SPACECRAFT INTERACTION WITH ATMOSPHERIC SPECIES IN LOW-EARTH-ORBIT

Spacecraft interaction with ambient atmospheric species (O, N-2, O+, a nd electrons) in low Earth orbit involves collisions at high energies, giving rise to such complex phenomena as the shuttle glow, plume-atmo sphere interactions, and plasma modifications. A survey of these and o ther effects is presented, and conclusions are drawn about possible am biguities in interpretation of present data. For example, a suggestion is made that ions may play a role in the Shuttle glow phenomenon. Lac k of data on the accommodation (in terms of energy and in terms of ads orption and subsequent reactions) of atmospheric species, such as O an d N-2, on amorphous surfaces at hyperthermal energies is a distinct ha ndicap in the development of appropriate numerical codes for predictin g the effects of spacecraft interactions.