Reythia
Squire
Hero
Registered: 11-2005
Posts: 928
|
|
Reply | Quote
|
|
Ice on Mars
Yet another interesting seminar day for me -- and so, of course, you get to hear about it! 
Today's talk was by Dr Holt at UTIG, who studies radar results of ice fields. He's done a lot of work using airborne radar in Antarctica, and recently has been using the SHARAD (pronounced llike the word "charade", which I find an amusing acronym!) imager on the Mars Reconnaissance Orbiter (MRO). The talk was about the latter work.
I knew that ice (water-ice, that is, not just CO2-ice) had been found on Mars, of course. The Phoenix pictures were very clear, and I'd also heard about the water-ice around the northern pole. But Holt talked about a new type of ice (to me, at least), which was fascinating.
Apparently there are THREE different locations that water-ice can be found on Mars:
1.) Near-surface "permafrost" water, like what Phoenix found.
2.) Permanent polar ice caps (on both poles, though the north's is larger).
3.) Mid-latitude rock-covered glaciers, sheltered by large, mesa-like hills.
Yeah, that's right: they think that Mars used to have GLACIERS, back when its orbital obliquity was much larger than now. (That's the same reason that Earth had ice ages, but the obliquity change would have been much larger on Mars, since it doesn't have a stabilizing moon orbiting it.) Anyhow, when Mars' orbit shifted again, most of the water-ice melted or sublimed. But some of the glaciers (or full ice sheets, even!) were backed up against these cliffs. The cliffs would occasionally experience landslides, which would bring layers of rock and dust down over the ice. Some of those glaciers were buried around the time of the obliquity-changing event, which would have protected them from a suddenly (geologically-speaking) cooler, drier atmosphere.
The part that shocked me, though, was the depths that SHARAD measured. Bear in mind that the instrument has a resolution of no less than 8-15 meters. It measured "no to little" overlying rock build-up -- meaning that less than 15 meters of rock is currently burying these glacial ice deposits. And the thickness of the modern glaciers? Maybe two kilometers thick!
Now there's a source for a near-future Mars scifi story. And, even more important to me, there are a few dozen excellent sites for real-life Mars colonies!
So... when do we leave?! 
---  -- YAR! |
|
6/30/2009, 8:27 pm
|
Send Email to Reythia
Send PM to Reythia
AIM
MSN
|
QS2
Shepherd
Hero
Registered: 03-2006
Posts: 1027
|
|
Reply | Quote
|
|
Re: Ice on Mars
Hehe, well that is interesting. I'd heard about speculation of ice or water further away from the poles before, but nothing quite as accessible or large as this. 
|
|
7/1/2009, 12:08 am
|
|