Gas-Surface Energy Transfer Experiment for OGO-F

A gas-surface energy transfer experiment for the Orbiting Geophysical Observatory, Mission F, is described. The experimentis to measure the kinetic energy flux of the upper atmosphere relative to the orbiting satellite, and what fraction of this energy is transferred at normal incidence to surfaces. Four probes that can detect energy transfer between 10 W/cm2 and 0.1 W/cm2 by the frequency change of temperature-sensitive oscillating quartz crystals are used to make the measurements. Probe accuracies of 3 percent and precision of measurements of better than 1 percent are maintained by periodic in-flight calibration of the crystal sensors. Data fromthe experiment will be used to determine the energy accommodation and drag coefficients of Al and Au, in 0 and N2, the main components of the upper atmosphere between 400 km and 1100 km, and the planned altitude range of OGO-F. The kinetic energy flux measurement, besides being used in the determination of accommodation and drag coefficients, offers a novel method for determination of the upper atmospheric density and its scale height by relating measurements of the energy flux to the satellite ephemeris.