Engineering topics

Cowley, J. R., Jr.

Publications and source records attributed to Cowley, J. R., Jr..

3 records

NASA NTRS1984

Spin dynamics and horizon sensor performance for the Solar Mesosphere Explorer

Numerical techniques for obtaining the trigger altitude of the Solar Mesosphere Explorer (SME) are detailed. The SME has a pair of fixed horizon sensors for attitude determination and initiation of the data acquisition procedures for measuring ozone concentrations at the limb. The spacecraft spin rate is calculated as each of the horizon sensors marks the limb with a pulse telemetered to the ground. A best fit spin dynamics model that takes into account the history of the satellite spin angle and all disturbances to the spin is described. Analyses show that the trigger altitude is calculated to an accuracy of 1.5-2.0 km. A significant indicator of the limb altitude is the stratospheric temperature at the 5 mb pressure level.

Lawrence, G. M.↗

NASA NTRS1976

Orbit selection for the 1978 Pioneer Venus mission

The Pioneer Venus Orbiter will be launched by NASA in the spring of 1978. Selection of the orbit in July, 1975, resulted from scientific, mission, spacecraft, and operational considerations summarized by this paper. The orbit will be inclined 105 deg to the ecliptic, and its periapsis will lie between 16 and 28 deg north celestial latitude. Its periapsis altitude will be maintained between 150 and 260 km above the solid surface, and its period will be kept near 24 hr. This orbit and the spinning spacecraft's ecliptic-normal attitude permit the scientific coverage geometry of Venus, which also is summarized here.

Cowley, J. R., Jr.↗

NASA NTRS1973

Pioneer Venus mission plan for atmospheric probes and an orbiter.

The mission concept is described for a spin-stabilized spacecraft being designed to deliver an array of aerodynamic probes over the surface of Venus, and, on a second flight mission, to inject the spacecraft into a Venusian orbit. Large and Small Probes and the instrumented 'Bus' structure will enter the Venusian atmosphere and directly measure its characteristics. An orbiting configuration of the same basic Bus spacecraft will serve as a platform from which to examine the planetary environment, the outer atmosphere and its interaction with the solar wind, as well as surface topography. The orbital mission will extend over a complete revolution of the planet around the sun and around its own axis. Requirements for cost effectiveness and firm adherence within early cost projections are emphatic program guidelines which affect every major element of the mission plan and conceptual design.

Dyer, J. W.↗