Considering as well the long flight time for the ARM (six to ten years), it is conceivable that an incompletely characterized aster-oid with a particularly favorable orbit (i.e. one that would result in a shorter travel time or a lower delta-v, and hence a lower cost for the mission) might be more enticing as a candidate than a better-studied small asteroid whose orbit is less favorable. As a result, a statistical study of the properties of small asteroids in general provides helpful insight as to the likely or worst-case properties of a potential target that is not yet fully characterized.
In the following sections, we collect the information available on VSAs in an attempt to paint a picture of a typical asteroid within the size range suitable to be an ARM target. This picture will include the most likely spin-state, shape, and composition of such an asteroid. In addition, we will also discuss the “worst-case” scenario for an ARM target in terms of extremes of rotation rate and the likelihood of a tumbler or non-principal axis (NPA) rotator.