Trading in space

Money has no value in space. When seven astronauts are living together in a cramped atmosphere the psychology of small isolated groups kicks in. Whoever has squirreled away the most M&Ms, tortillas or coffee has the most bargaining power. Those are items that are most prized at the end of a mission if someone runs short in their own stash. Astronauts’ meals are color coded on shuttle missions — and reliable sources tell ABC News some astronauts aren’t above switching the colored dots on their dehydrated meals if they have run out of say, lasagna, on day six and have way too much creamed spinach left.

Here is more and the story is interesting throughout.  Are they not allowed to bring money on the ship or does money temporarily lose its function as a general medium of exchange?  Does the use of money, or the promise of money, break down spaceship norms?  They’re allowed to bring iPods, so can songs become a medium of exchange?  Or does preventing a general medium of exchange produce network externalities (increasing returns) to enhance the liquidity of all the other goods which need to be traded?  You do in fact get the tortillas being squirreled away.  Can this be a case where the emergence of a general money would be inefficient?