Engineering topics

Dyer, John W.

Publications and source records attributed to Dyer, John W..

3 records

NASA NTRS1991

Pioneer Venus Orbiter search for Venusian lightning

The results are reported of a search during 1988 and 1990 for optical pulses from lightning on the Venus nightside using the star sensor aboard the Pioneer Venus Orbiter. No optical evidence for lightning activity is found. These searches covered a much larger latitude range than any previous search. The results show that the Beta and Phoebe Regio areas previously identified by Russell et al. (1988) as areas with high rates of lightning activity were not active during the two seasons of the present observations. The results imply that the global flash rate and energy dissipation rate derived by Krasnopol'sky (1983) from observations of a single storm are too high. Experimental measurements performed to determine the amount of scattering occurring in the star scanner optics indicate that a previously determined upper bound to lightning activity is too low.

Borucki, William J.↗

NASA NTRS1991

Conceptual design considerations for the Astrometric Telescope Facility

The system of an astrometric telescope on the Space Station and its support by the Station are described and its feasibility demonstrated. The conceptual design shows that such a facility provides a basis for the study of design alternatives and a point of departure for a detailed design. Basic requirements for this preliminary design are outlined.

Dyer, John W.↗

NASA NTRS1988

Planetary operations for the Pioneer Venus Orbiter mission

The Pioneer Venus Orbiter was inserted into Venus orbit on December 4, 1974 and is expected to operate until 1992. This paper discusses the scientific objectives of the Pioneer Venus Orbiter Project components, i.e., the Orbiter spacecraft, the atmosphere entry Probes, and the probe Bus, together with the design and operation characteristics of the Orbiter. Consideration is also given to the science instruments of the Orbiter, to their requirements with respect to pointing, orientation, and timing, and to the ground operations system. The Probes, the Bus, and the Orbiter were selected to study Venus in complementary ways: the Probes by sounding through most of the atmosphere at four locations, the probe Bus by sounding through the upper atmosphere during entry, and the Orbiter by in situ planet-wide observations of the ionosphere and the extreme upper atmosphere, and by examining the surface and interior remotely. In addition, the Orbiter also observes the interactions of Venus with the solar environment.

Jackson, Robert W.↗