Engineering topics

Davis, Randy

Publications and source records attributed to Davis, Randy.

3 records

NASA NTRS1994

Autonomous mission planning and scheduling: Innovative, integrated, responsive

Autonomous mission scheduling, a new concept for NASA ground data systems, is a decentralized and distributed approach to scientific spacecraft planning, scheduling, and command management. Systems and services are provided that enable investigators to operate their own instruments. In autonomous mission scheduling, separate nodes exist for each instrument and one or more operations nodes exist for the spacecraft. Each node is responsible for its own operations which include planning, scheduling, and commanding; and for resolving conflicts with other nodes. One or more database servers accessible to all nodes enable each to share mission and science planning, scheduling, and commanding information. The architecture for autonomous mission scheduling is based upon a realistic mix of state-of-the-art and emerging technology and services, e.g., high performance individual workstations, high speed communications, client-server computing, and relational databases. The concept is particularly suited to the smaller, less complex missions of the future.

Sary, Charisse↗

NASA NTRS1993

A reference model for scientific information interchange

This paper presents an overview of an Information Interchange Reference Model (IIRM) currently being developed by individuals participating in the Consultative Committee for Space Data Systems (CCSDS) Panel 2, the Planetary Data Systems (PDS), and the Committee on Earth Observing Satellites (CEOS). This is an ongoing research activity and is not an official position by these bodies. This reference model provides a framework for describing and assessing current and proposed methodologies for information interchange within and among the space agencies. It is hoped that this model will improve interoperability between the various methodologies. As such, this model attempts to address key information interchange issues as seen by the producers and users of space-related data and to put them into a coherent framework. Information is understood as the knowledge (e.g., the scientific content) represented by data. Therefore, concern is not primarily on mechanisms for transferring data from user to user (e.g., compact disk read-only memory (CD-ROM), wide-area networks, optical tape, and so forth) but on how information is encoded as data and how the information content is maintained with minimal loss or distortion during transmittal. The model assumes open systems, which means that the protocols or methods used should be fully described and the descriptions publicly available. Ideally these protocols are promoted by recognized standards organizations using processes that permit involvement by those most likely to be affected, thereby enhancing the protocol's stability and the likelihood of wide support.

Reich, Lou↗

NASA NTRS1993

EOS distributed planning and scheduling prototype

Some of the more significant lessons learned during the development of the Earth Observing System (EOS) Distributed Planning and Scheduling Prototype are presented. The need for a central scheduler is not demonstrated. A mapping of scheduling and conflict-resolution responsibility across the nodes of the EOS distributed scheduling system is developed and shown to be both feasible and appropriate. Complex instrument scheduling is mostly accomplished at the ICC/IST (instrument control center/instrumental support terminal) with 'slidable' flexibility for slews and some kinds of calibrations resolved at the EOS Operations Center (EOC). All nodes have full visibility interinstrument contention for resource and environmental rights, e.g., vibration, thermal, and electromagnetic. The EOC assigns, by activity, initial action responsibility for conflict resolution to a node which is party to the conflict. Most interinstrument conflicts are resolved by the ICCs and ISTs during an intermediate scheduling phase while the EOC is negotiating a TDRS schedule with the NCC.

Hull, Larry G.↗