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Freeman, H. R.

Publications and source records attributed to Freeman, H. R..

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

The International Ultraviolet Explorer: Case study in spacecraft design

The International Ultraviolet Explorer (IUE) is a geosynchronous scientific satellite that was conceived as an international space observatory capable of measuring UV spectra of faint celestial bodies. Simple operational procedures allow the astronomers to joystick the spaceborne telescope about the sky, using familiar ground-based observatory techniques. The present paper deals with the IUE project objectives, the technical problems, constraints, trade-offs, and the problem solving techniques used in the IUE program.

Freeman, H. R.↗
NASA NTRS1978

The IUE spacecraft and instrumentation

The paper describes the general design, instrumentation, and ground control system of the International Ultraviolet Explorer (IUE) satellite, which will serve as an astronomical observatory providing both high and low resolution UV spectra of sources other than the sun. Basic data are given on the telescope, the UV-visible converter, the spectrograph optics, the camera response, and the communications systems.

Boggess, A.↗
NASA NTRS1978

In-flight performance of the IUE

A report on the initial performance of the IUE satellite, launched in January, 1978, is given. Attention is given to optical performance, camera performance, background corrections, photometric performance, and data reduction. Samples of high-dispersion and low-dispersion spectra are shown. A remaining problem of proper separation of high dispersion orders in data reduction is discussed.

Boggess, A.↗
NASA NTRS1976

Three-axis attitude control for a geostationary satellite

The Applications Technology Satellite-6 was successfully launched into a geostationary orbit in May, 1974. Since that time, its attitude control subsystem has routinely demonstrated its ability to perform precision pointing and precision closed loop maneuvers. This paper describes the ATS-6 attitude control subsystem. The requirements imposed by the spacecraft mission objectives are outlined, and functional descriptions of the principal attitude control subsystem components and control laws are presented. The paper concludes with a summary comparison of in-orbit performance relative to its specified performance requirements.

Freeman, H. R.↗