Not a Rubble Pile?

Over the past decade, a consensus had started to emerge that comets are essentially blobs of rubble held together by gravity. In his Perspective, Weaver discusses reports in the same issue by teams from the Stardust mission to comet Wild 2 that throw that picture into doubt. Images of the comet9s nucleus show cratering that indicates substantial strength of a solid body. This suggests a more diverse range of nucleus types than previously thought and is sure to fire up debates over cometary structure. Wild 2 also shows unusual dust jet activity and some puzzling chemistry. But the biggest surprises may be still to come, as Stardust heads back to Earth with its payload of captured cometary material.