Yes. Once the oven is closed that's it, it can't be reopened to add another sample even if you've baked what was in there to nothing.

Hopefully there will be all 8 + 4 empty ovens at the end of the mission. Same as at landing

Paraphrased from the "Thermal and Evolved Gas Analyzer" document: it all depends on the ambient conditions (i.e. mainly the instruments' own heaters use) but is can be as low as 9.6W with all heaters off to as much as 78.0W with all heaters on and a sample oven on.

Airbag

TUCSON, Ariz. – One of the ovens on NASA's Phoenix Mars Lander continued baking its first sample of Martian soil over the weekend, while the Robotic Arm dug deeper into the soil to learn more about white material first revealed on June 3.

"The oven is working very well and living up to our expectations," said Phoenix co-investigator Bill Boynton of the University of Arizona, Tucson. Boynton leads the Thermal and Evolved-Gas Analyzer (TEGA), or oven instrument, for Phoenix.

From:

http://www.nasa.gov/mission_pages/phoenix/...x-20080616.html

Airbag

Space.com article says the first TEGA soil sample appears dry.
No water has been detected so far after the initial heating to 35 C, then to 175 C.


[Hmmm, if the white stuff is indeed ice, I woulda thought maybe a little bit of water crystals might've found there way into (via sublimation/deposition) pore spaces in the upper soil grains]

As they said in the briefing today, remember that that sample was exposed to the sun for several days before being delivered to TEGA. Any ice in there (if there was any to begin with) would surely have sublimated by then. Bill Boynton himself said he was "not surprised" by these results.

Plus, there's no guarantee that the white stuff in the scoop ever made it into the ovens.

3d glasses! Did you go to NYC recently ?

And now for the bad news...



The doors on TEGA oven 5 have not opened properly.

The team were very confident that the soil piled up would not impede the doors. I really hope there is not a design problem here, only 1 out of 4 (2 per oven) doors have opened properly so far

James

Animation of the attempted opening of oven 5

Very strange. Here's a (very) wild speculation: Did some dirt actually drop down into the oven and, when it was detected, the door opening sequence was halted?

No. I believe that the doors are spring loaded. A catch is released and the doors open very quickly.

Note that the soil on the left door (as we look at it) has been catapulted off and can bee seen on the surface near the top-left of the image.

I was afraid this partial opening would occur on other doors as well.

looking at James's animation, to me it looks like the soil is pinched between the door hinges, and that is preventing the doors from opening. Just speculation .

They stopped even a bit earlier than the first one. Are there any thoughts why they do (can) block this way?

How comfortable would they be trying to use the arm/scoop to sweep away some dirt from the oven doors?

(Having a little experience with automated equipment, I'd be nervous as hell).

Bill Boynton said in an earlier interview that the doors were spring-loaded, and, moreover, that the springs should be powerful enough to open a door buried under an inch of soil. It seems to me that spring-loaded doors should have been one of the simpler moving parts of this machine -- I'm at a loss even for suggestions as to why they wouldn't be springing open all the way if they spring open even part way. Could there be some weird mechanical thingy going on that isn't working under Mars gravity? That seems implausible.

--Emily

Could soil clumps be jamming up the hinges?

Why does the door on the left in James's animation not open?, there is nothing on that door.

Those springs are awfully cold, and may have been for quite a while. What temperature was the lander during cruise?

Or even programming moves to open them with the scoop...

This looks worrying. Can the scoop actually reach the doors?

the best way to open this doors is send more then ten comands to open and close this doors , this way the soil move down from this doors .

I don't understand that the doors have actuators that can flap them. They are spring loaded. You send the signal, a latch opens, and the door is supposed to pop open. There's no command for closing them.

That doesn't sound at all wild, it sounds quite likely (even if it is not the cause of the doors jamming). I don't see how they could have opened that set of doors even a chink without some falling in. When will we know this?

Do they have a way of deliberately doing only a partial opening - maybe to avoid throwing soil from the first dump even further along?

There isn't an actuator on the doors. Just a latch and spring. You command the latch to release the spring and the spring pops the doors open, like a jack-in-the-box. Once you've done that, there's nothing more the TEGA instrument can do to make the doors open any more -- there's no motors. The doors can't be closed once they're opened.

And I can't imagine they'd try to maul TEGA with the digging arm unless it was the last possible option. Remember they can't joystick the arm. They have to sequence its every move. I don't know what its accuracy is but for all of its normal operations -- digging and dumping -- it doesn't really need to be more accurate than a centimeter. (If somebody knows what the arm's positional accuracy is, that number would help in this conversation.) What happens if you command it to touch a door and it's a centimeter off?

--Emily

If it is no comand to closing them and open them again so only wibration is the way now which can make it .

This was totally unexpected. Maybe we should wait to get the other pictures with hopes that during the Martian day it got warmer ...

That's right, it's a once only deal, now that they have been released there is no way of moving them again. (Short of using the arm as others have suggested, something I'm pretty sure we won't see until well into any extended mission and after all ovens have been tried, if ever.)

Besides I don't think the problem is with soil obstruction. The fact that both the doors opened the same amount is telling I think. And remember that the first oven had a similar problem when there was no soil anywhere near it.

Looks more like an issue with the design operating in Martian conditions to me, although I'm at a loss to come up with any good ideas as to the mechanism.

James

Oh dear. My guess is that the doors can lift the weight of an inch's worth of soil from their top, but the soil has fallen into the hinges and is preventing them from turning. However, I find it hard to believe they didn't test this situation with actual soil of some kind. If they go with much smaller dumps in the future, it might not be a problem.

IIRC, in a recent call Ray mentioned that the arm goes where they tell it to within a couple centimeters. That was by way of comparing it (in fairly glowing terms) to the MER arms.

Yes it depends on how small steps the scoop can do. Otherwise it may depends how the doors are connected with the Analyzer and which parts of it could be (or not) battered when the scoop touch the door too hard.

It troubles me that neither door opened.

Can they attempt to vibrate the mesh beneath to see if something can make it 'Pop' open?

I just hope there isn't a misalignment that has caused some slight warping of the oven doors.

I'm sure the possibility of sample clogging the door hinges would have been obvious during design and testing, and allowed for. But then I can't believe they didn't test opening the doors with material on top in the temperature range it's designed to work at. I wonder if there's a link with the problems presumably caused by the sample's clumpiness when trying to get the first sample to fall through the screen into it's oven.

The other thing that springs to mind: is there any way that anything could have frozen out onto the mechanism, either during EDL or since landing? It's too warm on the surface now, but the TEGA would have been exposed to the atmosphere as soon as the backshell was jettisoned at an altitude of 1000m or so. Or exhaust from the thrusters,.. -I'm drifting...

Sure they can try, but remember the first oven was vibrated a LOT to get the sample in and the partially opened door on that oven hasn't moved at all, so I wouldn't hold out much hope if the same problem is responsible here.

[Arms waving wildly here...]

Is it at all possible that atmospheric water ice is being deposited in the hinge joints and freezing stuff up?

Yikes. I first thought soil under the hinges like others here. But now I doubt that's it for two reasons. First, both oven 5 doors opened to the same extent, but the right one presumably would have had much more soil under the hinge. Second, the left oven 4 door opened to a similar extent as these oven 5 doors, but when oven 4 was opened, there was no soil at all on top of tega. This suggests some unusual design flaw.

Maybe during launch or landing something got knocked out of alignment. I really doubt that it is soil or freezing causing the problem.

I wonder if they will attempt to shake soil, bit by bit through the small opening or if they will open a new set of doors. I bet the team is wondering the same thing. I'm sure they will not try to use the scoop to open the doors until other doors, and shaking dirt into the small opening have been tried.

A random observation - the door that opened best was an end one. If something has distorted the whole panel on which the door hinges are situated maybe the end hinges would be the least affected? Perhaps the one at the other end will open symmetrically with the first, and the two middle sets only a crack?

I agree with centsworth, it should be possible to get a sample in even through a crack.

I wonder if when they vibrate the mesh this will cause the first sample to work its way into the second oven. Now that the first sample has spread out it looks to me as if some could even work its way into the third oven.

imipak: Agreed, they must have tested the doors exhaustively (They did, didn't they?). It's hard to see how mere soil could jam up the doors. But if water or brine or whatever got into the hinges and froze, that could be another thing altogether.

Seems like repeatedly pushing on the doors with the scoop, allowing them to spring back over and over again, might work the ice/brine/grit out of the hinges. Or how about holding the scoop against the doors and vibrating the scoop? Just a thought.

And: Howdy all. Brilliant forum you got here!

The doors of TEGA are angled at around 45 degrees to the horizontal, so sprinkle technique from above the top of the ajar door is probably possible and may be effective. I hope that oven #5 is not lost.
Click to view attachment

Hello and welcome! It's not always this busy, but it takes a lot of people to fix a door hinge.

Question, James -- how do you know this is oven 5 and not 3? Or even some other number?

--Emily

Note for future missions: Bring a tool kit!

Seriously, a few attachments for the scoop would be really handy: A small pry-bar, something like a hammer, and a brush. Any other ideas?

Magnet?

Did they not say in the teleconference that they were opening oven 5 ready for the next sample?

I posted that image while listening to the conference in that background and was pretty sure of myself then, not so sure now. Anyone else remember hearing this in the teleconference?

James

I think they said oven 5 as well, both today and in a previous briefing.

Thanks. I wasn't able to listen to the teleconference very carefully today, so I didn't catch that.

--Emily

I'm glad somebody else heard 5. Because I started to doubt myself. I don't understand the numbering sequence if this really is #5, does that mean the numbering starts from 0? (0-3 on the other side) It would make more sense if this was #3 (5-8 on the other side). Or are there 5 on one side like it appears in the image peter59 posted above, unlike the 4+4 arrangement in the image here?

hi all
just a long shot as I don't know the layout of the doors but is it possible that all the four doors opened and three of them bounced back partially closing.
Roy