Engineering topics

O'Leary, B.

Publications and source records attributed to O'Leary, B..

7 records

NASA NTRS1974

Venus - Atmospheric motion and structure from Mariner 10 pictures

The Mariner 10 television cameras imaged the planet Venus in the visible and near ultraviolet for a period of 8 days at resolutions ranging from 100 meters to 130 kilometers. The general pattern of the atmospheric circulation in the upper tropospheric/lower stratospheric region is displayed in the pictures. Atmospheric flow is symmetrical between north and south hemispheres. The equatorial motions are zonal (east-west) at approximately 100 meters per second, consistent with the previously inferred 4-day retrograde rotation. Angular velocity increases with latitude. The subsolar region, and the region downwind from it, show evidence of large-scale convection that persists in spite of the main zonal motion. Dynamical interaction between the zonal motion and the relatively stationary region of convection is evidenced by bowlike waves.

Murray, B. C.↗

NASA NTRS1973

An atmosphere on Ganymede from its occultation of SAO 186800 on 7 June 1972.

The observational data obtained during the occultation are of sufficient quality to determine the occultation radius and to support the inference that Ganymede does possess at least a modest atmosphere. Assuming a circular cross section, the diameter of Ganymede was found to be 5271 km. Effects of the atmosphere on the accuracy of the value obtained for the Ganymede diameter are discussed.

Carlson, R. W.↗

NASA NTRS1973

Another possible post-eclipse brightening of Io.

Observation of an apparent posteclipse brightening of the Galilean satellite Io from two different observatories on June 25, 1971, employing the technique of area scanning in the ultraviolet. An apparent brightening was observed which amounted to about 0.2 mag at 3500 A and 0.15 mag at 4000 A. It is suggested that the brightening was a transient partial covering of high-albedo material where the contrast is by far greatest in the ultraviolet.

O'Leary, B.↗

NASA NTRS1973

Optical properties of Apollo 12 moon samples.

We present the photometric phase function, color, normal albedo, polarimetric phase function, and spectrophotometry of the Apollo 12 soil. With a few minor exceptions, the optical properties of the Apollo 12 soil are very similar to those of the Apollo 11 soil and of lunar mare surfaces.

O'Leary, B.↗

NASA NTRS1972

Io's triaxial figure.

Timings from photoelectric observations of four immersions and two emersions of the recent occultation of Beta Scorpii C by Io have made it possible to derive Io's apparent equatorial radius to an accuracy of 2 km. However, when the distortion of Io attributable to rotation and tides raised by Jupiter is considered, the derived mean radius becomes several kilometers less than the observed equatorial radius. If Io were a homogeneous fluid body in hydrostatic equilibrium and in synchronous rotation, it would show a bulge along a line to Jupiter about 20 km in radius greater than the polar radius. The mean radius thus derived is (1818 plus or minus 5) km and mean density (2.88 plus or minus 0.34) g/cu cm, the largest uncertainty being attributable to the value of Io's mass. The new value for Io's radius is higher than those previously determined and suggests about 30% lower values for mean densities of all Galilean satellites.

O'Leary, B.↗

NASA NTRS1972

Search for a Venus halo effect during 1970.

Photometric observations of Venus during 1970 inferior conjunction, in contrast to observations made during the 1969 inferior conjunction, show no evidence of a Venus halo effect at 158 phase angle. The upper limit to brightening is about 0.005 mag but can still be reconciled with earlier results. Because of the importance of the question of H2O-ice in the Venus clouds, further observations are encouraged to remove the marginality of most observations to date.

Ward, D.↗

NASA NTRS1972

Frequencies of occultations of stars by planets, satellites, and asteroids.

Calculations show that several occultations of stars by the large satellites of the outer planets, Pluto, and the large asteroids could be observed each decade with existing equipment at earth-based telescopes. A systematic program of occultation predictions and observations is urged in order to improve our knowledge about the atmospheres, sizes, shapes, topography, and positions of these poorly understood bodies, in support of forthcoming spacecraft missions to the outer solar system.

O'Leary, B.↗