I recall watching this docu on the new toilets for the next phase of the International Space Station. And, regardless of its design, the thing I took away from the show was this: The shuttle brings back all trash from the ISS and the crew, on each return flight. My flabberghasted question is, WHY!? We got enough garbage here on Earth, why bring Sh*t from space? Literally? Launch it out the airlock? Is that so bad? Why not launch it towards the sun? Id think with out big brains we could come up with a trajectory to do that. Even IF it happened to veer into Earth, I think it would burn up before it hit land. I dunno, I just think that the world is filled with garbage, why bring down space poop?