10029 Lunar Lander is a Discovery set released in 2003. It comes with the Apollo Lunar Lander, two Apollo Astronauts, and a small, three piece U.S. flag.
The grey ascent stage can be detached from the descent stage and has a detailed interior. This is probably the most realistic spaceflight related LEGO set to date, since it contains a model based off of a real spacecraft which is scaled correctly relative to the minifigures.
This is the only LEGO Discovery set that includes minifigures, as well as the only appearance of the torso pieces with the NASA astronaut pattern.