Christmas Day for scientists who study asteroids is coming in just two months when a small spacecraft carrying material from a distant rubble pile will land in a Utah desert.

The return of the OSIRIS-REx sample container on September 24 will cap the primary mission to capture material from an asteroid—in this case, the carbonaceous near-Earth asteroid Bennu—and return some of its pebbles and dust to Earth.

It has been a long time coming. This mission launched seven years ago and has been in the planning and development phase for over a decade. To say the scientists who have fought for and executed this mission are anxious and excited is an understatement. But there is an additional frisson with OSIRIS-REx, as scientists are not entirely sure what they’ve been able to pull away from the asteroid.