A comet in the lab

The Stardust sample-return mission has provided researchers with a glimpse of conditions in the early solar system, in the form of cometary dust with a surprising range of compositions. Some grains arose in the hot inner solar system, others in the cooler outer reaches where comets accrete. There are also grains that formed before the Sun itself. In all, the samples so far have raised as many questions as they have answered, but together they suggest that the early solar system was probably a more complex place than had been supposed.