I've had this book discussed in my classes some years ago, have been looking for it ever since. In the book, the man is the first to try and reach outer space (it's placed some time in the past), he gets so high that he blacks out from the lack of oxygen or something, he later wakes up on what seems to be a different planet. He finds a brass tag in the dirt with some faded lettering on it. The whole books is really vague, and you never really know if it all really happend, because the book was written by the man who supposedly performed this stunt.
That's about all I know, Any help would be greatly appreciated!