted to the wonderful IT site The Register for pointing out some amazing HiRISE pics of avalanches "caught in the act".

Of course the UMSF thread on this was started some 17 hours before that article was published.

[imipak]

Of course the UMSF thread on this was started some 17 hours before that article was published.

:blush: ! Apologies...

[SickNick]

Thanks everyone, I thought there'd be some interesting comments here as soon as I saw the story.

On a somewhat related note, I'm indebted to the wonderful IT site The Register for pointing out some amazing HiRISE pics of avalanches "caught in the act". Not terribly relevant to this discussion, but great images!

http://www.nasa.gov/mission_pages/MRO/mult...o20080303a.html
http://www.nasa.gov/images/content/214808m..._2640_hires.jpg

Don't be so quick to write off these avalanche pix. They're one end member of processes on Mars. Personally, I agree that the gullies are evidence of FLUIDS on Mars, but disagree about LIQUIDS. given the steep slopes of crater walls and other gully locations, and especially my favourite area of near-polar gullies, Sisyphi Cavi, where I argue we have ALREADY seen annual flows with the thaw of CO2 snowpack.

http://www.earthsci.unimelb.edu.au/mars/Polar.html

It's about time that I updated those web pages, but I've been a tad busy the last few years...

[Juramike]

space.com article references recent PNAS article. (PNAS article is still upcoming.)

The authors (Head et al.) conclude that some gullies were formed by melting windblown snow trapped in pockets left behind by recent martian glaciers.

-Mike

[marsbug]

As important as the question of water on present day / geologically recent mars is, it sometimes feels like we're going around in circles with it.
Edit: Apologies, especially to Juramike, that was bad tempered of me.

[Juramike]

(no offense taken...)

I'm sure the pendulum of scientific argument still has several more swings left to it.


[This crossed my desk the other day:
"When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."
-- Arthur C. Clarke, Clarke's first law]

[[PPS: The quote above is NOT pointed at anyone/any opinion in particular.]]

[stevesliva]

[[PPS: The quote above is NOT pointed at anyone/any opinion in particular.]]

oooh, but it's a great one to use in response to all of the first-blush opinions about other issues... on a different forum, of course Occam's razor isn't exactly the right tool.

MODERATOR EDITED

(Comment from Steve-- That's perfect, thanks )

[marsbug]

Personally ( and probably this is a bit weasel of me but even so..) I think conditions on mars have varied enough for both wet, damp, ever so slightly damp, and totally dry flows to have happened, although perhaps with a strong bias to the dry end of things. It just nags me that the issue keeps coming back up and being chewed over and none of us ever seem convinced enough by evidence one way or the other to reach a general consensus.

[Juramike]

Head et al. PNAS (2008) Early edition (August 25, 2008). "Formation of gullies on Mars: Link to recent climate history and insolation microenvironments implicate surface water flow origin." doi: 10.1073/pnas.0803760105

Article now available as Early Edition. Abstract here. (Warning: When published, this link might change.)

-Mike