PFS issue on Venus Express, PFS scanner stuck in its closed position Options

[tasp]

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....

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.

[Guest_BruceMoomaw_*]

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.

-

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.

[Guest_AlexBlackwell_*]

People never appreciate when I'm being facetious.

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

[Decepticon]

Do we know 100% that the instrument has failed?

Maybe it can be fixed?

[Guest_BruceMoomaw_*]

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.)

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

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

[GravityWaves]

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

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 .....

[The Messenger]

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

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?

[Guest_BruceMoomaw_*]

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.)

[Bob Shaw]

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

[djellison]

or you can interpret it to mean that we need small orbiting emergency-repair robots capable of tugging on stuck parts.

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

Doug

[Guest_BruceMoomaw_*]

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.)

[djellison]

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

[Guest_BruceMoomaw_*]

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.

[Borek]

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

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

Borek

[djellison]

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