  We focus on preventing collisions between debris and debris, for which there
is no current, effective mitigation strategy. We investigate the feasibility of
using a medium-powered (5 kW) ground-based laser combined with a ground-based
telescope to prevent collisions between debris objects in low-Earth orbit
(LEO). The scheme utilizes photon pressure alone as a means to perturb the
orbit of a debris object. Applied over multiple engagements, this alters the
debris orbit sufficiently to reduce the risk of an upcoming conjunction. We
employ standard assumptions for atmospheric conditions and the resulting beam
propagation. Using case studies designed to represent the properties (e.g. area
and mass) of the current debris population, we show that one could
significantly reduce the risk of nearly half of all catastrophic collisions
involving debris using only one such laser/telescope facility. We speculate on
whether this could mitigate the debris fragmentation rate such that it falls
below the natural debris re-entry rate due to atmospheric drag, and thus
whether continuous long-term operation could entirely mitigate the Kessler
syndrome in LEO, without need for relatively expensive active debris removal.
