Bad news for PFS. I hope they will be able to solve this issue.

The PFS scanner is stuck in its closed position.
Several attempts to move it were made at the time, but the instrument did not respond. Experts suspected a thermal problem by which low temperatures were blocking the rotation of the mechanism.
Another attempt to move the scanner was made on 16 March 2006, in warmer flight conditions. Unfortunately, the scanner remains stuck.

The next opportunity to perform another test on the spacecraft will be end of April, after the Venus Orbit Insertion.

From http://sci.esa.int/science-e/www/object/in...fobjectid=38964

"I knew it." "This confirms what I've been saying all along, and Jeff Bell completely agrees with me." "Obviously, this is a result of the continued draining of funds from unmanned space exploration by Shuttle/ISS." "I mentioned this obvious problem at the [insert your favorite planetary target] Focus Group meeting and everyone complimented me on bringing the issue up."

Everyone gets three guesses as to which UMSFer might utter these inevitable (a posteriori) "predictions." And the first two guesses don't count.

No, I didn't anticipate it at all, and it's all the Europeans' fault. So there.

You WILL notice that they discovered this back in December, and remained quiet as little mice about it until now.

Boys - don't make me come in here!! Inappropriate politics removed.

I'm amazed you've not had a dig at something/someone about this one though Bruce - deployment of devices in space is something you've enjoyed lambasting in the past ( based on Galileo and MEX )

Doug

I am only able to remember one instance where a stuck instrument cover was removed DURING the mission. The Viking Mars scoop cover that was shaken out over several days of back and forth motions of the motor controlling it. Are there more examples? All the others I can think of, Galileo HGA, Pioneer camera cover not popping off, Venera camera cover not popping off and some missions where solar panels fail to open, were never fixed....

Mariner 10 venus/mercury had two solar wind instruments.. a sunward facing proton and ion instrument and a rearward facing electron spectrometer. The cover on the sunward instrument never deployed.

The original partial deployment of MARSIS was cured by heating the kinked boom on the "inside" of the kink.
However You are right that the prognosis is not god. I remember how they tried everything with the Galileo HGA, opening slowly, opening quickly, heating it, cooling it, repeated "slamming" with the deployment engine, no luck.

I add my personal rant. For simple one-time mission-critical deployment tasks pyro actuators are preferable. They are simple, cheap, very reliable, light and can be made redundant at a low cost/weight penalty (just add another charge with a separate firing circuit). Not that they would necessarily be usable in this particular case. Pyros are generally too violent for deploying delicate instrument, but when it comes to things like getting rid of covers and cutting cables they are the best.

tty

It is not inappropriate to complain about the untimeliness of this release. In a worse case scenario, the failure will be traced to widget xyz, and the same widget has a deployment function on New Horizions.

Failures of space-based hardware need to be known and understood by the space design communtity in a timely manner, so we can look under the bonnet of anything we are building and fix it, before it hits the street. This is a space health management issue...

The Compton Gamma Ray Observatory almost didn't happen due to
the satellite's high-gain antenna being stuck by a wrapped-around
wire during its launch in April of 1991.

Fortunately for that mission, it had been sent up by the Space
Shuttle Atlantis (STS-37), so EVAing astronaut Jerry Ross was
able to fix the problem by hand after repeated commands from
the ground and even using the robot arm failed to do the trick.

http://en.wikipedia.org/wiki/STS-37

It IS inappropriate to bring Iraq into it, to use a rather crude phrasology when refering to the Italians and to have a post that saying nothing but "Grrrrrrrrr"

Doug

As long as we all agree it is very frustrating to have yet another space mission placed in jeopardy because the spring in the Jack-in-the-box does not work.


In my next IR&D funding request, I am going to propose building a satellobit - a little dude with strong clasps and a good lever arm, who could wrestle with stubborn booms, valves, shields, clasps, whatever. Include one in every mission - even a robotic eye camera that could aid in the diagnose root causes would be helpful. We have got to pay more attention, money and weight allowances to system health assessment and managagement.

I tend to agree - and in particular for the incredibly precise optical origami experiment known as the James Webb Space Telescope! Hubble didn't *really* need human attention (it's pretty obvious that it really needed a series of improved siblings, not a series of expensive upgrades) but JWST is s-o-o-o complicated in terms of the darn thing deploying that it really does need a hammer-wielding 'something' to be available, just in case. An astrobot would be fine, but a human would possibly be even better - and as a dry-run for some serious deep space Buck Rogers, what could be better than a mission to observe JWST deployment from a nice, safe distance, with the option of a repair / redeploy if required? If NASA doesn't want the job, put it out to competitive tender, and offer to fly some of the engineers who built the darn thing as Mission Specialists aboard a Dragon (or whatever). OK, it's not the cheapest way to run things, sending men out there - but the high price of a manned insurance mission is still pennies compared to the cost of JWST going down the sluice. If that happens, say cheerio to all those other fun big science missions...

Bob Shaw

Well - the mission is not in jeopardy, it's simply one instrument that's not going to be able to do it's job. I agree, it is highly frustrating, but it's just another reminder that this stuff isn't easy to do.

Doug

Well said, Doug. There is plenty of science to be had with the other instruments. And VEx PFS may not be lost - yet. Maybe the forces associated with VOI could have some type of beneficial effect or perhaps a post-VOI workaround can be found. We'll see.

Yeah, actually it was (although you'll note that I was actually sneering at US pretensions of superiority in that post, by doing a Merle Haggard imitation with a sarcastic snark at the end). My apologies. (Also, I thought Messenger was GRRRing at me, rather than at the damn PFS.)

I would imagine that solar cycling has as much chance of remedying this as anything, although it will be tricky to pull off.


If they can't correct this, it WILL be a pity to lose it -- PFS was the second most important instrument onboard. Yet again, moving parts prove to be the bane of space missions, and we have proof that it's better to err on the side of excess in designing the strength of actuators (whether motors or springs).

Dumb question, but is VIRTIS the primo instrument of VExpress? Are some mission objectives compromised if PFS remains stuck, or can VIRTIS still achieve the main science goals?

After Mars Express gave us the Great Boom Scare of '05, I wonder if some serious thought & money should be spent trying to make deploy-or-bust designs?

BINGO - Alex now owes me $1 - we had a book going on how long it'd be

He had 'increasingly obvious' for $2, and I had 'JAXA' for $3.

Good job you didnt mention the Discovery program, that would have emptied my wallet.

Doug

Did I happen to mention the central relevance of this to the Discovery Program?

more problems for Europe maybe they'll fix it ?... well at least Mars Express done great at Mars

The Venera incident was a bit different...the caps melted on!

For those that have not seen the BBC series 'The Planets' - a Venera scientists recalled the problem being described thus

Senior Engineer "I believe we have landed in something sticky and viscous"
Junior Engineer "Yes sir, in the sh**"



Doug

You blokes will take a wager on anything! I Guess Bruce's predictability is a safe bet

Most of the tasking in the building I work in is related to flight hardware predicability: We stress, we strain, we Eddy, ultrasound, Xray, thermal image for ply debonds and on and on. We do it in vacuum, at extreme temperatures. A chemist down-the-hall from me has even tested deployment in the 'vomit comet'. We do everything we can think of that will assure the hardware will perform the way we expect it to, where we expect it to.

What I am getting at, is I am sure they are doing these same things in Europe, and expecting the designs to work under any and all possible conditions. So why so many failures? We must not understand all the failure modes. I can't pull up the level of detail I think would be necessary for me to understand the deployment difficulties experienced by the Mars Express, and I cannot even begin to comment on whether or not the PFS problem is in any way related. But I get to wonder out-loud if the Venus Express engineers are completely on-top of the possible failure modes of the Mars probe, and if they addressed the issues.

We have a prospective of how tightly the different Huygens groups guard their data, not always sharing with each other. Did the Venus Express engineers have a detailed report on the Mar Express boom problem, and upon why Huygens channel A failed?

There is no commonality between the aparant failure of the PFS cover, and MARSIS or the Huygens problem. I know you like to think outside the box, but that's just wayyy waAYy outside it

Doug

I've wondered if missions shouldn't start adding "engineering webcams", similar to the Hazcams on MER that are there to monitor deployments and moving parts on sciencecraft. It might not have helped Galileo, but then again knowing the exact configuration of the antenna might have allowed for some kind of partial recovery by simulating the antenna coverage pattern.

In Galileo's case, while live imaging of the HGA deployment wasn't possible, I seem to recall that NIMS took an image of the spacecraft during cruise (I saw it in AW&ST) that gave a rough idea of the post-deployment antenna configuration. And analyses during cruise showed that the anomalous HGA deployment did not result in any usuable gain/side lobe patterns.



The only obvious commonality would be quality assurance inspections or pre-launch reviews but, as any U.S. scientist/engineer can tell you, even those can't catch everything.

In this era of miniaturization, would it be feasible to send along
a little repair robot or two to fix stuck wires, antenna, solar panels,
etc.? Or is that still just too expensive and science fictiony?

But some real robot repair tests have been made:

http://www.nasda.go.jp/press/1999/03/ets7_990319_e.html

And then there is this idea:

http://www.tsgc.utexas.edu/archive/fulltext/raptor.pdf

And this little guy:

http://www.firstscience.com/site/articles/droid.asp

Other relevant items:

http://arxiv.org/pdf/cs.RO/0601056

http://ranier.hq.nasa.gov/telerobotics_page/photos.html

Keeping on the theme of miniaturization, I think we should send out
groups of small probes to a target world, each with one or two
specific science tasks. If we lose a few, it is unfortunate, but does
not stop the overall mission. Multiple probes can cover more ground,
literally, and we won't have all our eggs in one basket.

Woudlnt it make more sense to simply spend the time, money, volume, mass and energy on making a more robust deployment mechanism in the first place? Anything dynamic and adaptable enough is going to be far far more complex than whatever mechanism it's sent to fix, and as a result, far more likely to fail that the mechanisms in question anyway

Doug

The MoomawBot script I wrote in Perl was fed the text of this thread and called for a massive reduction of the manned space program. It also referred to conversations it had had with members of the Decadal Survey that can be seen as insightful and pivotal in changing their opinions.

Well, you know, constant repetition is a very important tool in educating the slow...

By the way, I only got one chance to talk with members of the Solar System Decadal Survey -- during which, sure enough, one member thanked me for clearing up a misconception his subgroup had had (and printed in their first draft) about what New Horizons could do at Europa. (E-mail available on request.) See if any of YOU get invited to my Nobel Prize party.

True, to a point -- but the Big Lie theory of ideological control also calls for the repetition of the lie, over and over, until it's been heard and repeated so often that it's accepted without question...

Oh, and don't call those who legitimately disagree with you "slow" or "uneducated." Makes it sound more like you're pushing the Big Lie than it sounds like you're right.

-the other Doug

Voyager II had an apparent indication of the science boom failing to lock in place when it actually had. (kind of the reverse of the problem in this case)

One of the US lunar Surveyor crafts had a surface sensor (gamma ray surface composition device?) fail to deploy completely and the sampling scoop was used to position it correctly.

The Explorer craft (39?) orbiting the moon had incomplete extensions of the antennas, but the problem did not substantially effect the science return. Booms only extended (IIRC) 700+ feet instread of 1000+ ft.

Space shuttles have had payload door alignment problems during opening and closing (or failing to do so), but usually it is the thermal expansion of the vehicle that causes the problem and they know how to alleviate the problem.

People never appreciate when I'm being facetious.

Actually, I've always been under the impression that I don't just repeat the same line over and over; I actually do try to argue it. I'm not trying (at least consciously) to emulate Goebbels.

Sometimes I can't tell that you are being facetious and not, say, pompous. Thanks for clarifying this particular example, though

Do we know 100% that the instrument has failed?

Maybe it can be fixed?

That's just what we've been talking about -- it may be doable through thermal cycling, that is, alternately exposing the drive to hotter and colder temperatures. Alternatively, since the previous theory was that it was too cold, just warming it up more may do it. We simply do not know at this point. I would presume that they won't give up for a very long time. (I would also presume that they DO know, from telemetry, whether the deployment motor is actually drawing power.)



Actually, in your case, Alex, I WASN'T being facetious.

It's all a conspiracy ! now they're trying to cover up Venus

I'm going to ask Hoagland what he thinks of all this .....

What box? You lose five points for using the B word

The only common failure mode I can see is in quality control:

I don't see how a command as critical as 'switch on mains' can be dropped, if whoever is tasked with checking-off on all the software functions fills in all their little blocks. We were promised a report on this...some day.

Is there any hint on the nature of the PFS problem? Electrical? Hindrence? Damage? Lazy eye virus?

I'm somewhat inclined to be forgiving where moving-part problems on spacecraft are concerned, precisely because they ARE so common -- and so frequently connected with differential thermal expansion or contraction of different parts of the spacecraft, which can be hard to forecast even during ground tests. But we do have here further proof that it's always best to err on the side of excessive strength in your actuators.

(Note that -- if there hadn't been an astronaut standing by -- the failure of the Gamma Ray Observatory's antenna boom to deploy might have been the most expensive moving-part space failure of them all. You can perhaps interpret this as an argument for retaining at least small manned orbiting space vehicles through the current period -- or you can interpret it to mean that we need small orbiting emergency-repair robots capable of tugging on stuck parts.)

Bruce:

I keep saying it, but JWST is *exactly* the sort of vehicle that could do with some sort of hammer-wielding attendant, be it human or robotic... ...imagine if one of the petals get stuck, a million-odd miles away from home!

Bob Shaw

You mean something in the style of the robotic hubble mission which you love to hate

Doug

I would have loved the robotic Hubble mission IF THERE WAS ANY REASONABLE CHANCE IT COULD BE MADE TO WORK FOR LESS COST THAN JUST BUILDING AND LAUNCHING A HUBBLE REPLACEMENT. Unfortunately, after one looked at the idea for a little while, it was painfully apparent that there wasn't -- we simply did not have the time to develop the new robotic technology necessary to fly this mission at all in time to keep Hubble from breaking down completely and being destroyed, let alone to fly it for less than the cost of a replacement Hubble. Everyone who looked at the idea and (unlike O'Keefe) had any technical knowledge at all reached the same conclusion, which is why the Hubble Robot is now sleeping with the fishes. Had we gotten an earlier start on developing it, it might have been a different story -- ah, but had we done that, NASA would have lost one of its major (pre-Colombia) arguments for trumpeting that we Still Needed The Shuttle.

(Note also that the kind of repair work the Hubble Robot would have needed to do was far more complex than just latching onto a stuck part and giving it a yank.)

Not that much cheaper if you wanted to do anything of any value - if you wanted a chance of it working.. You would need dexterity, very very fine manouverability....and let's face it.....just launching a replacement's probably going to be cheaper

Doug

In most repair cases, yeah. But occasionally you're going to have a situation like the GRO -- in which a half-billion satellite is crippled by one dumb-ass boom that won't deploy properly -- and in those cases, it really might pay off to have a small robotic satellite capable of giving it a tug and/or kick.

You mean the main camera being out of focus, right?

Borek

The main camera isn't - but the last minute, rushed, bolted on the side SRC is.

Doug

High Resolution channel being out of focus or not, MEX DID a great job at Mars. And it still is doing!

I've E-mailed Formisano to ask him when the next attempt to deploy PFS will occur, and what procedures (such as thermally cycling that side of the craft) may be followed to do so. No reply yet; but then, I didn't really expect one.

Bruce,

I've e-mailed him just after the VOI with the same questions.
No answer yet.

-- Rakhir

Thanks much Rakhir for the pointing topic.

I was thinking that any probe, robot, rover or any spacecraft must carry along with him an useful and smart general purpose arm to solve for any problems that they might be stuckduring its exploration.

The robot arm plays the rol as an auxiliar for any mechanical problems such as to align correctly the motor troubled antenna; puff off the dirt from lens, unstuck the troubled panel solar; repair a panel solar; lift off from the surface the troubled wheel (the wheel must be designed to be able to lift off independently from the other, this is the MER's problem and MSL might have it); help to unstuck /stuck the IDD; push any interesing rock to see its bottom; help to tilt the rover to a right angle in anywhere when the battery is low; and many much useful auxiliar examples that a arm can help to rovers.

The good example was the ones from Shuttle. Its long arm has helped to simplify and solve the thermal problems by removing a small debris under the nose.... Why not any spacecraft bring an arm with itself! Spirit need a help from a smart arm to spin the injured wheel or knock softly it to see if the motor will turn on again

Of course, that carrying an extra weight of the arm, it would save millions dollars if the problem is arised. It is like a kind of space insurance. Now, the troubled PFS is the point of iceberg for this discussion.

Rodolfo

Unfortunately on the size, volume, mass, power, money, development budgets of anything short of a space shuttle, it just doesnt make a lot of sense, and is basically impossible.

For example - you'd have to ask "OK - do I want 6 instruments on VEX, or 2, plus an arm to make sure they deploy" or "an extra 50kg of hyrdazine for a great extended mission for 5 instruments, or a system that might or might not guarentee 6 instruments for 5 years less time"

Doug