What does "forward facing" mean for space telescopes?
This can best be described by two slides from this presentation.

"Forward-facing" implies looking towards Earth in the spacecraft's orbit, in the direction of the spacecraft's velocity vector:



"Backward-facing" implies looking in the opposite direction, away from Earth and in the opposite direction to that of the spacecraft's velocity vector:



These are from the C9 campaign, which also used a forward-facing orientation.