  CASTAway is a mission concept to explore our Solar System's main asteroid
belt. Asteroids and comets provide a window into the formation and evolution of
our Solar System and the composition of these objects can be inferred from
space-based remote sensing using spectroscopic techniques. Variations in
composition across the asteroid populations provide a tracer for the dynamical
evolution of the Solar System. The mission combines a long-range (point source)
telescopic survey of over 10,000 objects, targeted close encounters with 10 to
20 asteroids and serendipitous searches to constrain the distribution of
smaller (e.g. 10 m) size objects into a single concept. With a carefully
targeted trajectory that loops through the asteroid belt, CASTAway would
provide a comprehensive survey of the main belt at multiple scales. The
scientific payload comprises a 50 cm diameter telescope that includes an
integrated low-resolution (R = 30 to 100) spectrometer and visible context
imager, a thermal (e.g. 6 to 16 microns) imager for use during the flybys, and
modified star tracker cameras to detect small (approx. 10 m) asteroids. The
CASTAway spacecraft and payload have high levels of technology readiness and
are designed to fit within the programmatic and cost caps for a European Space
Agency medium class mission, whilst delivering a significant increase in
knowledge of our Solar System.
