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> That liquid water once stood on Mars' surface or flowed freely at times seems obvious. > However, climate models, based on the limited evidence to date of wh

> That liquid water once stood on Mars' surface or flowed freely at times seems obvious. > However, climate models, based on the limited evidence to date of what the atmosphere was like, have struggled to simulate a Mars on which conditions were warm enough to allow lots of liquid water. Much of it would have been locked up in ice, they suggest. Bit contradictory here.

andrewflnr 10y ago
Not really. We know there was liquid water, we just don't know how.
- avenoir 10y ago
  Do we? Sept. 28, 2015 - We found water! > These downhill flows, known as recurring slope lineae (RSL), often have been described as possibly related to liquid water. The new findings of hydrated salts on the slopes point to what that relationship may be to these dark features. The hydrated salts would lower the freezing point of a liquid brine, just as salt on roads here on Earth causes ice and snow to melt more rapidly. Scientists say it’s likely a shallow subsurface flow, with enough water wicking to the surface to explain the darkening. [1] Aug. 23, 2016 - Maybe not... > "Some type of water-related activity at the uphill end still might be a factor in triggering RSL, but the darkness of the ground is not associated with large amounts of water, either liquid or frozen," Edwards said. "Totally dry mechanisms for explaining RSL should not be ruled out." [2] [1] https://www.nasa.gov/press-release/nasa-confirms-evidence-that-liquid-water-flows-on-today-s-mars https://www.nasa.gov/press-release/nasa-confirms-evidence-th... [2] https://mars.jpl.nasa.gov/news/test-for-damp-ground-at-mars-seasonal-streaks-finds-none https://mars.jpl.nasa.gov/news/test-for-damp-ground-at-mars-...
  - lutusp 10y ago
    Your references discuss evidence for transient liquid water (brine) flowing in the present, not the past. There's good evidence that there was plenty of water on Mars billions of years ago.
  - quakeguy 10y ago
    Excellent! We cannot be sure about water on Mars, at all. Extraplanetary weather forecast is hard, and bound to produce a lot of errors.
rlkf 10y ago
Observations and models don't match, so there is some input that is missing. In this case it seems to be a heavier atmosphere (which has later blown away). Their hopes are that this added assumption will reconcile the observations and models, and thus give a more complete picture on how Mars developed.
the_d00d 10y ago
I disagree. The section you are quoting is titled 'climate conundrum'. The writer is saying that it is visually obvious that there was running water at some point, but climate models do not support this. That is why it is a .....conundrum.
- deleted 10y ago
  [deleted]
elastic_church 10y ago
I thought there was an isotope within mars water samples (or the dirt) that would allow water to stay in the liquid state at much lower temperatures
salesguy222 10y ago
It seems the photographic evidence shows there was once flowing water on Mars http://lmgtfy.com/?q=mars+pebbles+rocks+possible+water http://lmgtfy.com/?q=mars+pebbles+rocks+possible+water

andrewflnr 10y ago

Not really. We know there was liquid water, we just don't know how.

avenoir 10y ago
Do we? Sept. 28, 2015 - We found water! > These downhill flows, known as recurring slope lineae (RSL), often have been described as possibly related to liquid water. The new findings of hydrated salts on the slopes point to what that relationship may be to these dark features. The hydrated salts would lower the freezing point of a liquid brine, just as salt on roads here on Earth causes ice and snow to melt more rapidly. Scientists say it’s likely a shallow subsurface flow, with enough water wicking to the surface to explain the darkening. [1] Aug. 23, 2016 - Maybe not... > "Some type of water-related activity at the uphill end still might be a factor in triggering RSL, but the darkness of the ground is not associated with large amounts of water, either liquid or frozen," Edwards said. "Totally dry mechanisms for explaining RSL should not be ruled out." [2] [1] https://www.nasa.gov/press-release/nasa-confirms-evidence-that-liquid-water-flows-on-today-s-mars https://www.nasa.gov/press-release/nasa-confirms-evidence-th... [2] https://mars.jpl.nasa.gov/news/test-for-damp-ground-at-mars-seasonal-streaks-finds-none https://mars.jpl.nasa.gov/news/test-for-damp-ground-at-mars-...
- lutusp 10y ago
  Your references discuss evidence for transient liquid water (brine) flowing in the present, not the past. There's good evidence that there was plenty of water on Mars billions of years ago.
- quakeguy 10y ago
  Excellent! We cannot be sure about water on Mars, at all. Extraplanetary weather forecast is hard, and bound to produce a lot of errors.

rlkf 10y ago

Observations and models don't match, so there is some input that is missing. In this case it seems to be a heavier atmosphere (which has later blown away). Their hopes are that this added assumption will reconcile the observations and models, and thus give a more complete picture on how Mars developed.

the_d00d 10y ago

I disagree. The section you are quoting is titled 'climate conundrum'. The writer is saying that it is visually obvious that there was running water at some point, but climate models do not support this. That is why it is a .....conundrum.

deleted 10y ago
[deleted]

elastic_church 10y ago

I thought there was an isotope within mars water samples (or the dirt) that would allow water to stay in the liquid state at much lower temperatures

salesguy222 10y ago

It seems the photographic evidence shows there was once flowing water on Mars http://lmgtfy.com/?q=mars+pebbles+rocks+possible+water http://lmgtfy.com/?q=mars+pebbles+rocks+possible+water