there was a good historical paper on Prospector in the JBIS in 1995: D.L. Burnham "Mobile Explorers and Beasts of Burden: A History of NASA's Prospector and Lunar Logistic Vehicle Projects", vol 48, pp 213-228
A couple of pennies-worth from notes assembled at JPL far too many years ago to recall:
The only trouble was none of us had strong enough position, loud enough voice or leveraged clout to get that message heard! Except I do recall Carl Sagan listening very hard and mentioning this approach on the Hill.
And the Moon in all of this - what's that...?
Interesting. The text indicates that it was a current design under study. Obviously it was canceled. I would have to go digging, but I vaguely remember that the cost and timeline for Surveyor Orbiter was too much and so NASA called for a simpler and more straightforward orbiter that would not have instruments only an imager for high quality imagery in support of Apollo. Of course, the gold is all in the details--for instance, what exactly made Surveyor Orbiter so expensive and time-consuming? My guess is that the camera was not big enough and could not be bigger considering the other planned instruments. So NASA called for a design that put all the emphasis on the camera system.
Also, ISTR something about Lunar Orbiter being at a considerable advantage in that it was capable of being launched to the Moon on an Atlas-Agena, while Surveyor Orbiter (like the Surveyor Lander) required an Atlas-Centaur. I don't recall if that more to do with Agena availability or Centaur reliability at the time of the mission planning, though.
I think you're right about it being all about the camera system. The above design for a Surveyor Orbiter had a TV camera system, while Lunar Orbiter employed a film system with onboard photographic development and electronic (though not digital) read-out. Apollo planners at the time were requiring high-resolution imagery of the proposed Apollo landing sites ASAP, and IIRC the output of the television system would not have been good enough.
Quote from: the_other_Doug on 03/21/2015 03:09 amI think you're right about it being all about the camera system. The above design for a Surveyor Orbiter had a TV camera system, while Lunar Orbiter employed a film system with onboard photographic development and electronic (though not digital) read-out. Apollo planners at the time were requiring high-resolution imagery of the proposed Apollo landing sites ASAP, and IIRC the output of the television system would not have been good enough.It would be interesting to understand how the engineering requirements for Apollo translated into design requirements for Lunar Orbiter and Surveyor. For instance, what exactly did they need from a camera in terms of resolution, precision, and amount of territory covered? And why did they think they needed that?As I understand it, one of the problems with TV systems is that even if the resolution is okay their precision is poor--the distance between any two evenly-space spots on the image will not necessarily be the same. So it gets harder to rely upon that if you're feeding it into a set of calculations.
Exactly -- the spatial resolution, I believe it's called, was poor in the television imaging systems of the time, even if pixel resolution could be made to be good. And while I don't have the official Apollo imaging requirements at hand, I do know that good stereo coverage of each potential landing site was required. And not just within the landing ellipse -- they wanted good stereo imaging for the terrain overflown during the final stages of the descent trajectory, as well.This was at least partly so they could model the terrain for the benefit of the guidance computer -- if (as was the case for Site 2, Tranquility Base) there was a general slope of the terrain resulting in a significant difference in mean surface elevation from landing radar lock-on to landing, it helped for the guidance computer to know that. Site 2 had a general westward-trending downward slope of about four degrees throughout the final miles of the descent trajectory, and the guidance computer used a rough correction subroutine that took this into account.I'm pretty certain that the TV imaging systems of the time just weren't capable of providing stereo strips good enough to provide the terrain information required by Apollo planners. And since microgravity film development and electronic read-out had already been developed for reconnaissance satellites and the technology was available, that's what they ended up using.