Observations of comets and asteroids with SOFIA.

Comets and asteroids are examples of the type of material from which planetesimals, the building blocks of the solar system, formed. In particular, comets may provide the most pristine material in the solar system. Studies of their composition and physical structure provides information on the conditions in the pre-solar nebula and during early stages of planet formation. Important questions are the relation of the chemical composition of comets and asteroids to the interstellar medium and the amount of processing during solar system formation. The composition of the volatile ice component of comets can be deduced from the study of their neutral gas coma (e.g. H₂O, CO and others) in the near-infrared range. Measurements in the thermal infrared allow to determine the size of asteroids and cometary nuclei and, in comets close to the Sun, the study of their dust component. An overview on the studies possible with SOFIA is given.