The Interstellar Boundary Explorer (IBEX) spacecraft is providing the first
all-sky maps of the energetic neutral atoms (ENAs) produced by charge-exchange
between interstellar neutral \HI\ atoms and heliospheric solar wind and pickup
ions in the heliosphere boundary regions. The 'edge' of the interstellar cloud
presently surrounding the heliosphere extends less than 0.1 pc in the upwind
direction, terminating at an unknown distance, indicating that the outer
boundary conditions of the heliosphere could change during the lifetime of the
IBEX satellite. Using reasonable values for future outer heliosphere boundary
conditions, ENA fluxes are predicted for one possible source of ENAs coming
from outside of the heliopause. The ENA production simulations use
three-dimensional MHD plasma models of the heliosphere that include a kinetic
description of neutrals and a Lorentzian distribution for ions. Based on this
ENA production model, it is then shown that the sensitivities of the IBEX 1.1
keV skymaps are sufficient to detect the variations in ENA fluxes that are
expected to accompany the solar transition into the next upwind cloud.
Approximately 20% of the IBEX 1.1 keV pixels appear capable of detecting the
predicted model differences at the $ 3 \sigma$ level, with these pixels
concentrated in the Ribbon region. Regardless of the detailed ENA production
model, the success of the modeled \BdotR\ directions in reproducing the Ribbon
locus, together with our results, indicate that the Ribbon phenomenon traces
the variations in the heliosphere distortion caused by the relative pressures
of the interstellar magnetic and gaseous components.
