  The upcoming Comet Interceptor mission involves a parking phase around the
Sun-Earth L2 point before transferring to intercept the orbit of a long period
comet, interstellar object or a back-up target in the form of a short-period
comet. The target is not certain to be known before the launch in 2029. During
the parking phase there may thus arise a scenario wherein a decision needs to
be taken of whether to go for a particular comet or whether to discard that
option in the hope that a better target will appear within a reasonable time
frame later on. We present an expectation value-based formalism that could aid
in the associated decision making provided that outlined requirements for its
implementation exist.
