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#101 2012-08-30 21:27:21

SpaceNut
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

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#102 2012-09-01 11:32:07

GW Johnson
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Re:  Vincent post 88 on partial pressure --

What you said is true,  but there's a tad more to the picture.  A liquid water pool at 0 C in a closed system will evaporate slowly toward equilibrium,  and humidify the space above to a partial pressure of water vapor of 6.1 mbar,  regardless of any dry gas inside the container.  The total pressure in the container will then be the sum of that water vapor partial pressure,  and the original dry gas pressure,  which is now its partial pressure.  The same is true of a 0 C ice cube,  it's just slower. 

If on the other hand,  you put some 0 C liquid water in a closed container and suddenly (magically) remove all the atmosphere above it,  you have a very nonequilibrium situation.  That water will boil violently and suddenly freeze in the act of boiling (latent heat comes from internal energy).  The resulting ice will sublime,  getting colder as it does (again,  latent heat coming from internal energy),  putting a few mbar worth of water vapor as atmosphere in the closed container.  Eventually,  with transfer of a tad of heat into the container to bring the ice back to 0 C,  there is a 6.1 mb water vapor atmosphere in the container at final equilibrium. 

That thought experiment does not correspond exactly to Mars,  but it's not that far away,  either.  My point is that liquid water exposed on the surface of Mars in any significant volume will boil violently away,  as it cannot significantly humidify the atmosphere above it.  That's because the atmospheric currents carry the vapor cloud away as fast as the boiling can produce it.  It does take time for this to occur,  so you can have a temporary river or lake on Mars today,  but it will boil away,  sooner or later.  Water droplets may not actually boil,  but they will evaporate fairly quickly.  And thin layers of ice sublime away in hours or less,  we've already seen that. 

For that not to occur at 7-8 mbar local total pressure,  the local atmosphere must be at least 6.1 mbar water vapor,  leaving only 1-2 mbar CO2 pressure.  I do not see how that could occur,  even in a closed container,  since any gas can only hold a limited amount of water vapor without condensation.  Plus there's an enormous mass of 7-8 mbar CO2 on Mars,  not 1-2.  You might see a local snow flurry above a liquid pool boiling away on Mars,  but it would all eventually be carried away on the wind,  even the ice (because it would sublime). 

GW


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#103 2012-09-01 11:38:29

GW Johnson
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Re: Fuzzy pictures / disappointment with NASA --

Read the book "The Death of Common Sense" to find out why government bureaucracies petrify into uselessness and complete inability to function,  over time.  Yes,  this has happened in the US,  and yes,  it has happened to NASA (that's why they cannot do the amazing wonders rapidly,  like they did around 1960-1970).

Of course the pictures could and should be better for the price tag.  But it would take the NASA of 1960 to do that.  It's a wonder that NASA-JPL can still build probes that can land on Mars at all.  Sometimes I think that's the only part of NASA that still works at all. 

I yield the soapbox, 

GW


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#104 2012-09-01 18:45:26

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

GW wrote:
"A liquid water pool at 0 C in a closed system will evaporate slowly toward equilibrium,  and humidify the space above to a partial pressure of water vapor of 6.1 mbar,  regardless of any dry gas inside the container."

First, water "vapor" does not require 6.1mb, liquid water does. Second, dry gasses that were present do not simply disappear.

Also, NASA has some really great HD images. We are just not going to see them, unless they want us to.

Vincent


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#105 2012-09-02 15:37:35

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

There seems to be some confusion about 6.1 mbs. This is the triple point of water. This is the pressure that water can exist as a Vapor, liquid or solid. This is total pressure, not partial pressure.

Also, temperature regulates phase change, not pressure or partial pressure. On Eoropa Water ice has above it no atmospheric pressure. Zero, nothing. Here water ice behaves as a mineral. Like rock on Earth and water on Titan.


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#106 2012-09-02 15:58:39

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Now, what makes us think liquid water could exist on Mars? Well, we saw it in the polar regions. What was obvious frost in the AM, turned into a damp spot in the PM. Temperatures were -21C, but surface temperatures could have approached -10C.  But we found perchlorate. An antifreeze, indeed.

This image is from Hortonheardawho from the Mars Rover Blog. It looks like a damp spot because it is a damp spot.

Vincent

http://www.flickr.com/photos/11627092@N06/2621265008/


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#107 2012-09-02 18:33:45

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Er.... You want to see frost in the AM. You got it brother.

http://www.flickr.com/photos/11627092@N06/2922215614/


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#108 2012-09-03 09:01:27

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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

The triple point of any pure substance is that combination of temperature and pressure at which all three phases of that substance coexist simultaneously.

The critical point of any pure substance is a point on a three-dimensional graph of temperature, pressure, and molar volume (ratio of volume to amount-of-substance) beyond which that substance can exist only as a gas. Water, for example, has a critical temperature beyond which it will exist only as dry steam. To make it liquid again, one must cool it below this critical temperature and then apply the critical pressure (the pressure coordinate of the critical point).

http://www.co2info.com/co2.html

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#109 2012-09-03 12:40:51

GW Johnson
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

At the triple point of water,  the condensed phase temperature is 0C (ice or liquid),  and the vapor pressure (not total pressure),  is 6.1 mbar.  Look it up in any standard steam table,  metric or US units.  What is listed there is equilibrium vapor pressures.  Says so right on the column headings. 

Actual situations are usually not equilibrium,  but then,  they do not persist "very long" (a relative notion at best).  I doubt the ice surfaces on the outer moons are in equilibrium.  They are in fact slowly subliming.  There's just lots of ice.  4 billion years ago,  those same moons were very probably a lot larger. 

GW

Last edited by GW Johnson (2012-09-03 12:43:47)


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#110 2012-09-06 16:59:35

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Let me stand down from my attacks on the Curiosity Rover, for just a moment. Today there was an image that speaks for us all.

Every complainer, every dreamer, every striver, every wonderer is in this image.

It is an image of all the best ideas we have, posed high in the sky of another world. They have the "good stuff," May they give it, more often.

Vincent



7946242076_736f7c8af1.jpg

Now back to complaining. What would we give for a calibratable high apex color image of the Martian sky?

Last edited by Vincent (2012-09-06 17:16:24)


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#111 2012-09-08 17:46:42

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Now some would compare the state of a steam engine on Earth with Mars. I would not engage in a logical fallacy.
There is a guy on UMSF that could take a lens covered arm image and get this. My hats off.

His name is oersted. Give it up.

Vincent

7958686968_d603f673aa.jpg


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#112 2012-09-09 20:45:47

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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

NASA's Curiosity Mars rover, has driven 109 meters since landing from its landing site. The rover will extend its 2.1-meter arm on Wednesday for the first time since landing as engineers test out the arm and its instruments. Curiosity is about one-quarter the way to its first major destination.

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#113 2012-09-10 10:58:13

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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

If the Mars rover finds water, it could be H2 ... uh oh!.
By Louis Sahagun, Los Angeles Times
September 9, 2012, 5:30 p.m.
Curiosity was first proposed in 2004 under a mission category that would have allowed it to explore a region with ice and water. That category called for sterilizing portions of the spacecraft that would contact the surface of Mars to avoid contamination of moist areas where microbes — from Earth or from Mars — have the best chances of survival.
On Nov. 1, after learning that the drill bit box had been opened, Conley said she had the mission reclassified to one in which Curiosity could touch the surface of Mars "as long as there is no ice or water."
Conley's predecessor at NASA, John D. Rummel, a professor of biology at East Carolina University, said, partly in jest: "It will be a sad day for NASA if they do detect ice or water. That's because the Curiosity project will most likely be told, 'Gee, that's nice. Now turn around.' "
If water is found, Curiosity could still conduct tests from a distance with instruments including a laser and spectrometers.

http://www.latimes.com/news/local/la-me … 5701.story


   Bob Clark


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#114 2012-09-17 10:28:48

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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

New record high temperature in Gale Crater Mars. Since record keeping began over thirty days ago the new all-time record high temperature occurred on sol-35. It reached a balmy +5C or 41F. This is an equivalent September temperature. Expect temperatures to approach 90F in the lazy dusty days of Summer. I wonder if they have "dog days" on Mars.

Last edited by Vincent (2012-09-17 10:31:11)


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#115 2012-09-18 08:20:42

GW Johnson
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Recent news stories indicate they have photographed carbon dioxide snow falling on Mars.  Definitely CO2.  I suspect water ice deposits have been where they are (and shrinking as they sublime) for a long time.  Since the last time the atmosphere was a lot thicker.  Whenever that was. 

Not surprising that CO2 snow happens,  given a CO2 atmosphere and the cold temperatures we see reported.  Actually,  the large swing between very cold and quite warm is not surprising,  given that near-vacuum of an atmosphere.  On the airless moon,  the swing is even further.  It is definitely not a place like the Earth we are innately familiar with. 

GW


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#116 2012-09-19 11:45:58

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

CO2 snow has be reported in the Southern Polar regions. It is a lot colder there with a residual CO2 ice cap, in other words there is CO2 on the ground there all year round. At the Northern Polar Cap H2O ice persist year round and H2O snow was reported aloft. CO2 snow seems likely in the north as well in late winter. Temperatures required for solid CO2 is -125C, but would probably require -140C to reach saturation were precipitation would follow

We know it snows H2O further south because we have seen it in satellite date and surface observations. Image below.

Vincent

2980434815_b47a4d9b74.jpg

Last edited by Vincent (2012-09-19 11:51:50)


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#117 2012-09-19 11:57:47

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

They are looking for H20 in the soil in Gale crater with the Dan. An image this week was suggestive. I will post after the News Conference at 2PM EDT.

Tue, 18 Sep 2012 12:12:20 PM EDT
On Sol 42 (Sept. 17, 2012), Curiosity drove about 105 feet (32 meters), toward the east-southeast, bringing the mission's total driving distance to about 850 feet (259 meters). The Dynamic Albedo of Neutrons (DAN) instrument was used at two stops during the drive to check for hydrogen in the soil beneath the rover.
During this sol, the rover used its Mast Camera to observe Mars' two moons, Phobos and Deimos, as each passed in front of the sun.
Curiosity continues to work in good health. Sol 42, in Mars local mean solar time at Gale Crater, ends at 11:12 a.m. Sept. 18, PDT.


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#118 2012-09-19 13:21:12

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

This image from Hort was posted as a reference to the CHEMCAM  images. It clearly shows a dislodged rock. This shows a change in Albedo even after prolonged ultraviolet exposure.
This is an obvious water signature, unless there is some oil based liquid present on Mars. The tracks of the rover show some of the same characteristics of Miridiani, evident by the high reflectivity in the various light spectrums. This initiated the deployment of the (DAN).

I suspect crystallization under nocturnal conditions with a thermal inertia induced lag. This would preserve H2O crystals into the window of max heating, otherwise it would flash-off. Pressures are above 6.1 hPa

Vincent

8003914166_54362c0025.jpg
1Hort by dfrank39, on Flickr

Last edited by Vincent (2012-09-19 13:50:36)


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#119 2012-09-19 23:49:56

RGClark
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Vincent wrote:

New record high temperature in Gale Crater Mars. Since record keeping began over thirty days ago the new all-time record high temperature occurred on sol-35. It reached a balmy +5C or 41F. This is an equivalent September temperature. Expect temperatures to approach 90F in the lazy dusty days of Summer. I wonder if they have "dog days" on Mars.

Is this air temperature? I don't remember ever seeing for any other Mars lander air temperatures above freezing. Mars Pathfinder showed temperature drops as much as 20C between air temperatures and ground temperatures. So even if the ground temperature was above 0C, which does happen frequently during the day, the air temperature could still be below freezing.


  Bob Clark


Nanotechnology now can produce the space elevator and private orbital launchers. It now also makes possible the long desired 'flying cars'. This crowdfunding campaign is to prove it:
Nanotech: from air to space.
https://www.indiegogo.com/projects/nano … 13319568#/

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#120 2012-09-21 12:28:49

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Mr. Clark,

Here is the link to the mars weather page. You can see the ambient air temperatures. Hit the arrow keys adjacent to the sol to see past wx. Typically you can add 5-20 degrees to ground temperatures depending on albedo.

http://marsweather.com/data

Also of interest is the rock of no interest. Only a geologist could possibly want to waste another moment of good rover time on it. It must be the most boring rock in the universe, at least to a weatherman.

Vincent

0044ML0204000000E1_DXXX.jpg

Last edited by Vincent (2012-09-21 12:32:44)


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#121 2012-09-21 12:42:07

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

This is the thermal graph for air temperatures on the surface of Miridiani. This reported from the Opportunity Rover. It can get toasty on Mars. Record high from this site(not depicted) +35C

Ref link: http://marsrovers.jpl.nasa.gov/spotlight/20070612.html

20070612_Opportunity_LFHzczm_plot.jpg

Last edited by Vincent (2012-09-21 12:46:27)


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#122 2012-09-21 13:18:40

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Now some would think, such contempt I have. This is true. If you have been following along at home looking through the "jpeg haze," you would know my frustration. Think about all the images we have been fed, yes I said fed. Then just before the Curiosity landing we get this image from orbit. How utterly crisp and wonderful. Have you ever seen anything like it? Think they got more? You bet ya. Will we see them? Not a chance brother.

We is mushrooms.

Vincent

672847main_vasavada-4_full.jpg

Image Ref:http://www.nasa.gov/mission_pages/msl/multimedia/gallery-indexEvents.html

Last edited by Vincent (2012-09-21 13:21:35)


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#123 2012-09-21 14:12:27

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Would we like to see some MAHLI images of the Martian sky? They got to show those Egos their signature. I hope they got it. They are still made of dust and will fade into the nothingness from where they came.

Christ

0045MH0008000002R0_DXXX.jpg

Last edited by Vincent (2012-09-21 14:13:55)


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#124 2012-09-22 09:42:40

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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Hi Vincent
Could you comment on the wind (?) pattern in this marvelious picture from orbit?
I am most interested in the daily cycle of the wind arousing around Mt. Sharp.
In the daily weather report from the CAB people there is only 1 figure on wind direction and speed, E 2m/s.
In their weatherlog is some hint they lost one of the windsensors and try to compensate that.
thanks hjs

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#125 2012-09-23 05:38:26

Vincent
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

The Satellite image is significant in the dynamics it shows.  The clear area in mid image that is void of dust and clouds is a signature of strong winds aloft. Underneath this feature on Earth we would expect lift. This presents itself on Mars as dust clouds seeming to rise from the surface. This sets up a thermal gradient and a increase in surface winds along the gradient.

Winds on Mt Sharp seem to be at their highest when they are out of the west. Whether this is orographic due to topography or seasonal due to atmospheric shift we cannot be sure. With limited data we can only speculate.
This guess was made looking at satellite data. In this image we can surly see a dark wind tail east of Gale Crater. This dark material seems to be capable of wind transport. On the west side were the rover landed the dark material has been scoured and pushed into dunes at the base.

Also of note is a smooth top on Mt Sharp. This would indicate a more constant wind flow. Down sloping on the west side could really heat things up in the summer. Cool moist air from the lowlands could develop AM clouds along the ridge line. On sol 44 they did early morning atmospheric studies. We should live long enough to see them.

Vincent

8015109388_9f0a1bf6d6.jpg
20128415300286580_8 by dfrank39, on Flickr

Last edited by Vincent (2012-09-23 10:23:42)


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