Monday's post deserves to marinate for a while longer, but I'm compelled to point out that today is the 40th anniversary of the landing of the final manned mission to the Moon. On Dec. 11, 1972 Eugene Cernan and Harrison Schmitt became, as of today, the last humans to set foot on the Moon, beginning a three day mission. Cernan, who was the last to leave the lunar surface and aware that all future Apollo missions had been canceled, said:

I'm on the surface; and, as I take man's last step from the surface, back home for some time to come – but we believe not too long into the future – I'd like to just [say] what I believe history will record. That America's challenge of today has forged man's destiny of tomorrow. And, as we leave the Moon at Taurus-Littrow, we leave as we came and, God willing, as we shall return: with peace and hope for all mankind. Godspeed the crew of Apollo 17.

The Apollo program gave way to the brief and ill-fated Skylab program and then the Space Shuttle. Despite the great fanfare with which the latter program ended recently, in scientific terms it was a poor substitute for Apollo, Gemini, and Mercury. It signaled NASA's transition – in the 1980s, coincidentally enough – to a delivery and maintenance service for government and private sector satellites. Not quite as exciting as walking on the Moon (which, of course, can be criticized on the basis of its scientific value as well) and sadly indicative of a shift in national priorities.