SpaceWire is a
spacecraftA spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....
communication network based in part on the
IEEE 1355IEEE Standard 1355-1995, IEC 14575, or ISO 14575 is a data communications standard for Heterogeneous Interconnect . It is a low-cost, low latency, scalable serial interconnection system, originally intended for communication between large numbers of inexpensive computers. It lacks many of the...
standard of communications. It is coordinated by the
European Space AgencyThe European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
(ESA) in collaboration with international space agencies including
NASAThe National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
,
JAXAThe , or JAXA, is Japan's national aerospace agency. Through the merger of three previously independent organizations, JAXA was formed on October 1, 2003, as an Independent Administrative Institution administered by the Ministry of Education, Culture, Sports, Science and Technology and the...
and
RKAThe Russian Federal Space Agency , commonly called Roscosmos and abbreviated as FKA and RKA , is the government agency responsible for the Russian space science program and general aerospace research. It was previously the Russian Aviation and Space Agency .Headquarters of Roscosmos are located...
. Within a SpaceWire network the nodes are connected through low-cost, low-
latencyLag is a common word meaning to fail to keep up or to fall behind. In real-time applications, the term is used when the application fails to respond in a timely fashion to inputs...
, full-duplex, point-to-point serial links and
packet switchingPacket switching is a digital networking communications method that groups all transmitted data – regardless of content, type, or structure – into suitably sized blocks, called packets. Packet switching features delivery of variable-bit-rate data streams over a shared network...
wormhole routingWormhole flow control, also called wormhole switching or wormhole routing is a system of simple flow control in computer networking based on known fixed links. It is a subset of flow control methods called Flit-Buffer Flow Control....
routers. SpaceWire covers two (physical and data-link) of the seven layers of the
OSI modelThe Open Systems Interconnection model is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar...
for communications.
Architecture
SpaceWire's modulation and data formats generally follow the
data strobe encodingData strobe encoding is an encoding scheme for transmitting data in digital circuits.It uses two signal lines , Data and Strobe...
-
differential ended signalingDifferential signaling is a method of transmitting information electrically by means of two complementary signals sent on two separate wires. The technique can be used for both analog signaling, as in some audio systems, and digital signaling, as in RS-422, RS-485, Ethernet , PCI Express and USB...
(DS-DE) part of the IEEE Std 1355-1995. SpaceWire utilizes
asynchronous communicationIn telecommunications, asynchronous communication is transmission of data without the use of an external clock signal, where data can be transmitted intermittently rather than in a steady stream. Any timing required to recover data from the communication symbols is encoded within the symbols...
and allows speeds between 2 Mbit/s and 400 Mbit/s. DS-DE is well-favored because it describes modulation, bit formats, routing,
flow controlIn data communications, flow control is the process of managing the pacing of data transmission between two nodes to prevent a fast sender from outrunning a slow receiver. It provides a mechanism for the receiver to control the transmission speed, so that the receiving node is not overwhelmed with...
and error detection in hardware, with little need for software. SpaceWire also has very low error rates, deterministic system behavior, and relatively simple digital electronics. SpaceWire replaced old PECL differential drivers in the physical layer of IEEE 1355 DS-DE by low-voltage differential signaling (LVDS). SpaceWire also proposes the use of space-qualified 9-pin connectors. SpaceWire and IEEE 1355 DS-DE allows for a wider set of speeds for data transmission, and some new features for automatic
failoverIn computing, failover is automatic switching to a redundant or standby computer server, system, or network upon the failure or abnormal termination of the previously active application, server, system, or network...
. The fail-over features let data find alternate routes, so a spacecraft can have multiple data buses, and be made
fault-tolerantIn engineering, fault-tolerant design is a design that enables a system to continue operation, possibly at a reduced level , rather than failing completely, when some part of the system fails...
. SpaceWire also allows the propagation of time interrupts over SpaceWire links, eliminating the need for separate time discretes.
Uses
SpaceWire is used worldwide. Its use began primarily in
ESAThe European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
projects, but it is currently used by
NASAThe National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
,
JAXAThe , or JAXA, is Japan's national aerospace agency. Through the merger of three previously independent organizations, JAXA was formed on October 1, 2003, as an Independent Administrative Institution administered by the Ministry of Education, Culture, Sports, Science and Technology and the...
,
RKAThe Russian Federal Space Agency , commonly called Roscosmos and abbreviated as FKA and RKA , is the government agency responsible for the Russian space science program and general aerospace research. It was previously the Russian Aviation and Space Agency .Headquarters of Roscosmos are located...
, and many other organizations and companies. Some NASA projects using it include the
James Webb Space TelescopeThe James Webb Space Telescope , previously known as Next Generation Space Telescope , is a planned next-generation space telescope, optimized for observations in the infrared. The main technical features are a large and very cold 6.5 meter diameter mirror, an observing position far from Earth,...
,
Swift'sThe Swift Gamma-Ray Burst Mission consists of a robotic spacecraft called Swift, which was launched into orbit on 20 November 2004, 17:16:00 UTC on a Delta II 7320-10C expendable launch vehicle. Swift is managed by the NASA Goddard Space Flight Center, and was developed by an international...
Burst Alert Telescope, the
Lunar Reconnaissance OrbiterThe Lunar Precursor Robotic Program is a program of robotic spacecraft missions which NASA will use to prepare for future human spaceflight missions to the Moon. Two LPRP missions, the Lunar Reconnaissance Orbiter and the Lunar Crater Observation and Sensing Satellite , were launched in June 2009...
,
LCROSSThe Lunar Crater Observation and Sensing Satellite was a robotic spacecraft operated by NASA. The mission was conceived as a low-cost means of determining the nature of hydrogen detected at the polar regions of the moon. The main LCROSS mission objective was to explore the presence of water ice...
, the
Geostationary Operational Environmental SatelliteThe Geostationary Satellite system, operated by the United States National Environmental Satellite, Data, and Information Service , supports weather forecasting, severe storm tracking, and meteorology research. Spacecraft and ground-based elements of the system work together to provide a continuous...
(GOES-R), and the Communications, Navigation, and Networking Reconfigurable Testbed (CoNNeCT). It has also been selected by the
United States Department of DefenseThe United States Department of Defense is the U.S...
for Operationally Responsive Space. SpaceWire initiatives are being coordinated between several Space Agencies in the frame of
CCSDSThe Consultative Committee for Space Data Systems was formed in 1982 by the major space agencies of the world to provide a forum for discussion of common problems in the development and operation of space data systems...
in order to extend its communication model to the Network and Transport Layers of the
OSI modelThe Open Systems Interconnection model is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar...
.
Protocols
The ESA has a draft specification in place for the Protocol ID.
The following Protocol ID's have been assigned in ECSS-E-ST-50-11:
- 1: Remote Memory Access Protocol (RMAP)
- 2: CCSDS Packet Transfer Protocol
- 238: Proposal for Reliable Data Delivery Protocol (RDDP) (used on GOES-R
The Geostationary Satellite system, operated by the United States National Environmental Satellite, Data, and Information Service , supports weather forecasting, severe storm tracking, and meteorology research. Spacecraft and ground-based elements of the system work together to provide a continuous...
)
- 239: Serial Transfer Universal Protocol (STUP
Stup is a village in the municipality of Sjenica, Serbia. According to the 2002 census, the village has a population of 193 people.-References:...
) (Used on SMCS-332 ASICAn application-specific integrated circuit is an integrated circuit customized for a particular use, rather than intended for general-purpose use. For example, a chip designed solely to run a cell phone is an ASIC...
)
External links
Commercial providers of SpaceWire equipment:
Non-Commercial providers of SpaceWire:
SpaceWire IP Cores:
Articles: