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Barsoomer


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PostPosted: March 29, 2013 1:05 AM 

[link]

"Curious Mars" article says Gale had three deep lakes.

Barsoomer


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PostPosted: March 29, 2013 1:26 AM 

[link]

Quote:

"Recent measurements of air temperature and pressure recorded by the Mars Science Laboratory on the Curiosity Rover, which landed in Gale Crater last August, suggest that liquid water potentially would be stable there during the warmest portion of each day," said Dinwiddie.

hortonheardawho


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PostPosted: April 2, 2013 11:49 AM 

Sol 0231 3D MAHLI of white stuff in rock crack:

I flip-flop between seeing a fresh deposit of frost and an ancient deposit of gypsum.

Does anyone know exactly where this is - and perhaps have pictures before sol 0200?

Perhaps frost can persist for days or weeks or months after formation in protected spots? My Earthly experience is that ice and snow can persist for months in near zero C air temperatures with just a little bit of shade.

Wildcat


Posts: xxx

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PostPosted: April 2, 2013 2:11 PM 

I don't believe it is frost.

If that constitutes a "protected spot," we'd be seeing a lot more frost under shadowy overhangs and on the sides of rocks close to the ground.

Wildcat


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PostPosted: April 2, 2013 2:13 PM 

Unless, of course, Curiosity broke that rock before Sol 200 and the rock has been well-covered by Curiosity for over three weeks due to the lack of movement?

Wildcat


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PostPosted: April 2, 2013 2:17 PM 

But, comparing it to this image:

. . . it makes minerals more likely. Clearly, that is not frost in the picture I posted. The "frost rock" undoubtedly has these same minerals seeing as how they are close together and in the same area.

Wildcat


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PostPosted: April 2, 2013 2:28 PM 

Interesting formation:

Source:

Barsoomer


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PostPosted: April 3, 2013 4:07 PM 

http://www.uahirise.org/images/2013/details/cut/msl-parachute-motion.gif

MSL parachute flapping in the wind.

Wildcat


Posts: xxx

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PostPosted: April 7, 2013 9:46 PM 

Interesting dark "stains" on these rocks:

Kevin


Posts: xxx

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PostPosted: April 8, 2013 10:15 AM 

Curiosity traces the loss of Martian air:

http://www.bbc.co.uk/news/science-environment-22063337

MPJ


Posts: 250

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PostPosted: April 8, 2013 2:43 PM 

Some more signal among the medial noise around the MSL mission: humidity measurements published at last:
http://mars.jpl.nasa.gov/msl/multimedia/images/?ImageID=5208

40+ % RH during the first ~60 Sols of the mission sounds interesting. Interesting too: RH peaks recorded during lowest temperatures of the corresponding Sols and a sharp decrease after Sol 60 with follow up stabilizing plateuo RH measurements in the cause of Martian spring in Gale.

Barsoomer


Posts: 344

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PostPosted: April 8, 2013 3:57 PM 

Very interesting, MPJ. Thanks very much for that link.

If the absolute humidity stayed constant, the relative humidity should vary inversely with the temperature. This makes the peak in BOTH RH and coldest night-time temperature near Sol 50 puzzling and very interesting.

It may suggest a ground or atmospheric hot spot coupled with localized dampness. I wonder if DAN recorded a peak around the same time?

LWS


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PostPosted: April 9, 2013 12:51 AM 

MPJ / Barsoomer;

Were the Viking Humidity measurements made of absolute or relative humidity? NASA claims that these humidity measurements are the first made on Mars.

Winston

MPJ


Posts: 250

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PostPosted: April 9, 2013 4:42 AM 

On a second thought the result of peak RH readings at the lowest recorded temperatures is not really a surprise as colder air can hold less humidity than warmer air.

A measurement of absolute humidity really would come in handy to put the REMS data into a useful context. Figures at hand (from Wikipedia) is a general water vapor level at 210 ppm in the Martian atmosphere. That would roughly translate into a precipitable amount of 125 ppm (0,13g) h2o at 60% RH?

I think the REMS data regarding h2o needs a really detailed look at.

Winston, I cant find any references to Viking humidity measurements. Sad

hortonheardawho


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PostPosted: April 9, 2013 9:47 PM 

this is my first post from my s390g phone!

Mizar


Posts: 692

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PostPosted: April 10, 2013 4:00 PM 

Works fine Horton, I have make several posts from my HTC phone too ... Wink

LWS


Posts: 3062

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PostPosted: April 10, 2013 9:50 PM 

MPJ; I think Levin made reference to Humidity measurements by Viking in one of his papers. But I might be wrong.

Winston

Barsoomer


Posts: 344

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PostPosted: April 10, 2013 10:32 PM 

This paper has a formula for computing Absolute Humidity from Relative Humidity and temperature.

This paper says there is more than one way of computing Relative Humidity in subzero temperatures.

This [link] gives some general information.

MPJ


Posts: 250

Reply: 319



PostPosted: April 11, 2013 4:54 AM 

Winston, the figures for water vapor content of Mars (absolute humidity) of Wikipedia are based on Viking measurements (still no reference on how they obtained them back in the days). Also the given figure is questionable to be used for every spot of measurements on Mars. Compare with what is stated (Wikipedia) for the atmosphere of Earth: "About 1% water vapor (varies with climate)"

Nonetheless Barsoomers links above do show what I mean with "the REMS data regarding h2o needs a really detailed look at" Smile

Wasn't there some recent papers discussing super-cooling effects in atmospheric diurnal cycling of Mars lately?

Barsoomer


Posts: 344

Reply: 320



PostPosted: April 11, 2013 11:35 PM 

http://meetingorganizer.copernicus.org/EGU2013/EGU2013-3870-1.pdf

Quote:

"The humidity observations were validated after tedious efforts. This was needed to compensate for the artifacts of the transducer electronics. The compensation process includes an assumption that the relative humidity at Mars in the temperature range of 0 to -30 ◦C is about zero. The final relative humidity results appear to be convincing and are aligned with earlier observations of the total atmospheric precipitable water contents as well as with the modeling results. [3,4,5]"

In my mind, this calls into question their results.

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