The answer to the crossword for the term 2001 is 'Dave', which is a four letter word. Dave is the nickname of David Scott, an American astronaut and retired United States Air Force officer who was the seventh person to walk on the Moon. He was the commander of the Apollo 15 mission in 1971 and also flew on the Gemini 8 and Apollo 9 missions. Scott was the last living member of the Apollo 15 crew and was inducted into the Astronaut Hall of Fame in 2003.