A Case Study in NASA-DoD - The Black Vault

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STANDARD SPACECRAFT DESCRIPTIONS
Four unmanned standard spacecraft designs are involved in this case
study. As mentioned in Sec. I, during the first phase of this case
study, the Space Test Program Standard Satellite--a design proposed by
the Space Test Program Office of the Air Force Space and Missile Systems
Organization--and two NASA candidates--the Applications Explorer Mission
spacecraft and the Multimission Modular Spacecraft--were considered.
After the initial study phase was completed, a fourth candidate was
introduced--a larger and more capable AEM (L-AEM) configured by the
Boeing Company under NASA sponsorship to meet specifications jointly
agreed upon by NASA and the Air Force. In the material that follows,
each of the spacecraft configurations is described, then a comparison
is made of the spacecraft requirements, followed by a detailed description
of the modifications needed for their use by the Air Force Space
Test Program missions.
The purpose of a standard spacecraft is to provide all of the housekeeping
functions for the Space Test Program payloads during the life of the
mission. For example, once in orbit, the spacecraft stabilizes the payload
and points it in the correct direction, it provides the necessary power and
power conditioning to run the experiments and provide thermal protection to
the payload, and it provides the communication and data handling equipment
necessary to control the experiments and transmit the data back to earth.
In most of the cases examined in this study, the spacecraft also provides
the guidance and control necessary to translate the payload from the shurtle
parking orbit to the mission orbit.
The STPSS design (Fig. 1) consists of four modules: core, orientation,
propulsion, and payload cluster. The core module is coaon to all missions,
regardless of whether the spacecraft is spin- or three-axis stabilized. Two
types of orientation modules provide for the two stabilization modes. The
propulsion module, which fits into the circular space of the core and orientation
modules, is tailored for the specific mission weight, final orbital
parameters (perigee and apogee altitude and inclination), and the shuttle
parking orbital parameters. The STPSS is designed in a hexagonal, torusshaped
c~nfiguration, which surrounds the solid propellant propulsion modules.
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