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All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

A space demonstration of the next generation TT and C standards

An initiative to develop an integrated set of space data communication protocols, which will complement and expand upon the current Consultative Committee for Space Data Systems (CCSDS) telemetry and telecommand standards, is reported on. The aim is to provide a comprehensive set of spacecraft control and monitoring data handling services. The space communications protocol standards (SCPS) initiative will provide a set of spacecraft telemetry, telecommand and control (TT and C) standards that will serve a wide range of civilian and military space missions. A software flight test and demonstration of the capabilities of the SCPS protocols was performed using the in orbit space technology research vehicle and compared to laboratory simulations. The results from this test will contribute to the continued SCPS protocol development program.

Shave, N. P.↗
NASA NTRS1991

Standard formatted data units-control authority procedures

The purpose of this document is to establish a set of minimum and optional requirements for the implementation of Control Authority (CA) organizations within and among the Agencies participating in the Consultative Committee for Space Data Systems (CCSDS). By satisfying these requirements, the resultant cooperating set of CA organizations will produce a global CA service supporting information transfer with digital data under the Standard Formatted Data Unit (SFDU) concept. This service is primarily accomplished through the registration, permanent archiving, and dissemination of metadata in the form of Metadata Objects (MDO) that assist in the interpretation of data objects received in SFDU form. This Recommendation addresses the responsibilities, services, and interface protocols for a hierarchy of CA organizations. The top level, consisting of the CCSDS Secretariat and its operational agent, is unique and primarily provides a global coordination function. The lower levels are Agency CA organizations that have primary responsibility for the registration, archiving, and dissemination of MDOs. As experience is gained and technology evolves, the CA Procedures will be extended to include enhanced services and their supporting protocols. In particular, it is anticipated that eventually CA organizations will be linked via networks on a global basis, and will provide requestors with online automated access to CA services. While this Recommendation does not preclude such operations, it also does not recommend the specific protocols to be used to ensure global compatibility of these services. These recommendations will be generated as experience is gained.

Source record↗
NASA NTRS1991

Services, architectures, and protocols for space data systems

The author presents a comprehensive discussion of three major aspects of the work of the Consultative Committee for Space Data Systems (CCSDS), a worldwide cooperative effort of national space agencies. The author examines the CCSDS space data communications network concept on which the data communications facilities of future advanced orbiting systems will be based. He derives the specifications of an open communications architecture as a reference model for the development of services and protocols that support the transfer of information over space data communications networks. Detailed specifications of the communication services and information transfer protocols that have reached a high degree of maturity and stability are offered. The author also includes a complete list of currently available CCSDS standards and supporting documentation.

Helgert, Hermann J.↗
NASA NTRS2016

In-Space Networking On NASA's SCaN Testbed

The NASA Space Communications and Navigation (SCaN) Testbed, an external payload onboard the International Space Station, is equipped with three software defined radios (SDRs) and a programmable flight computer. The purpose of the Testbed is to conduct inspace research in the areas of communication, navigation, and networking in support of NASA missions and communication infrastructure. Multiple reprogrammable elements in the end to end system, along with several communication paths and a semi-operational environment, provides a unique opportunity to explore networking concepts and protocols envisioned for the future Solar System Internet (SSI). This paper will provide a general description of the system's design and the networking protocols implemented and characterized on the testbed, including Encapsulation, IP over CCSDS, and Delay-Tolerant Networking (DTN). Due to the research nature of the implementation, flexibility and robustness are considered in the design to enable expansion for future adaptive and cognitive techniques. Following a detailed design discussion, lessons learned and suggestions for future missions and communication infrastructure elements will be provided. Plans for the evolving research on SCaN Testbed as it moves towards a more adaptive, autonomous system will be discussed.

space networks↗
NASA NTRS2017

CCSDS USLP Activities

An overview of activities of the CCSDS (Consultative Committee for Space Data Systems) USLP (Unified Space Data Link Protocol) implementation.

Pitts, Lee↗
NASA NTRS2016

Using SpaceWire Time Codes for Spacecraft Time Synchronization

This paper describes how SpaceWire Time Codes can be used for synchronizing time within various subsystems of a spacecraft as well as, maintaining a common time reference needed for coordinating operations within a spacecraft. The algorithms to account for inaccuracies in the time distribution method were based on the NASA-4009 Space Telecommunication Radio System (STRS) standard [1], which defined an interface for synchronizing clocks running at different tick rates and tick resolutions.

SpaceWire Time Distribution Protocol↗
NASA NTRS2011

Space Flight Middleware: Remote AMS over DTN for Delay-Tolerant Messaging

This paper describes a technique for implementing scalable, reliable, multi-source multipoint data distribution in space flight communications -- Delay-Tolerant Reliable Multicast (DTRM) -- that is fully supported by the "Remote AMS" (RAMS) protocol of the Asynchronous Message Service (AMS) proposed for standardization within the Consultative Committee for Space Data Systems (CCSDS). The DTRM architecture enables applications to easily "publish" messages that will be reliably and efficiently delivered to an arbitrary number of "subscribing" applications residing anywhere in the space network, whether in the same subnet or in a subnet on a remote planet or vehicle separated by many light minutes of interplanetary space. The architecture comprises multiple levels of protocol, each included for a specific purpose and allocated specific responsibilities: "application AMS" traffic performs end-system data introduction and delivery subject to access control; underlying "remote AMS" directs this application traffic to populations of recipients at remote locations in a multicast distribution tree, enabling the architecture to scale up to large networks; further underlying Delay-Tolerant Networking (DTN) Bundle Protocol (BP) advances RAMS protocol data units through the distribution tree using delay-tolerant storeand- forward methods; and further underlying reliable "convergence-layer" protocols ensure successful data transfer over each segment of the end-to-end route. The result is scalable, reliable, delay-tolerant multi-source multicast that is largely self-configuring.

Disruption Tolerant Networking (DTN)↗
NASA NTRS1990

CCSDS Advanced Orbiting Systems - International data communications standards for the Space Station Freedom

Established in 1982, the Consultative Committee for Space Data Systems (CCSDS) is an international organization that is staffed by data-handling experts from nearly all of the world's major space agencies. Its goal is to develop standard data-communications techniques so that several agencies may cross-support each other's data flow and thus allow complex, international missions to be flown. Under the general umbrella of Advanced Orbiting Systems (AOS), an international CCSDS task force was formed in 1985 to develop standard data-communications concepts for manned missions, such as the Space Station Freedom and the Hermes space plane, and large unmanned vehicles, such as polar orbiting platforms. The history of the CCSDS and the development of the AOS recommendation are reviewed, and the user services and protocols embodied in its systems architecture are introduced.

Hooke, Adrian J.↗
NASA NTRS2011

CCSDS Advanced Orbiting Systems Virtual Channel Access Service for QoS MACHETE Model

To support various communications requirements imposed by different missions, interplanetary communication protocols need to be designed, validated, and evaluated carefully. Multimission Advanced Communications Hybrid Environment for Test and Evaluation (MACHETE), described in "Simulator of Space Communication Networks" (NPO-41373), NASA Tech Briefs, Vol. 29, No. 8 (August 2005), p. 44, combines various tools for simulation and performance analysis of space networks. The MACHETE environment supports orbital analysis, link budget analysis, communications network simulations, and hardware-in-the-loop testing. By building abstract behavioral models of network protocols, one can validate performance after identifying the appropriate metrics of interest. The innovators have extended the MACHETE model library to include a generic link-layer Virtual Channel (VC) model supporting quality-of-service (QoS) controls based on IP streams. The main purpose of this generic Virtual Channel model addition was to interface fine-grain flow-based QoS (quality of service) between the network and MAC layers of the QualNet simulator, a commercial component of MACHETE. This software model adds the capability of mapping IP streams, based on header fields, to virtual channel numbers, allowing extended QoS handling at link layer. This feature further refines the QoS v existing at the network layer. QoS at the network layer (e.g. diffserv) supports few QoS classes, so data from one class will be aggregated together; differentiating between flows internal to a class/priority is not supported. By adding QoS classification capability between network and MAC layers through VC, one maps multiple VCs onto the same physical link. Users then specify different VC weights, and different queuing and scheduling policies at the link layer. This VC model supports system performance analysis of various virtual channel link-layer QoS queuing schemes independent of the network-layer QoS systems.

Jennings, Esther H.↗
NASA NTRS2011

Asynchronous Message Service Reference Implementation

This software provides a library of middleware functions with a simple application programming interface, enabling implementation of distributed applications in conformance with the CCSDS AMS (Consultative Committee for Space Data Systems Asynchronous Message Service) specification. The AMS service, and its protocols, implement an architectural concept under which the modules of mission systems may be designed as if they were to operate in isolation, each one producing and consuming mission information without explicit awareness of which other modules are currently operating. Communication relationships among such modules are self-configuring; this tends to minimize complexity in the development and operations of modular data systems. A system built on this model is a society of generally autonomous, inter-operating modules that may fluctuate freely over time in response to changing mission objectives, modules functional upgrades, and recovery from individual module failure. The purpose of AMS, then, is to reduce mission cost and risk by providing standard, reusable infrastructure for the exchange of information among data system modules in a manner that is simple to use, highly automated, flexible, robust, scalable, and efficient. The implementation is designed to spawn multiple threads of AMS functionality under the control of an AMS application program. These threads enable all members of an AMS-based, distributed application to discover one another in real time, subscribe to messages on specific topics, and to publish messages on specific topics. The query/reply (client/server) communication model is also supported. Message exchange is optionally subject to encryption (to support confidentiality) and authorization. Fault tolerance measures in the discovery protocol minimize the likelihood of overall application failure due to any single operational error anywhere in the system. The multi-threaded design simplifies processing while enabling application nodes to operate at high speeds; linked lists protected by mutex semaphores and condition variables are used for efficient, inter-thread communication. Applications may use a variety of transport protocols underlying AMS itself, including TCP (Transmission Control Protocol), UDP (User Datagram Protocol), and message queues.

Burleigh, Scott C.↗
NASA NTRS1993

A reference model for space data system interconnection services

The widespread adoption of standard packet-based data communication protocols and services for spaceflight missions provides the foundation for other standard space data handling services. These space data handling services can be defined as increasingly sophisticated processing of data or information received from lower-level services, using a layering approach made famous in the International Organization for Standardization (ISO) Open System Interconnection Reference Model (OSI-RM). The Space Data System Interconnection Reference Model (SDSI-RM) incorporates the conventions of the OSIRM to provide a framework within which a complete set of space data handling services can be defined. The use of the SDSI-RM is illustrated through its application to data handling services and protocols that have been defined by, or are under consideration by, the Consultative Committee for Space Data Systems (CCSDS).

Pietras, John↗
NASA NTRS2005

Mission Operations and Information Management Area Spacecraft Monitoring and Control Working Group

Working group goals for this year are: Goal 1. Due to many review comments the green books will be updated and available for re-review by CCSDS. Submission of green books to CCSDS for approval. Goal 2.Initial set of 4 new drafts of the red books as following: SM&C protocol: update with received comments. SM&C common services: update with received comments and expand the service specification. SM&C core services: update with received comments and expand the service the information model. SM&C time services: (target objective): produce initial draft following template of core services.

Lokerson, Donald C.↗
NASA NTRS2003

Reliable Transport over SpaceWire for James Webb Space Telescope (JWST) Focal Plane Electronics (FPE) Network

NASA's James Webb Space Telescope (JWST) faces difficult technical and budgetary challenges to overcome before it is scheduled launch in 2010. The Integrated Science Instrument Module (ISIM), shares these challenges. The major challenge addressed in this paper is the data network used to collect, process, compresses and store Infrared data. A total of 114 Mbps of raw information must be collected from 19 sources and delivered to the two redundant data processing units across a twenty meter deployed thermally restricted interface. Further data must be transferred to the solid-state recorder and the spacecraft. The JWST detectors are kept at cryogenic temperatures to obtain the sensitivity necessary to measure faint energy sources. The Focal Plane Electronics (FPE) that sample the detector, generate packets from the samples, and transmit these packets to the processing electronics must dissipate little power in order to help keep the detectors at these cold temperatures. Separating the low powered front-end electronics from the higher-powered processing electronics, and using a simple high-speed protocol to transmit the detector data minimize the power dissipation near the detectors. Low Voltage Differential Signaling (LVDS) drivers were considered an obvious choice for physical layer because of their high speed and low power. The mechanical restriction on the number cables across the thermal interface force the Image packets to be concentrated upon two high-speed links. These links connect the many image packet sources, Focal Plane Electronics (FPE), located near the cryogenic detectors to the processing electronics on the spacecraft structure. From 12 to 10,000 seconds of raw data are processed to make up an image, various algorithms integrate the pixel data Loss of commands to configure the detectors as well as the loss of science data itself may cause inefficiency in the use of the telescope that are unacceptable given the high cost of the observatory. This combination of requirements necessitates a redundant, fault tolerant, high- speed, low mass, low power network with a low Bit error Rate(1E-9- 1E-12). The ISIM systems team performed many studies of the various network architectures that meeting these requirements. The architecture selected uses the Spacewire protocol, with the addition of a new transport and network layer added to implement end-to-end reliable transport. The network and reliable transport mechanism must be implemented in hardware because of the high average information rate and the restriction on the ability of the detectors to buffer data due to power and size restrictions. This network and transport mechanism was designed to be compatible with existing Spacewire links and routers so that existing equipment and designs may be leveraged upon. The transport layer specification is being coordinated with European Space Agency (ESA), Spacewire Working Group and the Consultative Committee for Space Data System (CCSDS) PlK Standard Onboard Interface (SOIF) panel, with the intent of developing a standard for reliable transport for Spacewire. Changes to the protocol presented are likely since negotiations are ongoing with these groups. A block of RTL VHDL that implements a multi-port Spacewire router with an external user interface will be developed and integrated with an existing Spacewire Link design. The external user interface will be the local interface that sources and sinks packets onto and off of the network (Figure 3). The external user interface implements the network and transport layer and handles acknowledgements and re-tries of packets for reliable transport over the network. Because the design is written in RTL, it may be ported to any technology but will initially be targeted to the new Actel Accelerator series (AX) part. Each link will run at 160 Mbps and the power will be about 0.165 Watt per link worst case in the Actel AX.

Rakow, Glenn↗
NASA NTRS1985

Standards for space data systems

NASA has chaired the Consultative Committee for Space Data Systems (CCSDS) for the past four years. During that time, a top-level, end-to-end reference model for space data sytems has been developed that identifies the functions anad services which must be provided by space data systems, and defines the interfaces between major functional elements. A group of definitions for standard protocols has been derived by analyzing these interfaces, and a set of detailed guidelines for space data system standards is in the final stages of negotiation among member CCSDS agencies. Two guidelines that address packet telemetry and channel coding have been approved and are being incorporated into the internal standards of member agencies. Others (packet telecommand, time code, standards data format unit) are in review within CCSDS technical panels and will soon be submitted for approval. These guidelines provide a mechanism for significant cost savings in the implementation of space data systems by allowing reuse of hardware and software for different payloads and for missions, and by enabling the substitution of new technology/higher performance elements at key points in the data system without causing major perturbations in the remainder of the system.

Connell, E. B.↗
NASA NTRS2006

Overview of AMS (CCSDS Asynchronous Message Service)

This viewgraph presentation gives an overview of the Consultative Committee for Space Data Systems (CCSDS) Asynchronous Message Service (AMS). The topics include: 1) Key Features; 2) A single AMS continuum; 3) The AMS Protocol Suite; 4) A multi-continuum venture; 5) Constraining transmissions; 6) Security; 7) Fault Tolerance; 8) Performance of Reference Implementation; 9) AMS vs Multicast (1); 10) AMS vs Multicast (2); 11) RAMS testing exercise; and 12) Results.

asynchronous↗
NASA NTRS2024

High-Rate Delay Tolerant Networking (HDTN) Software Requirements Analysis

This document serves as a detailed analysis of the main networking protocols implemented by HDTN. Sources of the protocol specifications include Internet Engineering Task Force (IETF) Request for Comments (RFC) and Consultative Committee for Space Data Systems (CCSDS) standards. The focus of this report is to derive software requirements suitable for NASA Procedural Requirements 7150.2D Class B compliance, including requirements traceability and software verification and validation, from the source specifications. This analysis will be incorporated into the finalized HDTN Software Requirements Specification (SRS) but does not encompass the full scope of the HDTN SRS. Requirements in this document are considered draft. The complete requirements will include bundle application requirements, interface requirements, computer resource requirements, software quality factors, and additional requirements as determined by the project. This document is publicly released to the greater community to receive feedback and foster collaboration opportunities.

Rachel Dudukovich↗
NASA NTRS2009

Wireless Network Communications Overview for Space Mission Operations

The mission of the On-Board Wireless Working Group (WWG) is to serve as a general CCSDS focus group for intra-vehicle wireless technologies. The WWG investigates and makes recommendations pursuant to standardization of applicable wireless network protocols, ensuring the interoperability of independently developed wireless communication assets. This document presents technical background information concerning uses and applicability of wireless networking technologies for space missions. Agency-relevant driving scenarios, for which wireless network communications will provide a significant return-on-investment benefiting the participating international agencies, are used to focus the scope of the enclosed technical information.

Fink, Patrick W.↗