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Posted by: tasp Dec 20 2007, 03:29 PM

Ok, obviously, furthest separation of spacecraft would be Pioneer 10 and depending on when we check, Pioneer 11, and later Voyager 1 and/or Voyager 2.

But what is the closest 2 craft have come on seperate missions ??

Were there any close approaches of Magellan to any Soviet orbiters at Venus ??

Has there any been a Soviet Lander on Mars close to either Viking ?? Any chance of the Halley armada vehicles being particularly close to each other during their missions ??


I would mostly be interested in active mission encountering each other, but a live mission 'checking out' a prior 'dead' one closely (Apollo 12 and Surveyor 3 type encounter for example, but keep in mind Apollo 12 was manned and not applicable here) would be interesting too.

Posted by: djellison Dec 20 2007, 04:17 PM

MGS vs MODY and MEX
http://www.msss.com/mars_images/moc/2005/05/19/

MGS to MODY was 90km (but I'm sure closer passes occur) - and MGS to MEX was 250

Oh BOY would I love to see HiRISE pull that off.

Doug

Posted by: ElkGroveDan Dec 20 2007, 04:24 PM

After the Lunar Surveyors (1 & 3) and Soviet Luna (16 & 20?), I'd say Viking 1 and 2. Of course if you are talking about any two craft as opposed to matched pairs, then on Mars it would be Viking 1 and Pathfinder

(Assuming we exclude possible classified ASAT touch and go encounters in Earth orbit.)

Posted by: nprev Dec 20 2007, 06:58 PM

Blue-sky and possibly OT thought here, but might there be an advantage to landing future rovers in close pairs for teamed exploration? If we have very long-lived vehicles in 20 years or more, it might be good if they each had a wingman to compensate for platform instrument failures (to say nothing of being able to help each other out...if Oppy had had a partner with a boom & a winch back at Purgatory, she'd've been free much more quickly).

Again, totally blue-sky, and of course expensive. But, if we reach the point technologically that we can confidently expect 10 or 20-year UMSF mobile surface survey missions on Mars, Titan, Triton, Europa, etc. (and in practice get 30 yrs. plus), having a buddy would be a big help, providing an excellent return on investment in terms of both science return and overall mission risk reduction. Historically, this strategy has worked extremely well for human exploration, and of course it's a fundamental tenet of military operations which are conducted in often unfamiliar, always potentially hostile environments.

Posted by: hendric Dec 21 2007, 04:48 PM

Not likely, I think. Would you prefer to have both Spirit and Opportunity at Gusev, for example? More locations would always trump having a wingman.

Posted by: nprev Dec 28 2007, 06:13 PM

Wouldn't have been appropriate for the MERs with just 90-day nominal missions. Thinking of 20+ year surface surveys, which definitely are beginning to look achievable in the near future. For example, if we were to fly rovers to Titan in 2030, I'd put a pair in one place & a pair in another (deep, deep pockets and/or very inexpensive yet reliable designs assumed, of course...)

Posted by: centsworth_II Dec 28 2007, 06:22 PM

I think most would agree that it would still be better to put them in four different
places. I don't see how the advantage to sending a rover as a buddy to another
rover could possibly outweigh the advantage to having a look at an entirely different
location. Even with a different science payload on each of two rovers, the use of two
sets of roving hardware (wheels, chassis, etc.) sent to one location would be an
extravagant waste of payload budget.

Posted by: nprev Dec 29 2007, 02:58 AM

Yeah, I think you're right. My thought was to provide some means of prolonging the overall mission at a given locale, but after further reflection how necessary is that really? 20 years is ideal for a comsat, but not for a planetary rover with limited range; there's only so much terrain that can be accessed properly.

Stay tuned for my next brilliant invention, the glass drum!

Posted by: edstrick Dec 29 2007, 09:58 AM

There are 2 reasons to sent a new mission to an old locale...sample return of "we gotta get THESE in the lab" ground-truthed samples, or to revisit a maximally important and partially well understood site with an entirely new set of instruments.

In Meridiani, there's lots better places to go to get access to eroded stacks of geology than the safe and surprisingly undull (except when stuck in sand traps) plains.

But at Gusev, the Columbia hills are *INTERESTING*. I doubt they're as interesting as places like the proposed MSL sites, but they're far more interesting than another randomly chosen (and they WERE randomly chosen, not part of the Spirit landing target lacustrine sediments at all). This is because we've now spent years picking apart their geology, have made partial sense of what the stratigraphy and history are, and so on. We'd be able to tell a sample return mission "goTHERE, and There, and there and tHeRe" to get samples for return.... or with new instruments we'd be able to really rip into the hills. These are probably to a significant extent, a sample of the ancient, 4+ billion year old geologic history of the planet, and the samples are diverse, variably altered, and have younger history in terms of sediments and salts sitting on them.

I'm not saying we SHOULD, but the MSL or ExoMars sites, assuming both succeede, will be inevitable candidates for sample return (with or without caching), and might end up being visited "in person".

Posted by: PhilCo126 Dec 29 2007, 10:26 AM

During the Millennium flyby of Jupiter, Galileo (launched onboard the Space Shuttle in October 1989) and Cassini-Huygens (launched in October 1997) simultaneously explored the planet Jupiter.
I also believe that the Venera landers came quiet close to each other on the surface of Venus (but I'll check this)

Posted by: PhilCo126 Dec 29 2007, 11:02 AM

Listed my Venera landers 'claim' in a separate topic in the VENUS sub-forum: http://www.unmannedspaceflight.com/index.php?showtopic=4868