  The NASA Standard Break-Up Model models collisions and explosions in space,
which identifies the future distribution of debris. Given a possible break-up
event, this work analyses the threat posed by the generated debris in the orbit
of an asset spacecraft. Using the Koopman Operator solution of the $J_2$
perturbed two-body dynamics, the family of all possible orbits that cross the
asset's pathway is identified and parameterized according to their velocity.
The threat level assessment of a collision onto the asset is estimated
considering the intersection between the velocities of the break-up model and
the Koopman transfer solutions.
