Well, I'm still curious with the story of STL probes to Venus and Moon of 1959. Maybe it'd be useful to move here some postings from http://www.unmannedspaceflight.com/index.php?showtopic=945
. I'll first quote a message:
QUOTE (BruceMoomaw @ May 31 2006, 09:18 AM)
The scheme was more complex than that. It did involve launching Pioneer 5 toward Venus in early June 1959, but without a midcourse correction motor no one thought it would get anywhere close. HOWEVER: it also involved simultaneously launching the very first of the much bigger Atlas-Able Pioneer orbiters to Venus -- and since that had two restartable hydrazine motors sticking out of its poles, the plan really would been to make an honest effort to put it into Venus orbit. Aviation Week had several short items on it in 1959 -- and the NY Times of (I believe) May 1, 1959 made the plan's last-minute cancellation its front-page headline. (It was cancelled on the grounds that "the science payload could not be gotten ready in time", by which NASA may have meant the entire spacecraft.)
A second Pioneer orbiter was to be built simultaneously to be put into lunar orbit later...
Anyway, after the cancellation of that plan, the goal of the smaller Pioneer 5 remained to be put into a solar orbit with its perihelion at Venus' orbit -- and after sitting on the pad through delay after delay during the last half of 1959, it finally got off the ground in March 1960 and became the only genuine success of the early Pioneers (although its perihelion ended up considerably outside Venus' orbit, and its power supply failed at a range of 22.5 million miles instead of the 50 million hoped for).
The plan to launch a single Atlas-Able orbiter to the Moon remained; and after its planned October launch was scrubbed when the booster blew up during a September static test, NASA grabbed the Atlas planned for the cancelled second Mercury "Big Joe" test and launched it in late November -- only to end up with the infamous "turkey shoot" in which the shroud came off due to inadequate venting of internal air pressure, and the air blast then tore off the probe and third stage and crippled the second stage. No doubt this would have been its fate had it been launched to Venus in June.
Since this meant that there was still one spare Pioneer orbiter, Eisenhower gave permission to try to launch it to the Moon in late 1960 -- and to build a third copy for one last attempt if the second one failed. Unfortunately, both the second AND third tries also failed ignominously (due to failures of the second stage, which by then was usually working pretty reliably on Thor-Able).
So I understand this as follows:
(1) Four different spacecraft were in design and productiion at STL in the spring of 1959: a HEO probe, a Venus flyby probe, a Venus orbiter and a Moon orbiter.
(2) The HEO probe was launched as Explorer VI (S-2) in August 1959, and the Venus orbiter was launched as Pioneer V (P-2) to a fake Venus target in March 1960.
(3) Three attempts of Moon orbiter launches were made in Nov 1959, Sep and Dec 1960, using the two probes remained and a third built from scratch.
So the principal question is: we know that a P-3 probe was lost in the Nov 1959 launch failure. But which orbiter was intended for launch to Moon in Oct 1959 and failed in Nov 1959, the initial Moon one -- or the converted Venus orbital probe? Was P-1 the designation of another probe, not launched in 1959? What was the difference in design between the two? For example, did they have the hydrazine tank of the same size and volume? And the last large question: with a constant rotation axis pointing, how would the probes achive the mid-course corrections and the orbit insertion?
Here are smaller scale questions as well.
Both Explorer VI and Pioneer V were based on a common almost spherical body with four vanes. What was the 'equatorial' diameter of the body, 26 or 29 inches -- publications tend to quote both figures? What was the size of Explorer VI vanes -- 18x18 inches or larger? (It is obvious that Pioneer V used a shortened version of Explorer VI vanes with only 600 cells per side instead of 1000.) Is it safe to say that one panel of Explorer VI could produce 15 W if it is known that one module of cells (2x50 cells from the two sides of a panel) would produce 0.75 W? And who built the photo cells?
Well, sources say that the 1960 P-30/P-31 spacecraft used 24x24 inch panels of 1100 cells per side, and a 100 cells module could produce 1.3 W. Is it safe to say that the cells were larger in size, or more efficient, or both? Did a spacecraft exist with 1200 cells per side, 9600 in total? What about the P-3 probe solar cells?