Results are presented from a Spherical Retarding Potential Analyzer (SRPA) and a spherical Langmuir Probe (LP) which were flown on the Spacelab-2 (SL-2) mission of the Space Shuttle Orbiter in August, 1985. The probes were mounted in such a position that for certain Orbiter orientations, the wake edge formed by the starboard payload bay sill swept across the probes at a roll rate of once per orbit about an inertially stabilized pointing direction. Profiles of O+ number density and electron number density across the wake edge showed that, after correction for the spatial separation of the sensors, the charge particle number densities declined into the wake at a faster rate than that predicted by theoretical models. At angles of more than 10¿ into the wake from its geometric edge we find two electron populations having different mean random energies and electrical potentials. One of these populations is suggested to be the result of selective filtering of the high energy tails of the ambient ionospheric population, the other a result of photo-emission from the payload bay surfaces. ¿American Geophysical Union 1987