Anyone who thinks they know why the soil is sticky, is welcome to suggest their recipe for a simulant soil mimicking the properties of Green Valley soil. So far the science team hasn't put together a recipe that acts the same.

If we are talking about creating a soil that mimics the Martian polar soil, but at STP for testing here on earth, I'd suggest making a damp sand, but use a wetting agent slightly heavier than water such as glycerin.

As soon as the US Congress straightens out the economy, they can tackle the sticky Martian sol.
Seems to me if we knew the answers, we shouldn't have gone there in the first place. This gives the next mission something to work on.

And then put the soil in a chamber which can simulate the Martian atmosphere and the temperature of the north polar region. Then put the Engineering mockup of the lander in there, let it cool down for a few hours (more likely days) and then see what happens when you start scooping up the soil.

Ouch.

I really sympathize with the engineers and program scientists.... figuring out all the possible variations of Martian soils, and how they would act in an actual Martian environment, must be really difficult.

Actually no. I wasn't suggesting that the cold, low pressure, low gravity, martian soil was laced with glycerin. I was suggesting a method of making the soil sticky to MIMIC martian conditions under Standard Temperature and Pressure, with the goal of testing how to manipulate that soil.

Right, but there's a difference between having the scientific facts in hand and having engineered for tolerance of varying outcomes. You wouldn't have to know the precise mechanical properties of martian soil to design a system that would have worked with a broader set of possibilities.

It looks to me like the arm has an A+ shoulder, an A+ elbow, an A+ wrist and dead fingers.

The ground operations of Phoenix are approximately 85% complete (could be 99% -- we're at the mercy of happenstance), and still no icy sample. Whether or not blame is merited (aside from the balky oven doors) is a topic I have no passion for, but the outcome so far is extremely disappointing to me. And as far as getting it right next time goes, remember that THIS was the re-fly of a mission that would have landed 9 years ago. It was bad enough to go 400 million km and lose MPL in the last 100 km, but it's just as frustrating to go 400 million km on the second try and end up with ice 5 cm from the oven.

Phoenix was successful enough in accomplishing some of the other goals that it makes the idea of a THIRD try even more painful. And there won't be the same legacy hardware in the closet to keep the cost down next time.

As I'd said before, with something like MPL all of the pain comes in one evening, but with this, it's been like watching a sports team lose and taking months to do it. It's been agonizing.

Astounding that you compare Phoenix to a losing sports team! The team has WON. It just hasn't gotten as many home runs as you would have liked. I have my own list of what could be done better on a second try. But this is a first try.

Even now, we don't know why the soil is so sticky. We don't know if the icy and ice-free soils are sticky for the same reasons.

Have any previous Mars landers given a hint of this degree of ...er...'clumpiness' (Yes it's ugly, but it's the only word I could conjure up on the spur of the moment.)? I certainly haven't noticed it from the MER. It's perhaps unfair to have expected the TEGA designers to allow for it.

but with this, it's been like watching a sports team lose and taking months to do it. It's been agonizing.
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Hrumpf.
NOT losers. Not by a long shot.

I've seen people try to rate the success/failure of missions that were partial successes, and never saw any good come out of those discussions.

But the ice is why the high latitudes were targeted and the tradeoffs made to land at 68N. The mission success criteria drawn up before the mission stipulate that TEGA would be used to profile H2O abundances using at least two (=partial mission success) or three (= full mission success) different samples. Relative to the possibilities that Mars itself makes possible (eg, the ice is within reach, not 40cm down), even those criteria are modest and the pace of operations has fallen behind from the first weeks and remains behind as the remaining time shrinks.

If you look at the higher-level objectives, the importance of the D:H ratios are clear. And we have samples that have that information inside them just centimeters from the detectors that could measure it. I find that frustrating, and nothing else the mission does makes up for that.

Barry Goldstein (one of the operations managers at JPL) summarized things last week as "We're now at the point ... where we have to struggle to do each of the things we need to do." I think that word "struggle" captures the feeling I've had since the electronics problems were reported and the doors started jamming.

This IS the re-fly (hence the name "Phoenix"). This is the mission that when the competition came around had the advantage of reusing hardware from the cancelled 2001 mission. I can't think of a time since Ranger and Surveyor that an objective was met by flying a third mission where two before had fallen short.

I have to agree with you on this...... I've lirked on this site for ages.....there are some very bright and talented people posting here...frankly a bit too tight for my liking but the only problem I have with that is that some of you "experts" are reluctant to call things the way "Joe Ordinary" would see it.

Who's Joe ?...why, that's me.....an ordinary person who has been following the Space program since the manned Mercury days....that's my credentials...maybe not much but that's all I got..

So why am I disappointed ??...because this was the mission that was going to get a real honest to gooodness taste of Martion H2O...it was there...we could see it viia instruments from Martian orbit but to get a significan sample tested, we need to be on Martian dirt.

Phoenix has accomplished some amazing things but without a significant ice sample and an analysis report showing that H20, something an "ordinary" person following this mission can undertand, I can't call this mission a success....

It's going to be a long time before another lander gets a crack at this soil...with that in mind, the soil/ice capture design should have been over engineered to ensure that any sample would be delivered to the testing instruments under any condition...

Just "Joe Ordinary's" $0.02....

I feel that solving the underlying cause of the sample 'stickiness' is just as important than getting a permafrost sample to the oven. The adhesive quality doesn't seem to be a function of ice as the sample from stone soup showed greater adhesion than the permafrost scrapings. With the lack of H2O from the probe results this seems to rule out H2O as a (major) contributing factor for the clumping.

Regardless, this is not an underperformance of the system. The screen is there to stop the introduction of large particles to the oven entrance where they could jam, so the clumping samples could not have got to the oven in any case. There is still the possibility that the sample will break down as the first one did and penetrate the screen in a few days time - so all is not yet lost.

I'm not sure why trying to make a soil analogue is important. Unlike the rovers where they were trying to experiment with extraction techniques for the bogged vehicle Phoenix is on a very short timescale before the arm usage must be restricted or terminated. A mixture of non representative substances may make a reasonable analogue for the initial 'stickiness', but it would almost certainly not have the same breakdown characteristics over time - particularly when I don't believe we have a clue what is causing the adhesion in the first place. The answer is probably there in the TEGA and MECA results.

I've walked through some kinds of mud and come away with clean soles -- the mud adheres to itself. Other kinds seems to suck the shoe off my foot. Is there a science that studies this? There certainly *could* be, but I don't know if anyone actually publishes on it. What would you even call it -- centigeology?

This reminds me of lots of phenomena that take place with ice freezing that on Earth might be more the subjects poets and fishermen study rather than scientists. But on Mars, the equivalent phenomena take on engineering importance, and arguably scientific importance.

But the D:H ratio is of fundamental importance. I'd say there are three things of utmost interest that Phoenix was looking for:

1) The dynamics and history of H2O at this latitude.
2) The possibility of organics in that ice.
3) The identity of the Viking oxidant.

So far, we have apparent success at #3 and we may get good data on #2 out of the data we already have, but #1 probably cannot be done with the trace amounts found in the earlier sample. So the major objectives of this mission will have a very large hole at the top if something doesn't break our way soon, with at most about 15% of the active surface operations to go.

I also have no special qualifications other than a general interest in science and I think the more interesting aspect of the Phoenix mission is a characterization of the soil chemistry. Witness the stir caused by the clumsy release of the perchlorate discovery. Can you really imagine that a similar popular interest could be stirred up by any revelation involving D:H ratios? I realize D:H is important to understanding transport of H2O on today's Mars and something of the history of H2O on Mars. But, really, ho hum. Try to get Joe Ordinary (you excepted) really interested in that. Give me the here and now soil chemistry for real excitement. Phoenix will do that to a great extent.

I too will be frustrated and disappointed if we can't get a D:H ratio. But I will not let that blind me to all the wonderful new things that Phoenix will teach us about Mars.

Well you seem to have done a fairly good job of it yourself (see below).


According to the Phoenix web site, "Phoenix is designed to study the history of water and habitability potential in the Martian arctic's ice-rich soil."

I would say that "study the habitability potential" is the more interesting aspect of the mission to the public. This part of the mission seems to have been largely successful. Don't let your disappointment ruin a chance to share in the excitement.