I thought I knew this story, and told what I knew in my old Atlas. Newell Trask of the U.S. Geological Survey in Menlo Park, CA was asked to identify targets and did so, providing a list to James Sasser of NASA’s Manned Spacecraft Center (now the Johnson Space Center near Houston). GLEP chose one and recommended it to ASSB, who then proposed it to the Apollo Program managers. Don Wilhelms tells this story in his book, but doesn’t identify the sites or the final target. I managed to find a memo from GLEP to ASSB with their recommendation in it, and that made it into my book. But even that was not the whole story.

Flagstaff to the rescue! Here I found Trask’s original memo to Sasser. To my surprise it was dated before Apollo 11, not after it, and it did not just cover Site 5. Trask was working on this in the weeks leading up to the launch of Apollo 11, and even though that mission was targeted at Site 2 in Mare Tranquillitatis, there was no certainty it would land there. Launch delays could push it to Site 3 in Sinus Medii or Site 5 further west again. So the second landing might be directed to any of those sites which Apollo 11 did not land at, possibly including Site 2. Trask identified 8 fresh craters in Site 2, 8 in Site 3 and 9 in Site 5, and he sent the memo to Sasser on June 19, 1969, a month before Apollo 11’s landing on the Moon. When Apollo 11 landed at Site 2, Apollo 12 was targeted at Surveyor 3 (which was called Site 7) and only Site 5 would work as a backup. One of Trask’s locations in Site 5 had not one but two small fresh craters, and another big advantage was a distinctive pattern of four larger craters called ‘Four Crater Cross’, which would be easy to spot on the approach to help the crew guide the LM down to the landing site.

There was only one problem with all of this. Trask’s target points were identified as measurements in centimeters on Lunar Orbiter images, not by latitude and longitude. Luckily, these images were usually printed at a standard size, and knowing that I could use scans of the Lunar Orbiter images from the Lunar and Planetary Institute website to find the locations. Figure 5 shows the pinpoint landing targets at all three Apollo sites, and Figure 6 shows the actual backup Apollo 12 site.

Now let’s go from the early landings to the last, Apollo 17. It carried Gene Cernan and Jack Schmitt to the Taurus-Littrow Valley, but there were several other potential targets for the last landing, and the most dramatic was the farside crater Tsiolkovsky. Schmitt pushed hard for that site but it was too difficult, and there was no extra money for a communication relay which would be essential for a farside landing. One scheme was to use a military communication satellite, one of a group which were being built at the time for the Department of Defense. Apart from those slated for launch, there were to be two spares, built and put into storage for later use in the event of an on-orbit failure. One of those might be used for Apollo 17. It would be placed in a loose halo orbit around the Earth-Moon Lagrangian point L2, above the lunar farside, from which it would be able to relay transmissions from the landed spacecraft directly to Earth. But it would need modifications, and the money was not available. Now, more than 4 decades later, the same idea is being planned by China for a farside lander and rover, the Chang’E 4 mission, in 2018, and probably for a later sample return mission.