Bird in Space is a sculpture by Constantin Brâncuși's that went into public domain this year. It is the inspiration for the game both in name and in the design of the ship. The image used for the game is a modified photo of the sculpture.
Oh, awesome! Thank you for the information. I somehow didn't catch that.
Edit: Maybe you should mention this on the game page, and maybe put a link to where the sculpture physically is? (If it has survived...)