Rate and collision probability of tethers and sails against debris or spacecraft

The work done on probability of collision between spherical objects in orbit is extended here to the case of one spherical object and one circular or rectangular object. The former is a model for spacecraft or debris, whereas the latter is a model for a sail or a tether. Two kinds of computations are done. The first kind is the computation of the collision rate when the flux of one object (typically debris) with respect to the other object is known. This information is important when planning a mission. The second kind is the computation of the collision probability for a particular pair of objects whose probability density functions of the positions are known. This information is necessary to decide whether an evasive maneuver will be performed or not.