Mariner Mars 1964, Mariners 3 and 4 to Mars: imaging plans? Options

[Phil Stooke]

I am currently working on a book about lunar exploration, but looking ahead to the next one, which will cover Mars. One question to which I think I have an answer - but I'd like to see what my fellow Mars enthusiasts think - is this:

Mariner 3 failed to leave Earth. But if it had flown successfully, what area on Mars would it have photographed?

My understanding is that there was no specific plan. The MM64 press kit, for instance, says nothing about image coverage for either Mariner 3 or Mariner 4. I believe that navigation to planetary distances was still so uncertain that the flight team could not predict at launch the sub-spacecraft point at closest approach - uncertainties included the exact time of the flyby, the distance and the point at which the spacecraft would pass through the target plane. These things would be known closer to the flyby but they weren't precisely predictable at launch, so Mariner 3 never got to the stage of having an imaging plan.

Am I right?

Phil

[JRehling]

I am currently working on a book about lunar exploration, but looking ahead to the next one, which will cover Mars.  One question to which I think I have an answer - but I'd like to see what my fellow Mars enthusiasts think - is this:

Mariner 3 failed to leave Earth.  But if it had flown successfully, what area on Mars would it have photographed?

My understanding is that there was no specific plan.  The MM64 press kit, for instance, says nothing about image coverage for either Mariner 3 or Mariner 4.  I believe that navigation to planetary distances was still so uncertain that the flight team could not predict at launch the sub-spacecraft point at closest approach - uncertainties included the exact time of the flyby
[...]

If the time of the flyby was not well-constrained, then the answer falls out of that. An arrival a few hours earlier or later would have rotated any target terrain out of view.
It's an interesting question, however, since telescopic maps of Mars did exist, and there would therefore have been a basis for prioritizing targets, if the operational precision were there.

As a side note, we're now in a very similar circumstance with Pluto. Our telescopic (incl. occultation) maps of Pluto have roughly the detail that pre-Mariner maps of Mars did, and the single flyby we'll get will only provide best resolution at one longitude. (Although NH will certainly image the rest of Pluto in a way that Mariner 3/4 could not for Mars. Of course, Pluto won't receive any followups anytime soon.) It would be interesting to ask Alan Stern if any plutonian targets have thereby been prioritized. Have 40 years and a dozen+ solid worlds flown by given us any insights for Pluto-2006-launch that we lacked for 1964-Mars-launch??? The comparison is flawed, however: I think geometry regarding Charon's orbital position will actually drive the decision, rather than the visibility of specific Pluto terrain.