GCMS's/pyrolysis systems have a lot of fine tubing that has to be heated with itty bity wires...shaking is an iffy proposition.

I was involved in the construction of a remotely operated GCMS/pyrolysis a few years ago. We burned up a couple of heaters before we got it put together right...and a couple after. Then we got the system working and mothballed it. I would bet a pound-on-a-penny another heater will fail when it is fired up again...and all we subjected the system to is mice.

Aerospace lives (and dies) by the mantra: Test Like You Fly and even uses the acronym TLYF commonly. So, "typical" testing would be "shake and bake" in that order, so as to simulate the launch, entry, landing and on-surface operations.



Considering this was mothballed from MSP '01, the Phoenix mission was supposed to benefit greatly by expanded test phase durations.

No idea what the source of the problem is, but I'm sure the TEGA team is focused and working their hardest to solve or work with these anomalies.

Of course, when you think about it, their first bake was a success! There may not have been water ice, but that's science...

Speaking of mothballed spacecraft, I wonder if they used the same springs in the doors as the Galileo used in its high gain antenna....
Though I don't think the instruments were locked up in storage that long?

The worst case scenario would be the TEGA doors closing under the weight of the soil without anything getting into the oven. If anything is wrong with the springs (i.e. it's not just stuck hinges), it's entirely possible that a sample weighing as much as the doors could close them.

I think that's quite unlikely considering how much dirt there is on top of the partly opened door of oven #4.

From the looks of all the pics wouldn't it seem like the soil worked itself into the spaces between the door and the frame of the instrument? That would be enough gum up the works. Like throwing sand into a mechanical clock! Probably built TEGA to too close tolerances.

From the latest update:

The plan is to use oven number zero. Let's hope this works...

Also from the latest update:
"Delivery to any TEGA oven involves a vibration action, and turning on the vibrator in any oven will cause oven number 4 to vibrate as well."

And from Emily's Planetary Society Blog:
"I had thought that the short circuit in oven #4 no longer posed any problem to the instrument.... But if I understand this update correctly, it appears that when they go through their sample delivery routine and vibrate a different oven (in this case, oven #0, which is located across the "rooftop" of the TEGA instrument from oven #4)... the vibration of oven #0 may trigger the short circuit problem in oven #4, with unknown implications for the health of TEGA."

I'm also confused. If vibrations transmitted from another oven to oven #4 can cause a problem, why use an adjacent oven? Why not use one of the most distant ovens, like #3 or #7? This assumes the following pattern of ovens:
7 6 5 4
3 2 1 0

I don't know that I'd consider oven #0 to be "adjacent," but I'm not engineer enough to know the redundant wiring between these ovens. We were told, quite explicitly, that the short circuit in oven #4 has no bearing on any other ovens. That's the source of Emily's confusion, and mine as well. I guess they've learned something new since then, and hopefully they've also learned not to speak in such explicit terms before they fully understand all the data they have before them.

Well, if we wait for them to "fully understand" what's going on with TEGA, then they'd never tell us anything. What they're telling us is what they believe to be true (or most likely to be true) at the time. They are doing their best to work through the problems with TEGA from millions of miles away, as quickly as they can so they can still pull out mission success. This is, in part, why it's premature to ask questions like how TEGA could have been sent to Mars with a component that was "not built to flight specifications" -- I am sure that they still don't quite understand the nature of the problems, and they are way too busy trying to figure out how to operate it "as is." Problems like the ones TEGA's having try our patience, but they also bring out the best from the flight engineers. At heart, any engineer loves to solve a problem, and these are some of the world's best engineers. If anyone can pull success from the jaws of failure, it's these guys.

--Emily

It's a balancing act for sure. If we want mission teams to reveal preliminary information we have to let them know we appreciate it and that we understand that such information is subject to revision. That's part of the excitement of feeling like we are along for the ride.

Now don't get me wrong, Emily. I'm pulling like heck for this instrument to have eight fulls ovens, not just two. And I know that the instrument is in the right hands. I have absolutely no doubt about this team's abilities and ingenuity.

My point is more about what is being said about the problem. We were told something about this short circuit that, it appears, was not entirely correct. I see one of two options: the problem was not fully understood and yet a blanket statement was made about TEGA's overall health for the press, or that it was understood and the problem was willfully misrepresented. I know it wasn't the latter option. But just like the idea of growing asparagus on Mars may not have represented their findings in the best possible way, perhaps this is a "lesson learned" about how to talk optimistically about overcoming spacecraft problems without misrepresenting those problems. That's all I'm saying.

One thing I have wondered about is the consequences of having a gap between scooping up a sample of sub-surface material and then delivering it anywhere. It seems to me that the material reaching the ovens/labs/whatever is going to be altered by the time they reach there, because it's been exposed to the atmosphere, jumbled about, etc. Maybe a dumb question, I'm sorry, but would material scooped up and deposited almost right away behave differently? I know it's not possible to "scoop and swoop", the arm can't move that fast, but it is something I wonder about.

I'm pretty sure this is one of those things that NO ONE KNOWS until it's done. After all, how much experience does anyone have scraping up frozen Martian soil/ice mixture and doing ANYTHING with it?

I'm standing right next to you. No need to shout! I was just thinking aloud here.

Anyway, I reckon they'll have an idea about this, or at least have pondered the situation... they'll have models of the soil and its properties now, having analysed one sample, surely? And it's a pretty obvious difference - fresh material vs material that's been sat in a scoop for a while...

Or that the emphasis at the time of the first statement was on what was known ("the short is confined to oven #4", "no direct effect on the other cells"); the emphasis at the time of the second was on what was unknown ("no way to assess the probability"). That's related to your first option, but not really the same. In any case, all problems being actively pursued will become better understood with time. That is the inherent hazard of news as opposed to textbooks.

That's actually the BEST question to ask regarding any type of analysis: "How modified did the material get before it hit the detector?"

(Which also falls under the Big Question my graduate advisor used to demand: "How do you know what you know?")

If I understand correctly, as soon as the ice is exposed (and as the soil burden is removed) the equilibrium will shift and the water ice should begin to sublimate into the atmosphere. Any salts/materials that were dissolved/suspended in the ice will remain behind. That might alter the material properties of the soil sample (clumpiness?) and the apparent concentrations of the dissolved/suspended materials. How big will this concentrating effect be?

The beauty is that the phase diagram of water is pretty well known. So I would guess that an estimate of the rate of sublimation expected at Mars temperature and pressure could be made (and probably already has been made). Even better, once a soil analysis is done, it should be possible to make up a simulated sample of water ice (including all the salts, materials types, and grain sizes) in a laboratory and check it's sublimation rate at Mars temperature and pressure over the time it took to deliver the sample - just to satisfy that paranoid question.

-Mike

I wonder if it's possible or practical to shift dig-and-dump operations to me a local midnight when the temps are more like -80 instead of -30.

Doug

One way to understand the manner in which exposed material gets modified would be to take regular pictures of scraped soil in the scoop at the highest magnification that the RA camera can use. This would preclude using the scoop for two or three days, so perhaps should only be done if they decide TEGA can't be used any more.

Chris

Doug, see post 189.

There's actually an online calculator to figure out how long ice particles will last given certain conditions:

Ice Sublimation Rate On Mars

A paper On the sublimation of ice particles on the surface of Mars; with applications to the 2007/8 Phoenix Scout mission has this chart for isolated particles of 0.5mm diameter:



The abstract reads:



Emphasis added. Thus it's interesting to note that a recent Phoenix news item says:



Quoting from the paper again:



Here's what they got with one "snow pile" experiment at the Extraterrestrial Materials Simulation Laboratory at JPL:



So it looks like about 20% loss in about 30 hours. That "snow pile" of 150 grams is a bit bigger than the ones described at Snow White of 10- to 20-cubic centimeters though.

I can't believe the team is taking a few days off to celebrate US Independence day.......

Can you work for 90 long days straight without a break without making a big mistake?

I know I can't.

5 weeks in, having a weekend, isn't a bad idea. It's not like the lander is going to sit idle. We're at the real beginning of the 'meat' of the mission. A few days break, come back refreshed, into top-gear for the good stuff in the weeks to come.

Doug

Excellent!!! Thank you very much for those links and for your detailed post!

Yes but the team does not consist of one person........

I think we have this discussion every year Usually it's the MER teams being criticised for taking a July 4th break, so only fair the Phoenix team should get it too I guess!

Joking apart, personally I'd be amazed - and worried - if they didn't take a break. There's "dedication" and then there's "obsession". After all, the Phoenix team have all been under enormous pressure up to this point, not just professional pressure because of schedules, problems, media demands etc, but family and domestic pressure too; I'm sure their families have been very supportive of them for having to work incredibly long hours right through from before landing to the point where we are at now, but this is (as I understand it) a huge deal of a holiday in the US, so even the most understanding and supportive families, kids and partners wouldn't be out of line in hoping for and expecting a bit of a break with their loved ones this weekend. They're human beings - fathers, sons and partners - first and Mars people second.

I mean, how many of us have heard partners sigh or groan "Are you looking at those ****** Mars pictures again?", and this is just our hobby; imagine the domestic pressures on the people who work on the missions, who have to live on Mars time, who have the press constantly hassling them for updates and have to try and find fixes for faulty ovens and more...

If any of the Phoenix team are reading this, have a GREAT vacation guys, you've earned it!

True!--didn't Pathfinder land on Independence Day?

The press releases lately have been very confusing and there have been very few of them. The second-to-last item concerned events that happened June 28:



Emphasis added. But the current news release says:



What to make of that? The Snow White samples dried out before they could get them to the TEGA? Why did they dally? Or maybe since they now are worried that the next TEGA bakeoff will be the last, they want a more perfect sample? I guess if so, there's a natural break at this point.

BTW, I submit that upcoming TEGA samples should be called "Hansel" and "Gretel" and the TEGA instrument be renamed "The Gingerbread House."

Of course, they probably know Phoenix will last for 200 days, so no hurry to try achieve full mission success.

I totally agree. I had my little grumbly-post last night, but that was about choice of words not quality of work. This mission has been phenomenal! Time to recharge the batteries, have a ton of fun and then tackle this TEGA delivery with fresh eyes.

:fireworks:

There is a good example in NASA history as to what happens when you try to enforce a no-time-off work schedule on even highly motivated individuals.

The Skylab 4 crew (third resident crew) had been aboard Skylab for about 6 weeks and had not yet gotten a single day off. Houston just kept finding more and more activities to fill their "free time" schedule blocks. So, one fine morning, the crew woke up and told Houston they were taking a day off. Period. End of discussion.

It was called a "mutiny" in the American press, and I know several people in NASA considered it such. Certainly Jerry Carr, the Skylab 4 mission commander, was never offered another space flight.

One of the hardest lessons learned from Skylab revolved around this incident, and the mission managers eventually realized that they, and not the crew, were at fault. No matter how motivated, people can't be expected to just push hard for weeks and months at a time. You have to give them time off, for a psychological break (if nothing else) from the work.

So, I have no problem with the Phoenix team taking a day or two off. In the long run, it's good for the team, and thus good for the mission.

-the other Doug

That probably goes back to the "chimp in a can" attitude of The Suits at NASA towards the astronaut/crews which evidently applies to the human components of the silicon-carbon lifeforms team. Remember how Gus Grissom (et al) had to fight for a window and a hatch that wasn't bolted on?

Program the 'Bots to do something useful, and have a good 4th.

--Bill

From MSNBC Thurs., July. 3, 2008

Mars lander’s next whiff could be its last
Scientists wary about short circuit in Phoenix’s soil-baking oven

I hope it does not short circuit again but it looks like it might???

http://www.msnbc.msn.com/id/25514374/

One thing to consider is this year they may observe the 4th as a holiday whereas previous years they did not. Some team members worked the 4th in prior years when the hardware was still in manufacuture, assembly & test phases here on Earth in order to meet the ever-important launch date. With the lander now successfully on Mars, a lot of the pressure is off.



Well said.

According to the media, TEGA initially did not detect any organics in first sample. Shouldn't we be worried about the that as much as the short circuit problem?

The tega results released so far are only preliminary, so small amounts of organics could still be revealed by more in depth analysis. If none are found then the mystery of where mars's organics went deepens. So far there haven't been any signs of peroxides or superoxides put forward as the leading theory of what got rid of them.

Worried? Why? We got there safely, the equipment works and we're starting to get answers. That's cause for celebration not worry to my mind.

And yes - having worked sometimes up to 90 days without a break myself (on survey ships, sometimes synchronising my 'day' with the tidal cycle which is not far off a martian sol) I absolutely agree the team needs a holiday. So I'm not worried about that either.

Now if our intrepid robots ever declare their Independence Day, and start doing things on their own initiative, THEN I'll worry.

Or maybe we should try to think outside the box......how about life in silicon instead of carbon

I would expect that the top cm of soil anywhere on Mars would be pretty much identical because it consists mostly of fine windblown sand. I have high expectations that the next sample taken from 2cm lower at the soil/ice interface will be much more interesting and may contain organics.

That was the conventional wisdom, but I wonder.... The benign character of the surface layer -- moderately alkaline, moderate salts, no strong oxidizers -- was a bit of a surprise. Do you think this is the general character of most of Mars' surface? Oxidizers look to be out as organics destroyers at this location, that leaves UV radiation. Is there any other possibility?

Scraping into the ice layer will give a sample that has been frozen in place, protected from radiation (for how long, I wonder).

I'm sure you would not deny that finding Martian microbes would be a fantastic boon to understanding life on Earth and it's origin. So maybe you can see how each indication that Mars is barren would cause worry in those hoping for such a boon. On the other hand, as you say, Mars is what it is and all data, compatible as well as incompatible with the possibility of life, should be welcome.

I was thinking that too, but remember that the polar regions get deeply buried underneath CO2 (and probably H2O clathrate) snow for many months during each Martian year. There has to be some effect on the immediate surface soil; what it might be, I don't know, nor does anyone really since the gross chemical composition of the deposits aren't really known. Mostly CO2, sure, but there has to be some trapped water as well.

have i missed it, or have they still not released the results from the first tega oven samples... they should have had them in just a few days..

Transcript June 26 briefing:



Might be more detail in Q&A. I didn't look.

7 posts on the pros and cons of transcribing 'uh's' deleted

1) Nothing to do with Tega
2) Nothing to do with UMSF
3) Everything to do with needing to get out more.

And I'm just as guilty as the other 6 posts.

Not the delete key.......ahhhhhh!!!! - ok delete deserved.


(Yup - Admin)

They have not yet opened the oven that they hope to deliver an ice sample to in the near future, have they? This is surprising to me. I would think that they would want to see how successful the opening is so that information can figure into their planning to get an ice sample quickly into TEGA.

I wonder if the TEGA doors on the other side is likely to suffer from the same problem we have seen on the two doors that have been tried?
The two sides are not connected mechanically I would guess. So should only be the same defect made on both sides that could cause similar problems.

As I understand it, they expect the four end doors to all open about the same as the first door (#4) and the six interior doors to open about like the second door opened (#5). But I would think that the situation is such that only in opening any door will it be known for sure how well it opens. Which is why I'm a little surprised that they would be preparing to make a quick ice delivery without yet knowing for sure what the door situation will be where the delivery is to be made. It doesn't seem like it's a problem to open the door a few days before a delivery is made.

Hmm. Are they trying to minimize windborne contamination? Only reason I can think of, though any blown dust really doesn't seem as if it would be a significant deterrent to the sample analysis. There's nothing confusing potentially outgassing from the spacecraft itself, is there?

Why utter the magic words (open sesame) any sooner than needed, say one day before delivery ?
Murphy's law is universal