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Q: Why were the SCPS protocols developed?

The principal goal of the SCPS effort was to lower lifecycle costs by reducing development and operations costs in space communications systems.

The SCPS program was initiated in response to several demands:

a) A need for standard protocols to support reliable data transfer.

b) The need to accommodate evolving multi-node mission configurations that require in-space network routing.

c) The need to significantly reduce operations costs and thus maintain the ability to produce results from space missions in the face of decreasing funding.

d) The need to provide compatibility and interoperability with the internet.

The SCPS are designed to meet these demands by increasing standardization and interoperability both within and among CCSDS Agencies and other developers and operators of spacecraft.

Q: Do SCPS replace earlier CCSDS protocols?

No. SCPS augments these protocols by providing reliable stream or file transfer over CCSDS frames at the link layer and dynamic networking for those missions that need it. CCSDS Packets remain as the telemetry and telecommand source message format. CCSDS RF and modulation Recommendations are also unaffected.

Note: At the time of publication, efforts were underway to enhance CCSDS link protocols to support multiplexing of SCPS Network Protocol and other
network-level data units into CCSDS virtual channel frames.

Some missions may choose not to use some features of earlier CCSDS protocols, if their needs are better met by SCPS. For example, a mission that uses SCPS network addressing over a CCSDS frames may find it unnecessary to use several virtual channels for data routing.

Q: What types of missions are the SCPS intended to support?

SCPS is aimed at a broad range of space missions including:

a) Support for spacecraft in low-earth and geosynchronous orbits, as well as
lunar and planetary spacecraft. The primary emphasis has been on support of missions at lunar distances or closer. SCPS network and security protocols are relatively immune to communications delay, and thus can support deep-space missions today. SCPS Phase 3, beginning in 1997, will provide additional capabilities for data transport and file transfer in deep-space missions.

b) Support of spacecraft with a range of on-board communication and on-board data handling resources, including those with limited on-board computer and memory resources, as well as those with multiple, high-capacity on-board computers with extensive data storage.

c) Support of multi-node in-space networks, including:

i) LEO spacecraft constellations

ii) Cluster-like missions

iii) Deep space orbiter/lander/rover planetary mission

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