ISO 22672:2021

Overview

ISO 22672:2021 - "Space data and information transfer systems - Space link extension (SLE) - Forward space packet service specification" defines the Forward Space Packet (FSP) service as an SLE transfer service for sending Space Packets to a spacecraft. Developed from the CCSDS SLE model, this ISO standard describes the FSP service abstractly: the required service operations, their parameters, resulting behaviors, and valid operation sequences. The standard is focused on online delivery, supports sequence‑controlled and expedited transfer modes, and is restricted to handling Space Packets transmitted via the Telecommand protocol stack. Offline delivery and alternative protocol stacks are outside the scope.

Keywords: ISO 22672:2021, Forward Space Packet, FSP service, Space Link Extension, SLE, Space Packets, telecommand protocol stack, online delivery, CCSDS.

Key Topics and Requirements

• Service definition and operations: Formalizes FSP operations (e.g., bind/unbind, start/stop, transfer-data, async notifications, status reports, directives and aborts) and the valid sequencing and behaviors for each.
• Parameter and data type specification: Defines operation parameters and data types (normative ASN.1 definitions are included in Annex A).
• Provider behavior and state model: Specifies dynamic behavior of the FSP service provider (state transitions, event handling).
• Multiplexing and queuing: Normative rules for multiplexing multiple FSP instances and forward TC Virtual Channels (Annex B).
• Production status and conformance: Production status model, functional group requirements, and a conformance matrix for implementations (Annexes C–E).
• Security and service management: High‑level security considerations and management context are described (service is independent of specific communications technologies).
• Scope limits: Does not prescribe physical implementations, RF transmission methods, or operational scheduling tools.

Applications and Who Uses It

• Space agencies and mission operations: For interoperable cross‑agency forward telecommand services between ground stations and mission control.
• Ground segment developers and integrators: To design SLE FSP service providers or mission user entities compatible with the CCSDS/ISO SLE framework.
• Vendor implementers of SLE products: For developing compliant middleware that transfers Space Packets over telecommand protocol stacks.
• Systems engineers and standards teams: As a basis for interoperability testing, conformance assessment, and architecture definition for forward link services.

Practical value: enables standardized, interoperable transfer of telecommands (Space Packets) to spacecraft in both controlled and expedited modes, reducing integration effort across agencies and vendors.

Related Standards

• CCSDS SLE Reference Model (Cross Support Reference Model - Part 1: SLE Services)
• Telecommand protocol stack standards referenced for Space Packet transmission (as noted in ISO 22672:2021)

For developers and program managers planning SLE FSP implementations, ISO 22672:2021 provides the formal service semantics and conformance criteria needed for interoperable forward telecommand services.