A good knowledge of temperature, total density, concentrations of gas constituents and pressure is important for many space missions exploiting the low-earth orbit regime (LEO), below approx. 1 000 km altitude. Aerodynamic forces on the spacecraft, due to the orbital motion of a satellite through a rarefied gas which itself can have variable high velocity winds, are important for the combination of planning satellite lifetime, for the maintenance of orbits, for sizing the necessary propulsion system, for the design of attitude control system, and for estimating the peak accelerations and torques imposed on sensitive payloads.
Surface corrosion effects due to the impact of large fluxes of atomic oxygen are assessed to predict the degradation of a wide range of sensitive coatings of spacecraft and instruments. The reactions of atomic oxygen around a spacecraft can also lead to intense “vehicle glow”.