"This may be the last time in this century that men will walk on the Moon, but space exploration will continue..."
Richard Nixon, on the lunar farewell of Apollo 17
Along with the names of Neil Armstrong, Edwin Aldrin, and Michael Collins, Richard Nixon's signature is inscribed on a plaque attached to the lower half of the Apollo 11 LEM, currently sitting in the Sea of Tranquility on Earth's natural satellite. Kennedy may have set the project in motion, and Nixon was the one who cancelled it, but Nixon's name is the one on the moon*; he is one of the men who visited the moon in peace for all mankind. This is a simple, small fact, but one of immense poignancy.
Subsequent plaques omitted Nixon's signature (he remained president throughout the remainder of the Apollo landings) - however, he remains one of a handful of human beings who have left a mark on another world; his memory might well outlast that of the human race.
* At least, legible to human eyes; selected passages from presidents Kennedy, Eisenhower, Johnson and Nixon, Nasa officials, and Pope Paul VI are printed on a tiny silicon disc, albeit in microscopically small print:
http://history.nasa.gov/SP-4223/ch2.htm#n1
In a reverse echo of a minor controversy from mid-2003, Nixon requested that the words 'under God' be inserted between 'we came in peace' and 'for all mankind' in the plaque's most famous phrase; his wish was not carried out.