Engineering topics

Johnson, Francis S.

Publications and source records attributed to Johnson, Francis S..

3 records

NASA NTRS1995

Investigation of the role of gravity waves in the generation of equatorial bubbles

The following areas of interest in this progress report are: (1) the continuation of software development in the examination of F-region gravity-wave power using in-situ data from the Atmosphere Explorer (AE-E); (2) the inquiry into the use of the San Marco data for the study of the initiation and growth of bubbles, particularly when the satellite passes through the early evening hours at relatively high altitudes, and the development of bubbles using not only the San Marco data but includes the use of airglow observations made in Hawaii; and (3) the promising development in the observation of distinct well formed waves at about 400 km altitude in the equatorial region. These waves look very much like waves seen over the polar cap that are attributed to internal gravity waves in the neutral atmosphere driving ionization up and down the magnetic field lines. These equatorial waves show no modulation of the total ion concentration.

Johnson, Francis S.↗

NASA NTRS1992

Viking 2 electron observations at Mars

An analysis of the electron mode sweeps made in Viking 2 above the ionosphere is presented. An observation of the electron energy spectrum over the range 0 to 78 eV was recorded in 1 s and observations were made at intervals of 4 or 8 s. The concentrations and temperatures were highly variable in the altitude range 14,000 to 9000 km. Evidence for two Maxwellian components were present in most of the records. The general trend of concentration and temperature for the predominant component was from 2/cu cm and 100,000 K at 15,600 km to 5/cu cm at 220,000 K and 900 km, in good agreement with the Mars 3 observations of Gringauz et al. (1974). The higher-temperature component was generally characterized by a temperature near 400,000 K and concentrations near 0.1/cu cm. The electron plasma pressures near 800 km were about a factor of 20 lower than those obtained from Viking 1, the difference being much greater than expected from the normal distribution around the stagnation point in the shocked solar wind.

Johnson, Francis S.↗

NASA NTRS1991

Viking 1 electron observations at Mars

An analysis of the electron mode sweeps made by Viking 1 above the Martian ionosphere is presented. The initial electron concentrations near 15,000 km were slightly less than 1/cu cm and were characterized by a temperature of about 40,000 K and by what is interpreted as a backstreaming component from the planetary shock of about 0.1/cu cm at about 250,000 K. The shock appeared to be quasi-parallel. The hottest region was near 850 km, and is assumed to be characterized by energies of about 200 eV.

Johnson, Francis S.↗