Taking into account that all other variables related to the spring-door system have been not only simulated, but actually tested ( space & martian environment, including pressure, temperature, exhaust gases, He release, forces during landing ), and centering ourselves on the 1st door failure ( the left door of oven #4 ), because there are quite more artifacts involved in the failure of the oven #5 door. Only unknown enviromental factors apply. Atmosphere composition, exposition to sunlight, electrostatic buildups among the trigger mechanism components... btw, maybe the 20º of the left door was forced by the force applied to his lip by the quick opening of the right door.

Anyway, we are going to have full RAC coverage, at max freq/shutter speed, on the next opening event, I bet #6. Maybe the dynamics of the failure - if any - tell us something.

And then, there is the hammer mode of the RA...

Don't forget the more gentle touch and vibrate mode.

Yes, because it is not like at vending machines which only feed your money. It's more like if your oldsmobile hatch does not open properly.

I agree. that would be surprising if true.

The bent panel suggestion in my post 238 was an attempt to explain both failures, and the difference in degree between them, with a single cause. There were no takers so I'm assuming it's phooey, but I'd be most grateful if someone would point out why so I can stop thinking about it.

Good update from Emily.

Ah, that makes a lot of sense. Does 'not manufactured to flight specifications' mean that something bent in transit?

Sounds more like "It wasn't made how we asked for it to be made" to me...

Yeah, could be, but they must have opened OK when tested before launch. I'm sure we'll hear ALL about it in due course! Anyhow it's great that they can still deliver samples. Let's hope the other ovens open no worse than no. 5.

From the same update:

This is definitely good news, though I have to wonder how clumpy the soil was in their lab test...

Maybe I've missed something, but what happened to the preliminary results from the last two oven heatings of the sample that was already collected? The first two heatings, going up to 175 deg celcius I think, were reported briefly in a press conference, but I've heard nothing about the second two, going up to 1000 degrees. Did the other problems lead to them being cancelled?

Edit: also I was wondering if there will be a wet chemistry lab thread?

Agreed. Somebody's butt better be on the broiler for this, and right soon.

Barry Goldstein says this in his chat with Emily on her TPS blog:

"It was problematic, and it could've been better if we didn't have the problem at all, but we're working around it."

That middle line definitely sounds grrrrrr'y to me.

But I'm sure now isn't the time to start hunting down witches with rasp-ended pitchforks, they've more important things to think about. But if there was a manufacturing mistake then later... well, as Mal would say, I'm pretty sure there'll be a reckonin' ...

My guess would be that the science team is waiting to be allowed to use the Flash memory again (real soon now) before reading-out such important data (which you wouldn't want to trust to the vagaries of volatile memory).

There had better be. Someone went to the trouble of speccing out a piece of equipment so that it would work on another planet where it is somewhat problematic to send a repair tech! There is no excuse for not building such equipment to spec. I hope somebody "names names".

At least we know MET will work perfectly. It was built in Canada.

Brian

I'm sure there'll be a "murder board" but nothing like MO or Stardust or etc... maybe a micro-murder board.


No we won't blame Canada. (Although I do remember the Space Station Arm had a bad joint that had to be replaced. But that was built in Toronto

Paul (ex-Canadian)

Toronto. Spit!

Brian

Just try to keep that spit off London.

Phil

'not fabricated to flight specifications' is a bit broad brush and normally means 'we really don't know'. Was it the specification that was in error, or the manufacturing, or the assembly or the multiple QA checks and pre flight testing that somehow didn't pick the problem up?

A question. The oven door mechanism was undoubtedly tested under martian conditions, but was the whole assembly subjected to the stresses expected during flight and then tested under martian conditions? Would that be normal practice? (I'm totally ignorant here, just curious.)

Aussie - we must have been typing together there, and thinking along the same lines too.

'not fabricated to flight specifications' is a bit broad brush and normally means 'we really don't know'. "...

That's a bit different from Hubble's mirror, which was perfectly ground to the wrong shape <because of a bad figure tester they over-trusted to be correct> From what they're saying, they think it's mis-built, not mis-designed.

Yes, but why did we have to go all the way to Mars to find this out?

THAT's the interesting question.

Could it be that the paranoia of losing the lander on the way down a-la MPL was so big they focussed the largest majority of their testing on EDL (which, consequently, went perfectly), not actual instruments? I find that hard to believe, but still - finding out a piece of hardware was not built according to specs only after landing on Mars is... interesting.

Stuff happens.....on the positive side the ovens can still be used with only a few mm of openings. Also they are confident the Lander will operate till November, so we get 60 extra days of science .

Call me crazy, but I think TEGA might actually work better with doors that open just a tad. It will only allow the particles that are just barely big enough to enter, or so I would guess...

And regarding clumpy texture maybe the drag of the doors could also help when the filter vibrates.

My guess is that this is the result of a tight budget limiting testing.

I would call you optimistic -- and maybe right. (I'm optimistic too.) So little material is needed to fill the oven and hopefully the gradual shake delivery method will prevent the small opening in the door from clogging up.

Yet another reason future missions should include some simple tools. A small pry-bar attachment for the robot arm would be really handy right now. Doesn't even need to be a moving part, it could just be a probe extending from the back of the scoop. Retract the scoop all the way and use the probe to lift the door open.

We already have a "hammer" of sorts, by touching the scoop to balky equipment and vibrating.

Spirit and Opportunity should have brought a feather duster.

A 2 million dollar duster, so we cut the mini-tes out ?
Mer was designed to last 90 sols, thought the engineers knew better but kept it quiet......

Yeah, but picture the rovers running around brandishing a feather duster! And wearing a little apron!

(sorry: too much coffee, not enough sleep)

I agree, that is not crazy at all, given the observed soil properties. I was wondering too if sampling through a raised slit might actually help reduce cross-contamination beween samples.

Well, I sure hope so; some serendipity would sure be nice at this point.

Re 'not built to flight specs': A broad statement to be sure, but with definite implications. It means either/or/and: a- incorrect materials, b- incorrect subcomponent dimensions c- incorrect lubrication (if applicable) d- incorrect installation hardware or technique (like fastener torque values) e- a whole bunch of other possible things.

I was a bit peeved yesterday, but hey: we're all human. This happens. Hopefully there will indeed be an effective workaround, and a number of lessons learned.

Looks like they attempted or practised a sample drop on the TEGA oven #5 right after the WCL drop:
http://fawkes3.lpl.arizona.edu/images/gallery/lg_7662.jpg
http://fawkes3.lpl.arizona.edu/images/gallery/lg_7666.jpg
http://fawkes3.lpl.arizona.edu/images/gallery/lg_7668.jpg

Uh Oh... poor TEGA... poor team....

http://phoenix.lpl.arizona.edu/06_25_pr.php

"Scientists believe the first soil sample delivered to TEGA was so clumpy that soil particles clogged a screen over the opening. Four days of vibration eventually succeeded at getting the soil through the screen. However, engineers believe the use of a motor to create the vibration may also have caused a short circuit in wiring near that oven. Concern about triggering other short circuits has prompted the Phoenix team to be cautious about the use of other TEGA cells."

Next telecon is tomorrow 06/26/08 at 10:30am PDT (1:30pm EDT)

http://www.nasa.gov/news/media/newsaudio/index.html

Craig

akuo, looks about right with the practice.
Doesn't appear to be anything in the scoop.
Click to view attachment
animated gif
Astro0

akuo. Looks like a waypoint learning process. (Program the movements with the arm as a dry run and if it looks within tolerance have the arm repeat the waypoints with a full scoop).

Wonder how subjecting the system to extended vibration matches the expected mission profile and whether this really translates to a manufacturing fault.

Looks like it's going to be a picture postcard mission only.

There's still MECA and the soil probe, and the lidar, met station, etc even in the (hopefully unlikely) event that they can't use any of the other TEGA ovens.

We have samples in one oven, no reason so suspect we can't get samples into others, samples in one of the WCL's, met, lidar, MECA TECP to use...AND pretty pictures.

Doug

I note that "mechanical interference" may prevent the oven doors from opening fully. So, was that mechanical interference present pre-launch (difficult to believe since they presumably worked in tests)? Or did something move or deform during flight? If the latter, was this in response to g-forces, temperature changes, or what?

(Lest it be thought that I am focussing on this issue in a whingeing or blaming way I'd like to make it absolutely clear that my sole interest here is curiosity about the mechanics of the problem. Unlike computers, hinges springs and mechanical obstructions are within my conceptual comfort zone. )

From the tone of the article that electrical short circuit doesn't sound like a show stopper. Phoenix has already done much more than provide postcard views and I expect it will still go on to achieve further great things despite the difficulties.

Since they are at the point of predicting differing outcomes for the remaining doors, it sounds like they have a good handle on what exactly went wrong. Today's press conference should be interesting. And agreed about the short circuit not sounding like a show stopper, the way they put it. I.e., did running the vibrator too long cause some components to overheat/short just in the circuitry for that vibrator? Maybe the other circuits are OK, just that they have to be careful to not overdo the shaking prior to baking.

Well, I made a similar prediction last week without having a clue.

Seriously, I'm looking forward to finding out.

I'd be getting perilously close to picking up the largest rock I could find with the arm, and indulging in percussive maintenance on TEGA until it started working properly again.

Luckily, the Phoenix persons are much more qualified than myself. I hope they figure out the problems soon, and get back to collecting data!

Folks...

I want to say that when I used the phrase "poor TEGA poor tea" I in NO way meant that statement as a reflection of the quality of this mission team. I hope no one read it that way.

The internet is great, but it also allows us to make comments off the cuff, that can easily be misinterpreted.

What this team has accomplished already is incredible. Landing succcessfully on another world is a near miraculous feat.
I am certain the team will find whatever workarounds they need, and get every last drop of data that they can, given what they have to work with.

Look forward to what Phoenix has to tell us. And what Mars has to deliver.

Craig

I read here of delivering soil through the narrow slit opening. That's not how the test images look, nor does it sound expedient. I expect they'll aim for the triangular opening of the doors at the apex of the slope-roofed TEGA, and let gravity pull the sprinkled particles down along the (maybe vibrating) mesh screen. That wider hole looks like a much larger target that the narrow gap.

TEGA, sol 26


The triangular hole (bottom of image), from the RAC, aimed downhill, sol 25


Positioning for the sprinkled delivery

Quite positive teleconference today. Most questions were about the science, instead moaning about TEGA problems. Nice listen.

I didn't quite catch Bill Boynton's explanation about the sprinkle method. Did he say that they got a sample with every simulation they tried, including sprinkling through the narrow slit?

He didn't answer Emily's question very well, I thought. But what I thought I understood was that yes, they received a sample with every test they ran and that again yes, it was through the slit and not the triangular opening.

I think it's evident from all post sample deilvery images to date that sample will fall over the slit and the end opening no matter where they "aim".

AHHH.. what a relief...

Short circuit was oven #4 only.... from Emily's blog...

http://www.planetary.org/blog/article/00001526/

A press release yesterday mentioned a new problem that was discovered after a sample was finally shaken into oven #4: "Four days of vibration eventually succeeded at getting the soil through the screen. However, engineers believe the use of a motor to create the vibration may also have caused a short circuit in wiring near that oven. Concern about triggering other short circuits has prompted the Phoenix team to be cautious about the use of other TEGA cells." Today, Barry Goldstein clarified this. He said that the short is confined to oven #4, which they're now done with; so the short has no direct effect on the other cells. It's just that the fact that it happened will make them more cautious about doing so much shaking in the future."

Also the team feels confident they can get a sample thru the small slit opening on oven #5.

Cool...

Craig