Pioneer Jupiter/saturn Orbiter Options

[Chmee]

Well a big difference in what would have been returned if we had the Pionneer-type orbital craft at Jupiter would have likely been at least one craft there in orbit when the comet Shoemaker-Levy crashed into its surface in 1994. The imagery from a craft in orbit would have been outstanding!

Of course, if the Challenger acident had not happened the Cassini itself would have been there by 1990 and would have see it as well.


Bad timing all around!

[Guest_AlexBlackwell_*]

Of course, if the Challenger acident had not happened the Cassini itself would have been there by 1990 and would have see it as well.

I presume you meant Galileo, right?

[Guest_BruceMoomaw_*]

Actually, that's NOT true. One of the bizarre ironies of the Galileo Saga (which is definitely worthy of a book; it took up literally half of my entire life) is that, if it hadn't been for every single one of the delays -- including the one caused by the Challenger tragedy -- Galileo would have failed completely before even reaching Jupiter, and it wouldn't even have been America's fault!

West Germany's Messerschmidt was assigned the job of building Galileo's main engine and maneuvering thrusters. They used the same thrusters on West Germany's first direct-broadcast comsat, TVSat-1, launched in early 1987. The satellite immediately became useless for its purpose because one of the technicians had failed to take all the pre-launch retention latches out of one of the solar panels and it wouldn't unfold, reducing the satellite's power by half -- but they then decided to use it for engineering tests. Lo and behold, within just a few months the attitude thrusters all started to burn out; it turned out that Messerschmidt had made a serious design error and not tested them enough to catch it. Galileo's thrusters would similarly have burned out -- or exploded -- within a short time of launch. One JPL engineer told Aviation Week, "We would have tried to find a work-around, but I doubt we could have done it." NASA and Messerschmidt then began a frenzied program to redesign, retest and reinstall new thrusters before Galileo's late 1989 launch; they made it with just a few months to spare.

So -- notwithstanding the fact that the Challenger accident was also indrectly responsible for jamming Galileo's high-gain dish -- if it hadn't been for that tragedy and all the previous years of repeated delays, the mission would have been TOTALLY lost and had to be reflown.

A mission that I'm wondering whether it was proposed and how much it might have been studied is a Mariner 9+ Venus orbiter. Take the Mariner 9 design, modify it for Venus thermal and communications requirments, maybe take out the telephoto camera, add a near-infrared spectrometer and/or radar altimeter and you'd have had a hell of a mission.

Mariner 10 ended up flying as the first Mercury recon with a very useful Venus flyby with non-optimum geometry and instruments for Venus. Pioneer Venus Orbiter did a lot with a smaller spacecraft, though a terrible scientific loss was the failure of the infrared atmosphere radiometer which was one fine instrument that only lasted some 1/5 of the primary mission.

They could have done that very easily indeed. Aviation Week, at the time, mentioned that a Venus orbiter was one of several alternative uses being considered for the Mariner 10 backup spacecraft. (Another was having it make a flyby of Comet Encke, albeit at a rather distant several thousand km because of the difficulty of installing dust shielding on it.) Needless to say, they ended up using it for nothing at all, and so it now hangs in solitary glory on the wall of the Air and Space Museum, near Voyager 3 and Viking Lander 3. (When I visited the Museum in 1983, I ground my teeth at that particular part of the displays.) I suppose it could indeed have been used to fly the Pioneer 12 mission at lower total cost -- although, since it wasn't spin-stabilized, its total observation time would have been a lot less.

[edstrick]

They came fairly close to flying the Mariner 10 backup vehicle. They had an Atlas Centaur reserved and everything, I think.

When Mariner 10 was launched, they had two immediate hardware failures.

The sun-facing part of the solar wind instrument never opened it's door to look at the direct solar wind, and all they got was data from the electron spectrometer that looked anti-sunward.

Potentially more disastrously, the heaters on the twin super-telephoto lenses on the imaging system's cameras failed to come on and the lenses's temps promptly headed for something like -40 or -60C.

They quickly improvised some imaging sequences (I'm not sure they had ANY planned for immediately after launch) and imaged the Earth, Moon and some star cluster, maybe the Pleiades while (I think) they started preparing a contingency launch of the backup. For the-great-old-ones-havent-told-us-why reasons, the cameras DID NOT defocus as they were expected to. For much of the mission, they kept the cameras powered up (inviting failure) to keep things as warm as possible, and some time later, maybe after the Venus encounter, the heaters decided to come on all by themselves, ending the problem. (And the lenses didn't promptly DEFOCUS, either!)

Go Figure.

So they cancelled the backup launch and mothballed the spare spacecraft.

Boeing built Mariner 10 instead of JPL. It had a several times higher inflight level of problems and glitches and failures than Mariners 69, Mariner 9 and the Viking Orbiters, all JPL built.

[Guest_BruceMoomaw_*]

Oh, yes. Bruce Murray's "Flight to Mercury" provides a splendid summary of that bizarre Perils of Pauline story -- they practically had pieces fall off the craft all the way to Mercury. The fact that it succeeded was a miracle -- the flight crew worked themselves literally into exhaustion devising solutions for the problems they could, and all the critical problems that they couldn't solve (such as a crack in the signal lead to the high-gain antenna) miraculously fixed themselves just in time. This was actually NASA's first experiment with the Better-Faster-Cheaper policy, and I suspect it scared them into rejecting it again until the 1990s. It had far more glitches and serious failures than ALL the previous Mariners put together, with the possible exception of Mariner 2 (which had quite a Perils of Pauline ride itself, although I continue to marvel at the bizarre fact that the US got a successful probe to Venus 19 months before it got one to the Moon. What SF writer would ever have dared predict that?)

As for the cameras: their shots of the Earth and Moon (all planned long before launch) revealed that the cameras were teetering on the very brink of defocusing without QUITE going over -- some of the shots show strange, small smeared strips where they actually did defocus. Mariner 11, had it flown, would have been on an Atlas-Centaur swiped from an imminent comsat launch -- a plan also devised long in advance.

[JRehling]

It's too bad a second Mercury Mariner wasn't launched, but in a different window, so as to image the other side of Mercury and give us ~90% coverage of the surface. Messenger's second flyby will finish the elementary "reveal" of inner solar system surfaces.

[edstrick]

I have a pre Mariner 10 study document on mission concepts, and one thing that was considered but relatively high risk and not "in the budget" was development of a electron-beam-recorded-tape data recorder. A technology that never expanded out of the laboratory, it used an electron beam to write onto a tape, altering the tape surface (sort of like burning a CD) and could achieve very high data density compared with magnetic tape of the time.

They had ideas of a rapid-fire imaging system, more like viking's, and an ability to image the entire sunlit surface during a flyby at some 50 meters resolution.

The primary mission mode was tape and dump, but they developed an experimental high-speed data link that (with high bit error rates) was able to transmit direct to earth at something like 144,000 bits/sec instead of 16,000 or so like Mariners 69 did experimentally and Mariner 9 did operationally.

Not as good as the EB recorded tape but much better than a Mariner 69 type flyby.

[ljk4-1]

This should probably go in the Mercury folder, but while the discussion
is here, I found this Web site with lots of images and other data on
the Mariner 10 mission, including original NASA bulletins:

http://cps.earth.northwestern.edu/merc.html


Also the online NASA publication The Voyager of Mariner 10:

http://history.nasa.gov/SP-424/contents.htm


Mariner 10 Image Browser and Reconstructor:

http://members.tripod.com/petermasek/mariner.html

[gndonald]

They could have done that very easily indeed. Aviation Week, at the time, mentioned that a Venus orbiter was one of several alternative uses being considered for the Mariner 10 backup spacecraft. (Another was having it make a flyby of Comet Encke, albeit at a rather distant several thousand km because of the difficulty of installing dust shielding on it.) Needless to say, they ended up using it for nothing at all, and so it now hangs in solitary glory on the wall of the Air and Space Museum, near Voyager 3 and Viking Lander 3. (When I visited the Museum in 1983, I ground my teeth at that particular part of the displays.) I suppose it could indeed have been used to fly the Pioneer 12 mission at lower total cost -- although, since it wasn't spin-stabilized, its total observation time would have been a lot less.

Sorry to reopen an old thread but I ran into a proposal that can be related to the one I linked to in the OP, Ames made a similar proposal to regarding the Pioneer 10/11 backup spacecraft. Dubbed 'Pioneer H', the mission would have used a trajectory similar to that flown by the Ulysses mission.

One planned launch date was in 1974 with the Jupiter encounter taking place in June 1975 (After Pioneer 10 in December 1973 & Pioneer 11 in December 1974.).

Sadly it ended up on the wall Smithsonian along with a number of other flight spares.

The details of what was planned, can be found in the following document:

Pioneer H Jupiter swingby out-of-the-ecliptic: Mission study, 1971