Once again, we learn via the Houston Chronicle, NASA is having trouble getting its astronauts to drink piss.It's apparently not because they think the idea is disgusting; it's because they can't get their pee-cleansing machine to work.The Urine Processor Assembly has been balky ever since it was installed last year on the space station.The machine is supposed to take urine and sweat from the astronauts and, through some mysterious alchemy, make it all yummy and tasty.Of course, some people just