Space Forum / Space Flight / July 2005

The exhaust plume from the initial (departure or perigee)
burn will deorbit very rapidly, within minutes.  The
plume from the apogee burn is a bit more complex; BOTE
calculation suggests it will mostly wind up in a range
of elliptical orbits with perigees high enough to avoid
rapid deorbiting.  And it won't rapidly be carried away
by the solar wind, because it will be too deep in the
Earth's magnetosphere for the wind to reach.

Which suggests charge exchange capture into the inner
Van Allen belt as one possible fate.  Others would be
perturbation into a re-entry or escape trajectory, with
radiation pressure as a likely perturbing force.  Note,
though, that individual molecules are too small to be
effective broadband absorbers or reflectors of anything
close to visible light, so that might take a while.

And I don't have my spectroscopy references with the
cross-section data handy, so I'll pass on figuring out
what "a while" is likely to be.