Ionospheric Undulations following Apollo 14 Launching

Abstract

Chimonas and Hines¹ predicted that a supersonic shock within the atmosphere would be followed by ionospheric disturbances observable from some distance. Such effects were observed during the total solar eclipse of March 7, 1970 (ref. 2). Similar ionospheric effects are to be expected when a large missile and its exhaust plume travel with supersonic velocity close to ionospheric heights. This effect was observed at Fort Monmouth, New Jersey, on January 31, 1971, after the Apollo 14 launching. Ionograms taken from vertical sounding at the Red Hill Station (74 : 07 : 52 W long.; 40 : 23 : 25 N lat.) every 5 min have been converted to true-height electron-density profiles (Fig. 1). Each curve in the figure describes the true height variation of a noted plasma frequency (MHz). Since sporadic-E was present during part of the experiment, the figure is restricted to F-region data. Three successive compressions or undulations within the lower part of the region are indicated. The second undulation, however, is noticeable throughout the entire bottomside region.