Engineering topics

Sherrill, T. J.

Publications and source records attributed to Sherrill, T. J..

2 records

NASA NTRS1984

Space Telescope mission planning

Planning and scheduling for the Space Telescope astronomy mission involves a combination of concerns regarding orbital environment constraints and spacecraft operational characteristics. In many cases proper selection or sequencing of observations can minimize the impact of disadvantageous orbital geometry with respect to targets of interest or of repeatedly encountered environmental factors such as spacecraft passages through high radiant regions on the earth's upper atmosphere. An overview is presented of the characteristics of viewing celestial targets from low earth orbit and the principal effects and operational considerations which constrain or restrict the scheduling of observations of them.

Sherrill, T. J.↗

NASA NTRS1981

Space Telescope orbital viewing constraints

Astronomical observations with the Space Telescope will be constrained by spacecraft operational requirements and capabilities, orbital viewing conditions, and the space environment. While ultraviolet or bright visual-range observations may be performed for 53 to 94.6 minutes per orbit (from a 500 kilometer altitude), certain stray light sensitive experiments may be limited to 0-48 minutes of viewing per orbit. Careful operations planning may make possible observations of 'secondary' targets while a primary target is occulted, of objects as close as 18 deg to the sun, or of objects visible when the spacecraft is in a high radiation environment.

Sherrill, T. J.↗