Douglas Adams's Starship Titanic

Arguably the greatest collaboration in the whole history of comedy!
Bestselling author Douglas Adams wrote the storyline based on his CD-ROM game of the same name (as this novel, not as him, obviously).
Terry Jones of Monty Python wrote the book. In the nude! Parents be warned! Most of the words in this book were written by a naked man!
So. You want to argue with that? All right, we give in.
Starship Titanic is the greatest, most fabulous, most technologically advanced interstellar cruise line ever built. It is like a cross between the Queen Mary, the Chrysler Building, Tutankhamen's tomb, and Venice. Furthermore, it cannot possibly go wrong. . . .
Sadly, however, seconds after its launch it undergoes SMEF, or Spontaneous Massive Existence Failure. And disappears.
Except, everything's got to be somewhere.
Coming home that night, on a little known planet called Earth, Dan and Lucy Gibson find something very large and very, very shiny sticking into their house. . .