NASA has announced its fifth Centennial Challenges prize competition: the Regolith Excavation Challenge. Teams will compete head to head in 2006 or 2007 to see whose digging machine can excavate the most lunar soil, or regolith, in 30 minutes and deliver it to a collector. Any future moon base will require large quantities of regolith to be moved around by robotic diggers, so NASA is hoping to see innovative ideas now to base future technologies around.