Escape becomes momentum
Pluto is no longer the ground beneath the expedition. It dwindles to a glimmer behind the ship as the departure manoeuvre ends and the familiar frontier falls away.
The unease comes from continued acceleration without a new point of reference. Space opens ahead while the last recognizable landmark fades behind the ship.
Beyond Pluto is more than a location. Departure has become crossing, and the mission has become a voyage without a familiar horizon.
When the last familiar landmark is behind you, what still counts as a route?