I've been looking through the NTRS server and recently found a document dealing with plans to fit a Centaur stage to a Saturn Ib rocket. (Saturn Ib/Centaur Study (3.8mb)) (Picture Below). The simulated 'launch stats' in the document are for a 4 (metric) ton flyby probe on the Mariner 6/7 trajectory to Mars and I'm curious to find out just how far out of the planning stage this got, can anyone help?

Congratulations, you have just found an early study document related to the very ambitious Voyager Mars program of the 1960s (the farther back you go into the 60s, the more ambitious the program was). Around 1962/63, the plans were for a Mariner Mars 1966 flyby with atmospheric probe and a Voyager Mars orbiter and lander for 1969. Voyager Mars was a heavy spacecraft that would have used the Saturn IB-Centaur. When that rocket was cancelled, Voyager was actually scheduled to launch on a Saturn V!

The great book "On Mars: Exploration of the Red Planet 1958-1978" (NASA SP-4212) has a very detailed history of all this in Chapter 4. Fortunately, this is available online (and free) from NASA at:

history.nasa.gov/SP-4212/contents.html (click on: "Chapter 4: Voyager: Perils of Advance Planning, 1960-1967")

Thanks for that, I did think of Voyager Mars at first, but as I 'knew' that mission in the dual launch on a Saturn V I dismissed it. However, the other reason I dismissed Voyager Mars is that the writers clearly state that the hypothetical mission is a flyby mission and again what I knew of Voyager Mars was that it was going to be an orbiter lander.

I think I might go digging on the NTRS again and see if I can bring this to light, after all there may be something here that didn't make the official history. As an example I've seen several mentions to AS-207/208 being slated for the Apollo '2' CSM/LM rendezvous in orbit that later became Apollo 9, I've since found a report that indicates it would have been AS-205/208 for that mission.

Yeah, the history of the Voyager Mars program, and of all other Mars mission planning in the 1960s, is very complex. Not just unmanned Mars missions, but also manned missions (including flyby-only scenarios). I recommended Chapter 4 of "On Mars" because it specifically mentions the Saturn IB-Centaur. It's hard to imagine what a four-ton flyby spacecraft would have been used for. Maybe a dual spacecraft in one launcher (or a single Soviet flyby craft at that time ).

I have a special fondness for Voyager Mars, because it would have carried the Automated Biological Laboratory hard lander, which gets my vote for the coolest Mars spacecraft NASA never launched.

Actually, I do remember one other Mars idea that was floating around in the 60s. There was talk of sending a spacecraft which might have been a flyby to swing around Mars, take as many high resolution photos as possible ON FILM, and return to Earth. Not making it an orbiter would have considerably reduced the complexity and cost of the mission, but the fuel required would have necessitated a heavy spacecraft. The logic, of course, was that film would allow much higher resolution than you could get using transmission rates and data recorder capabilities at that time. I think the idea was ultimately rejected because it would have been most useful to prepare for a near-term manned mission, which was replaced as a national goal with Skylab and the space shuttle.

Initially the planning was to use AS-205 to launch the CSM and AS-208 to launch the LM. Then, after the Fire, the planning was pushed back farther into the Saturn IB inventory and the CSM was shifted off of AS-205 and onto AS-207. All of this planning went away when the manned Apollo flights were pushed back long enough for the Saturn V program to mature and produce a flyable booster prior to the Earth-orbital manned LM checkout flight.

The initial mission was informally referred to as "AS-258," the later one informally designated "AS-278." Eventually, Apollo 9 flew as AS-504.

-the other Doug

Yep -- I especially liked Voyager's "sticky string" method of gathering samples for its biological lab to analyze.

-the other Doug