Recently in the Getaway Special Category

Airlines can not afford to fly with empty seats very often - and Space Shuttle orbiters can't leave valuable payload capacity "on the ground." Costing hundreds of millions of dollars per flight, NASA filled extra space in the shuttle's cargo bay using the Shuttle Small Payloads Project (SSPP). Hooks and power buses built into the shuttle bays allowed hundreds of small, modular experiments and technology test units to make the best use of missions that didn't need all 50,000 pounds of payload capacity. Between 1982 and 2003, more than 200 of these projects, including Get-Away Special (GAS) Cannisters, Hitchhikers and Spartans, flew in 108 missions.