Sprinkle from the RAC point of view

BTW, thanks for "your" blog at the TPS.
I didn't know you've been an extragalactic astronomer, I thought you were an "extragalactic" image wizard only

NASA News Audio Live Streaming

COMING UP:

2 p.m. EDT, Wednesday, June 11
(11 a.m. PDT) ( 6 p.m. UTC)

Phoenix Mars Lander Update

* A link to the streaming audio will appear here before the event.

last night´s final run using the vibrator was successful - the oven is full!

It's because they tried, Harder

Good one, Climber! France - Holland 1-0
I hope there will be a similar opportunity to refer to your nickname when Oppy is halfway up Cape Verde!

PS It looks like the other thread is now continueing with discussions on TEGA, microscopic imager, sublimation of ice in sample etc. Doug can remove this last message from me and leave yr very apt message as a good closure of this thread

Yeah, soil in the TEGA oven.

It was the last of the periodic vibration tries, the seventh. Shortly after starting, the program ended prematurely, and they found: it was because suddenly the oven was full. Once started, it took just a second. It sounds like once the soil was ready, it was really ready.

(My speculation: it was a humidity change that triggered success. Is there anything else that could have changed between 6th vibe that failed and 7th that quickly worked? Temperature? The death of all the bacteria (ha!) in the sample?)

Very close to constipation symptoms here on Earth

As my aunt always used to say about ketchup: "Shake the bottle, shake the bottle, none'll come, and then a lot'll"

" "Shake the bottle, shake the bottle, none'll come, and then a lot'll""

I remember Len Fairclough saying that to Elsie Tanner.

Phil

One thing that comes to mind is that the soil is electrostatically clumpy, and that prolonged exposure to UV light from the sun dissipated the charge. It could also be that the soil is icy and the ice sublimated.

I prefer the ketchup model- you keep nudging the system until you push it over a critical threshold. Though maybe with ketchup, acoustic fluidization is important too...

John.

I can't believe the chances of 6 failed shakes and then the last one which noone had any hopes for works. This is great news. Looks like there's no such thing as too-clumpy soil, just inadequately shaken soil...

Are you thinking that the regolith has thixotropic properties?

I suspect that the sample underwent some sorting as it was vibrated downhill across the screen, and finally and adequate amount made it to the sample vial.

--Bill

As I mentioned on another thread, it's hard for me to see how UV could equalize charging in clumps if elecrostatics is in fact the mechanism holding them together; would believe that laying the stuff on the metal surface of the oven port could equalize charges enough for the clumps to fall apart.

Likewise, I have a hard time believing that ice is holding them together, since this would appear to require capillary action in the soil, which in turn implies liquid water, which doesn't appear to be possible on the Martian surface. Is it possible a few cm underneath, despite the temperature (or does it warm up enough below the surface from solar absorption to make this possible)?

Something interesting's going on here; really not at all sure what. I'm betting on electrostatic effects, frankly.

I'm sure most of us know the electrostatic effects of Lunar dust, might it be possible with Martian dust as well?

Also, anyone know what the filter was made out of?

Or is it just the cornflakes syndrome. Shake it long enough and large particles rise, small ones head downwards. Hmm. Have we ended up with a selective sample of small non magnetic/charged particles not indicative of the real soil constituents.

Could be. Unfortunately, we are left with what we can get, regardless.

Actually, if the electrostatic hypothesis is correct, we might end up with more paydirt in any case; they're looking for organics, not ferric/ferrous minerals.

Another advantage of crushing the sample somewhat before delivery. I assume they still plan to do that with all future samples?

I liked the chart of triple points of different brines in this paper, focusing on the "Mars Surface" portion in Figure 2:

http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1689.pdf

Checking the weather report from Phoenix, the lows are about 190K and the highs are about 240K. Pure water should really be solid across the whole range, but at least some of the brines would be liquid for a good bit of that range. Clumpy wet soil doesn't seem so outrageous.

So when will we have results from the oven? And will that tell us for sure?

--Greg

Look for very preliminary results in about a week (if all goes to plan), with more definitive results following several weeks/about a month after that.

There's a televised press briefing tomorrow.

Mixtures are odd. They sort themselves differently, depending on a lot of factors, sizes, particle friction, densities, container characteristics, interparticle gasses, frequency and amplitude of shaking, and surely more. There is both a Brazil-nut effect (Wikipedia) and a reverse-Brazil-nut effect.

But if finally there was success, then apparently conditions, for some reason, became ripe for smaller particles to descend and pass through.

You beat me to the punch. That's my guess as well. I'm glad the sample is now inside the TEGA.

I'll stick my neck out now and speculate that not much hydrocarbon material will be detected due to the presence of oxidants.

Maybe they'll show Astro0's image for fun.

It's already on TPS

Greg, those low temperatures are for chloride brines. Except locally, chloride salts appear to have been largely leached from the martian surface, probably owing to frost. That is, if they'd react with frost or atmospheric moisture to turn liquid now, they would have done so in the past, and the resulting brine would have dripped into the subsurface until it again froze. I (and others) have used this effect (chloride brine drip resulting from frost leaching) to explain the surface enrichment in sulfates as opposed to chlorides. Note that such dense concentrated salt solutions, for the right (calcium-rich) chemistry, should be able to melt their way downwards even into solid ice, if its summer temperature was above about 220K.

That does not mean that minor amounts of chloride salt don't remain in the soil, sufficient to render the surface soil slightly moist and sticky - this has been hypothesized for the slightly "sticky" aspect of the equatorial soils revealed by the two rovers. The observation that presumably frost-rich polar soils (we should know just how frosty soon) tentatively appear to be even stickier than soils at the equator might be consistent with your hypothesis. Dry as a bone soils with purely electrostatic interactions is another possibility, of course, at least until the TEGA results are in.

--HDP Don

We'll know more in a few days when the TEGA numbres start rolling in and we get some samples under the microscope. The idea of a sticky, hygroscopic soil is a decent first guess, but alas, too terracentric. Remember, this is a really alien world.

Ah, to have a handlens and a gloved hand at the site...

--Bill

Sure but like any good geologist in the field, you know you'd pull the glove off to feel it, and probably taste it too.

Ferric sulphate has also been suggested here, and since iron and sulphate compounds are more common than chlorides on the surface are probably more likely culprits, if it is dampness. As Doug has pointed out in the past, there are any number of things you can mix with water to lower its freezing point. Also I remember that very thin films of water adhered to grains can come under enough pressure from van deer waals forces (If I've spelt that right) to lower the freezing point to 180 kelvin. Also there are a lot of other possible causes of stickiness. We'll know better when TEGA spits out some results.
I feel like a small child in a car shouting 'are we nearly there yet' at his long suffering parents...

Marsbug - Crystalline ferric sulfates (jarosite and so on) appear to be stable on the dry, cold surface of Mars, but an aqueous solution would be strongly acid and therefore should react with other mineral grains in the soil (e.g., feldspar, olivine, pyroxene) to neutralize itself, unless the acid were continuously being replenished, as by bacterial action on an actively weathering sulfide-rich terrestrial mine dump. In other words, the terracentric proposal in that reference seems to ignore the basic nature of the martian regolith, not to mention the lack of active weathering. On the other hand, crystalline ferric sulfates, or other sulfate salts, might themselves be sticky enough to yield the observed Phoenix soil properties. Pure speculation, without more observational and experimental data.

-- HDP Don

With (likely) iron sulfates? Gak, pa-tooey, not likely...

But yes, the urge to get up close and personal would still be there...

--Bill

Agreed, but it also seems to be a really salty world. (This result is perhaps not unexpected, if most of its original liquid water froze solid or was lost to space.) Salts can be sticky, after all.

MODERATOR EDITED - let's not go there
-- HDP Don

Its a little ironic that the Phoenix instruments cannot analyse the soil until whatever is giving it its 'unusual and unexpected' property has gone away! Can someone explain (in beginners terms) how, in spite of this, the analyses will shed light on what was causing the clumping?

The analysis is not specifically designed to determine why the soil was clumpy. They said it might have just clumped together on the screen as they dumped too much in one go. In future they will quickly chop the soil up and only dribble a little onto a screen. The analysis will determine all of the gases that were in the soil/rock particles, that's the whole point of TEGA. Later they will dig down further and do more analysis, and finally dig and scape up the presumed water ice and test it, I guess when they do that they will get Hydrogen and Oxygen - H2O............

Some sol 18 pics came down.
Looks like they greatly elongated the trenches.

http://www.met.tamu.edu/mars/i/SS018EFF897...6_12540R2M1.jpg

No, but I'm hoping it will anyway, maybe indirectly. Of course there's so much more to learn than just this. Exciting times indeed!

Even if the soil was wet and later it dried out, there is always a chance some moisture remains on a microscopic level, and the TEGA will detect that. It's like damp sand v dripping wet sand, if you know what I mean, its still at some level of wetness......

I see. If that scenario remains a possibility would digging, sampling and closing the oven at the coldest possible time of day be advantageous?

And if it's electrostatic clumping is there any way the instruments could positively establish this? Maybe from sprinkle patterns in the microscope samples?

Brittle crust on top, clumpy underneath. 'Damp/dry' could account for both. Electrostatic charge probably only the latter, requiring a separate explanation for the crust. Perfectly possible of course.

I think it would be very interesting to sample some soil from the same spot again, using the new techniques so that we can get the sample in a bit faster, and see if there's any difference in the two samples.

This could be done at the end of the mission -- if nothing so interesting as to use all the remaining ovens on deeper samples shows up.

I would guess H2O2 (lots of it) ....

It easily decomposes into oxygen and water if I remember, although ... here's a wild speculation to pass the time: H2O2 from the atmosphere (theorized to form during dust storms) is mixed with the soil, and then partly decomposes into a highly concentrated H2O-H2O2 mix with a freezing point low enough to stay stable in martian arctic conditions, producing dampness and making the soil stck together ... ...Nah I can't make an argument for that, I don't know what conditions it needs to decompose. (coughs and looks a little embarresed)
Presumably TEGA could guess at which it was by looking at the ratio of oxygen to hydrogen released?

EDIT: Actually to quote wikipidea: so I'll put an 'I told you so' in my pocket just in case

How will the operation of the TEGA oven affect Phoenix' overall energy budget? Do other operations have to be curtailed at certain stages of the cooking process? With the declining sun angle later on in the mission, at what stage will it cease to be possible to operate the TEGA?

I guess the question is, would any TEGA oven be saved for an extended mission, or is it predetermined that they will all be used in the 90 day primary mission. In which case your question is moot.

Well, Cents, my first question isn't "moot". And your comment in response to the second one assumes that there will be enough energy to operate the ovens out to the 90 day mark, which may be true, but I was trying not to take that for granted. It would be very surprising and illogical if the primary mission plan called for holding resources in reserve for a followup mission, but in practice you should bear in mind that, as we have already seen, things may not proceed as quickly as intended.

No it isn't. As a matter of curiosity, it would be nice to know what part of the energy budget goes to TEGA. I don't think it's a matter for concern though. Both solar panels are open and providing at least as much power as planned for. Barring a serious dust storm, I can't imagine that there will be energy problems for the main mission. Of course a mechanical or electrical failure can change things at any time.

Here's a question:

The ovens are single use right?

Are they really? What if you put a sample in the oven that was, say 75% water ice. Baked the living hell out of it and received a rich data set. Great, mission accomplished!

Time passes and you're on to the extended mission; one sol you dig up something interesting. Darn, wish we could TEGA this sample.

Since the water is now baked out of the original sample you've got space in that oven that wasn't there after the initial dump. You re-bake the oven at the highest temp to characterize the remaining material in the oven and account for any change that may have occurred during the intervening sols and you've got yourself a new tega oven!

Deliver new sample, run a new workup. I realize this would be a rather ill controlled experiment. You would be adding un-baked material to what would now be thrice baked material but it could be better than nothing at all.

Is this possible?

I'm assuming of course a light sprinkle of the original sample on the screen, not a massive dump like the first TEGA go 'round

Kung

It would be very useful to have a rough idea of the energy budget overall and some details of the power requirements for the various instrumentation packages but even without that we can be pretty sure that energy budget concerns are not likely to be a major factor in limiting extended mission activities up to around Sol 150. Preflight press releases said that Phoenix could manage with just one functioning solar panel and whatever the initial power generating capacity actually was with two functioning panels she will still be generating more power from two at Sol 180 than she would have initially with just one. Ambient temperatures don't change significantly (+-10 degrees) until after around Sol 150 but they start to drop pretty fast after that, by Sol 180 they will have dropped by 25-30 degrees so power for heating is could become a significant part of the energy budget by then.

Even though heating takes a lot of energy, the TEGA ovens are so tiny that I suspect the energy requirements of the many digging activities make the robotic arm the energy hog of the mission. (Not that I know anything.)