Technology for Small Spacecraft (1994) / Chapter Skim
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2 Systems Engineering and Operations
2 Systems Engineering and Operations
Pages 12-22
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From page 12... ...
Several examples are included in Table 2-~. Some of these programs are successfully demonstrating systems for tracking, telemetry, and mission data operations that employ, when appropriate, the latest standard commercial communications equipment, data processing equipment, and software, as well as substantial automation technology, to reduce cost while maximizing performance.
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From page 13... ...
Ellipsat Starsys Global Positioning, Inc. SMALL SPACECRAFT/LAUNCH VEHICLE ACTIVITY Small Explorer Program Mars Pathfinder Miniature Sensor Technology Integration Program (MSTI)
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From page 14... ...
use of one of the existing or one of several soon-to-be-available small spacecraft launch vehicles; (2) use of a medium launch vehicle that can launch several small spacecraft at once; or (3)
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From page 15... ...
Many of these developments could have application to small spacecraft and launch vehicles. In addition, NASA has ongoing technology efforts to evaluate architecture, instrumentation, and software for both vehicle and propulsion system health monitoring.
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From page 16... ...
A range safety officer monitors the trajectory ano initiates a destruct command if the launch vehicle displays performance that is outside of preset limits. Much ground equipment and many maintenance and operations personnel could be eliminated if a highly reliable and accurate on-board system for determination of trajectory were available.
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From page 17... ...
A computer program for flight programming that would prepare the flight programming software for the launch upon insertion of several trajectory and launch vehicle parameters could reduce the time and cost required for this activity. The BMDO/McDonnell Douglas Single-Stage-to-Orbit project was working on the development of such a program prior to its cancellation ~ Hybrid rockets employ a liquid oxidizer with a solid, inert fuel.
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From page 18... ...
; the Deep Space Network, maintained and operated by JPL for planetary and high Earth orbit missions; the Ground/Space Tracking and Data Network, which is made up of various smaller ground facilities for general tracking and data reception and retransmission; the Wallops Island ground station, which is used for the Small Explorer program; and a number of services maintained and operated by commercial and common carriers. The TDRSS, Deep Space Network, and Ground/Space Tracking and Data Network all offer some standardized communications interfaces.
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From page 19... ...
The technical challenge is to develop a data ~ _ _ distribution system that gets the data from the spacecraft to the user's computers In the appropriate timeframe and medium. For example, the Radio Amateur Satellite Organization and the NASA Solar Mesosphere Explorer program both have ground stations that allow experimenters to receive data directly from the spacecraft.
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From page 20... ...
Tracking aM orbit data formats require use of a common data structure for spacecraft tracking data and a common set of conventions for the models and coordinate systems used to process the tracking data by all agencies participating. Telecommunications characteristics require using common frequency bands; ground-timing stability criteria; and command, telemetry, and ranging bandwidths among and within all facilities and agencies participating.
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From page 21... ...
Tools that would be useful are 21 operational mission concepts; many small spacecraft versus larger, fully integrated systems; the degree of autonomy on the spacecraft and on the ground; the effect of launch strategy and vehicle selection; the degree of acceptable risk and approach to reliability; and dedicated versus shared mission operations facilities. data bases and cost estimating software that address life-cycle cost of small missions; and nationally available data bases for existing parts, components, and new technologies.
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From page 22... ...
These should utilize expert systems when appropriate, including, as a minimum, the following: on-board health monitoring and checkout and, where economical, fault correction, for both the launch vehicle ant! the spacecraft; techniques for remote system checkout; automated preparation of flight software for guidance and control of both the launch vehicle and spacecraft; a set of standard hardware interfaces for small launch vehicles and spacecraft; on-board launch trajectory determination for range safety tracking; spacecraft accessibility late in the countdown; and reduction of launch pad safety requirements through use of technologies such as hybrid propulsion and nonexplosive separation devices.
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