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Pioneer Spacecraft First Into The Asteroid Belt
ugordan
post Jan 25 2006, 10:33 PM
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QUOTE (Planet X @ Jan 25 2006, 08:36 PM)
I've gotten a few different versions of how Pioneer 11 could have reached Uranus over the years.  Once, I read that the Saturn encounter would have been rather distant, beyond the A Ring.  Another source hinted at Pioneer 11 flying through the Cassini Division before closest approach.  Finally, yet another source hinted at Pioneer 11 flying inside the D ring.  Both of the latter sources had Pioneer 11 flying to within 3000 miles of Saturn's cloudtops.  To me, only the latter 2 possibilities make sense.
*

Well, I don't know about the Cassini Division as it turned out to be not as empty as it was thought. It would have been interesting to watch that fly-through unfold, though wink.gif


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ljk4-1
post May 30 2006, 05:48 PM
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You know that "model" of the Pioneer 10-11 probe hanging in the main
gallery of the National Air and Space Museum in Washington, D.C.?

It isn't a model:

http://en.wikipedia.org/wiki/Pioneer_H


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"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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Guest_BruceMoomaw_*
post May 31 2006, 06:32 AM
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Yep -- that's the backup. NASA briefly considered using it for a Jupiter orbiter or an out-of-ecliptic solar orbiter -- that is, as an earlier Ulysses (for which it would have required almost no modification). All those plans vanished, along with so many other interesting space science proposals, into the Shuttle's bottomless and pointless (except for pork enthusiasts) maw. Going to the Museum and seeing it, the third Voyager, the third Viking lander, and the Mariner 10 backup all hanging on the walls (or, in Viking's case, sitting on the floor) and gathering dust is enough to make one think of "Ozymandias".
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dvandorn
post May 31 2006, 11:26 AM
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QUOTE (BruceMoomaw @ May 31 2006, 01:32 AM) *
...Going to the Museum and seeing it, the third Voyager, the third Viking lander, and the Mariner 10 backup all hanging on the walls (or, in Viking's case, sitting on the floor) and gathering dust is enough to make one think of "Ozymandias".

"I am become death, the destroyer of worlds"? Surely that's a touch melodramatic, Bruce? smile.gif

Backup spacecraft are built primarily to ensure that the prime mission will be accomplished -- it's sometimes more wasteful to lose an entire mission than to build a spare spacecraft you can use if the primary one (or, more likely, its booster) fails. Indeed, how many times has a backup spacecraft actually been flown later, on a different mission? I know it's happened a few times, but the majority of backup spacecraft only ever serve the function they were built for -- to back up the primary, and be retired to a museum (or, more often, scrapped) if the primary works properly.

I don't think it's fair to get upset at NASA for failing to fly every backup spacecraft ever built. In most cases, I'm just happy that the primaries were flown. After all, the MERs came awfully close to becoming museum pieces, and they weren't no backups!

Personally, I'd prefer to see missions continue in pairs. We've seen the impact of losing single-spacecraft missions, in whole (MCO, MPL) or in part (Galileo). You have to wait years, sometimes decades, for the primary mission to be re-attempted. Sometimes both spacecraft in a paired mission work, and you get fabulous returns, a la the MERs, Voyagers and Pioneers. But had the Mariner 64 or 71 missions been single-probe flights, backups might not have been ready to fly within the same launch opportunities after the losses of Mariners 3 and 8.

I think it's *always* better to see a third spacecraft in a museum, along with displays of the results of the *two* flight vehicles that completed their missions. Seeing a backup vehicle from a mission that failed in a museum -- now *that* is a tragedy.

-the other Doug


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odave
post May 31 2006, 01:26 PM
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I think he was thinking more along the lines of "Look upon my works, ye Mighty, and despair" smile.gif

I agree with Other Doug: Given that the science return from those missions is certainly a net positive, the feeling for me would be "wouldn't it have been great if", rather than despair.


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Astrophil
post May 31 2006, 01:29 PM
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What odave said, and -

Nothing beside remains: round the decay
Of that colossal wreck, boundless and bare,
The lone and level sands stretch far away.

http://www.bartleby.com/106/246.html

Great desert in this poem, by the way. Sounds like Terra Meridiani.
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tedstryk
post May 31 2006, 07:05 PM
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It could have gone to Uranus and Neptune, but for one thing, the bean counters didn't see the point, since it would be beaten there by Voyager. But the biggest thing that kept any big push from happening was that no one fathomed how long we would be able to track the Pioneers, and how long they would be able to send data back.


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JRehling
post May 31 2006, 10:26 PM
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QUOTE (dvandorn @ May 31 2006, 04:26 AM) *
"I am become death, the destroyer of worlds"? Surely that's a touch melodramatic, Bruce? smile.gif

-the other Doug


That line is from the Bhagavad Gita, famously quoted by Robert Oppenheimer in reference to his role in the development of the atomic bomb.
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Guest_BruceMoomaw_*
post May 31 2006, 11:31 PM
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QUOTE (tedstryk @ May 31 2006, 07:05 PM) *
It could have gone to Uranus and Neptune, but for one thing, the bean counters didn't see the point, since it would be beaten there by Voyager. But the biggest thing that kept any big push from happening was that no one fathomed how long we would be able to track the Pioneers, and how long they would be able to send data back.


Communications distance certainly wouldn't have been any block to using Pioneer H as a Ulysses-type out-of-ecliptic solar orbiter -- that article quotes James Van Allen as saying that NASA simply blocked the move on money grounds. (Of course, ISPP -- the mission that was later downscaled to Ulysses -- started out as a much more ambitious project involving two simultaneous spacecraft, one of them equipped with a small solar telescope, before the Reagan Administration zapped our half of it. In short, as usual, NASA preferred to bite off more than it could chew.)
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Planet X
post Sep 6 2010, 01:10 AM
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QUOTE (tedstryk @ May 31 2006, 01:05 PM) *
It could have gone to Uranus and Neptune, but for one thing, the bean counters didn't see the point, since it would be beaten there by Voyager.


I've performed the simulation of sending Pioneer 11 on to Uranus via Gravity Simulator. Pioneer 11 ended up flying to within a distance of 2058 km from Saturn's cloud tops, with a top speed of 130,086 kmph at periapsis. I then typed out the data on an XYZ coodinate file for graphical display in Celestia. As it turned out, the ring plane crossing occurred inside the D ring just over eight minutes after periapsis, at a distance of 3282 km from Saturn's cloudtops. Pioneer 11's encounter with Uranus took place on December 2, 1985. I deliberately sent the spacecraft to within 81,000 km of Uranus's cloud tops, as this was the distance chosen for Voyager 2's January 1986 encounter. So yes, Pioneer 11 beat Voyager 2 to Uranus!

Just for fun, I also sent Pioneer 11 to Neptune in a different simulation of it's Uranus encounter. To reach Neptune, Pioneer 11's encounter with Uranus would have been more distant, beyond the orbit of Miranda. The fake Neptune encounter took place sometime in April 1990, clearly an impractical option! Later!

J P
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