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PFS issue on Venus Express, PFS scanner stuck in its closed position
ugordan
post Apr 5 2006, 07:06 PM
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High Resolution channel being out of focus or not, MEX DID a great job at Mars. And it still is doing!


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Guest_BruceMoomaw_*
post Apr 12 2006, 11:05 PM
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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.
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Rakhir
post Apr 13 2006, 07:04 AM
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Bruce,

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

-- Rakhir
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RNeuhaus
post Apr 15 2006, 01:49 PM
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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 wink.gif

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
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djellison
post Apr 15 2006, 02:51 PM
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QUOTE (RNeuhaus @ Apr 15 2006, 01:49 PM) *
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


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
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Bob Shaw
post Apr 15 2006, 03:00 PM
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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


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RNeuhaus
post Apr 15 2006, 03:22 PM
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QUOTE (djellison @ Apr 15 2006, 09:51 AM) *
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.

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
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Guest_BruceMoomaw_*
post Apr 15 2006, 10:38 PM
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Weight-wise and expense-wise, it would make MUCH more sense to simply provide stronger motion actuators (both springs and motors).
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nprev
post Apr 16 2006, 12:33 AM
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QUOTE (Bob Shaw @ Apr 15 2006, 08:00 AM) *
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


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.


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JRehling
post Apr 16 2006, 04:36 AM
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QUOTE (BruceMoomaw @ Apr 15 2006, 03:38 PM) *
Weight-wise and expense-wise, it would make MUCH more sense to simply provide stronger motion actuators (both springs and motors).


In fact, it would even make more sense to duplicate the most important instruments.
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Guest_BruceMoomaw_*
post Apr 16 2006, 08:44 AM
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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.
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tty
post Apr 16 2006, 04:45 PM
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QUOTE (JRehling @ Apr 16 2006, 06:36 AM) *
In fact, it would even make more sense to duplicate the most important instruments.


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

tty
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Rakhir
post May 2 2006, 07:00 AM
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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 sad.gif )

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

-- Rakhir
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Guest_Sunspot_*
post May 2 2006, 11:57 AM
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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.
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sawyer
post May 2 2006, 03:02 PM
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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.
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