So far, as far as we know Wild 2 is a unique object.

We?re using this comet as a library that picked up records and stored them far from the sun at very low temperatures for 4.5 billion years.

We're confident that the things coming out [of Comet Wild 2] are the same as those that went in. We believe that we collected the most pristine samples of a comet, those that have never been warmed.

We're seeing a variety of things that we know absolutely come from a comet.

We fully expect some of the comet particles to be older than the sun.

Scientifically, that's great, because there's been lots of discussion of whether comets contain minerals or glass.