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PFS issue on Venus Express, PFS scanner stuck in its closed position
Rakhir
post Mar 21 2006, 09:03 PM
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Bad news for PFS. I hope they will be able to solve this issue. sad.gif

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
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Guest_AlexBlackwell_*
post Mar 21 2006, 09:19 PM
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QUOTE (Rakhir @ Mar 21 2006, 09:03 PM) *
Bad news for PFS.

"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. tongue.gif
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Guest_BruceMoomaw_*
post Mar 21 2006, 09:36 PM
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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.
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djellison
post Mar 22 2006, 08:37 AM
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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
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deglr6328
post Mar 22 2006, 09:13 AM
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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....
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edstrick
post Mar 22 2006, 11:14 AM
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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.
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tty
post Mar 22 2006, 12:22 PM
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QUOTE (deglr6328 @ Mar 22 2006, 10:13 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....


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
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The Messenger
post Mar 22 2006, 03:07 PM
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QUOTE (djellison @ Mar 22 2006, 01:37 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

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...
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ljk4-1
post Mar 22 2006, 03:21 PM
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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


--------------------
"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

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djellison
post Mar 22 2006, 04:05 PM
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QUOTE (The Messenger @ Mar 22 2006, 03:07 PM) *
It is not inappropriate to complain about the untimeliness of this release...


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
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The Messenger
post Mar 22 2006, 05:27 PM
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QUOTE
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"


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.

QUOTE (ljk4-1 @ Mar 22 2006, 08:21 AM) *
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

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.
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Bob Shaw
post Mar 22 2006, 06:52 PM
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QUOTE (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.


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


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Remember: Time Flies like the wind - but Fruit Flies like bananas!
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djellison
post Mar 22 2006, 06:58 PM
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QUOTE (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.


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
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Guest_AlexBlackwell_*
post Mar 22 2006, 07:05 PM
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QUOTE (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.

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.
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Guest_BruceMoomaw_*
post Mar 22 2006, 08:15 PM
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QUOTE (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


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).
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