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Posted by: Rakhir Mar 21 2006, 09:03 PM

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/index.cfm?fobjectid=38964

Posted by: AlexBlackwell Mar 21 2006, 09:19 PM

"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.

Posted by: BruceMoomaw Mar 21 2006, 09:36 PM

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.

Posted by: djellison Mar 22 2006, 08:37 AM

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

Posted by: deglr6328 Mar 22 2006, 09:13 AM

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....

Posted by: edstrick Mar 22 2006, 11:14 AM

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.

Posted by: tty Mar 22 2006, 12:22 PM

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

Posted by: The Messenger Mar 22 2006, 03:07 PM

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...

Posted by: ljk4-1 Mar 22 2006, 03:21 PM

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

Posted by: djellison Mar 22 2006, 04:05 PM

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

Posted by: The Messenger Mar 22 2006, 05:27 PM

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.

Posted by: Bob Shaw Mar 22 2006, 06:52 PM

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

Posted by: djellison Mar 22 2006, 06:58 PM

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

Posted by: AlexBlackwell Mar 22 2006, 07:05 PM

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.

Posted by: BruceMoomaw Mar 22 2006, 08:15 PM

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).

Posted by: Marz Mar 22 2006, 10:04 PM

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?

Posted by: djellison Mar 22 2006, 10:31 PM

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

Posted by: BruceMoomaw Mar 23 2006, 01:34 AM

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

Posted by: GravityWaves Mar 23 2006, 02:21 PM

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

Posted by: tedstryk Mar 23 2006, 03:14 PM

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

Posted by: djellison Mar 23 2006, 03:29 PM

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

Posted by: The Messenger Mar 23 2006, 04:06 PM

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?

Posted by: djellison Mar 23 2006, 04:46 PM

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

Posted by: hendric Mar 23 2006, 04:49 PM

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.

Posted by: AlexBlackwell Mar 23 2006, 04:56 PM

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.

Posted by: ljk4-1 Mar 23 2006, 05:23 PM

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.

Posted by: djellison Mar 23 2006, 05:30 PM

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

Posted by: JRehling Mar 23 2006, 07:31 PM

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.

Posted by: BruceMoomaw Mar 23 2006, 09:30 PM

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.

Posted by: dvandorn Mar 24 2006, 12:47 AM

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

Posted by: tasp Mar 24 2006, 01:26 AM

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.

Posted by: BruceMoomaw Mar 24 2006, 02:16 AM

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.

Posted by: AlexBlackwell Mar 24 2006, 02:20 AM

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

Posted by: Decepticon Mar 24 2006, 03:15 AM

Do we know 100% that the instrument has failed?

Maybe it can be fixed?

Posted by: BruceMoomaw Mar 24 2006, 06:12 AM

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.

Posted by: GravityWaves Mar 25 2006, 05:24 PM

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 .....

Posted by: The Messenger Mar 25 2006, 05:42 PM

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?

Posted by: BruceMoomaw Mar 25 2006, 09:50 PM

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.)

Posted by: Bob Shaw Mar 25 2006, 10:20 PM

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

Posted by: djellison Mar 25 2006, 10:40 PM

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

Doug

Posted by: BruceMoomaw Mar 26 2006, 03:48 AM

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.)

Posted by: djellison Mar 26 2006, 10:03 AM

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

Posted by: BruceMoomaw Mar 27 2006, 07:16 AM

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.

Posted by: Borek Apr 5 2006, 07:02 PM

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

Borek

Posted by: djellison Apr 5 2006, 07:05 PM

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

Doug

Posted by: ugordan Apr 5 2006, 07:06 PM

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

Posted by: BruceMoomaw Apr 12 2006, 11:05 PM

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.

Posted by: Rakhir Apr 13 2006, 07:04 AM

Bruce,

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

-- Rakhir

Posted by: RNeuhaus Apr 15 2006, 01:49 PM

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

Posted by: djellison Apr 15 2006, 02:51 PM

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

Posted by: Bob Shaw Apr 15 2006, 03:00 PM

Doug:

Just give up on unmanned spacecraft, and make it a condition of PI status (hell, no make it for all of 'em) on future vehicles that they be 'briefly manned' by whoever's instrument has gone most over budget. The lucky loser gets launched with the spacecraft and has the task of manually removing all covers, straightening any booms and clearing off debris before their PLSS oxygen runs out. If Tombaugh can go to Pluto or Shoemaker can go to the Moon *after* they're dead, why not just bow to the inevitable and send them just *before* they pop their corks? It'd certainly make the JWST more doable, and as for Lunar landers...

Bob Shaw

Posted by: RNeuhaus Apr 15 2006, 03:22 PM

Interesting view. The weight of sense is the factor to decide if it worth or not to take an multi-purpose arm as an kind of space insurance (orbiters and rovers) and also for science purposes which would be most useful for rovers. The money is a balance decision factor for many things according to our monetary society. It is the product of our still young technology of propulsion system.

Rodolfo

Posted by: BruceMoomaw Apr 15 2006, 10:38 PM

Weight-wise and expense-wise, it would make MUCH more sense to simply provide stronger motion actuators (both springs and motors).

Posted by: nprev Apr 16 2006, 12:33 AM

Yeow...nihilistic to the nth, Bob...but I sympathize!

Project management as a discipline in aerospace has unfortuntately degenerated into a political rather than practical exercise in too many respects. No-kidding systems engineering would prevent stupid things like the PFS anomaly; the challenge is to make the investment in effort & materiel up-front.

Posted by: JRehling Apr 16 2006, 04:36 AM

In fact, it would even make more sense to duplicate the most important instruments.

Posted by: BruceMoomaw Apr 16 2006, 08:44 AM

I'm not sure I'd go THAT far -- that would necessitate one hell of a big jump in the mass and cost of the craft, which would go mostly to waste if the first copy of the instrument failed (although it WOULD prolong the craft's observation time with that instrument -- indeed, we just had a spectaacular example of that with the PFS on Mars Express, which would have come to a premature end if they hadn't provided a backup "pendulum" system). What I'm proposing is, to put it mildly, less ambitious.

Posted by: tty Apr 16 2006, 04:45 PM

Better make that two somewhat different instruments. There is something called common-cause failures.

tty

Posted by: Rakhir May 2 2006, 07:00 AM

Emily reported in her blog that the VEX team managed to move slightly the PFS mirror out of its launch configuration pointing.
The issue is not solved for the moment but after this move there is still hope to recover this instrument.

BTW, she reported also that the next images from VEX are gorgeous. I can't wait for the next release ! (it seems to be for July )

http://www.planetary.org/blog/article/00000557/

-- Rakhir

Posted by: Sunspot May 2 2006, 11:57 AM

Well its not like the public are ever going to get to see data from Venus Express (judging from ESA's terrible record so far) only a handful of scientists working on the mission will see that..... so from th publics (and us) perspective it probably doesnt matter what does and doesnt work.

Posted by: sawyer May 2 2006, 03:02 PM

I've thought that a very smaller crawler robot (maybe something centipede like) would be what to put on a craft. It would have ability to charge up at some outlet, wireless communication (not absolutely necessary as the plug for power could also allow download communication capability), some optical recording capability, and a few small appendages. This general purpose crawler could relay state information of anything it could reach...and because of its small crawler design that would be a lot of the at least external portion of the craft. It could also provide some leverage or force (like a snake using its body for leverage), to help unstick some pesky parts, but the main help would probably just be relaying information about the actual state of the craft so that intelligent remedial action could be taken.

Posted by: The Messenger May 2 2006, 03:08 PM

Its not quite that bad - they often trumpet new discoveries (I expect we will hear soon that they have discovered that Venus has an atmosphere).

In any case, we have a thread for this kind of venting:

http://www.unmannedspaceflight.com/index.php?showtopic=1777&pid=51717&st=60&#entry51717

Feel free to indulge there.

It is interesting, that in the status logs, they have simply been stating that the PFS is 'off line', the same as other instruments.

Posted by: DonPMitchell May 6 2006, 05:11 PM

It is bad news. The Fourier spectrometer was very important. Does anyone know how its characteristics compare to the Venera-15 FS?

With regard to ESA data, they have an official site where science data is supposed to be publically posted, like NASA's PDS system: http://www.rssd.esa.int/index.php?project=PSA.

Let me know if you can find any actual data there ("Have you in fact got any cheese here at all?").

Posted by: djellison May 6 2006, 06:28 PM

Another member shows his true colours..

"Well, I'm sorry, buy I'm going to have to shoot you"
"Right'O Sir"



Doug

Posted by: dvandorn May 7 2006, 07:23 AM

Not... as such, sir, no.

-the other Doug

Posted by: The Messenger May 7 2006, 07:56 PM

Sure:



And this is copied from the "Entry point to understand the contents of the PFS data sets"

Posted by: Bob Shaw May 7 2006, 08:30 PM

It's a secret! If you are to be given the data, then first you must be killed...

Bob Shaw

Posted by: BruceMoomaw May 8 2006, 01:51 PM

Tentative good news on the PFS mirror front from "New Scientist" ( http://www.newscientistspace.com/article/dn9123-mirror-jams-on-venus-express-spacecraft.html ): Vittorio Formisano announced that on April 27 they moved the mirror not "a tiny amount" as we'd heard before, but fully 30 degrees. "Formisano... told New Scientist he hopes the team will be able to rotate the mirror 90° as early as this week, putting it in a usable position." This would seem to suggest that warming it up is indeed loosening the jam, as the PFS team originally thought.

Posted by: BruceMoomaw May 31 2006, 05:51 AM

Glum news on the subject from the May 22 Aviation Week: "ESA engineers will decide at the end of July, at a final commission review, whether they can recover full use of a scanning mirror on the PFS spectrometer...Tests following the probe's arrival into final orbit around the planet on May 9 showed the mirror to be blocked at the calibration point, and hopes that the changing temperature regime might release it have not materialized. However, engineers say there is enough overlap among the probe's instruments to minimize data loss."

That last is the usual sour-grapes language we hear in such cases. PFS was one of the two key instruments on VeX -- it was not regarded as worth funding without both of them, and it and VIRTIS were supposed to work simultaneously to help make each other's atmospheric measurements comprehensible. This is a very serious loss.

Posted by: ljk4-1 May 31 2006, 03:05 PM

Any chance they could use the probe's thrusters to shake up
the craft enuogh to perhaps loosen the blockage?

I know, it didn't work any better for Galileo's stuck antenna,
but in lieu of sending a repair crew to Venus....

Posted by: DonPMitchell May 31 2006, 05:46 PM

I agree, this is a very bad news. VEX will tell us nothing about the composition of the Venusian clouds without the Fourier spectrometer. Let's hope that VIRTIS will at least reveal some new clues to the circulation of the clouds and atmosphere. Maybe we will be surprised by VMC also, but it seems like a rather crude camera.

Posted by: gpurcell May 31 2006, 09:54 PM

I sense PFS Discovery proposal memos being generated by researchers as we speak....

Posted by: BruceMoomaw May 31 2006, 10:54 PM

It might be possible to add such a spectrometer to (say) Bruce Campbell's "VISTA" Venus radar orbiter -- but the trouble is that the proposals for the next Discovery mission are, I believe, already past due. Certainly we have here further proof that the enduring bane of spacecraft is moving parts, and that more attention should be paid to this problem.

Posted by: gpurcell Jun 1 2006, 01:43 PM

Bruce, would the procurement rules for Discovery allow a PI to add capacity to a mission if it is selected as a candidate for further study?

Posted by: JRehling Jun 1 2006, 04:16 PM

Messenger has two spectrometers and is making a flyby of Venus. Atmospheres are better mixed than surfaces: one great flyby might do a lot of the good as far as composition goes.

Solomon et al [2006] says of the flyby: <<MDIS will image the nightside in near-infrared bands, and color and higher-resolution monochrome mosaics will be made of both the approaching and departing hemispheres. The UVVS will make profiles ofatmospheric species on the dayside and nightside as well as observations of the exospheric tail on departure. The VIRS will observe the planet near closest approach to sense cloud chemical proper-ties and near-infrared returns from the surface.>>

VEx can perhaps image the same areas at or (with not total loss of purpose -- the cloud formations don't utterly remake themselves in hours) a day or so before or after the Messenger observations.

Messenger's VIRS covers from 300nm to 1.45 microns (through the entire visible range) and will have resolution as good as 100 m at Mercury. I think along with the other instruments on VEx, the loss of science regarding atmospheric composition will be seriously blunted.

What's really lost with PFS is an ongoing record of temperature scans to correlate with vis/UV images of the clouds. Adding such an instrument to a radar orbiter would not mean as much without having vis/UV imaging to go along with it, and adding two major instruments to a planned craft is a heck of a redesign.

Remember, Japan is still planning to launch a Venus orbiter that *would* have pretty much these capabilities and arrive in 2010. This could be a big moment for Japan if they can get the data on the circulation.

Posted by: BruceMoomaw Jun 1 2006, 10:46 PM

I don't think so; that falls into the "bait and switch" category.

Posted by: centsworth_II Jun 2 2006, 02:54 AM

Yes, but could or would NASA ask to have another instrument added? I recall reading in "Roving Mars" that Steve Squyres et al were only planning on one rover and NASA asked them to build two.

Posted by: ljk4-1 Jun 5 2006, 02:37 PM

If someone could clarify for me: What could be done from Earth
to make up for the PFS?

Posted by: DonPMitchell Jun 5 2006, 08:06 PM

I think they were hoping to correlate PFS read readings with cloud pictures, to get a better idea of what the mysterious UV-darkening substance is, and also perhaps why the cold collar is different (it appears to be a higher-altitude white haze layer). That's not easy from Earth. In general, the confusion of the Earth's atmosphere has made precise spectroscopy of other planets very difficult. In the case of Venus, there were decades of different scientists publishing, "There's water", "No there isn't", "Yes there is, and we see oxygen too!", "I don't!"...

Posted by: ljk4-1 Jun 5 2006, 08:09 PM

Hmm... how about a telescope in Earth orbit that could examine Venus
for those features?

Posted by: JRehling Jun 5 2006, 08:31 PM

I think the problem is the high spatial resolution that's desired. Imaging spectrometers (like VIMS on Cassini) need to be up-close to get the spatial resolution. If you're summing over a big parcel of the cloudtop area, you don't find out what distinguishes the darker clouds from the lighter ones.

It seems to me that Messenger, of all unexpected calvaries, should actually perform some pretty significant science in this regard, but it's a one-flyby shot. But assuming the weather patterns on Venus tend to be similar from one month to the next (shouldn't be any seasons at all), one snapshot in time might be 80% as good as the same thing repeated for a year of orbiter data.

Posted by: DonPMitchell Jun 5 2006, 09:27 PM

FYI, here is the hubble photo of Venus. I dug up the original image, because I wanted to see what was really there before someone produced the ugly purple-colored over-sharpened image that gets published all the time:

[attachment=6082:attachment]

This is enlarged 4 times with a windowed sinc filter, and it's taken with a UV filter.

Posted by: The Messenger Jun 27 2006, 01:29 PM

Notta about the PFS in the latest ESA press release. No news is good news?

Posted by: ustrax Jun 27 2006, 01:34 PM

"PFS -
The instrument is currently OFF and is not included in the routine planning. Any further attempt to move the scanner is now suspended until further notice."

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=39421 you have more regular updates on the operations.

Link edited

Posted by: Rakhir Jul 21 2006, 03:05 PM

Current planning does not forsee any PFS testing until early end September/early October 2006.

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=39710

Posted by: PhilHorzempa Jul 24 2006, 03:57 AM

I have it, from a Brilliant Reliable Unmanned Craft Expert,
that the PFS on Venus Express may still be "cured."
Since ESA tests indicate that warming the PFS up
seems to help, they may be considering the possibilities of a more intense
thermal shock. This would mean exposing that side of VEX to the Sun in
a major way to heat up the PFS a lot more, but doing careful studies
to make sure that they won't damage the other instruments in the process,
and also making a lot of high-priority science observations with them
before risking this type of maneuver.
They may also try cycling it between strong heat and
strong cold. Sometimes such thermal shock works, as with
MARSIS' antenna, and sometimes it doesn't, as with
the forward plasma-analyzer door on Mariner 10.
The other option would be to try to include a replacement on Japan's Venus
probe.


Another Phil

Posted by: AlexBlackwell Sep 7 2006, 10:29 PM

PFS is still off according to the latest http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=39970.

BTW, VEx will be the subject of a special issue of an upcoming issue of http://www.sciencedirect.com/science/journal/00320633. I don't think these will be science results, but rather pre-launch science papers.

Posted by: JRehling Sep 7 2006, 11:14 PM

Messenger will fly by Venus in six weeks. Does anyone have any information about possible coordinated observations?

Posted by: AlexBlackwell Sep 7 2006, 11:19 PM

I think I http://www.unmannedspaceflight.com/index.php?s=&showtopic=893&view=findpost&p=31320 something about this late last year.

Posted by: JRehling Sep 8 2006, 01:54 AM

Right -- I simply misplaced in my memory which encounter would be the "blind" one and which one would be the science one. Delayed gratification again...

Posted by: stevesliva Sep 18 2006, 08:09 PM

It worked with the Stardust navcam, after outgassing contaminated the lens.

Posted by: Rakhir Oct 6 2006, 08:56 AM

A hardware safe occured while the PFS was ON (additionnal tests was scheduled last week to troubleshoot the PFS issue).
However, the http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=40088 doesn't tell if any result of the tests was obtained before the safe mode occured.

-- Rakhir

Posted by: Rakhir Oct 10 2006, 04:03 PM

Still no news in the http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=40119 concerning the PFS tests performed two weeks ago.
In this case, no news is usually bad news.