When did astronauts last walk on the moon?

Apollo 17 set down in the Taurus-Littrow valley on 11 December 1972, at a site chosen for its mix of ancient highland material and what looked like much younger volcanic deposits. Eugene Cernan and Harrison Schmitt, a geologist and the only scientist to reach the surface, spent three days there while Ronald Evans orbited overhead. They drove the lunar rover away from the module on three excursions, found the orange soil at Shorty crater that turned out to be ancient volcanic glass, and brought back the largest sample haul of the programme. The ascent stage lifted off on 14 December 1972, and they became the last of the twelve people who have walked on the Moon.

Apollo did not stop because it failed. It stopped because its purpose had been political, and that purpose was spent. The last planned missions were cancelled while hardware still existed, budgets moved to the Space Shuttle and then to a space station, and no government saw a return worth the cost of landing people again. The Moon kept being visited by robots, which are far cheaper and do not need a way home.

Artemis is not Apollo with better computers. It aims at the lunar south pole, where water ice sits in permanently shadowed craters and where low sun angles, cold and communications make operations harder. It also depends on large landers derived from commercial vehicles that must be refuelled in space rather than a single stack thrown at the Moon in one launch. That architecture buys capability and repeat visits, and it is the main reason the schedule has slipped repeatedly: the pieces are genuinely more ambitious than the ones Cernan flew.