That's not to say that 35 billion dollars is nothing. It's important to look critically at any project this big to be sure it is a worthy undertaking, being carried out in an intelligent and efficient way. The point is, if we want to resume human exploration of the Moon, money is not the obstacle to doing it. If we want to double the size of NASA's Discovery program so that the agency could approve missions to Venus, Io and Triton this year, money is not the obstacle to doing that, either. Adding another Discovery mission would have an incremental cost of about 450 million dollars, or about 0.1 percent of the amount the federal government put into its secretive business bailout COVID-19 fund (I'm not even dealing here with the horrific human toll of the pandemic, which lies entirely beyond these number-driven discussions of costs and benefits).
The gap — no, make that the chasm — between what we can do and what we are choosing to do right now got me thinking about another aspect of NASA history and the Apollo program: not how it began, but how it ended. I started thinking in particular about Apollo 18, the marvelous Moon expedition that never happened.
NASA had plans for three more lunar landings after Apollo 17. Most of the equipment for them was built. Two of the Saturn V rockets that would have taken them to the Moon were built. The crews had been tentatively selected. But those missions never happened, of course. In January 1970, responding to budget cuts, NASA cancelled Apollo 20. In September 1970, Congress cut off funding for Apollo 18 and 19 as well. When Apollo 17 returned to Earth on December 19, 1972, the era of humans on the Moon came to an end.
The proximate cause for the cancellation of the last three Apollo missions was that Congress was unwilling to support a continued human presence on the Moon, and President Nixon had no interest in fighting for it. Beyond the literal cost, the Apollo program seemed an extravagant waste at a time when the economy was hurting and the U.S. was still deeply enmeshed in the war in Vietnam.
It's worth noting that the immediate budgetary impact from scrapping Apollo 18 and 19 was negligible. By NASA's official accounting, the cancellations saved just 42 million dollars, since all of the equipment and personnel were already in place for those missions. The obstacle wasn't money, then, and it certainly was not technology. It was a matter of will.
We easily could have gone back to the Moon one or two more times after Apollo 17. The late missions would have been the most science-focused ones. Apollo 18 was tentatively set to land in a giant impact crater, either Tycho or Gassendi. But we — the president, Congress and the public that elected them — chose not to go back.