A data-communication and -processing network of compact, laptop-computer-based portable stations communicating via the World Wide Web (WWW) has been proposed as a relatively inexpensive end-to-end ground support system for future spacecraft missions. At present, end-to-end ground support functions (receiving, tracking, telemetry, command, monitoring, and control) are distributed among several subsystems in rack-mounted chassis (see figure). Many of these subsystems have outdated designs that entail high reproduction, maintenance, and operational (labor) costs. The costs are even higher than they might otherwise be because some functions are duplicated by two independent systems at NASA's Jet Propulsion Laboratory: the Deep Space Communications Complex (DSCC) and the Advanced Multi-Mission Operation System (AMMOS). The AMMOS is an intermediate product of evolution toward the proposed system and is not an end-to-end system; in the AMMOS, some telemetric and interfacial functions are implemented in software on a laptop computer, at data rates that are too low for typical spacecraft missions.

Mission-Support Electronic Systems Are Evolving from assemblies of expensive, obsolescent, rack-mounted units in central locations to cheaper, laptop-computer-based portable units.

In the proposed system, only the antenna subsystems, central command subsystems, receivers, transmitters, and data-storage or -buffering equipment would be retained at the DSCC. The other subsystems and the duplication between the DSCC and the AMMOS would be eliminated. Functions of tracking, ranging, command, monitoring and control, simulation and processing of telemetric data, central processing of data, and operation of the network would be performed by combinations of hardware and software in the portable stations.

To keep costs low, the portable stations would be made of commercial off-the-shelf products to the extent possible. To achieve the required data rates and promote modularity and interoperability, separate subsystem functions (e.g., telemetry, tracking, ranging, and command) would be implemented in hardware on separate circuit cards that conform to the Personal Computer Memory Card International Association (PCMCIA) standard. The sizes of integrated circuits on the PCMCIA cards could be reduced by use of multichip-module (MCM) packaging techniques.

A portable station could be operated at any suitable location in the world; for example, at the DSCC, aboard a vessel, at a field site on land, or in a researcher's office or laboratory at a university. The system would enable a scientist to perform multiple tasks simultaneously from such a location. For example, a scientist could perform a sea-floor geodesy experiment by use of the Global Positioning System while tracking a spacecraft and processing telemetric data. Inasmuch as only one operator (the scientist or an assistant) would be able to manage all of these tasks, the cost of operating the system would be less than that of operating the present system, which depends on multiple operators. The innovations discussed here are formulated concepts, and have not been fully reduced to practice.

This work was done by Barbara Lam of Caltech for NASA's Jet Propulsion Laboratory. NPO-20286

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Terrestrial portable spacecraft-mission-support stations

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This article first appeared in the July, 1998 issue of NASA Tech Briefs Magazine.

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