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Shrewsberry, D. J.

Publications and source records attributed to Shrewsberry, D. J..

8 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

The Spartan 1 mission

The first Spartan mission is documented. The Spartan program, an outgrowth of a joint Naval Research Laboratory (NRL)/National Aeronautics and Space Administration (NASA)-Goddard Space Flight Center (GSFC) development effort, was instituted by NASA for launching autonomous, recoverable payloads from the Space Shuttle. These payloads have a precise pointing system and are intended to support a wide range of space-science observations and experiments. The first Spartan, carrying an NRL X-ray astronomy instrument, was launched by the orbiter Discovery (STS51G) on June 20, 1985 and recovered successfully 45 h later, on June 22. During this period, Spartan 1 conducted a preprogrammed series of observations of two X-ray sources: the Perseus cluster of galaxies and the center of our galaxy. The mission was successful from both on engineering and a scientific viewpoint. Only one problem was encountered, the attitude control system (ACS) shut down earlier than planned because of high attitude control system gas consumption. A preplanned emergency mode then placed Spartan 1 into a stable, safe condition and allowed a safe recovery. The events are described of the mission and presents X-ray maps of the two observed sources, which were produced from the flight data.

Cruddace, R. G.↗
NASA NTRS1989

The Spartan 1 mission

The first Spartan mission is documented. The Spartan program, an outgrowth of a joint Naval Research Laboratory (NRL)/National Aeronautics and Space Administration (NASA)-Goddard Space Flight Center (GSFC) development effort, was instituted by NASA for launching autonomous, recoverable payloads from the space shuttle. These payloads have a precise pointing system and are intended to support a wide range of space-science observations and experiments. The first Spartan, carrying an NRL X-ray astronomy instrument, was launched by the orbiter Discovery (STS51G) on June 20, 1985 and recovered successfully 45 h later, on June 22. During this period, Spartan 1 conducted a preprogrammed series of observations of two X-ray sources: the Perseus cluster of galaxies and the center of our galaxy. The mission was successful from both on engineering and a scientific viewpoint. Only one problem was encountered, the attitude control system (ACS) shut down earlier than planned because of high attitude control system gas consumption. A preplanned emergency mode then placed Spartan 1 into a stable, safe condition and allowed a safe recovery. The events are described of the mission and presents X-ray maps of the two observed sources, which were produced from the flight data.

Cruddace, Raymond G.↗
NASA NTRS1986

Experiments of opportunity pay loads revisited

The design and operation of the Spartan program are discussed. The objective of the Spartan program is to utilize the Space Shuttle for conducting exoatmospheric science research. The Spartan 1 data storage and handling, attitude control, power, and thermal control systems and structure are described. The Spartan 1 was to study the structure of two prominent cosmic X-ray sources, the Perseus cluster of galaxies, and the center of the Milky Way. Spartan 1 was launched on June 17, 1985, deployed on June 20, and retrieved on June 22. The performance of the Spartan's system, and the collected data are analyzed; it was observed that the systems performed as planned. The methods used to minimize the Spartan program costs are considered.

Shrewsberry, D. J.↗
NASA NTRS1985

Space research and Spartan

For a number of years, space research has been primarily conducted with sounding rockets and orbiting satellites. The use of satellites has disadvantages related to cost and the long lead time from design to launch, while a drawback in the case of sounding rockets is the short flight time of only a few minutes. The development of the Shuttle led to the proposal to employ for space research an autonomous free-flying payload deployed and recovered by the Shuttle. The proposed payload, called SPEAR (Small Payload Ejection and Recovery), looked very much like a rocket payload. Subsequently, the payload developed into a more compact form, and its name became Spartan-1. Attention is given to the demands of space research, the Spartan-1 payload, the payload functional control system, the thermal control system, the Spartan-1 mission, and the future of Spartan.

Cruddace, R. G.↗
NASA NTRS1980

Development of an experiment of opportunity test payload for the space transportation system

This paper describes a means for flying existing Sounding Rocket payloads aboard the Space Shuttle by developing small experiment carriers which become detached from the Orbiter and are later retrieved and reused. An effort is underway at the Goddard Space Flight Center to develop such a carrier which would be flown as an Experiment of Opportunity Payload (EOP). The activity is viewed as a feasibility test, and success will encourage the construction of similar packages for additional sounding rocket experiments, for eventual evolution of p

Shrewsberry, D. J.↗
NASA NTRS1973

STRAP IV - High accuracy, low drift attitude control system.

The STRAP IV attitude control system was designed, tested, and successfully launched to provide stable high accuracy pointing at nontrackable X-ray sources. On its initial flight (May 19, 1972), the STRAP IV control system updated its high accuracy, rate integrating gyros on two successive stellar targets and then maneuvered the rocket body to point the experimental payload at two separate X-ray sources and an X-ray-free background location. The third axis, which remained under the control of a coarse free gyro, was updated by a technique of successive star-target coordinate transformation to ensure the correct fine-axis azimuth alignment for the high accuracy inertial maneuvers. Pointing accuracies of 4 arc min with limit cycle stability of less than 20 arc sec peak to peak were obtained on all targets.

Shrewsberry, D. J.↗
NASA NTRS1973

STRAP 4 sounding rocket attitude control system

A sounding rocket attitude control system is reported that uses rate integrated gyros operating in both closed loop and open loop modes at very low drift rates. In normal operation the gyros are zeroed on a nearby star and torqued to the proper location in the closed loop mode; rate output is electronically integrated to provide a position displacement signal. Once closed loop torquing is completed, the caging loop is opened and the gyro is operated as angular displacement sensor to provide limit cycle control while viewing the target.

Shrewsberry, D. J.↗