Temperature and pressure at Gale, Suitable (for short periods) for liquid water? |
Temperature and pressure at Gale, Suitable (for short periods) for liquid water? |
Sep 30 2012, 03:23 PM
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Junior Member Group: Members Posts: 62 Joined: 11-July 11 Member No.: 6058 |
Just a quick query from someone with no background in science. Obviously, MSL has AFAIK not returned evidence of recent (i.e. years/decades) liquid water in its vicinity; however, I was interested by the following graphs:
08.21.2012: First Pressure Readings on Mars http://mars.jpl.nasa.gov/msl/multimedia/images/?ImageID=4501 08.21.2012: Taking Mars' Temperature http://mars.jpl.nasa.gov/msl/multimedia/images/?ImageID=4502 The first indicates that the pressure between 15 Aug and 18 Aug never dropped below c. 690 millibars; the second shows that, for a period of a couple of hours on 16 Aug, the temperature rose above freezing. If water had been present on the surface, then, would it have been liquid during this brief period? The pressure and temperature seemed to satisfy the conditions for liquid water as I understand them (indeed, the pressure seems to be high enough (just) on a 24-hour basis to allow for the presence of liquid water). Thanks in advance for your opinions (corroborative or not!) on this. |
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Oct 11 2012, 04:43 AM
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Newbie Group: Members Posts: 5 Joined: 20-August 12 From: Knoxville, TN Member No.: 6595 |
In a private message to me, Eyesonmars indicated that:
QUOTE ... southern summer daytime temperatures (are) about 30c warmer than the equivalent latitude in the northern hemisphere. In my previous post, I had made the erroneous assumption that Mars would be symmetrical with regards to average temps at a given latitude. I knew that there is a big average elevation asymmetry between north and south, but I didn't know about the temperature difference. I have since learned that the difference is caused primarily by the high orbital eccentricity, whereby Mars is significantly closer to the sun during southern summer compared to northern summer. With a little digging I found the TES (Thermal Emissions Spectrometer) data from the MGS (Mars Global Surveyor) mission. This graph shows clearly that the daily max temperatures are well above freezing in the Hellas Basin during many days in the local summer, just as Eyesonmars pointed out. I apologize for the mistake -- I should have been more careful. It seems clear to me that the pressure/temperature conditions are such that, at least in some places and at some times of the year (including Gale and Hellas), liquid water COULD exist during the day on the surface of Mars -- although, as has already been mentioned up-thread, the evaporation rate would likely be very high. And of course, this is only relevant IF there is any water left to be liquid. Mark |
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