Where is the spaceship in fallout 3?

West and slightly north of the Greener Pastures Disposal Facility, two grid spaces West and one to the North (but it is near the Southern part of this grid square). It is also almost due North of Minefield. An indication that you are close is that you will begin to pick up the "Recon Craft Theta" radio signal. Once you see the crashed alien ship, search around. The alien corpse is nearby, as well as the Alien Blaster gun