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Posted by: Steve G May 30 2008, 05:15 AM

Tricky to line up the two RAC images but here is my attempt.

Posted by: MicroKid May 30 2008, 06:26 AM

Any idea what the long spiral looking object (lower left) next to the landing pad is?

Posted by: Steve G May 30 2008, 06:48 AM

I was wondering that when I stitched the images together, and the first thing that came to mind was Khan's pet ear wig . . .

It is out of sight from the SOL 1 footpad image and nearly beneath the lander, but by the surrounding soil, it looks like it fell from the lander. The resoltion of the RAC is only 256 X 512 so we need to creep lower for a better look.

Posted by: djellison May 30 2008, 07:51 AM

EGD had a go at this in the Sol 3+ thread, I'm kicking of an RAC lander-imaging thread with my own attemt.

Posted by: djellison May 30 2008, 07:54 AM

If I had to guess what it was - I'd say something to do with...

-Biobarrier deployment
-SSI deployment
-Helium vent valve
-RA deployment
-Met deployment

If I had to pick one - Helium vent valve.

Posted by: um3k May 31 2008, 03:47 AM

Sure looks like ice to me: http://fawkes3.lpl.arizona.edu/images.php?gID=1018&cID=26

Posted by: bcory May 31 2008, 04:18 AM

Looks more like a ice hockey pond !

Posted by: dvandorn May 31 2008, 04:57 AM

Could be ancient duricrust, buried under a more recent dust/soil layer.

Could be pavement-flattened rocks of the type we see in Meridiani, again underlying a more recent dust/soil layer.

No. What am I thinking?

It's ice. It just looks *obviously* like ice. Maybe not a perfect layer of water ice, but at the very least a good, solid permafrost layer.

Looks like we'll need to burr some of that out, doesn't it? Looks really, really hard to me.

BTW -- is there a danger of significant sublimation of exposed water ice at these pressures and temperatures? I'd hate to see the cleared permafrost layer under the lander sublimate out into a nice little Phoenix-gobbling sinkhole...

-the other Doug

Posted by: ElkGroveDan May 31 2008, 05:35 AM

Holy cow, where's that swear jar?

This is the mission that keeps on giving.

Posted by: ElkGroveDan May 31 2008, 05:40 AM

Dang I was thinking that same thing just as I read your post.

Probably not, since the blanket of dust and sand that has been keeping it all in place for eons would soon be replaced. If the patches under the lander started to slump they would gather nearby sand and dust. It would be covered before any significant slumping reached as far as the foot pads - I suspect. But it's a darn interesting thought to ponder.

Posted by: centsworth_II May 31 2008, 05:51 AM

If that is exposed ice, what a time lapse movie that could make, watching its evolution over several months.

Posted by: James Sorenson May 31 2008, 06:24 AM

OMFG Im gonna need that swear jar now .

It looks like the phoenix website was hacked.


EDIT: Now its back to normal, it said that it was hacked by vital.

Posted by: djellison May 31 2008, 08:36 AM

The arm can't get to THAT Ice, the 'upper arm' is probably longer than the height from where the arm meets the deck to ground. But - you can see that where the dust blew away - it's everywhere. 5cm of soil, then ice. As they predicted (maybe )

Doug

Posted by: Marcel May 31 2008, 08:59 AM

Could be a danger.

Another one. If it's ice: could the heat that the lander collects from sun radiation during daytime melt the ice under it's footpads ? ....slowly sinking in ? For rocks it doesn't seem to happen, the exposed surface of the whole lander (and the energy it collects) concentrates on quite small footpads though

Posted by: djellison May 31 2008, 11:15 AM

Couple of RAC obs.

Posted by: Doc May 31 2008, 11:39 AM

I dont think thats ice. Wouldnt we see signs of sublimation (smoke)
They ought to get a series of pictures to see the changes if its ice.

Posted by: eeergo May 31 2008, 12:04 PM

I don't think smoke would be seen if it was ice: it's cold up there and sublimation wouldn't be too fast or spectacular... snow on Earth also sublimes and we don't see smoke coming out of it. Just my view, not necessarily correct, but I think so.

Posted by: nprev May 31 2008, 12:38 PM

Wouldn't the ability of any 'smoke' to be seen from sublimation be a function of atmospheric relative humidity in a addition to pressure & temp?

Don't think that the met package measures humidity, but I'd be very surprised if the RH of the air was anything but extremely low, which IIRC means that the H2O molecules would disperse too rapidly to form visible vapor.

Posted by: tasp May 31 2008, 12:47 PM

Visible 'plumage' from exposed ice would depend on local relative humidity, optical depth of the column you're looking through, mineral content of the ice itself (dissolved materials would effect freezing point of the material and the resulting rate of sublimation), wind speed, thermal input to the ice, sensitivity/noise ratio/dynamic range and compression of the camera, temperature of the atmosphere, shading from the vehicle, possibility of contaminants in the ice to form 'crustage' and probably several other factors it is too early in the morning for me to think of.

For those so inclined, you might want to consider an outcropping of dirty ice under Phoenix to be a cometary phenomena. A little more bang for the buck for the mission!

Posted by: tasp May 31 2008, 12:49 PM

LOL.

See what happens when it takes me 10 minutes to compose a post first thing in the morning without coffee. I get pre-empted by nprev.

Posted by: ustrax May 31 2008, 01:36 PM

If that is ice...that is GOLD!!!

The Heimdal image is great but this man...this is what we were looking for...

DIG!

Posted by: DDAVIS May 31 2008, 02:12 PM

'Visible 'plumage' from exposed ice would depend on...'

One important factor would be Sun angle. Presenting a chunk of previously buried Mars ice to the Sunlight with a camera fairly near the shadow of the sample could possibly reveal comet like plumage against the dark sky due to forward scattering, if it isn't windy.

Don

Posted by: nprev May 31 2008, 02:32 PM

Just out of curiousity, with respect to the viewpoint of the "ice" image, which way did Phoenix come in from horizontally? Seem to remember that there was some horizonal motion just before touchdown.

Reason I ask is that the exposed area doesn't look like it's directly underneath a thruster set; could have my perspective all wrong, though. Also wondering if this stuff might be shallower then we think; haven't seen any significant 'dunes' of blown dust around Phoenix from the motors.

Posted by: bcory May 31 2008, 03:11 PM

All I can say that it seems to me that whatever it is, the sun glare/reflection is highly indicative to me of ice.

And as a Canadian I know ice!

Posted by: ilbasso May 31 2008, 03:14 PM

What's the size of those patches relative to the other polygons that we see on the surface? What's under the polygons on Earth's permafrost? Would we expect similar plates of ice?

Posted by: scalbers May 31 2008, 03:24 PM

It was interesting at Friday's news conference how Ray Arvidson showed a similar image from Viking 1 (link below) very near the lander that was duricrust. He said he's still rooting for ice with Phoenix though the scientific method should be followed to find out. The crust does look more uniform in the Phoenix image that would support ice.

http://www.jpl.nasa.gov/images/phoenix/collection_16/vl_12A081-v2_800-600.jpg

Steve

Posted by: Marz May 31 2008, 04:25 PM

Assuming those plates are ice [w00t!!!], then are there any estimates for how old it is? Does this ice ever melt and reform annually, or has it been this frozen block since the last time the north pole was warm enough to melt ice (is that around 10 million years?).

I second the command to DIG!

Posted by: MahFL May 31 2008, 04:33 PM

The Phoenix site seems down

Posted by: bcory May 31 2008, 04:40 PM

It got hacked by a Russian last night

Posted by: Decepticon May 31 2008, 04:46 PM

If this does to turn out to frozen water, will this end the Naysayers of there no water on Mars!?

Posted by: vikingmars May 31 2008, 04:49 PM

With alittle processing you can see more easily under the lander the "ice" extending towards the RAC with a soil pile in-between built-up by the engine exhausts. Enjoy !

Posted by: centsworth_II May 31 2008, 04:54 PM

I'm worried that if the ice is too solid and too near the surface all around, there may be no real digging possible.

Posted by: scalbers May 31 2008, 04:59 PM

These under the lander images are really neat and something that we didn't have with Viking. Do all the cleared off spots correlate well with the locations of the descent engine nozzles? Will also be interesting to see different exposures to get more dynamic range in the bright areas. The high albedo really seems to support an ice hypothesis here. Is there any "shininess" here due to specular reflection? Hard to say. Even the shadowed areas look bright and one can interpret that as high albedo without specular reflection.

Steve

Posted by: Decepticon May 31 2008, 05:05 PM

Now that's the question! Do the nozzles line up with the exposed area?

How do we test this theory?

Posted by: nilstycho May 31 2008, 05:08 PM

Phoenix http://twitter.com/MarsPhoenix/statuses/823648809 "The picture shows a little piece of hardware on the ground, probably a pin. The team is checking it out. No worries. :-)" Later, she http://twitter.com/MarsPhoenix/statuses/823848361 "A loose screw on Mars can't stop me now."

As for ice, there's a JPL http://www.jpl.nasa.gov/news/news.cfm?release=2008-090 that calls the duricrust-looking stuff "possible ice". About the ice-looking struff, Phoenix http://twitter.com/MarsPhoenix/statuses/823849886 "Is this the mother lode of the polar region? Ice!?" Seems confident for a scientist...

Posted by: teck May 31 2008, 05:09 PM

Is this a Philips screw?

Posted by: James Sorenson May 31 2008, 05:10 PM

This exposed ice has been exposed to the atmosphere and sun for almost a week now, and to me shows no significant sublimation. Why would that be?. I am also worryed that this could mean that digging mght be dificult, it sure looks VERY hard and possibly thick. Well its what we came here to find, and we found it without even trying, mars came to us it looks like, where is a broom when you need one .

Posted by: scalbers May 31 2008, 05:20 PM

At the cold ambient temperatures sublimation would be really slow, unless it is sped up by the action of sunlight. Even then how fast would it be?

Posted by: ugordan May 31 2008, 05:24 PM

Yeah, who knew all we really needed was:

1 rocket engine
1 camera
1 UHF antenna

Posted by: um3k May 31 2008, 05:25 PM

Did someone neglect to inform him that the cold war has been over for ~20 years?

Posted by: dot.dk May 31 2008, 05:27 PM

Remember there is the rasp on the backside of the scoop

Posted by: centsworth_II May 31 2008, 05:33 PM

To get a sample, not to dig.

Posted by: eeergo May 31 2008, 05:44 PM

They were expecting the hard ground, remember they were talking about being able to dig in a soil as hard as concrete. See this answer in Twitter: "Yup, I can dig into frozen ground as hard as concrete. The scoop has special blades and a powered "rasp" to scrape ice. Cool!" It may be a bit more difficult, but no worries...

Posted by: nilstycho May 31 2008, 05:47 PM

I wonder what would be the pros and cons of a heated filament or blade on the cutting edge of the scoop. Delicate, expensive, complicated? Would it require more or less power to dig through ice? How about a pellet of plutonium embedded inside?

Posted by: centsworth_II May 31 2008, 05:51 PM

In one of the press briefings it was stated that they could dig in frozen soil, but not in ice. So if the permafrost is soil with frozen water in the spaces between grains, no problem. But if it is solid frozen water, no digging.

Posted by: bcory May 31 2008, 06:04 PM

http://www.nasa.gov/images/content/234067main_under-full.jpg

Seems they concur about the ice in the "ponds" image.

"The Robotic Arm Camera on NASA's Phoenix Mars Lander captured this image underneath the lander on the fifth Martian day, or sol, of the mission. Descent thrusters on the bottom of the lander are visible at the top of the image.

This view from the north side of the lander toward the southern leg shows smooth surfaces cleared from overlying soil by the rocket exhaust during landing. One exposed edge of the underlying material was seen in Sol 4 images, but the newer image reveals a greater extent of it. The abundance of excavated smooth and level surfaces adds evidence to a hypothesis that the underlying material is an ice table covered by a thin blanket of soil.

The bright-looking surface material in the center, where the image is partly overexposed may not be inherently brighter than the foreground material in shadow."

http://www.nasa.gov/mission_pages/phoenix/images/press/20080531.html

Posted by: OWW May 31 2008, 06:26 PM

Scary thought: It could be frozen pools of leaked/vented rocket fuel....

Posted by: Cargo Cult May 31 2008, 06:37 PM

If does prove to be the latter, the next trip should carry a modified http://en.wikipedia.org/wiki/Ice_core. Just imagine the layers of Martian history!

Posted by: centsworth_II May 31 2008, 06:58 PM

That's what I've been imagining. I hope it's not stymied by a layer of solid ice. I won't worry too much right now though... no use in that.

Posted by: climber May 31 2008, 07:03 PM

Holy cow, it's ICE : http://planetary.org/blog

Posted by: Steve G May 31 2008, 07:03 PM

I think this is a splendid opportunity to put MARDI to good use! If the "Snow Queen" is its field of view (and reasonably focused) it would be a freebie to watch the ice sublime over time. From what I read on the site, it looks like it has a very wide angle lens. (66%) Just depends on the placement. Maybe the microphone attached to it could listen for sublimation!

Posted by: 4th rock from the sun May 31 2008, 07:04 PM

I've enhanced to under-side image to improve visibility on the shadowed areas and I noticed an interesting thing on the lander leg to the left. It looks as some dirt has sicked to it. The interesting thing is that it's only on this leg, the others look clean.

Just for reference, the same processing applied to the previous "ice" images, here joined in a mosaic and averaged over the overlapping area to reduce compression artifacts.

Posted by: bcory May 31 2008, 07:39 PM

Maybe the thrusters melted some of the ice and formed a slurry with the dirt and dust that re-froze and stuck to the lander leg

Posted by: MahFL May 31 2008, 08:24 PM

The whole point of the mission is to find Water Ice, remember this is frozen water you can melt and drink, not frozen carbon dioxide. Also to test the ice to see if it has been regularly melted, but with current summer high temps of -30 C that seems unlikely. Though at one time it does seem liquid water flowed all over Mars.

Posted by: mars loon May 31 2008, 10:12 PM

This JPL press release has a bit more detail about this fantastic find of "ice" including quotes from Horst Keller and Peter Smith:

http://www.jpl.nasa.gov/news/news.cfm?release=release=2008-090b

News Releases

A view of the ground underneath NASA's Phoenix Mars Lander adds to evidence that descent thrusters dispersed overlying soil and exposed a harder substrate that may be ice.


Camera on Arm Looks Beneath NASA Mars Lander
May 31, 2008

A view of the ground underneath NASA's Phoenix Mars Lander adds to evidence that descent thrusters dispersed overlying soil and exposed a harder substrate that may be ice.

The image received Friday night from the spacecraft's Robotic Arm Camera shows patches of smooth and level surfaces beneath the thrusters.

"This suggests we have an ice table under a thin layer of loose soil," said the lead scientist for the Robotic Arm Camera, Horst Uwe Keller of Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany.

"We were expecting to find ice within two to six inches of the surface," said Peter Smith of the University of Arizona, Tucson, principal investigator for Phoenix. "The thrusters have excavated two to six inches and, sure enough, we see something that looks like ice. It's not impossible that it's something else, but our leading interpretation is ice."

Posted by: nprev May 31 2008, 11:38 PM

Phoenix site back up!

Some trivia: Most cyberattacks & viruses originate in Russia & Eastern Europe per Symantec. Might be an artifact of organized criime activities, and transiently high-traffic sites are an obvious proving ground for new methods. In other words, no need to take it personally.

We now return you to our regular program.

Posted by: SpaceListener May 31 2008, 11:45 PM

Normally, the surface of ice is plain, 90 degree to the gravity. However, the show ice pictures, the surface seems not to be smooth.
How can a water ice have rough surface.

Posted by: mars loon May 31 2008, 11:51 PM

It was down about half the day for me. back up a few hours now

Fox News even reported on this hacking at about 720 PM EDT (30 min ago), saying that initially a website story had been changed.

More importantly, they reported on the "ice" finding after a shuttle launch report.

CNN has reported on the shuttle launch , but not yet on the ice

Posted by: nprev Jun 1 2008, 12:04 AM

Glad to hear that CNN is exercising some restraint on the "ice". IMHO, the possibility that this is ice should not be trumpeted to the mass media unless there is confirmation.

It's really easy to say something to the press, but REALLY hard to retract it, and if this stuff turns out to be duricrust or pavement-stone sedimentary rock al a Meridiani the Phoenix team will take a beating that they just don't need.

Posted by: eeergo Jun 1 2008, 12:28 AM

Take a look at natural ice in some glacier or in Antarctica/the Arctic... obviously, the surface of ice is flat so as long no distubing factors appear: different slabs of ice freezing together and crushing each other with the expansion (as in the Arctic), breakages for other reasons with later refreezing, partial sublimation/fusion by weathering, local impurities within the ice which may cause some areas proner to evaporate first... Well, I could go on, but anyone who's seen ice outside the fridge or a frozen puddle knows ice surface doesn't equal smooth shiny surface. In fact, it's preety rare when it does.

Posted by: bcory Jun 1 2008, 12:32 AM

Accept here we're talking about permafrost ground ice.

Totaly different

Posted by: jmjawors Jun 1 2008, 12:36 AM

For the record, CNN http://www.cnn.com/2008/TECH/space/05/31/phoenix.mars.ap/index.html it, but thankfully using cautionary terms.

Posted by: Thu Jun 1 2008, 01:45 AM

The ChemCam should be very helpful in this case. Did they ever think of shooting the ice using laser? Anyway the next few days are going to be interesting. I wonder if we're just standing on top of an iceberg

Posted by: SpaceListener Jun 1 2008, 02:36 AM

Thanks for your comments. I am starting to understand it and am convinced that the ice surface does not be necessary to be smooth.

Hope that RAC would take pictures not only one but the rest of two more patches below of rocket thrusters.

Posted by: tuvas Jun 1 2008, 03:11 AM

ChemCam is MSL, right? Anyways, from what I've heard, the science team is very interested in this artifact, and can reach the site with the arm of the lander. Should be quite interesting...

Posted by: JRehling Jun 1 2008, 03:38 AM

The polygonal surface of the soil is enough to tell us that we're seeing something other than platonically perfect concentric spheres, even if the deviation is only on a scale of centimeters. Which is to be expected. Although how it relates to terrestrial permafrost is unclear.

Posted by: James Sorenson Jun 1 2008, 05:26 AM

New images, is this a scoop mark in the soil?

http://phoenix.lpl.arizona.edu/images.php?gID=1114&cID=27

Posted by: ElkGroveDan Jun 1 2008, 05:34 AM

Now this one is cool, scoop, CD, and flag all in one shot.

http://phoenix.lpl.arizona.edu/images/gallery/lg_1103.jpg

Don't know why but it kind of reminds me of this http://www.lee-knight.com/Main/images/cover_art/are_you_my_mother.jpg

Posted by: jmjawors Jun 1 2008, 05:41 AM

Kind of looks like a footprint.

Actually, it looked like a rock at first, and then my eyes readjusted so I could see it as the depression that it is. Definitely looks like a 'scoop mark' to me.

Posted by: glennwsmith Jun 1 2008, 06:53 AM

ElkGroveDan,

I thought you were going to reference this child's book:

http://www.amazon.com/gp/reader/0395169615/ref=sib_dp_pt#reader-link

Posted by: 1101001 Jun 1 2008, 07:02 AM

Any speculation as to the cause of the hollows in this rock?
http://phoenix.lpl.arizona.edu/images.php?gID=1159&cID=27

Could it have been recently modified by a nearby heat source.

Posted by: Steve G Jun 1 2008, 07:28 AM

Sure looks like dirty ice, like what you see in the spring when it's melting off your driveway after a long winter.

Looks like channeling and definately a couple of vents. Hard to say if this is from the thrusters that acted like a blowtorch into the ice. Hard to tell, but doesn't seem to have much change in the pattern from the Sol 4 image. The artifact observed on Sol 4 is beginning to look like a spring of some kind.

Posted by: climber Jun 1 2008, 08:06 AM

I agree we've got to be cautious but, come on guys, such a rounded shaped will be hard to find in a rock

Posted by: centsworth_II Jun 1 2008, 08:22 AM

Don't forget duricrust.

Posted by: djellison Jun 1 2008, 09:04 AM

It might be the RA 'touch' they were talking about on the Friday press conf to characterise surface characteristics.

Posted by: Syrinx Jun 1 2008, 09:15 AM

Sorry to deviate from the excitement of ice for a moment...

Regarding the screw underneath the lander. Might it be an explosive bolt from the lander-backshell separation? Perhaps this particular bolt didn't explode exactly as planned.

Posted by: climber Jun 1 2008, 10:11 AM

Doug proposed it is related to the helium venting

Posted by: Airbag Jun 1 2008, 01:21 PM

I attempted to make an RGB image with one of the sol 6 RAC R/G/B LED illuminated images, but I suspect the ambient lighting drowns out pretty much any effect of the LEDs as the resulting image was still effectively greyscale. Any attempts to tease out more color information just caused the JPG artifacts to be enhanced. I wonder if they will use those LEDs at night? At least then there is no ambient lighting.

Hum, that gives me an idea - what if one were to subtract the "D" filter image from each of the R/G/B images first before combining them? That may work with the raw images but probably not with the stretched JPGs. Also depends on whether the camera uses the exact same exposure for each of the images or not - or at least knowledge of the relative exposures.

Airbag

Posted by: dvandorn Jun 1 2008, 04:16 PM

Here is an observation that I will note I haven't seen here yet.

Recall that this area sees complete cover by dry ice every winter. Since we don't know what the deposition process was for the water ice, is it at least possible that there may be dry ice pockets within the water ice permafrost layer?

If so, a very small pocket of dry ice (or a few of them) could explain things like the rounded hole that appears to have been blasted out of the ice beneath the thruster bells.

Dry ice wil indeed sublimate very fast, almost explosively, in the current temperatures and pressures, no? We see it sublimating explosively and creating "dirt geysers" during springtime, which is colder than what we're seeing now.

So, if there are nuggets of CO2 ice buried in the permafrost, what further manifestations ought we be looking for (other than the possibility of Phoenix taking an unplanned-for hop)?

-the other Doug

Posted by: nilstycho Jun 1 2008, 04:30 PM

But we do have relative knowledge of exposures! :-)

Open the orginal-size image in a text editor. It will start with something like this:

Looks like both SSI and RAC have this information. I was wondering if anyone could explain how it's possible to adjust the brightness (?) of RGB channels in Photoshop or ImageJ according to this information. Wouldn't this give us almost exactly the right hues without any human estimation?

Posted by: mhoward Jun 1 2008, 04:34 PM

Unfortunately, probably not. As slinted pointed out elsewhere, the jpg images are still auto-stretched to improve contrast (like MER, and I guess Cassini). Although we have some exposure information, we don't have the parameters that were used to brightness-stretch the public images. It's a bit funny, actually.

Adding: However, maybe something could be done with the auto-panos, I don't know.

Posted by: ugordan Jun 1 2008, 04:41 PM

Knowing the exposures doesn't help us really. That information is rendered useless by the histogram stretch. The ultimate raw image would also contain original DNs that were scaled to 0 and 255 respectively.

Posted by: Phil Stooke Jun 1 2008, 04:42 PM

"Regarding the screw underneath the lander. Might it be an explosive bolt from the lander-backshell separation? Perhaps this particular bolt didn't explode exactly as planned.
------
Doug proposed it is related to the helium venting"
-----------------------------

Or the biobarrier?

(PS great mission so far! The pictures taken under the lander are very cool - I hadn't anticipated that. Remember when some of us were concerned this would be dull compared to the rovers? I'm frustrated I'm not in my office with Photoshop to play with. I want to make a circular version of the exaggerated relief panorama as soon as I get back)

Phil

Posted by: nilstycho Jun 1 2008, 09:16 PM

Ah, OK. I forgot about the histogram stretch. So out of curiosity, what do the pros do about that? Is it something complicated that can't be easily automated? Is there a piece of information distinct from the image that tells them how much it was stretched?

Posted by: djellison Jun 1 2008, 10:14 PM

They don't have to deal with it - they have calibrated data. The raw JPG's are just processed to be 'sensible to look at' not calibrated.

Doug

Posted by: cschmidt Jun 1 2008, 10:51 PM

Thinking again about the ice, I have been wondering about something:

I am given to understand that the arm will dig down into loose soil, trenching, making tidy piles of soil, etc.
But given the high abundance of water here, isn't the soil going to be like plate of granite? Won't it be difficult or even impossible in this case for the scoop to dig?
The appearance of platy ice under that loose regolith undersores my impression that the "soil" will be really hard, except for the loose sandy top layer.

Idea: Why didn't they attach a convex lens to the end of the arm to zap ice into liquid/vapor via solar energy, then take a picture....

Thanks to all of you, especially Stuart, for this wonderful forum.

Posted by: jbytów Jun 1 2008, 11:25 PM

.

Posted by: nilstycho Jun 1 2008, 11:40 PM

So do the originals hit PDS eventually, and until then the public just gets the raw jpgs plus press releases? Or do we not get the originals at all? This mission is so incredibly open and transparent, I hate to ask this, but why aren't the originals released as fast as the jpgs? (Sorry to be OT, but I'm interested.)

Posted by: john_s Jun 2 2008, 12:24 AM

Two reasons really- one is that the science team want to be sure that the "real" data are properly calibrated and ready for scientific analysis before releasing them, so people don't jump to premature conclusions from preliminary data. The other is that exclusive access to the full data set for a few months is the reward the science teams get for all the work they've done to make the data possible. Till recently, most the images from most missions weren't publicly available in any form, except for selected press release images, until a year or more after the data came down, so the availability of JPEGs is a big step towards open access. And yes, the original data will eventually hit the PDS for all to enjoy, probably within less than a year.

John.

Posted by: nilstycho Jun 2 2008, 01:24 AM

Of course: Anti-scoopage. Thank you.

Posted by: elakdawalla Jun 2 2008, 01:50 AM

Anti-scoopage is an important part of it, but that calibration part is really important too. They do a lot of work to characterize the camera before it flies, but the launch with all its vibrations, and cruise with its cold temperatures, and landing and operation with both, in the dirty environment of Mars, can change the characteristics of the camera in subtle ways, which they can't begin to understand until they've operated it on the surface for a while. So they need months to make sure that all the digital numbers in each image pixel are telling researchers good information about the way that the materials they see reflect light.

--Emily

Posted by: nprev Jun 2 2008, 02:17 AM

Kind of hate to ask this, but if a given amount of scoopage contacts an equivalent amount of anti-scoopage, what happens?

(I'm truly sorry...just couldn't resist!)

Posted by: Tom Tamlyn Jun 2 2008, 03:33 AM

One of the MRO engineers is continuing to post fascinating information concerning the problems with the MRO UHF radio (Electra) on his http://spacenerd.blogspot.com/.
Here's a http://spacenerd.blogspot.com/2008/05/state-of-things-as-they-are.html, and http://spacenerd.blogspot.com/2008/05/its-friday.html, for readers from the future.

TTT

Posted by: alan Jun 2 2008, 04:51 AM

Speaking of scoopage the arm has grabbed its first sample
http://fawkes1.lpl.arizona.edu/images.php?gID=1404&cID=28

Posted by: jmjawors Jun 2 2008, 05:06 AM

Oh my!

So this is the scoop and dump, right? Still in that characterization phase.

Posted by: Reed Jun 2 2008, 05:22 AM

Looks like it was scooped from the same area as the touch test http://phoenix.lpl.arizona.edu/images/gallery/lg_1428.jpg

Posted by: dvandorn Jun 2 2008, 05:43 AM

If this was the scoop-and-dump, the scoop leaks.

Here's an image of the lander deck from the RAC at 11:12 local time:



And here's an image from 12:38 local time:



Note the small pile of soil sitting just inside the wiring bundle in the second image. In both images, the foreground reflective surface is the side of the scoop.

All subsequent images of this portion of the lander deck show this little pile of soil.

-the other Doug

Posted by: James Sorenson Jun 2 2008, 05:59 AM

False-color image saturated to 60%, of the RA scoop soiling it self .

Posted by: Marz Jun 2 2008, 06:07 AM

whoa! Are the small clumps of blueish-white stuff in the upper-right portion of the image perchance ice?

Posted by: djellison Jun 2 2008, 06:14 AM

I had a go at it myself - the LED's really work at this range - not so great imaging the surface at any sort of distance though.

Posted by: James Sorenson Jun 2 2008, 06:21 AM

It looks like ice.

Posted by: Greg Watson Jun 2 2008, 06:38 AM

A hole in Mars:

Posted by: Greg Watson Jun 2 2008, 07:44 AM

Higher resolution version. Interesting pattern lower right on the rear wall of the first dig.

Posted by: stevelu Jun 2 2008, 08:29 AM

Do you mean the chain of 4-5 largish granules near the top of the right side of the rear wall of the dig (i.e., just below the 'crest' in the soil at the back of the scoopage) or something else/lower down/?

Posted by: Ant103 Jun 2 2008, 09:18 AM

Greg : do you really think that we can have a "3d" impression with such big pictures. My eyes can't merge the two frame to have the relief impression.

Posted by: climber Jun 2 2008, 09:52 AM

It seams to me that the part further than the actual sample and before the distinctive mark of the arm colapsed a little bit I guess under the pressure of the arm. I have the feeling that the consitency of the soil is like talcum powder (Yeti) even if we can see these little clods.

Posted by: stevelu Jun 2 2008, 10:30 AM

Yes, even finer than talc probably. I believe that the dust on Mars is much finer than any that is stable in Earth's environment -- probably because of the moisture in our air. But still substantive enough that the Martian winds can clean the rover's solar panels of it, and can whip it up into storms that homogenize it, to some degree at least, planetwide.

But I'm an amateur. Anybody want to tell me if I got that right? Is Ann Clayborne in the house?

Posted by: nprev Jun 2 2008, 11:50 AM

Well, speaking as an amateur myself, I've always wondered about the electrostatic properties of Martian dust. Are the clods sticking together because of this?

Posted by: slinted Jun 2 2008, 12:26 PM

Here's my try at RAC color. Since they are starting each sequence with an unlit image followed by the R, G, and B lit images, I tried subtracting each lit image from the unlit image, isolating just the contribution of each light. The results are vaguely un-awful, even working from the raw jpegs (although I did blur them significantly to reduce the compression artifacts). I look forward to seeing what can be done with the calibrated data!



update: Changed the method a bit, and updated the image. Now I'm using the color information from the subtraction images and the luminance information from the "no light" image for a sharper look. Anything not lit by the LEDs comes out psychedelic

Posted by: silylene Jun 2 2008, 12:32 PM

Also interestingly, it looks like to me from the 3D image in the undisturbed soil that there are possibly many tiny blackish 'weep holes' scattered about in the surface soil crust. Perhaps these possible weep holes are formed by outgassing of subliming water and CO2 ices?

Posted by: Bill Harris Jun 2 2008, 01:19 PM

Remember the depositional environment here. The fine dust is an aeolian deposit, and very fine material likely in the micron-range, with some volcanic ash. The coarser material are likely re-worked regolith and fractured rock from nearby impact ejecta (eg, Heimdal). Some rocks may be made of water ice with sediment and gases (possibly even in a clathrate). The ice we see is likely from repeated deposition of hoar-frost, which may end up being preserved when an insulating blanket of regolith/dust is emplaced. I'd suspect many discontinuous layers ranging from ice-rich/soil poor to ice-poor/soil-rich.

Has anyone worked out a particle-size distribution of the aeolian sediments of the dust based on Stokes Law?

A very alien environment.

--Bill

Posted by: ugordan Jun 2 2008, 01:58 PM

Great stuff. If I understand correctly the impact of a uniform bias (such as solar "white" illumination leaking into the scoop here) on the result of CIE XYZ calculations, they should in principle only desaturate the color of a sample illuminated with RGB diodes, but not completely in shadow. Of course, the luminance of each diode most likely complicates this a lot since for calibration you'd have to scale each filter by their relative brightnesses and then you end up messing with solar whitepoint bias as well. Long story short, we need to look at samples during nighttime

Here's my take on the color assuming the scoop interior is sufficiently in darkness and the scoop itself is more or less gray. 2 observations were done at two distances, I've merged two of the same. The upper shot seems to be in better focus.

Posted by: climber Jun 2 2008, 02:16 PM

It also show a ochre/gold color barely visible on the other picture.
I'm not a specialist (nevertheless I'm in the agriculture buisness) but it's the more Earthlike soil I've ever seen on Mars.
We've gona need a scoop or arm emoticon I guess

Posted by: ugordan Jun 2 2008, 02:18 PM

Be very wary when interpreting the color in these raw composites! This is just representative stuff. About the only safe conclusion we can make is that the soil color is different that the scoop color.

EDIT: Here's a different processing, this time also with subtracting the monochromatic signal and filtered to remove noise:


I'm inclined to think the above is a more accurate version than my first try. Definitely looks more Martian. The purple bit is due to low S/N of raw files.

Posted by: centsworth_II Jun 2 2008, 02:58 PM

I gather that in the images taken so far with the RBG LEDs, solar light is a complication. I wonder how taking such images at "night" would work.

Posted by: jamescanvin Jun 2 2008, 03:06 PM

Quite well I would expect, the images of the scoop taken during cruse when it was very dark inside were good.
However, calibration shouldn't be too difficult given the data the team has, I doubt we'll see them resort to night time shots.

Of course you'd have to wait a good while yet for any night to arrive!

Posted by: climber Jun 2 2008, 03:56 PM

OK, I maintain it's Earthlike...at least Roland Garros like

Posted by: jamescanvin Jun 2 2008, 05:48 PM

Official colour version of the first scoopful.

http://fawkes3.lpl.arizona.edu/images/gallery/lg_1698.jpg

Posted by: ugordan Jun 2 2008, 05:58 PM

Hey, if you kick the saturation up of my http://www.unmannedspaceflight.com/index.php?s=&showtopic=5185&view=findpost&p=116714 by 40 Photoshop units, turns out it doesn't look that much different!

Great release. Looks like they glued in the overexposed edge of the scoop to the right, though.

I was wondering if that whitish stuff was a sun reflection, but it didn't move as I'd expect. Looks like it's definitely scraped off bits of something white.

Posted by: climber Jun 2 2008, 06:10 PM

and Roland Garros like color too

Posted by: elakdawalla Jun 2 2008, 06:32 PM

They just pointed out that if you look at the high-res image of the dig site, you can see a whitish area at exactly the same position as the whitish material in the scoop, so they're pretty confident they dug up something whitish, but they don't know whether they're looking at icy materials or salts.

Also they said today's telecon should be available online later today.

--Emily

Posted by: Greg Watson Jun 2 2008, 10:59 PM

I use a 3D image viewer (Stereo Photo Maker) to zoom in, out and wander around the landscape. Almost never look at the original.

Posted by: Greg Watson Jun 2 2008, 11:09 PM

Have a look here. The two images seen together in 3D seem to increase the resolution of either alone. There appears to be a radial darker pattern on the lighter rear dig wall emanating from a central point? Also a lighter / whiter core of the darker radial pattern? At least to my old eyes. Or is it just a clump of fallen dirt and some JPEG noise?

The pattern on the rear right bottom dig wall is also visible in this colour image:

Posted by: Pedro_Sondas Jun 3 2008, 09:16 AM

Eppur si muove..... ??

Posted by: ugordan Jun 3 2008, 09:32 AM

3 exposure stack to improve S/N ratio:

Posted by: MahFL Jun 3 2008, 12:57 PM

To me that sure looks like the lander blasted the soil away and exposed the ice.

Posted by: Julius Jun 3 2008, 01:05 PM

Judging from the colour images,martian soil looks like rust and the way it stains the sides of the scoop,it seems to be wet powdery rust!

Posted by: Big Joe Jun 3 2008, 01:36 PM

Hello to everyone :-)


So I am wondering why the change between the two sol's?

Here is my version.

Posted by: djellison Jun 3 2008, 01:40 PM

Different camera location, different camera orientation, different illumination.

Posted by: Stu Jun 3 2008, 01:51 PM

Hey Big Joe (and welcome to all our other "newbie" members too, there sure are a lot of you suddenly!)...

Doug just beat me to it. I think the only diffences visible between those images are due to shifts in perspective / viewing angle, etc. There doesn't appear to be any change to the position of the leg footpad on the surface, no surface movement or change either.

Posted by: djellison Jun 3 2008, 01:58 PM

Given the ambient temperature of between -83 and -28 deg C - 'wet' is somewhat unlikely. The arms actuators are heated, but the scoop itself is not, and whilst some thermal conductivity into the scoop is inevitable, I don't believe, at such cold temperatures, it would be enough to bring the ices over 0 deg C.

Try scooping dry flour or talc or other exceptionally fine grained material and it will also stick to surfaces in a similar way.

As for rust - well - there's a reason Mars is the colour it is - it's rammed full of Iron Oxides

Posted by: helvick Jun 3 2008, 02:17 PM

The sublimation of pure water ice in the Martian north polar region at the sort of ambient temperatures that Phoenix is seeing would, if I'm remembering correctly, result in the loss of something of the order of 2-10microns from the surface per day. Even factoring in the additional IR heating from the the lander I can't see how that would result in any noticeable change over a couple of Sols. I don't have a reference for that number though and I can't even recall where I read it so I'd welcome any reference to something that either backed it up or proved it wrong.

Posted by: Julius Jun 3 2008, 04:40 PM

well,i meant 'wet' ,not in the literal sense but thanks for the reply Doug

Posted by: Big Joe Jun 3 2008, 05:01 PM

Thank you for the welcome just found the site when I went looking for any info on the Phoenix mission.

What I meant to ask is where I have the arrow pointing in this image with regards to the soil/"ice" edge is that a result of a different angle of camera?

Thanks!

Posted by: gallen_53 Jun 3 2008, 05:06 PM

I've experienced similar dust in rural Queensland, Australia. Australians call it "bulldust". Bulldust has a similar color to Martian regolith. Bulldust is finer than talcum powder and flows like water when hit with an automobile's tire. If one drives into a deep patch of bulldust, it's very difficult to get out (MER-B was once in an analogous situation). Typically one must tie a steel cable to a tree and then pull the car out with a winch.

Posted by: djellison Jun 3 2008, 05:13 PM

I think so - just a perspective issue. If you rotated them 90 degrees, you could make an anaglyph from them.

Doug

Posted by: nprev Jun 3 2008, 05:19 PM

The dust in Saudi Arabia might be similar in properties aside from color. It's just miserable; gets everywhere. It also seems to form duricrust rather readily given any sort of exposure to moisture, presumably because of its extremely fine consistency.

Come to that, a lot of the volcanic soils (mostly ash) in Alaska act the same way. During the spring, windstorms blow that crap off of the mountain slopes and you'll suddenly have this drifting grey material that, if moistened, turns into a pretty good imitation of concrete after it dries.

Posted by: fredk Jun 3 2008, 05:26 PM

My thought exactly. Here's a cross-eyed version:

Big Joe, as far as the change you arrowed, I'm pretty sure it's due to the fact that the time of day, and sun angle, is a bit different in the two frames, so there's a bit more soil in direct sun in one frame than in the other.

Posted by: Big Joe Jun 3 2008, 05:38 PM

Thank you for the response's. It's wonderful to have a forum to discuss the images as they come down.

Posted by: fredk Jun 3 2008, 06:25 PM

I was wondering whether anyone expected the thrusters to expose the ice, here's the answer:
http://www.ns.umich.edu/htdocs/releases/story.php?id=6592

Posted by: Oersted Jun 3 2008, 09:06 PM

And very valuable to have new, active members. Welcome!

Posted by: Greg Watson Jun 4 2008, 07:15 AM

How can I determine which RAC led illuminated the scoop contents? There doesn't seem to be anything on the image site or in the file name which is a help?

Posted by: jamescanvin Jun 4 2008, 07:27 AM

It's in the file name just like the filters numbers for the SSI. At the end: M?M1 ?=R,G,B,D (Red, Green, Blue, Off)

See http://www.met.tamu.edu/mars/filenames.html

Posted by: Greg Watson Jun 4 2008, 07:36 AM

http://fawkes3.lpl.arizona.edu/images/gallery/lg_2753.jpg

Is what I get for file names from the Arizona Phoenix site. I take it there is another site with the full / real file names?

Posted by: Ant103 Jun 4 2008, 07:42 AM

Colors in the showel. This need to put the saturation at high level to have the colors clearly visible.

Posted by: jamescanvin Jun 4 2008, 07:43 AM

You have four options:

Open that file with an EXIF reader to get the product ID.
Download with MMB which now renames the files.
Download from my site where I have renamed them (see my sig)
Download from the NASA site http://www.nasa.gov/mission_pages/phoenix/images/index.html

James

Posted by: Greg Watson Jun 4 2008, 07:47 AM

Hi James,

It's digitally encoded in the JPEG data stream. I should have realised that. Thanks for the clarification.

Greg

Posted by: ugordan Jun 4 2008, 08:17 AM

New DirtShot (TM?) in approx. color:

Posted by: climber Jun 4 2008, 08:34 AM

This sample has been taken deaper than the 1 st one : http://phoenix.lpl.arizona.edu/images.php?gID=2746&cID=42
It look's like there are at least two "pieces" more consistant/ stone like (down and left in the scoop) including one "brighter" than the genral color of the sample. Your feeling ?

Posted by: slinted Jun 4 2008, 10:38 AM

The sol 9 dig further exposed the 'bright spot'. Here's a comparison between the sol 7 trench and the sol 9 trench:
http://www.lyle.org/~markoff/collections/sol7_sol9.gif

Full filter color of the sol 9 trench :
http://www.lyle.org/~markoff/processed/SS009ESF897014436_11A20RC.jpg

and the sol 9 scoop:
http://www.lyle.org/~markoff/processed/RS009EFF897007559_119F0MB.jpg

Posted by: Tman Jun 4 2008, 10:51 AM

Wow, looks like near the "ice" already!

Posted by: ugordan Jun 4 2008, 11:22 AM

If that's ice, it looks awfully easy to scrape off, no? Makes me rethink the whole exposed-ice-under-the-lander idea.

Posted by: djellison Jun 4 2008, 11:31 AM

Looks like a small dry powdery deposit of some sort to me - ice isn't whiter than white like that.

Doug

Posted by: eeergo Jun 4 2008, 11:38 AM

I don't know, the color in the images is quite lighter than the official releases, maybe it isn't so white after all... and that blueish/blackish rim surrounding the white patch looks like dirty ice to my much untrained eye.

I don't think it's so easy to dig, it just looks scraped.

Posted by: djellison Jun 4 2008, 11:42 AM

It just reminds me more of the Tyrone / Silica Valley / Paso Robles type desposits at Gusev more than the ice we see under the lander. Then gain, the more I look at it, the more it looks like the top of a 'layer' of some sort, which just has to be the ice. We'll know soon enough - that's the fun with exploration

Doug

Posted by: Tman Jun 4 2008, 12:00 PM

Guess the next digging probe should it already prove.
If there is somewhere pure ice, wouldn't it be much deeper in the ground, resulting from higher weight/compression?
The thrusters probably melted that layer slightly.

Posted by: ugordan Jun 4 2008, 12:10 PM

It's damn hard to infer color properties from overexposed raw data. Whatever it is, it looks much darker in longer wavelength filters. I'd expect ice to be near uniformly reflective at wavelengths less than 1 micron and to be the brightest stuff in the scene. The filtered images show that there are otherwise grayish rocks that appear brighter in the red spectrum, while at the blue end the stuff is http://www.nasa.gov/mission_pages/phoenix/images/raw/SSI/SS009ESF897013270_11A20L2M1.html (apart from lander deck, it's by far the brightest stuff and it's still overexposed).

If I'd hazard a wild guess, I'd say this stuff might actually turn out blue-greenish in natural color once exposures are adjusted.

Posted by: climber Jun 4 2008, 12:11 PM

The thruster could also have removed the "white layer" (if this is not ice) and get to the ice then. In this theory, the white layer would have spread all over the place.

Posted by: ugordan Jun 4 2008, 12:17 PM

Why don't we see it, then?

Posted by: Oersted Jun 4 2008, 12:53 PM

Occam's Razor says it is ice.

Posted by: Ant103 Jun 4 2008, 02:08 PM

Hi,

Continue playing with "raw" jpegs

This famous trench and hypothetic ice
http://www.astrosurf.com/merimages/Phoenix/images_couleurs/238087main_SS009ESF897014260_11A20-Rcoul.jpg

An analgyph
http://www.astrosurf.com/merimages/Phoenix/images_couleurs/Sol9-Trench-glaceprobable-anaglyphe-coul.png

A parrallel eyes :


The Phoenix deck :
http://www.astrosurf.com/merimages/Phoenix/panoramas/Sol9-pano-deck.jpg

Posted by: Greg Watson Jun 4 2008, 02:50 PM

Here is the trench with some zoom and a bit of resampling (screen shot from Stereo Photo Maker).

There doesn't appear to be any depth to the whitish area, which if it were the top layer of an underground ice layer seems strange. More like something lying on the bottom of the first trench. Ok I know there are no liquids at this temp and pressure but the image is suggestive of a fluid flow that froze??

Yes I do know that is supposed to be impossible but hey this is Mars and this may be the first up close contact with Martian brine / salts / minerals / acid or whatever that blue green stuff its made of.

PS, that strange pattern I noticed on the right lower corner of the first rear dig wall has reduced in size and lost it's whitish core??
http://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=14544

Posted by: fredk Jun 4 2008, 04:02 PM

Thanks for the images, all. I see they decided to dump the latest dig onto the smooth track left by the sliding/rolling rock.

Ant, is there any chance you could post the colour parallel eye version at full resolution (or the two separate full-resolution colour frames)? With stereo photomaker, we can view in stereo no matter how large the image. Thanks!

Posted by: Ant103 Jun 4 2008, 04:06 PM

Yes, I can do that Fredk

Posted by: Greg Watson Jun 4 2008, 04:29 PM

Hail Ants,

With respect, you have the left and right eyes reversed. The trench comes out a hill. BTW I like the blinker. Always a goodie and very informative.

Greg

Posted by: Ant103 Jun 4 2008, 04:34 PM

Greg : it's parallel, not crossed eyes (or maybe I ever made a confusion... ).

Posted by: Greg Watson Jun 4 2008, 04:53 PM

Ants,

When I copied and pasted your image into Stereo Photo Maker (as a side by side stereo image) and swapped the left and right images, the cross eyed 3d effect was perfect. BTW what is parallel? Aren't the images left and right as taken by the stereo camera? But hey, I'm not an expert, just learning from them.

Greg

Posted by: Oersted Jun 4 2008, 08:04 PM

parallel is when you focus behind the images, cross-eye is when you focus in front of the images. I always found it easier to do cross-eyes, have a hard time making myself focus at infinity when there's a computer screen just in front of my nose..

Posted by: SpaceListener Jun 5 2008, 03:29 PM

See what is the Phoenix work area, the RA reach http://www.jpl.nasa.gov/news/phoenix/images.php?fileID=12690

Posted by: ToSeek Jun 5 2008, 07:24 PM

Beyond a certain point, it's impossible to do parallel. Cross-eyes works pretty much no matter how much displacement there is between the two images.

Posted by: Rain Jun 5 2008, 11:14 PM

Can it be silica?

http://www.nasa.gov/mission_pages/mer/mer-20070521.html

Posted by: Reed Jun 5 2008, 11:25 PM

This was discussed in yesterdays press conference, and the answer is that silica would be completely unexpected in this environment.

Posted by: fredk Jun 5 2008, 11:29 PM

At a recent press conference one of the panel thought it was unlikely to be silica based on the geological context (no evidence for volcanism or geothermal activity at the Phoenix site). I'd add that, apart from a few white bits in the first scoop, there's no sign that the white stuff was moved around by the scoop, and I'd expect a powder to get easily redistributed in the trench by the scoop. As far as the brightness, it's hard to say - on our planet, ice can vary quite a bit in its brightness. It's worth keeping in mind that the albedo of Martian soil is typically quite low (really it should be called brown rather than orange), so ice could apear much brighter than the soil.

Posted by: ugordan Jun 6 2008, 08:39 AM

Sol 11 scoop with more of that salty whitish stuff:

Posted by: slinted Jun 6 2008, 08:46 AM

Here's quick look at the sol 11 "Baby Bear" scoop, from the images that are down so far.
http://fawkes2.lpl.arizona.edu/images.php?gID=3238

http://www.lyle.org/~markoff/processed/RS011EFF897190317_11BD0MB.jpg

http://www.lyle.org/~markoff/processed/RS011EFF897191487_11BD0MB.jpg

Posted by: rlorenz Jun 6 2008, 01:25 PM

I can understand that viewpoint, but on the other hand, wasnt the silica that was discovered by MER
completely unexpected there too ?

Posted by: imipak Jun 6 2008, 07:12 PM

Only until they found it.

Posted by: garybeau Jun 6 2008, 09:49 PM

Ice?

Posted by: Airbag Jun 6 2008, 09:54 PM

What are you comparing - same filter, different times, or same time, different filters? Can make a big difference.

Airbag

Posted by: garybeau Jun 6 2008, 10:39 PM

Ahhh - Your correct, it's just a filter change. I should have looked at the time stamps first. It had the looks
of a depression left by sublimed ice. The white area must be overexposed giving it the appearance that the
depression is filled.

Posted by: gallen_53 Jun 6 2008, 11:16 PM

Maybe. It could be any of the following:

1) water ice
2) dry ice
3) salt
4) pure silica such as observed by MER
5) something unexpected

Occam's Razor fails on Mars because our simplist explanations are based upon terrestrial experience.

Posted by: foxfire Jun 7 2008, 02:29 AM

Has anybody commented on what appears to be the obvious strata in the rear (distal) wall of of Dodo Trench? [For reference, a good example (among many) appears in the June 3 blog by AJS Rayl in the Planetary News: Phoenix (2008) Phoenix Scoops Mars and Digs It--in this instance the site is called the Knave of Hearts; I surmise to distinguish it from the trench itself.] I've searched in vain for comments on the strata. If these are "Mars-annual", it is hard to understand how the "varves" can form underneath the apparent topsoil/dust layer.

Posted by: JRehling Jun 7 2008, 03:33 AM

But Odyssey data indicates a major source of hydrogen in the immediate subsurface. And CO2 (which doesn't have hydrogen anyway) is a gas at this pressure/temperature. So even operating on martian data, I'd agree that Occam's Razor falls hard on the side of this being (largely) water ice. We don't yet have absolute proof, but I'd say we're well in excess of 90% confidence that this is water ice at some significant degree of concentration. (Perhaps salty or acidic.)

Posted by: brianc Jun 7 2008, 07:12 AM

On this subject of electrostatic process - not sure if arm can reach but would be interesting to see if particles ended up being stuck to any underside flat surfaces
underneath the lander and see if over a period of time any such particles drop off the underneath - might give some insite into electrostatic properties or other 'sticking' mechanisms (so far the under-lander images have only shown ground underneath lander and the underside itself is tantalisingly out of view at the top of image apart from the descent thrusters)

Also switching to Mars Rovers - can the rover's robotic arm look on any underside surfaces of the rover with the MI - to get close-up of any dust sticking to under surface of lander or lander solar arrays ???

Posted by: imipak Jun 7 2008, 10:34 AM

...but the Odyssey GRS apparently has http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=2001-014A-02, so presumably localised concentrations of "other stuff" (e.g. kieserite) aren't ruled out. My uninformed personal opinion was that the scoop's hitting small patches of salts, but that Holy Cow is ice, based purely on visual appearance... and then DnD 2 changed my mind. Er, I think. (Who knows? It's just nice to know that TEGA will give us an answer in a few sols' time )

That said, I suppose if TEGA sees both ice and salts, we could be debating what this or that particular whitish patch is for a long time to come.

Posted by: ahecht Jun 7 2008, 03:56 PM

The MECA microscope will actually be doing a bit of this. In addition to the "sticky" silicone substrate that we've seen so far, there are sixty-nine different substrates on the wheel. By seeing how much the dirt sticks to the various substrates as it is rotated from horizontal to vertical, a lot can be learned about the electrostatic (and magnetic) properties of the soil.

Posted by: fredk Jun 7 2008, 05:21 PM

I don't think this is what you had in mind, but we can see what I think are some essentially vertical surfaces that were coated with light-coloured splotches during landing (see white arrows in image below). Most of those splotches are on upwards-facing surfaces, but if I've got my geometry right the arrowed ones are on vertical or even slightly downwards-facing surfaces.

Posted by: teck Jun 10 2008, 03:05 PM

Nasa just released some info on this: it is part of a spring.

Posted by: As old as Voyager Jun 10 2008, 07:46 PM

Glad the location from which the spring fell has been identified.

It would've only been a matter of time before Hoaxland declared it as 'evidence'

Posted by: dburt Jun 11 2008, 12:19 AM

I suspect that what you have in mind is not Occam's Razor, but what is sometimes called the "Rosenthal effect" (or experimenter expectancy effect) named for psychology Prof. Robert Rosenthal, recently honored for "groundbreaking research into experimenter bias and self-fulfilling prophecy": that is, for proving that most people see only what they expect to see, and that their expectations influence the outcome of supposedly unbiased experiments and trials (in the social sciences and in jury trials, at least). Based on personal experience, when it comes to data-deficient Mars this effect is hardly restricted to the social sciences, natural scientists being people too, and that's what you seem to be saying also (i.e., if we expect Mars to be analogous to Earth, then we will interpret it using terrestrial experience). See, e.g.,
http://www.newsroom.ucr.edu/cgi-bin/display.cgi?id=1752
or http://www.encyclopedia.com/doc/1O87-experimenterexpectncyffct.html

Still, ice seems the most likely explanation for that patch, with salts a close second, and silica or some other substance way down there, at least for the moment (keeping in mind that combinations are permitted too). Getting the data could end that argument!

-- HDP Don

Posted by: Oersted Jun 11 2008, 10:18 PM

Well, what result did Dr. Rosenthal expect?

Posted by: nprev Jun 11 2008, 11:02 PM

"Rosenthal Effect"...thanks, Don! I've long suspected that such a thing might exist, and our experience in planetary exploration seems to prove it in spades. We are often surprised that the Solar System isn't what we expected it to be, and we shouldn't be.

Suggest a new mantra to be chanted everytime we see a new piece of data from UMSF: "It's an alien world, it's an alien world..."

Posted by: ElkGroveDan Jun 11 2008, 11:17 PM

Don's post is only proof that you wanted and expected such an effect to exist all along.

Posted by: nprev Jun 12 2008, 02:20 AM

...great...NOW my CPU has overloaded in a death-spiral of recursive logic which only massive amounts of alcohol can cool to the point of safe rebooting...thanks, Dan, love ya, man!

Posted by: dburt Jun 12 2008, 05:23 AM

Congratulations, Oersted and EGD and nprev, for spotting that recursive paradox, one that was considered early on (and that Dr. Rosenthal apparently tried to alleviate by effectively isolating himself from the actual experiments). So, is Dr. Rosenthal telling us that the canals on Mars are really there after all, and that it's simply our modern expectations that aren't up to snuff?? Or was it simply that additional data became available? In any case, as I stated above, additional data (and an absolutely open mind, free of expectations) are commonly required to do good science.

-- HDP Don

Posted by: Oersted Jun 12 2008, 08:02 PM

Just looked recursion up in my dictionary:

Recursion, see Recursion

Posted by: climber Jun 12 2008, 10:18 PM

Very interesting traduction in French = récursion

Posted by: dburt Jun 13 2008, 05:21 AM

Thanks for that, which famously gets the basic idea across (lots of well-informed and clever people on this forum). Actually some of the dictionary definitions for recursive are worse, but I just meant the simplest: defined in terms of itself. As an example of a similar paradox, Paul Knauth told me that at the beginning of the semester, he likes to ask in class for a show of hands by "those students who never raise their hands in class".

With regard to Prof. Rosenthal and experimenter expectancy, I should have mentioned that modern social/medical scientists habitually engage in what is called double-blind testing. This means that neither the tester nor the subject know who is receiving say, the Coke or the Pepsi in taste testing. Similarly, in drug trials, neither the physicians nor the patients (or the rats, in animal testing) know who is receiving what - the new treatment, the standard treatment, or the placebo (cf. the famous placebo effect). In other words, zero special expectations by design. NASA seems never to have considered such a careful protocol for Mars, possibly because Mars the planet is neither a person nor an animal (although the story of the blind men examining the elephant comes to mind). Nevertheless, as implied in the post that started this commentary, when you are told to "follow the water" and are confidently expecting to find ice where you land, might this bias your thinking about the bright patch under the lander, or about other bright patches?

Another example might be if Phoenix identifies some (long-sought) carbon compounds. Our expectations regarding these as indicators of life might blind us to the fact that carbonaceous chondrites (a common type of meteorite) have been delivering copious quantities of organic compounds to the surface of Mars for billions of years. Although the scientists might be properly cautious about the significance of such an ambiguous discovery, the news media would probably be much less so (I can see the headlines now). The ultimate victims of the Rosenthal effect might then be the reporters (and thus the public), whose extremely high expectations for science itself could lead them astray.

Being well-informed and clever, I'm sure most of you can figure out why I bothered to explain this in such detail. (And I much regret that Alex Blackwell will not be making a uniquely dead-pan reply.)

-- HDP Don

Posted by: dvandorn Jun 13 2008, 08:07 AM

I will point out that tests to make general-to-specific characterizations of large, complex systems don't lend themselves well to double-blind testing concepts. I mean, would you have the MERs bring along a suite of various rock types with them to Mars, selected by a group of people who have no communication with the PIs, and have every measurement taken on Mars include this test suite, with the PIs not being informed of which set of results belonged to native Martian rock and which to the terrestrial samples?

As you see, the specific double-blind process doesn't lend itself to the work at hand. Not that I don't see a need for some way to try and reduce the Rosenthal effect.

That said, what I note strongly in the process of designing science payloads for planetary probes is that it seems to reward those who have developed very detailed models of their expected findings, and have thence designed their instruments to most effectively collect the expected data.

It seems as if any experiment proposal that includes the phrase, in any form, "We don't know what we'll find" is automatically rejected because of the possibility that, by not meeting some preselected expectation, the experiment runs a high risk of being viewed as a "failure."

That's a process that not only allows a fair amount of the Rosenthal effect, it fairly demands it. When you design your instruments to show you only what you expect to see, it's awfully hard to see those things that *are* there that you never expected.

One of the worst examples of this effect, I think, was the life detection suite aboard the Viking landers. They were designed to say Yes or No to a very specific (and very terrestrial) set of life-bounded conditions, so the PIs didn't look closely enough at what Maybe results might mean, or how they might be interpreted.

I think the worst unflown example of this effect would have to be a contender for the 2001 lander program who, if I'm remembering the details from Squyres' "Roving Mars" correctly, wanted to devote an entire science payload to positively identifying amino acids within the Martian regolith. That would have been a good portion of a billion dollars to answer what is probably not *nearly* the most useful question to be asking.

The spacecraft that suffered the least from this effect? IMHO, at least for fairly recent probes, I would say Stardust. Yes, the designers of the Stardust collectors had to make some assumptions about the size of the particles they were going for, and the density of particles in their collection location. But the whole point of Stardust was "Let's go grab some comet dust, bring it back, and then see whatever we see when we get our hands on it." That mission design, since it brought samples back to where a great multitude of tests could be run on them as appropriate, was able to follow a more simple paradigm of "grab what you can and then see what you've got."

It seems to me, though, that until we can bring samples back and have the luxury of running whatever tests on them that seem appropriate (to answer all the new questions that the the initial test results pose), you have to narrow your data collection based on some form of triage theory. You can't fly all of the tools you want to fly that would truly enable you to just follow up on what you find rather than looking for what you expect. That's a given, considering mass budgets and funding budgets.

So, you *have* to narrow the focus to what you can afford to place in situ. Granted, the current process encourages that narrowing more than it should... but I'm not coming up with any good ideas on how to change the process to reduce the Rosenthal effect.

-the other Doug

Posted by: nprev Jun 13 2008, 12:28 PM

Great post, oDoug!

That's exactly why I like the basic question that Phoenix is trying to answer: "Are there organic compounds on the surface of Mars in this locale?" That's constrained well enough to answer with the equipment available without making a whole bunch of other assumptions...good, focused science.

No disrespect to the Viking experiments intended, BTW. They were extremely audacious, but as Doug said there really wasn't very much interpretation space available for "maybe" results. We just don't know enough about both organic and inorganic chemistry in non-terrestrial conditions to draw definitive conclusions from any experiment designed to detect indirect evidence of biological activity.

Posted by: climber Jun 13 2008, 01:01 PM

Yes, great post O doug,

This can lead also to "Mission success" requierements.
BTW, does anybody know what are Mission sucesses requirements for Phoenix ?

Posted by: MahFL Jun 13 2008, 01:38 PM

I found it....

http://mars-scout.larc.nasa.gov/PDF_FILES/Phoenix_L1_Amendment_51405.pdf

Posted by: Skyrunner Jun 13 2008, 01:58 PM

Minimum Mission Success Criteria
To achieve minimum success, the Phoenix Project shall:

• Land successfully on the surface of Mars and achieve a power safe state.
• Acquire a 120 degree monochromatic panorama of the landing site.
• Provide samples of the surface soil as well as samples from one depth beneath the surface to either TEGA or MECA wet chemistry.
• If TEGA, it shall analyze at least 2 soil samples to create a profile of H2O (in the form of hydrated minerals, adsorbed water, or possibly ice at the deepest level) and mineral abundances near the surface. It shall also analyze an atmospheric sample in its mass spectrometer.
• If MECA, it shall analyze the wet chemistry of 2 soil samples.
• Document all non-atmospheric samples and their collection locations with images.

Full Mission Success Criteria
In order to be fully successful, the Phoenix Project shall:

• Land successfully on the surface of Mars and achieve a power safe state.
• Acquire a true color (RGB), 360° panorama of the landing site.
• Obtain calibrated optical spectra of at least 3 locations that include both rocks and soil.
• Provide temperature and pressure measurements throughout landed surface operations at a frequency that determines key atmospheric properties.
• Provide samples of the surface soil as well as samples from two depths beneath the surface to both TEGA and MECA.
• Use TEGA to analyze at least 3 soil samples to create a profile of H2O (in the form of hydrated minerals, adsorbed water, or possibly ice at the deepest level) and mineral abundances near the surface. It shall also analyze an atmospheric sample in its mass spectrometer.
• Use MECA to analyze the wet chemistry of at least 3 soil samples. It shall also analyze 3 additional samples in its microscopy station.
• Document all 9 non-atmospheric samples and their collection locations (before and after sampling) with images.

EDIT: MahFL has beaten me to it:-p

Posted by: BrianL Jun 13 2008, 03:26 PM

So, does that mean full mission success can be achieved without actually reaching, sampling and analyzing solid ice?

Brian

Posted by: centsworth_II Jun 13 2008, 03:33 PM

It seems to me that mission success should be based analysis of the landing site, whatever the results of that analysis are. Also, let us hope that there is no layer of solid ice, especially near the surface, as that would mark the end of the dig, depth-wise anyway.

Posted by: Sunspot Jun 13 2008, 03:39 PM

I want them to dig a MASSIVE trench !!

Posted by: ugordan Jun 13 2008, 04:11 PM

Here's an animated gif of the digging. 21 frames spanning almost 2 hours. It's half resolution because the full res was too large to upload anywhere (9 meg). The overexposed part of the sequence covers 50 minutes and during that time no visible change in the white stuff can be seen.

http://www.fileden.com/files/2007/9/14/1431389/digging_small.gif

And an anaglyph of the resulting trenches:

http://i108.photobucket.com/albums/n15/ugordan/trench_anaglyph2_18.jpg

Posted by: fredk Jun 13 2008, 05:25 PM

Thanks for the animation and anaglyph. It appears to me that the bright "ice-like" surface exposed at the bottom of the trenches is not flat - there is relief to it. This is most clear on the right side trench.

I think we can expect more time-lapse trench images like this. On a recent press briefing there was an interesting comment from Smith I believe, who said that there was quite a discussion amongst the team about whether we were seeing true changes in the bright "ice" or whether it was just due to changes in illumination (phase) angle.

I guess this doesn't really fit in "RAC - Lander and Under-side observations" - perhaps we need a thread dedicated to trenching?

Posted by: ugordan Jun 13 2008, 10:57 PM

To continue on the animation I posted and seeing the Phoenix team today alluded at hints of change of white stuff in time-lapse frames (change not necessarily illumination-related), here's a crop of the animation with two patches definitely fading out over time. Phase angle effect? It doesn't look that way to me, the neighbouring areas don't show nearly as much dependance. There's a frame each 3.5 minutes or so, except a 20 minute gap between 11:45 and 12:05. During this time the two spots change most prominently. There are also some smaller specks that appear to fade out, but they're not very conclusive. The rest of the bright stuff appears to not change at all or change very little.

Ice particles sublimating? Any thoughts on this?

http://i108.photobucket.com/albums/n15/ugordan/fading.gif

Posted by: scalbers Jun 13 2008, 11:13 PM

At the average ambient temperatures we expect sublimation to be quite slow. This might be accelerated by the action of sunlight shining on a dark bed of soil with a white ice particle sitting on top (if it is).

On another note, it seems remarkable that the ice could be just under the surface in such a wide area, yet there are no outcrops anywhere.

On yet another note (as I mentioned in another thread), I wonder if Peter Smith or anyone has commented on the "Holy Cow" image beyond what was briefly mentioned at today's press conference? It would be interesting to see how they would describe this image in front of an audience.

Posted by: glennwsmith Jun 13 2008, 11:22 PM

One answer as to why the ice would be nowhere exposed but everywhere covered by a thin layer of regolith is, of course, that the exposed ice has sublimated. I guess you need to be old enough -- I am 59 -- to remember stories of how ice covered with saw dust could last a remarkably long time. Gad, watching that trench being dug is some way cool stuff (pun intended)!

Posted by: Bill Harris Jun 14 2008, 12:07 AM

> guess you need to be old enough -- I am 59 -- to remember stories of how ice covered with saw dust could last a remarkably long time.

That is likely and accurate observation. The regolith, being partially aeolian, may have a "fairy castle" structure with a thermal conductivity approaching zero so even a few centimeters would allow possible temperatures to remain below the sublimation point of dihydrogen oxide.

I seem to recall a temperature/etc/ probe on the arm, so ew can expect temperature data soon enough.

--Bill

Posted by: fredk Jun 14 2008, 12:09 AM

Thanks again for this, this is interesting. I would guess we are seeing a phase angle effect (perhaps the extreme case of this, specular reflection). I say this because there are definitely small patches that get brighter over the series. I've circled one in the attached frame:

On a related note, I think I wrote this before, but we've now exposed quite a bit of the "substrate" and with each dig we haven't seen much in the way of loose powdery white stuff moved around by the scoop (unlike the salts exposed by Spirit). Also, Smith mentioned today that the scoop appears to be "bouncing" along the bottom of the trench, as if along a hard surface. So my question: is there any viable scenario in which the "substrate" is salt, but is hard rather than loose and powdery?

Posted by: cschmidt Jun 14 2008, 02:11 AM

Indeed, I had brought this up in an earlier post: if the abundance of water is so high and the temperatures so low, then why wouldn't you expect the subsurface be just a massive block of ice, thus impenetrable by the scoop.

The response was given that salts would make the ice chunky, well-gardened.

Posted by: dburt Jun 14 2008, 03:51 AM

I agree we're probably looking at ice, but the answer is basically the same whether it's ice or salt. In either case you have to consider a role for liquid water or brine.

In order to change powdery snow or frost into solid ice, you have to compact and recrystallize it, so as to eliminate air. This process is greatly facilitated if there is at least some liquid water on grain boundaries, so that the ice can dissolve and reprecipitate into larger crystals, expelling the air. (This recrystallization process is analogous to metamorphism of rocks such as limestone or sandstone.) The ice may start out as a filling between mineral grains (i.e., permafrost), but generally at least some of it will separate, again owing to recrystallization (and flowage), into zones or pods of pure ice, or perhaps into veins. The same sort of maturation/segregation process presumably is involved in the formation of ice polygons (w.r.t. which I claim no special expertise). If massive ice formation happens on a slope, and involves enough ice, then the ice starts to move, and you have a glacier.

The above process might appear to be limited to temperatures above 0C (273K) for pure ice and its meltwater, but could conceivably continue to temperatures as low as 220K or so if there were minor amounts of windblown chloride-rich salts mixed in. In that case the grain-boundary liquid could be a concentrated chloride brine, similar to those found beneath the surface of some permanently frozen Antarctic lakes, and the temperature range available overlaps the range measured by Phoenix (as discussed in other posts). Like air, the brine would eventually get squeezed out, ideally downwards, being denser than ice and able to flow. I discussed this idea in papers with Paul Knauth in 2002 and 2003.

If instead the substrate starts out as powdery efflorescent or wind-blown salt crystals, you similarly need at least some liquid water or brine along grain boundaries in order that the salt crystals can dissolve and reprecipitate (recrystallize) to eliminate air. In the case of salt, this liquid is almost certain to be a concentrated (saturated) brine, stable over the same possible temperature range as discussed above (assuming it is chloride rich - sulfate salts exhibit very little freezing point depression). The recrystallization should occur much faster for salts that are relatively soluble (e.g., chloride salts and magnesium sulfates) than for salts that are relatively insoluble (e.g., gypsum, a calcium sulfate). (This effect gives you one explanation for why only the least soluble common salt, gypsum, occurs in dunes - it doesn't recrystallize before the wind plucks it.) As with ice, salt recrystallization and migration could yield separate pods or zones or layers of relatively pure salt, as well as salt filling interstices between other mineral grains (a "saltcrete"). In a frozen recrystallized system involving ice, salts, and brines you ideally might end up with a "brine sandwich" involving less dense ice on top, a thin zone of concentrated (eutectic) brine, and denser precipitated salts beneath. Cooling below 220 K should cause the intermediate brine zone to freeze (crystallize) into a mixture of ice (above) and salts (below). These ideas are likewise discussed in our 2002 and 2003 papers (which were inspired by the "young gully" phenomenon).

The important point is that if there are hard layered zones of recrystallized salt at the landing site, they should underlie a thick zone of less dense ice (if brine was involved in their recrystallization, at least). That's one reason that I suspect the hard, bright patches currently under discussion are recrystallized ice rather than salt. Nevertheless, minor salt may have had an important role in allowing the ice to recrystallize under subfreezing conditions (thus making the massive ice extremely difficult to scrape).

Inasmuch as I'm not a specialist on permafrost, and have only been to Antarctica once, someone else may be kind enough to give you a more accurate (and hopefully much shorter) answer.

-- HDP Don

Posted by: CosmicRocker Jun 14 2008, 05:03 AM

Interestingly, it was suggested in today's briefing that they might "lay waste" to their entire "national park system" to expose the topography of the purported ice surface. If they can't dig anywhere deeply, strip-mining the area to the basement "rock" is a project I can support.

Just for fun, I noticed that the Phoenix SSI is doing its visual color filtering with the right camera, and I realized that we might be able to produce sort of semi-colored anaglyphs with certain image sets. I'm not very good at color balancing false color images to make them appear as "approximate true color," so I used http://www.jpl.nasa.gov/news/phoenix/images.php?fileID=13775 for the right half of this anaglyph, and the L1 grayscale for the left half. This is of the Dodo and Goldilocks trenches.

I use red/cyan glasses to view anaglyphs, which allow some red, blue, and green information to reach my brain from an image like this, albeit via different eyes. That's why I think this anaglyph appears to me in somewhat muted (rather than vivid) colors. I am curious to hear how it might appear to someone using red/blue glasses, or other filter pairs.

Posted by: nprev Jun 14 2008, 05:06 AM

Don, that was very interesting and informative; thanks!

Question: Although I know you're not a specialist in such matters, what effect would the ambient temperature, the low atmospheric pressure, and the fact that the material discussed is (barely) subsurface have on H2O phase states?

I get the feeling that liquid water in this region is an impossibility unless it's WAY underground, and unless water can rapidly sublimate and refreeze in an amorphous state in these conditions I'm having a hard time understanding why it would exist in any form other then as a stratum or as a big chunk of same like Holy Cow might be; basically, as a discrete mineral.

Posted by: dburt Jun 14 2008, 05:17 AM

In keeping with those who have already commented, I think your post provides an excellent summary of the practical impossibility of eliminating prior expectations in planetary missions. My only quibble is that most of it deals with obtaining funding plus experiment and hardware design (something for which NASA is justifiably world-famous) rather than with the psychological problem of how best to interpret the observations, and then how best to interpret them to the media (which have their own expectations). I think we agree that the present system just might have problems in this regard. A simple systemic recognition of the Rosenthal effect, and its potential pitfalls, might be a start (in case the "canals" and "face on Mars" don't provide enough of a cautionary note - ugh).

It should be interesting to see how NASA deals with organic matter, if any is found.

-- HDP Don

Posted by: dburt Jun 14 2008, 06:29 AM

Thank you. Actually, I *am* supposed to be a specialist in phase diagrams, or at least I teach about them. My best answer without drawing any would be that at these low ambient temperatures, for concentrated brines, the low atmospheric pressure would not be much of a factor, especially in the shallow subsurface, when we're just talking about grain boundary films (i.e., moisture). The reason is that such syrupy brines, in addition to having a greatly lowered freezing temperature, also have a greatly lowered vapor pressure. This has been discussed in prior posts, I believe (probably dealing with gullies). Like you, I'd worry more about the temperature than about the pressure - we should be getting close to the freezing limit for even the briniest of liquids, so close to the poles (unless ice recrystallization occurred in a prior climate regime). On the other hand, I don't know of a better way to encourage recrystallization. Simple squeezing under pressure might suffice, but that would imply considerable erosion/sublimation since the ice originally recrystallized. Possible, I suppose. (But would we see polygons then?)

Repeat: I'm not a permafrost specialist. I live in Phoenix, Arizona, where it sometimes gets up to 122F (50C). I can tell you about the chemical theory while I'm frying eggs on the sidewalk, but that's about it.

-- HDP Don

Posted by: SickNick Jun 14 2008, 06:57 AM

Accumulating thick and "solid" ice...

One thing we're perhaps tripping over here is timescales on Mars, compared to Earth, and the role of vapour to solid transitions. On Earth, almost all ice is formed either from accumulated snowpack, or from frozen water. The accumulated snowpack (snow->firn->ice) is quite well understood and DOES have an important role for boundary-layer water films in facilitating recrystallisation. On Mars, we *may* be dealing with a different system where solid-state dcrystal growth occurs direct from the vapour phase.

Over many annual, decadal, millenial cycles, the ice surface may sublime away, or accrete, essentially ALWAYS in the solid state. On Earth, we grow polycrystalline diamonds by this method from carbon-rich high-temperature vapours.

The mechansims for ice and dust segregation on Mars - whether they involve ephemeral liquids or not - are most likely to be closest to processes in the very cold dry Antarctic valleys, but remember, that Antarctica is so hot and wet and high-pressure compared to Mars that it is unlikely to be a direct analogue. We may need to extrapolate another couple of orders of magnitude!

The ice-sheets of Antarctica are highly dynamic on a time-scale of tens or hundreds of thousands of years. Reports of million-year ages for deposits overlying ice in the Antarctic dry valleys are still uncertain, but even if they are, most parts of Mars have surface ages of tens to hundreds of millions of years and are much older. Something that is insignificant on Earth *could* be important on Mars.

I like one aspect of Don's analysis - he suggests that any liquids that might form by interacting with salts have probably *already* done so and *already* left the scene.

People often argue that areas like the base of Hellas are warmer and more liquid-friendly than other areas of Mars, but let's look how that plays-out on earth. The Sahara Desert is one of the hottest areas on Earth (or a better analogue, the Taklimakan depression in Western China). These areas become searingly hot, by earth standards. All the near-surface water is baked out, blown away in the wind, and finally falls as precipitation in distant areas, perhaps even as snow in the mountains.

On Mars, Hellas is the Taklimakan depression. it's hot as hell (by Martian standards) and any casual H2O will be vapourised, advected by winds, and will exit the basin, ultimately ending up as precipitation in the cold-spots of Mars like the polecaps (or equatorial icecaps, in high-obliquity times). Remember that we KNOW that large amounts of material have been removed from hellas, by the exposed weathering patterns of e.g. the honeycomb terrain. Over the millennia, hundreds of metres of sediment have been blown away by the winds, and all the associated water is probably long-gone.

Phoenix in in area where ice is stable. Anything that you can engineer to generate liquid water there would have done it thousands of years ago and, as Don suggests, leached down into the subsurface.

We're likely looking at a volatile-poor residual crust of ice, which has been frequently sublimed and re-accreted, and processed to a very pure state.

But let's see what the ovens have to say...

Posted by: dburt Jun 14 2008, 10:28 AM

Hi Nick, Thanks for noticing I was floundering. I like your suggestion of direct ice growth from the vapor phase, plus repeated daily/seasonal cycling. Lets you do it as cold as you like, for as long as you like, without any special pleading regarding salts or brines or changing climates or deep burial. Shows that my trip to Antarctica may have hurt my Mars intuition far more than it helped (good thing I wasn't there long enough to make me an expert ). Occam would be proud of you!

-- HDP Don

Posted by: Airbag Jun 14 2008, 12:57 PM

Looks great to me with plenty of color detail using the more red/blue "Sky & Telescope" cardboard glasses; very nice job on that anaglyph. I'm sure that was quite a bit of work making everything line up right, but I hope you do more of them!

Airbag

Posted by: scalbers Jun 14 2008, 02:57 PM

Is there a possibility that during high obliquity times we would get continuous sunlight on the polar region and actually make it up to the melting point? At least presently, the pressure is enough for liquid water to exist at this elevation.

I recall that in the book "The New Solar System" there were some interesting diagrams of stability of ice as a function of latitude and depth. The Mars chapter in several of the editions was written by Michael Carr. The diagrams would need some modification perhaps based on the Odyssey observations. I'm also unsure they would account for the variable obliquity over geological (areological) time.

Posted by: SickNick Jun 14 2008, 03:23 PM

Oh, sure, if you took Mars today, and twisted it with a space-time vortex and tomorrow it was in high obliquity. No problem.

The issue is, it takes tens of thousands of years to move from one state to the other, and the near-surface ices have plenty of time to advance or retreat, and end up at a depth where vapour equilibrium dominates, and there is not then any liquid, under the conditions of the day.

Remember we're dealing with a DYNAMIC equilibroum - things change. TO coin a phrase - "Mars climate changes in a way that *always* frustrates one's preferred model"

I can't *prove* that there is never, ever, liquid water on Mars, but the ESA mineralogy results show that there has been *almost never* liquid water on Mars. A Mars model that has thin liquid water films TODAY at any random location is precluded.

Posted by: scalbers Jun 14 2008, 03:38 PM

I think I did imply in my post that the obliquity varies over long periods of time Interesting point that the dynamic equlibrium can change rapidly enough in response to this. How close to the surface would this be true for?

I thought I did hear Peter Smith suggest they could look for organic chemistry in the ice based on the possibility of past melting in the "recent" (though not that recent) times of high obliquity. Perhaps I misinterpreted what I had heard. I guess as you say earlier we'll let the ovens speak.

Steve

Posted by: marsbug Jun 14 2008, 04:28 PM

Nick I don't fault your logic, but can we make water crystals from vapour with no liquid stage, in simulated mars conditions, here on earth? I was under the impression that as a crystal forms from vapour below 273 kelvin but above roughly 180 kelvin there is a nanometers thick liquid layer over its surface kept liquid not by impurities but by pressure from van der waals forces. I hope you don't take this as a nitpick, I'm just trying to be sure of what you mean.

Posted by: scalbers Jun 14 2008, 04:52 PM

Disregarding the possibility of a thin liquid film, we can get ice crystals condensing directly from water vapor when it's well below freezing on earth. If you've seen an "ice fog" or ice crystals floating in the air that produce sun pillars or streetlight pillars, this can happen without a supporting cloud of supercooled liquid water droplets.

Frost would be another example of going directly from vapor to ice crystals. I would assume this could also be possible under simulated Mars conditions.

Steve

Posted by: dvandorn Jun 14 2008, 05:03 PM

Hey -- we can nitpick Nick's and Don's theories on the emplacement processes for this ice layer that we seem to be literally unearthing, here. But at least they're dealing with potential deposition and emplacement processes.

I think it's important to have some well-nitpicked theories for emplacement processes as we start looking at this ice layer in detail. As much as models can put blinders on investigators, they are also incalculably helpful in interpreting empirical results.

In my mind, each of the observations we've been making on this apparent ice layer bring up questions on how such a layer could exist during the present day. And those questions can only be answered in the context of a model of ice deposition, sublimation and maintenance.

I'm looking forward to hearing more from Nick, Don and all others on how our observations fit with various ice emplacement models.

-the other Doug

Posted by: ugordan Jun 14 2008, 05:35 PM

Does this make a more convincing case? Obviously there's been some digging in Baby Bear, but Dodo is intact as far as I can tell. The local time is the same to within 2 minutes so no phase angle effects this time. Same filter in both shots; R2 (blue).

Posted by: ahecht Jun 14 2008, 05:54 PM

If you're being literal, wouldn't it be "unmarsing"?

Posted by: marsbug Jun 14 2008, 06:03 PM

I was wondering when someone would say that! What I was getting at was whether or not Nick was suggesting the ice formed in a way that normally occurs at much lower temperatures, and if he is, why he thinks this would be the case? Crystal formation, is something I'm studying as part of my PhD so I was wondering if nick had some piece of knowledge on how the martian conditions affected the ice forming process.
EDIT: I changed some things for clarity.

Posted by: fredk Jun 14 2008, 06:40 PM

Yes! This is extremely interesting. The differences in your latest gif are clearly not phase related - looking at frames on a single sol (either 18 or 19), you can compare the frame in your gif with frames taken a couple of minutes later or earlier on the same sol, and there are no significant chages (only specular reflection could have given changes that quickly).

As you say, the left side trench is largely untouched between your two frames, although there are a few new sprinkles towards the bottom. But for the most part, we must be seeing genuine changes here!

I'm very intrigued by the nature of the change. Generally, the "bright substrate" has become darker. But, the peripheral parts of the "bright substrate" have become very dark on sol 19 - in fact, they have become darker than the surrounding soil! I've highlighted a prominent darkened region on the sol 19 frame:

I've noticed these dark peripheral regions before, but I haven't read any discussion on them. Now we see clearly that they develop over time. What's going on here?

\begin{brazen, uncalled for speculation by a non-geologist}
Could this be darkening due to dampness? Ie soil warms in sun, warms adjacent ice, soil gets slightly damp.
\end{brazen, uncalled for speculation by a non-geologist}

Posted by: tty Jun 14 2008, 06:51 PM

As for obliquity- and other Milankovich-type changes, they are important here on Earth too, and pretty slow (the most important periodicities are 41,000 and 100,000 years). However they can still cause quite abrupt climatic changes, especially between glacial and interglacial conditions. These are apparently due to conditions passing a critical treshold and flipping rather suddenly from one semi-stable state to another. It seems to me that this could happen on Mars too. As a matter of fact the layered terrain at the poles rather suggests that it does.

Posted by: jmjawors Jun 14 2008, 06:55 PM

Forgive me for interrupting this discussion of the images from people who are far more knowledgeable than I, but to a totally untrained eye, assuming that the white "stuff" is indeed water ice, the darker spots that have appeared look to me a lot like it's melted and that the soil is wet.

Let me state for the record that I'm not a chemist and know nothing about the behavior of water under different pressures and temperatures, or its properties once mixed with other substances. Just posting my thoughts here because sometimes an uninformed opinion can be a breath of fresh air. Maybe that's the case with this post, maybe not.

Though I realize that this may turn out not to be ice at all, it still *looks* like melt with some slight capillary spread.

Posted by: scalbers Jun 14 2008, 06:59 PM

I agree we should at least entertain the hypothesis of melting in the sunlight. Exactly how warm can a surface get when exposed to the sun at that location? The answer would vary depending on whether we assume glancing incidence (to a level surface), or normal incidence to an inclined surface.

We know that maximum air temperatures are about -30C. The ground (at least the darker component) can likely get somewhat warmer.

The atmospheric pressure is high enough to support liquid here. What a uniquely fascinating mission!

Posted by: marsbug Jun 14 2008, 07:12 PM

I think the ground is usually about 15 degrees warmer than the air temperature, which would mean the ground is at -15 deg celcius, at a very rough guess. That's still to cold for pure water to melt, so unless the experiments show something in the ice which lowers the melting point either: its not melting it just looks a bit like it is, or that's not water ice, or the apparent darkening is some kind of camera artefact, or something else I haven't thought of...

Posted by: scalbers Jun 14 2008, 07:32 PM

Here's an interesting reference I found on another forum. It agrees with the 15C difference, but suggests the ground temperature can approach 0C.

http://www.lpi.usra.edu/meetings/7thmars2007/pdf/3147.pdf

(see upper right paragraph on the third page)

Elsewhere in the forum thread, it is suggested that polar regions can reach +10C ground temperature judging from early Earth based observations.

http://www.marsroverblog.com/discuss-70688-phoenix-readings-of-mars-surface-temperatures.html

Steve

Posted by: marsbug Jun 14 2008, 09:04 PM

That's an enticing thought Steve, but since we don't know if that even is ice yet (for sure), and we have no way of measuring ground temperature I think we're getting ahead of ourselves. Assuming it is ice I'd like to know why its formed a solid layer just beneath the surface, I'd read it was expected that ice deposited from vapour would simply fill the pores in the soil, implying processes involving liquid might displace the soil. How far down does the liquid formed by frost leaching travel before it hits temperatures cold enough to freeze it? I'm wondering if the solid layer could be the result of hundreds of thousands of years of tiny amounts of brine from frost leaching sinking into the soil? If it is cold and protected enough there it might have been there for a looong time.

Posted by: scalbers Jun 14 2008, 10:11 PM

For more background info on this I found an UMSF thread on Mars Odyssey THEMIS IR temperature measurements (of "skin" temperature). In some cases warm readings imply instrument noise or localized hot spots. In other cases, even the minimum values in the field of view are remarkably warm at high latitudes. Is this measurement correct?

THEMIS Image Data Page for I02967002.
CENTER_LATITUDE = 76.7838
CENTER_LONGITUDE = 128.354
MINIMUM_BRIGHTNESS_TEMPERATURE = 267.048
MAXIMUM_BRIGHTNESS_TEMPERATURE = 314.033
http://themis-data.asu.edu/img/I02967002

http://www.unmannedspaceflight.com/index.php?showtopic=1229

Posted by: marsbug Jun 14 2008, 10:20 PM

That's a helluva knack for thread finding you've got there! One of the threads mentions that the brightness temperature doesn't necessarily match directly with actual ground temperature, but if there's a close enough relationship between the two then water could have formed, and be stable over a narrow range of temperatures. The pressure seems high enough (barely but it is high enough). There's a lot of ifs to get past though, I'd only put it in the 'maybe' pile. If I had one.

Posted by: scalbers Jun 14 2008, 10:45 PM

OK, at the risk of speculating some Earth based analogies to Mars, I think the difference between the brightness temperature and the extreme top layer of ground might be just a few degrees. Things that can throw this off would be surface emissivity and atmospheric effects.

I do see in the UMSF thread a mention that the warm readings of 300K are unusual with most readings in the 250s, so we could be looking at some sort of instrument anomaly in this isolated case. We'll have to look a bit closer at the data perhaps.

Here's another report based in part on Viking IRTM (Infra-red Thermal Mapper) data.

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=30104

It suggests max temperatures at the surface (figure 1b) roughly 265-270K if I read the chart correctly, at least up to 60 degrees N latitude. So this seems overall like a close call.

Posted by: James Sorenson Jun 15 2008, 12:51 AM

Correct me if im wrong, but I thought the TECP on the arm could messure the electrical propertys of the soil and also measure temperature?.

Posted by: scalbers Jun 15 2008, 01:25 AM

Greetings,

Yes James, I see in this reference the TECP can do a lot, even detecting the electrical properties of "unfrozen" water that is heated within a trench.

http://www.cosis.net/abstracts/EGU04/01134/EGU04-J-01134.pdf

I will speculate again on another consideration I've been thinking about. Given the shape of the trench, and the appearance of it being well illuminated, I wonder if there could be some reradiation of IR energy from the walls of the trench onto the floor? If so, this might give us a few extra degrees to work with. Think of standing next to a brick building on a warm sunny day.

Steve

Posted by: James Sorenson Jun 15 2008, 02:00 AM

Thought so, I read an artical saying that the TECP could also be used to measure the wind direction.

http://www.decagon.com/mars/info/GeneralTECPmeasurement.pdf

Does anyone know when the first use of this usefull instrument will be used?, or have they used it allready?.

I got an idea, is there any heaters in the scoop?, if there is why not press the scoop down on the possible ice and use the RAC to see if any of the ice melts?.

Posted by: Stu Jun 15 2008, 07:32 AM

Love the crumbly texture and detail visible in the right hand trench...

Posted by: Stu Jun 15 2008, 07:55 AM

... and a recent "dirt dump" shows up really nicely in this 3D...

Posted by: teck Jun 15 2008, 10:11 AM

I have downloaded some R G B images from the RAC. I do I combined them to get a color photo using GIMP?
If I used the regular compose tool, I still get BW images. I undertand that these are illuminated R G B shots and not filtered. If I compose from the SSI images, I get color photos.

Posted by: um3k Jun 15 2008, 11:27 AM

To make color images from the RAC, you have to match the levels of the color-LED images and the no-LED image, subtract the no-LED image from the color-LED images, and then combine the color-LED image. Sometimes this just isn't possible without calibration data (or even with it!).

Posted by: slinted Jun 15 2008, 01:01 PM

Here's a blink comparison of sol 18 and sol 19 dig sites for a little context. A much wider area of the 'bright stuff' has been exposed along the o'le Dodo trench. And please put no confidence in the colors for the bright areas. As I'm sure many of you have noticed, the raws are bled out pretty bad in the longer exposures.

http://www.lyle.org/~markoff/collections/sol18_19comp.gif
http://www.lyle.org/~markoff/collections/sol18_19comp.gif

Posted by: SteveM Jun 15 2008, 03:51 PM

Just a note, the TECP measures wind velocity, the telltale (http://www.unmannedspaceflight.com/index.php?showtopic=5184) indicates wind direction.

Steve M

Posted by: slinted Jun 15 2008, 04:00 PM

Comparison of sol 19 and sol 20 dig site:

http://www.lyle.org/~markoff/collections/sol19_20comp.gif
http://www.lyle.org/~markoff/collections/sol19_20comp.gif

Posted by: jekbradbury Jun 15 2008, 05:37 PM

Here's an RGB mosaic of the dig site and the dump pile, sol 20:

Posted by: Decepticon Jun 15 2008, 06:19 PM

How deep is that at deepest point?

Posted by: glennwsmith Jun 15 2008, 07:26 PM

Jekbradbury, you've really worked magic with your colorizing of the trench image.

It's hard to believe that there can be a mission to rival the excitement of the MERS, but here it is! And as Stu can elaborate for us, there is no more engaging tale than the dig, the next scoopful of earth revealing a wooden chest, a marble head, a bison rib with paleo point embedded -- or white, aeons-old ice beneath the dry, red dust of Mars!!!

Posted by: Phil Stooke Jun 15 2008, 07:45 PM

Yes, there was some scepticism before landing that Phoenix would rival MER for interest. But it does.

And what do we do after Phoenix and - shudder - MER are all deceased? Let me suggest that these trench animations and other goodies could be repeated for Viking. I imagine a "Virtual Viking" mission, with people taking Viking images sol by sol - easy to find in the Planetary Image Atlas - and recreating that mission from scratch. Day by day trench digging early in the mission, plus longer range surface changes, all animated and coloured. What's out there now is very mediocre - this would really bring some amazing space history to life.

Phil

Posted by: Reckless Jun 15 2008, 07:47 PM

Jekbradbury

That's the most ice like picture of the white stuff in the trench yet.
good picture

Roy

Posted by: ugordan Jun 15 2008, 07:48 PM

Non-overexposed glimpse of the bright stuff and dumped soil:

http://i108.photobucket.com/albums/n15/ugordan/sol20_soil.jpg

Posted by: Phil Stooke Jun 15 2008, 08:08 PM

Here's a polar pan of one of the cylindrical mosaics of RAC images that have been appearing on the Phoenix mosaics pages.

Phil

Posted by: jekbradbury Jun 15 2008, 08:12 PM

The colorization there is just a GIMP compose of these three images:

http://www.met.tamu.edu/mars/i/SS020EFF897998709_12A10RAM1.jpg
http://www.met.tamu.edu/mars/i/SS020EFF897998763_12A10RBM1.jpg
http://www.met.tamu.edu/mars/i/SS020EFF897998814_12A10RCM1.jpg

and these three:

http://www.met.tamu.edu/mars/i/SS020EFF897999006_12A20RAM1.jpg
http://www.met.tamu.edu/mars/i/SS020EFF897999057_12A20RBM1.jpg
http://www.met.tamu.edu/mars/i/SS020EFF897999108_12A20RCM1.jpg

with a curves stretch applied to the first and then a lot of color fudging to get the second to equal. The mosaicing was really just trial and error. As to why it might look more ice-like than others, I tried to get as much contrast out of the ice by stretching that part of the range.

Posted by: teck Jun 15 2008, 09:13 PM

I have tried this method, but it does not work for the set of images lg_5206..7..8..9.jpg. I think this is due to the saturation of the images from the overexpose scoup in the upper right corner. I would like to see this image in color . It might revealed if this is ice or not !

Posted by: fredk Jun 15 2008, 10:12 PM

I think the problem with those Snow Queen images is that the RAC couldn't get very close to the target (ice/substrate), so the illumination is dominated by the ambient light rather than the LEDs. I'd think that to have any hope of extracting colour from them you'd need the raw images.

Anyway, as we expand the trench system we'll soon have much better SSI imagery of the white stuff...

Posted by: jekbradbury Jun 15 2008, 10:18 PM

The range of the red, green, and blue LEDs on the RAC is quite poor. They are mainly intended for the images of samples already in the scoop, which has less ambient illumination and is about ten times closer. However, this data may still be sufficient to colorize the image IF we can get non-jpeg and/or >8bits/channel images. As far as I know, these are not available to the public.

EDIT: Beaten to it!

Posted by: mike Jun 16 2008, 01:00 AM

Not available to the public..? Why?

Posted by: fredk Jun 16 2008, 01:10 AM

This was answered well a while ago:
http://www.unmannedspaceflight.com/index.php?s=&showtopic=5185&view=findpost&p=116655

Posted by: jmknapp Jun 16 2008, 01:43 AM

If the bright stuff is ice, could someone explain how the geology works? I.e., if it's permafrost isn't it weird that it's only overlain by a couple inches of very loose dirt and some smallish rocks (presumably remnants of some impact)? If it's not permafrost but seasonal deposits, then how does it get covered by said dirt and rocks?

Posted by: mike Jun 16 2008, 02:18 AM

Ah, so the RGB scoop images will be released eventually.. they must think it holds some really good science.

Posted by: JRehling Jun 16 2008, 05:35 AM

I think models going back many years predicted (not necessarily as scripture, mind you) the idea of ice covered by slight amounts of soil.

Basically, permafrost occurs where the annual average temperature is cold enough to keep H2O solid without sublimation. As on any other solid body, the temperature will vary most at the surface, and vary less so the deeper beneath the surface. If the top few centimeters see enough variation for ice to melt or sublimate at the very warmest moment of the year, then they will end up ice-free. At whatever depth the variation is too slight for the annual maximum to melt/sublimate the ice, that's where the ice will collect.

If you scraped all the dust/rocks away, and left a big ice sheet here, it would just be a matter of time before wind blew a thin coat of dust on top, making the albedo about 0.15 instead of 0.8. Then the ice within a few cm of that new surface would sublimate over the years, lowering the surface but leaving increasing deposits of dust/rock on top until the equilibrium were restored anew.

The same thing should exist, qualitatively speaking, down to much lower latitudes, too, but with a deeper layer of dust and rock. And at high enough latitudes, you get to the point where the annual surface maximum is too cold to disrupt the ice, and that's where you have the small permanent H2O icecap. This is just a midpoint on that continuum. From the morphology of craters, it seems that only at very low latitudes is there rock "all the way down" with no ice layer.

Posted by: Skyrunner Jun 16 2008, 08:01 AM

Here is your answer:
http://www.met.tamu.edu/mars/021.html

Man I love the descriptions on Marks page No surface touching with the TECP yet but wind speed measurement.

Posted by: Skyrunner Jun 16 2008, 08:41 AM

There are film heaters on the motors, gearbox and output. The wrist motor needs to be heated a lot longer before use than the azimuth, elevation and elbow joints. The heaters aren't that powerful: only 10 Watts or so. But still inside temperatures could go up to 30 deg C . A thermostat prevents temperatures above 85 deg C but a case was tested in which the wrist thermostat was stuck in the "on" position and it still operated fine (without continues using it off course).

There isn't much thermal insulation on the RA to prevent tangling of the wiring so the wrist actuator will lose some heat by radiation, natural convection and conduction. I have no idea about how much conduction heat loss there is when the scoop (or any other part) touches the soil. I don't expect (it would greatly surprise me) them to use the scoop to warm the soil a bit...at least not before they now much conduction loss they can expect. The TECP can help answer that question though.

EDIT: it just hit me that the TECP actually heats the soil to measure thermal properties. So instead of using the scoop they can just use the TECP for it's intended use and get some pre and post touch images with the RAC.

Posted by: jmknapp Jun 16 2008, 12:12 PM

With a supposed equilibrium at just a few cm of loose dirt, it would seem that the temperature must drop very quickly in just that short distance if the ice is to be stable. If the max air temperature measured by the lander is -26C (high for Sol 17), then would it be logical that the max temperature at the surface is well above that?

Might that it's not ice be the simpler explanation in this case?

Or maybe the ice isn't stable, but is disappearing on a geologic time frame (global Mars warming), & the dirt layer is still building up?

Posted by: teck Jun 16 2008, 01:10 PM

I did a pseudo color image by adjusting the gamma value of each gray-scale photos.

Not much help there

Posted by: algorimancer Jun 16 2008, 02:28 PM

Differentiating this whitish material between ice and salt seems a bit difficult from the images - presumably both would be nearly white. If we assume that ice is more likely to be distinctly translucent, then the RAC could be used to capture a close stereo pair (ideally in color) focused on the white material, and if we can see into the material then it would presumably be more likely to be ice. Seems like a simple thing to try.

Posted by: ugordan Jun 16 2008, 03:43 PM

Sol 20 red + blue w/ a synthetic green view of the trenches (pre-sol 20 dig), again nicely exposed due to shiny robotic arm. Local time 10:45.

http://i108.photobucket.com/albums/n15/ugordan/synthetic.jpg

The blue colored variations in the white stuff are probably (?) processing artifacts (it's likely more grayish judging by official composites), but this image sure gives me the feeling of the scoop scraping up something hard.

Posted by: slinted Jun 16 2008, 03:47 PM

Great job ugordon! That image shows both the dark borders and the bright spots of the materials very well.

Posted by: Stu Jun 16 2008, 03:54 PM

The "rock pile" is really catching my eye. It shows just how busy Phoenix is now... scooping up, dropping, extending trenches, exposing might-be-ice...

Posted by: ahecht Jun 16 2008, 03:58 PM

You're thinking about temperature from an earth-centric point of view. On Earth, with a thick atmosphere, most heat transfer is done via convection, followed by conduction, and lastly followed by radiation. On Mars, however, the thin atmospher means that convection and conduction are quite minimal compared with radiation. A prime example of this is the http://nssdc.gsfc.nasa.gov/planetary/text/lp_pr_19980903.txt -- the fact that some craters were perpetually in shadow created enough of a temperature difference to prevent ice from sublimating.

On Mars the soil is light and fluffy (as we saw when Yeti was created), and there is little atmosphere between the grains, so the ice would be well insulated from conductive heating from the surface. There would be little (if any) convection, and the soil is opaque enough to prevent radiation. Therefore, the gradient in temperature could be HUGE after digging down only a few centimeters.

Posted by: James Sorenson Jun 16 2008, 04:54 PM

Awesome!!. I hope they have this planned using the RAC to take a sequenced movie of heating the ice.


ahecht, if that was in responce to my question, I was talking about placing the heated scoop on solid ice, not soil.

Posted by: centsworth_II Jun 16 2008, 05:51 PM

I think the TECP is designed to measure heat flow through ice, not melt it. I wonder if there is any intention that the TECP experiments would result in the production of even a microscopic amount of water at the probe tips.

Posted by: jmknapp Jun 16 2008, 06:03 PM

Interesting... thanks. BTW, are you anything to Dr. Michael Hecht, co-investigator on the MECA team?

Posted by: ahecht Jun 16 2008, 06:04 PM

James, I was responing to jmknapp. I could've sworn I had a quote in my post, but it didn't show up originally.

Posted by: JRehling Jun 16 2008, 07:14 PM

I may be comparing apples and oranges, but I think the maximum reported "airborne" temperature from Pathfinder was -10C, at an altitude of 25 cm, and the maximum at Viking 1 was -17 C, at 1.5 meters altitude. But surface temperatures have been estimated as 27 C (Viking). That would naively imply a difference of about 37 degrees K between 25 cm and the solid surface. I'm not sure of the error bars on the two observations, but it seems like a real difference exists. And it would make sense, since dark ground should trap a lot of heat and thin, clearish air would trap little either in the form of direct sunlight or that irradiated up from the ground.

As for the subsurface changes, we could look quickly at a terrestrial analogue. A cave on Prince of Wales Island has a reported constant temperature of about 5 C at probably just a few meters depth. The surface maximum is probably about 35 C. (Over geological time, maybe 40 C or a bit higher?) So that indicates somewhere in the neighborhood of 5 to 15 degrees K per meter for the difference between surface and subsurface temperatures. I think we could expect some rather sharp boundaries because there'd be little variation other than the annual/daily cycle a few centimeters down. Wherever conditions meet the chemical property in question (phase change), that boundary should be pretty well defined and abrupt.

Posted by: Stu Jun 16 2008, 07:17 PM

Thought I'd try something a bit different for my latest poem... hope a few of you like it

I've put the http://journals.aol.com/stuartatk/TheVerse/entries/2008/06/16/the-phoenix-feeds.../821 up on my poetry blog for anyone who wants the plain version.

Posted by: fredk Jun 16 2008, 08:13 PM

During today's press briefing they mentioned that they want to monitor the bright clump visible in this sol 19 image:

But that clump is already gone in the sol 20 images, presumably due to further trenching - see slinted's animation http://www.unmannedspaceflight.com/index.php?s=&showtopic=5185&view=findpost&p=118290

Posted by: David Jun 17 2008, 12:51 AM

Perhaps it tumbled into the deeper end of the trench, and is still visible?

Posted by: jmknapp Jun 17 2008, 02:36 PM

In that vein, this chart from "The presence and stability of ground ice in the southern hemisphere of Mars" (Icarus 169 (2004) 324–340) is of interest:



So those charts show the temperature at depth at about 180K (-93C), with the diurnal range narrowing in a short distance for the "layered" case, which in this case assumed a 50cm depth of ice-free soil over the ice table.

Posted by: fredk Jun 17 2008, 03:18 PM

Or, as http://www.met.tamu.edu/mars/directory.html puts it,

Posted by: helvick Jun 17 2008, 03:24 PM

That was exactly what I was thinking. I wonder did this happen because they are pushing an aggressive schedule (which they need to we're ~25% of the way into the primary mission already) and didn't have time to react to this interesting nugget or did they see it and decide to proceed in any case?