I visited JPL yesterday for their anual open house.  I got to see many of their amazing toys.  We even got to the spacecraft assembly facility.  A giant clean room where the final assembly of their spacecrafts, probes, satellites and landers take place.  For a room that is roughly 50 years old, it looks bran spank’n new.  How do you maintain a clean room with a giant door big enough for a spacecraft to fit in?  well, first off the giant door opens to an airlock.  Second, the pressure is actually higher inside the clean room then outside.  this way, if any air escapes, it is clean air escaping the clean room and not the other way round.  I also learned about JPL/NASA’s spin on one of my favorite inventions, the Tweel!  it’s a combination tire/wheel.  It actually resembles a bicycle wheel more then a car wheel in that it is suspended by the spokes from the top rather then held up from the bottom.  Apparently, rubber doesn’t do so well i a vacuum or in the cold (forgive me, i grew up in LA).  That is why they make theirs out of some kind of space aged glass polymer.  neat stuff.  here are some photos.  enjoy.