I wondered the same thing, and have assumed that they expect CO2 frost to form on the panels because they'll be solid surfaces below the dewpoint, or whatever the CO2 equivalent is. I do wonder, though, why it would be assumed that one they're covered in a thin opaque layer of frost, that the deposition would still weigh them down enough before the surface frost rises up...

Good thought, but it doesn't work out. The orbiter must have a camera sensitive to 532 nm, which isn't too common And the beam has to not get swamped by the sensor being very broad band or the resolution being low. Good news is the Hirise blue-green channel sort of qualifies (its broad band). The possibility of detection, though, relies on the beam not spreading much. Assuming arbitrarily that the beam width is 1 m at orbital altitudes, the orbiter camera has to pass through that 1 m. There are 8000 km available to pass through in the Phoenix altitude circle. Unless I messed up my math, an orbiter would have one look directly into the laser beam every 900 years, give or take.

How about HiRISE imaging the lidar beam at angle, and not directly over the beam?.

Sounds like a pretty tough request. Almost like asking them to image a craft during EDL.

Can I just get confirmation from someone that the white stuff in this picture is CO2 frost ?
Thank you.

Frost ?

Is it cold enough yet?

New York Times: Who Cares if There’s Ice on Mars?



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:

Yes, that's frost


And in Snow White :

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

Temps are @ 1 metre IIRC.

Also Oven 2 appears to have partially opened. Sol 118.

SSI as imaged by the RAC Sol 117.
Click to view attachment

Click to view attachment

The originals were very dark, so I have cropped, enlarged, brightened & contrast enhanced them.

Andrew Brown.

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.

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

Plenty of life left in our fiery bird yet...

Sol 118 colourisation... nice chunka frost on the right there... local time 17.30...

Click to view attachment

Next dust devil near Phoenix - sol 117.
Click to view attachment

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.

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

Never, or close enough.

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?

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...

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

Click to view attachment

That's a seriously cloudy sky. I wonder what it's doing to the solar power levels?

John.

Been away for a couple of days - enjoyed unexpected stay at a Scottish castle... as you do... saw a stunningly clear and dark sky last night, wow, I'd forgotten what one looked like, to be honest - so catching up Big Time here...

First things first: NAAAJFF ("Not Accurate At All, Just For Fun") colourisation of dust grains on Sol 121...

Click to view attachment

Edit: there are some more "Disco Dancin' Dust Grains!" in my Gallery here, if anyone wants a look. I'm sure Dan can produce a much better, 'stabilised' version but either PS Elements doesn't have that facility or, after looking for half an hour, I'm just too stoopid to find it...

Awh, shucks. Flattery will get you everywhere.

That's what I was counting on...

Nice job, Dan... why am I reminded of one of those Monty Python animations with people shuffling along..?

Actually I was picturing little cartoon characters like talking raisins, with helium voices crying out, "save, us, save us!"

To me, it looks like somebody coming back from the beach with a Jeans with some sand on it...

Peter Smith: "Curses, we're busted! They figured out that we didn't go to Mars, we faked the whole thing like in Capricorn One when we found out that the springs in the TEGA doors were actually from old slinkies... I knew those close-ups of Steve Squyres' dirty jean pockets would give the game away eventually...!!!"

"Boil that dust grain! Boil that dust grain! Boil! Boil! Boil! Boil!"



-the other Doug

Fortunately for power, clouds are sporadic and concentrate in the mornings (that movie is early afternoon). Optical depth measurements have typically been low, even the afternoon of the movie.

I hope Jim Whiteway gets a chance to talk about clouds and such at the press conference.

There are 4 RGB sets of the same sample.

Click to view attachment

I think I've seen already several green grains (olivine?) that seem to have a sandy core.

...of which you're showing two "scoops". Look like vanila-strawberry color to me

MECA colors won't look martian, anyway. Maybe we should rename the Northern Plains to the Vanilla-Strawberry Plains.

... or that hideous "Tooti Frutti" ice cream with the coloured, hard bits of What-the-hell-is-that? embedded in it...

When is the Phoenix team going to deliver the last TEGA sample? 30th September or later? according to their energy levels until when is this possible? Now we should wait the next sample to be from "Upper Cupboard"(ice sample)? in which oven are they going to drop it? are the previous two deliveries, from "Snow White" and OFB successful?

I think they didn't put out news releases about all that so they'd have some things to talk about at the briefing today.

Phoenix Lander Update Briefing: Monday, September 29

NASA TV Schedule:



NASA TV (or NASA TV Yahoo! source or high-resolution)
NASA TV Media Channel

More colourised microscope images here if anyone wants a look... as usual, just for fun, not claiming colour or science accuracy.

Just tuned in to the NASA webcast. They have started the Q & A after the presentation. I'm in a rush as I have to start work but from the first Qs looks like they have found C Carbonate. Possibly around 7 to 8% according to prelim analysis. Possible P Silicates found in trace amounts. Boyton - if organics there then not v much.

Suggestive of past interaction with water. How does this square with perchorate findings (little or no water)?

This data is enough to 'start rewriting the book of Martian geochem'.

Annoying but I've got to go...... but sounds like exciting stuff. I'm sure we'll be having a full discussion on this and Emily and AJS Rayl from Planetary Society will keep us up to date........

Actually, Hugh, you've captured nearly all the news from this press briefing! The neatest bit I heard was the presentation of the MET team showing evidence for high-altitude snow falling -- they said they'll keep watching to see if any of it reaches the ground.

--Emily

Release: JPL Phoenix Mission News: NASA Mars Lander Sees Falling Snow, Soil Data Suggest Liquid Past (September 29)

My own inept live transcript -- with connection glitches -- begins at BAUT Forum article in topic Phoenix on Mars: Extended Mission

Virga!!

I missed the conference sadly. Was there a not as to what kind of snow (Water vs Dry Ice)?

[edit: seeing the link above, one seems left at the assumption of water ice snow, without such being explicitly stated.]



-- Pertinax

"For nearly three months after landing, the sun never went below the horizon at our landing site," said Barry Goldstein, JPL Phoenix project manager. "Now it is gone for more than four hours each night, and the output from our solar panels is dropping each week. Before the end of October, there won't be enough energy to keep using the robotic arm."

Wow, I guess we will have to swallow hard and admit that all good things do indeed come to an end. Phoenix is one of the few "intermediate" lifetime explorers we have been following. There were some probes with very short (and planned to be so) lifetimes, such as the Huygens probe. And we have been spoiled with our hardy friends farther south on Mars, as well as such veterans as Cassini and the Voyagers. In this case, I find myself thinking, "Phoenix, we hardly knew ye!"

Reading the prior discussions hypothesizing about someday finding Phoenix encased in ice reminded me of the final act of Steven Spielberg's "A.I.", when the robots in the far future find our hero in the frozen ocean off of what was once New York. (Hope I didn't spoil the movie for anyone!)

Can't find the reference now, but I saw it described yesterday as "diamond dust" -

"Diamond dust - This is the name given to the sparkling clouds of tiny ice crystals that appear to fall out of a cloudless sky. The ice crystals can disappear before they reach the ground through a process called sublimation."

Mmh, does the calcium carbonate either rule out the 'acid water ancient Mars' picture or the 'Mars was wet but not anymore' picture?

They also talked about the possibility of a wet ground when the martian axis was more tilted towards the Sun. But Phoenix is actually at a quite high latitude. How may the Phoenix findings extrapolate to the meridional Northern Plains, with warmer temperatures, if there's any ice under the soil?

For example:
http://marsoweb.nas.nasa.gov/HiRISE/hirise...SP_002439_2265/

Edit: I totally forgot about this... this has been one of my favourite HiRISE images since the beggining of the mission:

http://marsoweb.nas.nasa.gov/HiRISE/hirise...RA_000856_2265/

Back then I even cropped this section because there was a bright spot that really looked like exposed ice. It even could make sense after seeing Holy Cow:

Click to view attachment

Well.. the article says "NASA's Phoenix Mars Lander has detected snow falling from Martian clouds."
so not from a cloudless sky. It seems to be real snow.

So the soil is now bone dry but has minerals in it that must have formed in the presence of water? Interesting. I'd got the impression that the warming due to mars axial tilt was to slow for the ice to melt , it would simply sublimate and re-condense somewhere else without ever reaching the liquid phase. Is this evidence against that, or could there have been melting from volcanic or impact heat that lasted long enough to leave this impression? There is a large crater just down the plain. How long does the observed amount of calcium carbonate take to form? Mars throws us more mysteries....

No information asked or volunteered about nitrogen content in the soil. Since nitrogen seems to be essential for habitability on Earth, why does no one mention this issue? Has TEGA detected any nitrogen?

For some reason a couple of the neat graphics they showed at the briefing haven't made it to the mission websites yet, but I got them from the PIO office and they're in my update now. Falling snow!

--Emily

All..

today's (September 29th, 08) Phoenix press conference can be seen here
http://www.space-multimedia.nl.eu.org/inde...13&Itemid=1

Craig

They note that Phoenix is on a reasonably recent ejecta layer and that the ground is bone dry. (We really need a new word to describe just how dry this is). So the carbonates and clays were almost certainly excavated from the crater and the discovery would seem to be a strong indicator of a warmer wetter far past, but little to do with the current environment in this area, or the salty, acid sulphate environment seen elsewhere.

I'm not sure what the fuss is concerning the high altitude snow. As the temperature drops the vapour must freeze out. Snow, both water and CO2 has been referenced numerous times in analysis of both poles. Interesting in that the LIDAR got such compelling images but surely the 'diamond dust effect' or snow was an expected outcome? I also thought that the Atacama perchlorates were thought to have been formed as aerosols so again no real surprises?

The big surprise is no organics or superoxides. Since organics should be falling from space on a fairly regular basis where are they? I just get the feeling that any real info is being held back for conference papers and learned contributions to Nature, and I look forward to those with great anticipation. The briefing did not in fact say very much at all.

*cough*cough*
Aussie, I really don't think that the Phoenix team is known for 'holding information back'.
As demonstrated recently, they are VERY open when it comes to data and their scientific process.
If they had something important to tell us, they'd say so.

Also, I think that the 'fuss over snow' is justified.
They know that something like "it's snowing on Mars" is media and public outreach gold.
Are you going to get any attention if you just say "we found calcium carbonate".
A snow report is a hook to hang the rest of your science on.

Great and open outreach!

Astro0

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