Engineering topics

Macy, W. W., Jr.

Publications and source records attributed to Macy, W. W., Jr..

4 records

NASA NTRS1980

Five-micrometer measurements of Uranus and Neptune

Five-micron brightness temperatures and brightness temperature upper limits for Uranus and Neptune have been obtained which are substantially lower than those of Jupiter and Saturn and which correspond to a geometric albedo of approximately 0.01, in agreement with results reported by Gillett and Rieke (1977). Phosphine and CH3D, which are observed at 5 microns on Jupiter and Saturn, are discussed as possible sources of opacity at 5 microns in the atmospheres of Uranus and Neptune.

Macy, W. W., Jr.↗

NASA NTRS1977

Evidence for two major changes in the Venus aerosol distribution - 1972-1975

High-spatial-and-spectral-resolution observations of Venus CO2 line profiles taken over a three-year interval are analyzed using inhomogeneous atmospheric models with anisotropic scattering. The data exhibit two sudden significant changes in the structure of the atmosphere, one occurring near April 1973, and the other near November 1974. Two models are developed to describe the vertical cloud structure of the atmosphere of Venus in the more quiescent periods after these changes. For each model, the CO2 specific abundance must decrease with increasing atmospheric pressure; i.e., the clouds are thinnest high in the atmosphere and become denser with depth. No evidence is found that the cloud particles must change their scattering phase function with altitude.

Cochran, W. D.↗

NASA NTRS1977

Observations of the phase variation of Venus CO2 equivalent widths

Equivalent widths determined from photoelectric scans of Venus CO2 absorption lines measured at phase angles of 5.1 to 170 deg are presented. The data-reduction procedure is described in detail, and phase curves are plotted for three model atmospheres in which CO2 is homogeneously mixed with Mie-scattering particles or inhomogeneously mixed with Henyey-Greenstein particles. All three data sets are found to indicate that the equivalent-width maximum occurs at a phase angle much lower than 100 deg. It is concluded that two scattering layers are not required on Venus to explain the shape of the observed phase curve and that the mixing ratio of scattering particles to CO2 increases with depth at high altitudes.

Barker, E. S.↗

NASA NTRS1975

Io's sodium emission cloud

Strong evidence that Io's sodium emission is due to resonant scattering is given by our observations which show a monotonic increase of emission intensity with residual solar intensity. In addition we detected no emission during three eclipse observations of Io. We propose a resonant scattering model with two spacial components comprising an optically thick atmosphere extending 1000 km above Io's surface surrounded by an optically thin cloud which forms a partial torus around Jupiter. In this model, sodium atoms are sputtered from Io's surface by heavy energetic ions which are accelerated in a plasma sheath around Io. The atoms sputtered from the surface collide with atoms in Io's atmosphere so the equipartition of kinetic energy is established. During Io's day, sodium and other atmospheric constituents are ionized, giving rise to the ionosphere observed by Pioneer 10. Atoms escape by means of Jeans escape from the critical level, which is at the top of the atmosphere and the base of the cloud.

Macy, W. W., Jr.↗