I am making a 2D game with XNA 3.1 where I want to make my space ship move with the arrow keys. atm when I press left or right arrow the ship rotates around its own axis. but now I want to make it fly into the direction its facing at the moment I press the up arrow. I dont know how I should tell the computer which direction the ship is facing at a point in time.
any ideas?

thanks in advance :)