IPB

Welcome Guest ( Log In | Register )

14 Pages V  « < 4 5 6 7 8 > »   
Reply to this topicStart new topic
NASA Images Suggest Water Still Flows on Mars
tuvas
post Dec 6 2006, 10:48 PM
Post #76


Member
***

Group: Members
Posts: 428
Joined: 21-August 06
From: Tucson, AZ
Member No.: 1062



QUOTE (deglr6328 @ Dec 6 2006, 03:29 PM) *
It should be noted that IF this is water (I want to see NIR spectra with a niiiiiice OH stretch absorption peak right at 1.5 microns before I totally discount liquid CO2) then the conditions are perfect for lyophilization of bacteria etc. in the water as it escapes the ice dam and vaporizes/freezes. This would be THEE ideal spot to collect samples for a return analysis.


Liquid CO2? Is that even possible at Mars? Somehow I don't think so... But I could be wrong...
Go to the top of the page
 
+Quote Post
mhoward
post Dec 6 2006, 10:50 PM
Post #77


Senior Member
****

Group: Moderator
Posts: 3385
Joined: 11-August 04
From: USA
Member No.: 98



QUOTE (Stu @ Dec 6 2006, 09:10 PM) *
That "flowing, boiling acidic" water might be thick with microbes all shouting "Wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee!!!!!!!!!!!!!!" as they fly through the air... admittedly mere seconds before dying a horrible death, but hey... wink.gif


You pays your money, you takes your chances...
Go to the top of the page
 
+Quote Post
Guest_AlexBlackwell_*
post Dec 6 2006, 10:52 PM
Post #78





Guests






QUOTE (tuvas @ Dec 6 2006, 12:48 PM) *
Liquid CO2? Is that even possible at Mars? Somehow I don't think so... But I could be wrong...

Most of us don't think so.

But I see you haven't visited the Wild, Wild World of Hoffmanland. In that case, you'll need directions.

Make sure you're seated during the tour, though rolleyes.gif
Go to the top of the page
 
+Quote Post
Anoolios
post Dec 6 2006, 11:11 PM
Post #79


Newbie
*

Group: Members
Posts: 6
Joined: 5-January 06
Member No.: 635



This amateur is still skeptical, is the only evidence of water in these gullies the relative albedo (light instead of dark like most other dust/sand deposits)? The most likely explaination seems to me to be dry avalanches.
Go to the top of the page
 
+Quote Post
Guest_AlexBlackwell_*
post Dec 6 2006, 11:17 PM
Post #80





Guests






QUOTE (Anoolios @ Dec 6 2006, 01:11 PM) *
This amateur is still skeptical, is the only evidence of water in these gullies the relative albedo (light instead of dark like most other dust/sand deposits)? The most likely explaination seems to me to be dry avalanches.

It's always good to be skeptical, Anoolios. That is a hallmark of good science.

As for your question, have you seen this page? Note that Malin et al. don't rely just on albedo, though that is a key piece of evidence.
Go to the top of the page
 
+Quote Post
helvick
post Dec 6 2006, 11:23 PM
Post #81


Dublin Correspondent
****

Group: Admin
Posts: 1792
Joined: 28-March 05
From: Celbridge, Ireland
Member No.: 220



QUOTE (John M. Dollan @ Dec 6 2006, 08:27 PM) *
Considering the rate that the Earth intercepts meteors, and adding to that Mars' thinner atmopshere, would it not stand to reason that impacts would reach the surface much, much more often?

The rate is higher but it's not as high as you might think given the difference in densities at the surface. The martian atmosphere is extremely thin and at the surface is comparable to the Earth's at around 35KM but because of the lower martian gravity it's scale height is higher (~11km vs ~6km for earth) it is remarkably similar in density to the Earth's atmosphere once you get above 75km or so if I remember correctly. For the most part it filters out a similar amount of "stuff". By similar I'd guess we're talking about a similar order of magnitude here but I'd have to do some digging to get a number I'd be willing to defend.

The percentage that reaches the ground is higher for another reason that could well be as important - the average atmospheric impact speed at mars orbit is slightly slower (5-10km/sec slower) and so there is less energy to dissipate. For asteroidal debris this is quite significant as the impact speed can be as low as 7km/sec at mars (vs ~17km/sec typically for Earth) so only about 17% of the energy needs to be disipated. Cometary and retrograde impacts are a different animal and the difference at Mars for these (compared to earth) is 80% and 50% respectively.

The main reason there are more apparent craters on Mars is that the surface is (for the most part) really and truly ancient and erosion rates are many orders of magnitude slower than on earth.
Go to the top of the page
 
+Quote Post
Guest_AlexBlackwell_*
post Dec 6 2006, 11:29 PM
Post #82





Guests






QUOTE (helvick @ Dec 6 2006, 01:23 PM) *
The main reason there are more apparent craters on Mars is that the surface is (for the most part) really and truly ancient and erosion rates are many orders of magnitude slower than on earth.

Also, proximity to the asteroid belt and Jupiter.
Go to the top of the page
 
+Quote Post
John M. Dollan
post Dec 6 2006, 11:31 PM
Post #83


Junior Member
**

Group: Members
Posts: 21
Joined: 31-January 05
From: Havre, MT
Member No.: 163



QUOTE (helvick @ Dec 6 2006, 04:23 PM) *
The rate is higher but it's not as high as you might think...


Thanks for that clarification. It definitely helped me with an off-list discussion.

...John...


--------------------
"To make an apple pie from scratch, you must first create the universe..."
-- Carl Sagan
Go to the top of the page
 
+Quote Post
centsworth_II
post Dec 6 2006, 11:40 PM
Post #84


Senior Member
****

Group: Members
Posts: 2024
Joined: 28-December 04
Member No.: 132



QUOTE (Stu @ Dec 6 2006, 04:47 PM) *
.... but come ON people!!! WATER ON MARS!!!! I refuse to let anyone spoil this night for me, not after I've longed for this news for so long....

The reason this news IS really exciting is that for the first time we can think of sending instruments to examine material which recently interacted with liquid water on Mars. Previously it was looking like we would have to wait for a machine which could drill hundreds of meters beneath the surface. The big question now is was the water ancient ice, melted and released in one brief event or are there liquid aquifers which occasionally find their way to the surface?
Go to the top of the page
 
+Quote Post
ElkGroveDan
post Dec 6 2006, 11:47 PM
Post #85


Senior Member
****

Group: Admin
Posts: 4636
Joined: 15-March 05
From: Sloughhouse, CA
Member No.: 197



QUOTE (tuvas @ Dec 6 2006, 02:48 PM) *
Liquid CO2? Is that even possible at Mars?


You decide:
Attached thumbnail(s)
Attached Image
 


--------------------
If Occam had heard my theory, things would be very different now.
Go to the top of the page
 
+Quote Post
Guest_Myran_*
post Dec 6 2006, 11:58 PM
Post #86





Guests






QUOTE
tuvas wrote: Liquid CO2? Is that even possible at Mars? Somehow I don't think so... But I could be wrong...


Liquid CO2 will not be possible in 'open air' with the Martian air as thin as it is, same as on Earth.
But nothing prevents liquid CO2 from being kept underground if it have a good nice aquifier or perhaps a lid of frozen water. Yes the pressure would be great, but this could also explain features like the ones we see here.

I personally think CO2 are a more likely explanation. This simply from looking at the martian temperature range. The surface are simply cold, and when we look underground it should be even colder in most places!
(This except any and still-not-found-despite-looking geotermal hotspots).
Colder conditions underground places the thermometer in the right range for frozen CO2, which happens at -78 C.

Narrow cracks in the ground might become CO2 traps when the area chills down in the night. We also seen signs of karst topography in Meridiani, if that idea turns out to be correct there might even be larger caves where CO2 ice accumulate on the walls. When it melts at −57 C there might not be space for it to expand and reach the gasous phase and so it rush towards the nearest opening - and so we have a gully.

So I am fairly in the same camp as deglr6328 on this one.
Go to the top of the page
 
+Quote Post
Guest_AlexBlackwell_*
post Dec 7 2006, 12:06 AM
Post #87





Guests






QUOTE (Myran @ Dec 6 2006, 01:58 PM) *
Liquid CO2 will not be possible in 'open air' with the Martian air as thin as it is, same as on Earth.
But nothing prevents liquid CO2 from being kept underground if it have a good nice aquifier or perhaps a lid of frozen water. Yes the pressure would be great, but this could also explain features like the ones we see here.

There are plausibility arguments against sequestration of liquid CO2 in the martian near-surface. For example, see Stewart and Nimmo [2002] (440 Kb PDF).
Go to the top of the page
 
+Quote Post
Guest_Myran_*
post Dec 7 2006, 12:28 AM
Post #88





Guests






QUOTE
AlexBlackwell wrote: There are plausibility arguments against sequestration of liquid CO2 in the martian near-surface.


Thank you, and I took the time to speed read a part of that text you linked. smile.gif

But you are absolutely right, I wrote about liquid CO2 in the first paragraph since that was what tuvas asked about.

But the following sentence lacks the word 'frozen' and should have read.
"I personally think frozen CO2 are a more likely explanation .......... at -78 C."

(And for once I dont edit, since I got back to the subject so fast)

Finally I take the opportunity to link a text where the author points out that the gullies seems to appear on the slopes facing away from the sun. Something that again are one sign that we might not be seeing the activity of water here.

And then again another link to one text that also discuss the CO2 as one alternative explanation for the gullies. Liquid CO2, Not Water, Likely Created Martian Gullies
Go to the top of the page
 
+Quote Post
Guest_AlexBlackwell_*
post Dec 7 2006, 12:33 AM
Post #89





Guests






QUOTE (Myran @ Dec 6 2006, 02:28 PM) *
Finally I take the opportunity to link a text where the author points out that the gullies seems to appear on the slopes facing away from the sun.

Thanks, Myran. And yes, I'm familiar with Nick Hoffman's views. biggrin.gif
Go to the top of the page
 
+Quote Post
exoplanet
post Dec 7 2006, 12:33 AM
Post #90


Junior Member
**

Group: Members
Posts: 47
Joined: 19-February 05
Member No.: 171



QUOTE (Steve @ Dec 6 2006, 07:21 PM) *
"As Steve Squyres mentioned in response to a question at Open University, the "water" on mars is acidic and inhospitable to life. That suggests that this AP article may be premature.
Steve"


Ahem . . . but we have at least one if not many more examples . . . which proves that life in extemely acidic niches on earth is actually TEEMING with microbes.

Please see this article. If you need more, Steve . . . please let me know.

http://www.sfgate.com/cgi-bin/article.cgi?...MNGBCCCDD21.DTL

I hope that Steve Squires has at least noted recently that extremely acidic environments on earth are not barren of life but do support strong colonies of microorganisms. What this means on Mars should not preclude that life does not exist. To the contrary with regards to the recent images and future images to come:)
Go to the top of the page
 
+Quote Post

14 Pages V  « < 4 5 6 7 8 > » 
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 20th April 2014 - 05:45 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.