Unfortunately the breakdown would probably be accompanied by a loss of ice. Still no H20 analysis.


It will be interesting to see what there is to be learned from all the data that Phoenix has collected during its full life on mars. I suspect it will be a lot. We will have to wait months and perhaps years for the data to be analyzed and the papers written.

Would expect some of the data to be discussed at AGU in December.

I cited the mission's own official priorities -- both the programmatic list of success criteria and then, although I paraphrased, their own explanation of the science objectives, in the order they mention them. You or I could have personal objectives for the mission, and it's those I wouldn't see much point in contrasting at length (if we have them), but their own criteria are right to the point.

I don't think it'll be helpful to try to get to the bottom of whether or not my excitement or lack thereof is of the right degree.

Perhaps there is a technical reason why this couldn't be done, but...

Why didn't they just put a heating element in the scoop so that the ice scrapings could melt there and then be poured as a liquid into the TEGA chamber?

I wonder what ice:soil ratio in the scrapings is. If you got any liquid water at all after accounting for sublimation before reaching the melting point and boiling off after, it would be absorbed by any soil present. You might just end up with mud stuck in the scoop.

I don't think there is a liquid phase of water at this pressure. If you heated it, it would turn directly into a gas, and you'd get nothing in the oven. At least, the pressure is very near the triple point, so you wouldn't want to count on the [considerable!] diurnal cycles in pressure to work in your favor.

In hindsight, it's the passive dropping/dumping that can't be counted on. If there were a "fist" on the arm that ground and pounded and jammed the sample into place, that would do the trick. Presumably grinding and extrusion of the sample could minimize sublimation if the oven were sealed promptly.

That is why we should call it a permafrost sample rather than ice sample. I wonder just how much of a H2O ice content is there in the permafrost?

Next failure - TEGA Oven #2

http://phoenix.lpl.arizona.edu/images/gallery/lg_33892.jpg

I think your approach is the right one to assess the success of Phoenix.

It would be great if there was some way to tell the overall frustration level amongst the science team at the end of the mission and if in fact they would be kicking themselves for making certain assumptions rather than others about the nature of the soil/ice they would be sampling. The TEGA doors are a partial engineering mistake, but it's not clear that that's what's costing them. The 'broken fingers' (nice one) are only broken when it comes to delivering the ice-rich sample, otherwise its been a champ Swiss Army knife.

For me it comes down to 'poor engineering guess' or 'Martian Mystery.' If the former, the whole mission is a success (but with an annoying little fly buzzing around), if the latter, even without the ice it's a great success. Get the ice ratio stuff and it's Heroic.

At this point in the mission, why not "rasp till ya' drop"....there doesn't seem to be much problem in collecting an ice sample via the rasp...why not run the rasp over the hard ice areas until the scoop is full, hoping that a full scoop will have enough weight to overcome the clumpiness/stickiness of th soil and fall into a collector ??...I realize there is some danger in burning out the rasp motor but at this stage, so what ???

Maybe the soil will get less sticky once it gets colder say after there is a significant period without sunlight during a sol. Doing the scope and dump overnight then may be more successful.

The worst thing that can be done with this sticky soil/ice is to dump it all at once. This did not work in the first TEGA delivery. Hense the development of the "sprinkle" delivery method. The "dump in a clump" method has even clogged the wide-mouthed MECA.

So why is there a clogged MECA funnel? I assume they didn't use the sprinkle method developed for TEGA deliveries. If they had, I don't think the MECA delivery would have fouled.

I recall they were suspicious that more rasping caused more stickiness, because the rasp motor lies right behind the rear wall of the scoop, and more heat from the motor -- like more heat from the Sun -- made the stickiness worse.

BBC News: Phoenix tries again for ice test

I wouldn't assume that. MECA WCL #3 got two deliveries, because the first failed. They were sol 96, Golden Goose 2, and sol 102, Golden Goose 3.

I think sprinkle has become the standard for delivery to both TEGA and MECA WCL. I'd expect sprinkle was used for the initial attempt to deliver a sample to MECA WCL #3.

JPL Blog: Deborah Bass: Water Ice and Soil Samples on Mars:



The first delivery to WCL #3 didn't succeed. If they used the routine sprinkle and it still failed, then they might have changed method and attempted a more forceful large dump for the second, also failed, delivery attempt, yielding the mound of soil we now see on the cell mouth.