Sol 90+, Extended mission |
Sol 90+, Extended mission |
Sep 24 2008, 02:08 PM
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#256
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Member Group: Members Posts: 101 Joined: 29-January 06 Member No.: 667 |
Can I just get confirmation from someone that the white stuff in this picture is CO2 frost ? Thank you. Is it cold enough yet? New York Times: Who Cares if There’s Ice on Mars? QUOTE Even the low temperature of minus-122 [F] degrees is still too warm for freezing carbon dioxide in Mars' atmospheric conditions. But when winter returns, temperatures will drop, carbon dioxide will begin freezing out of the air again, and Phoenix will become entombed in dry ice. Mars Weather Report: Sol 109 Minimum: -86C -122.8 F Edit: Here's a source for a CO2 freezing point on Mars, NASA: Mars Polar Lander: QUOTE The composition of Mars' atmosphere results in a very unfamiliar seasonal effect. Carbon Dioxide, which makes up 99% of the air on Mars, turns to solid, or "dry ice", when it freezes at 148 ° Kelvin (-193 °F).
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Sep 24 2008, 03:05 PM
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#257
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Senior Member Group: Members Posts: 1619 Joined: 12-February 06 From: Bergerac - FR Member No.: 678 |
Can I just get confirmation from someone that the white stuff in this picture is CO2 frost ? Thank you. Frost ? Yes, that's frost And in Snow White : -------------------- |
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Sep 24 2008, 07:08 PM
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#258
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Member Group: Members Posts: 198 Joined: 2-March 05 From: Richmond, VA USA Member No.: 181 |
Is it cold enough yet? Mars Weather Report: Sol 109 Minimum: -86C -122.8 F Two other things to keep in mind: 1) at what elevation is the -86C being measured at (either 0.25, 0.5, or 1.0m) 2) how much more does the surface of the ground cool relative even to the 0.25m temperature value due to radiational cooling? Remember, even frost can form here on a still clear night on even with temperatures near 40F. I am not arguing that that is CO2 frost (personally I think it's H2O), rather that I think we'll see CO2 frost before the met mast notes the CO2 frost point. -- Pertinax |
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Sep 24 2008, 07:16 PM
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#259
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Junior Member Group: Members Posts: 47 Joined: 27-June 08 From: Ashford, Kent, United Kingdom. Member No.: 4244 |
Temps are @ 1 metre IIRC.
Also Oven 2 appears to have partially opened. Sol 118. SSI as imaged by the RAC Sol 117. The originals were very dark, so I have cropped, enlarged, brightened & contrast enhanced them. Andrew Brown. -------------------- "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.
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Sep 24 2008, 08:22 PM
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#260
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Member Group: Members Posts: 101 Joined: 29-January 06 Member No.: 667 |
I am not arguing that that is CO2 frost (personally I think it's H2O), rather that I think we'll see CO2 frost before the met mast notes the CO2 frost point. Maybe we'll see it. When it does happen it'll probably be hard to see, happening on top of a nice layer of water frost, which has a much higher freezing point. Is the current difference between measured air temperature and ground likely to be the required circa 40 degrees C (air, minimum, maybe an average of the several mast sensor readings, recently: -86 C, freezing point: -125 C) for carbon dioxide frost? I don't think so. It's still mid-calendar-summer for Phoenix. Autumn begins around our Christmas time. The cold is coming. The CO2 frost is coming too. But also conjunction is coming mid-November, and speculation by Barry Goldstein (I think) was that might be the last we hear from Phoenix. |
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Sep 24 2008, 08:24 PM
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#261
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Administrator Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 |
Goldstein said to me that the downward-trending power prediction graph intersected with the minimum-power level on a date that was, coincidentally, very close to the date of Mars solar conjunction. Keeping in mind that, as an engineer, it's his job to be a pessimist, he was pessimistic about Phoenix surviving beyond conjunction.
--Emily -------------------- My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
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Sep 24 2008, 08:32 PM
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#262
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The Poet Dude Group: Moderator Posts: 5551 Joined: 15-March 04 From: Kendal, Cumbria, UK Member No.: 60 |
Plenty of life left in our fiery bird yet...
Sol 118 colourisation... nice chunka frost on the right there... local time 17.30... -------------------- |
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Sep 24 2008, 08:44 PM
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#263
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Member Group: Members Posts: 568 Joined: 20-April 05 From: Silesia Member No.: 299 |
-------------------- Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html |
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Sep 24 2008, 08:50 PM
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#264
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
The ground will have a much greater thermal inertial than the skinny solar panels, so it seems to me that they could become foci of frost formation long before the ground would be cold for enough of the cycle to allow massive depositions. This is the "bridges may be icy" effect. A bridge is cooled by the air on all sides, above and below. The ground is only cooled from above. A "wave of cold" can penetrate to the center of mass of the bridge or solar panel, but can never do that with the planet below.
In both cases, there should be a runaway effect, because the dark panels and dark ground will suddenly absorb much less heat when frost covers them. (Relevant if the sun is still adding any heat at all.) That could cause the fraction of sunlight absorbed to plummet from 80-90% down to 10%. Those solar panels will quickly win or tie the contest for the coldest surfaces around. It's hard to say if the frost would build up on them faster than the ground layer would grow up to them. Obviously, it's a function of their height. My guess is it will build up on them first. IIRC, the whole seasonal layer is only about 2 m thick. Maybe we'll see some springtime pictures of panels lying next to the lander. If they do break off, they could become, in springtime, the foci of interesting melting effects. Maybe they could even drift horizontally as the base of ice sublimates. |
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Sep 24 2008, 09:22 PM
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#265
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Solar System Cartographer Group: Members Posts: 10153 Joined: 5-April 05 From: Canada Member No.: 227 |
Ah yes, 'bridges may be icy'. It always surprises me to see that sign at the corner of Space Center and NASA Boulevard (NASA Road 1) adjacent to JSC. How often is it icy there?
If the panels were lying next to the lander it could be a bit difficult to power up the camera to photograph them. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Sep 25 2008, 01:25 AM
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#266
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Member Group: Members Posts: 202 Joined: 9-September 08 Member No.: 4334 |
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Sep 25 2008, 10:36 PM
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#267
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Member Group: Members Posts: 144 Joined: 17-July 07 From: Canberra Australia Member No.: 2865 |
What is the temperature gradient profile from the ground up? I would have anticipated that CO2 would freeze out and fall as 'snow' in which case it will collect on the upper areas of Phoenix and the area immediately below the solar panels/body would have minimal buildup of CO2 ice. The solar panels wouldn't hold out for long in that scenario. But I am outside my comfort zone here and the atmospheric freeze scenario is too alien for me to get my mind around. What would be the likely ground level wind movement at the Phoenix site when the freeze starts? Lots of horizontal movement of ice crystals or more of a vertical deposition?
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Sep 25 2008, 11:46 PM
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#268
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Member Group: Members Posts: 507 Joined: 10-September 08 Member No.: 4338 |
If there is some slack in the wires connecting the solar panels to the spacecraft, then maybe the panels can break off and fall to the ground, but still function again when the Spring thaw comes?
Perhaps the robot arm could even pile some dirt under the panels to help support them so they won't break off, if they are not too high above the ground... |
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Sep 26 2008, 07:20 PM
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#269
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Member Group: Members Posts: 808 Joined: 10-October 06 From: Maynard Mass USA Member No.: 1241 |
I downloaded a little 'gif animator' (I wont tell you which one, you will just have to slueth it out )
Here are some clouds going by Phoenix as she looked for dust devils -------------------- CLA CLL
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Sep 26 2008, 09:25 PM
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#270
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Member Group: Members Posts: 699 Joined: 3-December 04 From: Boulder, Colorado, USA Member No.: 117 |
That's a seriously cloudy sky. I wonder what it's doing to the solar power levels?
John. |
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