What does "forward facing" mean for space telescopes? I just noticed this announcement from the K2 mission that the field observed for Campaign 16 of the K2 mission would be changed so that the telescope would be "forward facing", saying that "observing in this mode allows for simultaneous observations from K2 and from Earth."

(an aside: Campaign 17 was originally planned to be a forward facing to facilitate supernova science, but it was discovered that the telescope may not have enough fuel to last through Campaign 17, hence the modification to Campaign 16 to still facilitate supernova science)

What exactly does it mean to be forward facing?
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.