ABSTRACT
This chapter describes the model for space missions, where spacecraft communicate at layer-2 (OSI Data Link Layer) with their mission operations centers. It provides an overview of the Delay Tolerant networks (DTN) model for space communications, describes the requirements for a space internetworking architecture, and a number of alternatives to realize such architecture. The chapter also describes the space-specific capabilities developed to support the DTN architecture in space, including modifications to the Licklider Transmission Protocol (LTP) and the Bundle Protocol made by the Consultative Committee for Space Data Systems (CCSDS). It explains the benefits of DTN to space missions. The chapter discusses some standard DTN applications to support interoperability with legacy spacecraft and emergency operations. It also discusses experiments and operational space missions demonstrating and using DTN. LTP for CCSDS also defines a Service Data Aggregation service that is not present in RFC5326. Aggregate Custody Signaling was developed to support initial DTN experimentation on the International Space Station.
