The Space Communications Protocol Standards (SCPS) specify a developmental system of international protocols for data communications between spacecraft and points on Earth. SCPS protocols are intended to make a spacecraft appear, to a terrestrial computer user, as just another node on the Internet. The protocols are implemented to be as interoperable as possible to other systems. The SCPS file protocols are based partly on the Internet File Transfer Protocol (FTP), but include additional features necessary for smooth communication over channels that include interruptible Earth/spacecraft links; unlike the Internet FTP, the SCPS protocols provide for restart of interrupted file transfers and provide record read/update services. The SCPS protocols include (1) a file-handling protocol based on the Internet FTP, with modifications to optimize performance for typical spacecraft data streams; (2) an underlying retransmission protocol based on the Internet Transmission Control Protocol (TCP), with modifications to ensure reliability in the face of interruptions; (3) a data-protection protocol derived from a number of security protocols; and (4) a scalable networking protocol for routing of messages, based on the Internet Protocol (IP), with modifications to support space routing and increase communication efficiency.

This program was written by Eric Travis, Robert Durst, Patrick Feighery, and Mary Jo Zukoski of Mitre Corp. and by Steven Sides of SAIC for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at  under the Software category.

This software is available for commercial licensing. Please contact Don Hart of the California Institute of Technology at (818) 393-3425. Refer to NPO-20282.

This Brief includes a Technical Support Package (TSP).
Software for Spacecraft/Ground Communication via the Internet

(reference NPO-20282) is currently available for download from the TSP library.

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This article first appeared in the April, 2000 issue of NASA Tech Briefs Magazine.

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