We explore the possibility of remote, from 1 AU, study of the heliopause by
an observer outside the geocorona. We argue that the heliopause, a boundar
y that separates the solar wind and the galactic plasma of the local inters
tellar medium (LISM), can be imaged by detecting solar extreme ultraviolet
(EUV) radiation reflected by interstellar ions. Such EW imaging would map t
he heliopause and provide important insight into its three-dimensional stru
cture and the LISM parameters as well. We consider heliopause mapping in th
e oxygen O+ ion resonance line (83.4 nm); imaging in the helium He+ ion lin
e (30.4 nm) will be considered in a future article. We show that the expect
ed heliopause brightness map at 83.4 nm is essentially different from that
of the foreground glow of the solar wind O+ pickup ions. The interstellar p
lasma glow is brighter in the upwind (with respect to the interstellar wind
) direction, while the pickup ion glow dominates in the downwind direction.
The spectral characteristics of the radiation scattered by the LISM plasma
and by the pickup ions are significantly different. The all-sky images at
83.4 nm are highly sensitive to the ionization state of the LISM and would
allow one to probe the asymmetry of the interstellar magnetic field. We bri
efly discuss the experimental requirements to heliopause EUV mapping, which
would require 3 orders of magnitude improvement in instrumentation sensiti
vity. This is a challenging but not impossible task.