Space Communications and Navigation Program
Encyclopedia
The Space Communications and Navigation (SCaN) program places the three prime NASA
space communications networks, Space Network
(SN), Near Earth Network
(NEN) (previously known as the Ground Network or GN), and the Deep Space Network
(DSN), under one Management
and Systems Engineering
umbrella. It was established in 2006. It was previously known as the Space Communications & Data Systems (SCDS) Program.
created SCaN to direct an integrated networks program, different organizations at NASA Headquarters have managed the Agency’s space communications capabilities and functions under separate Programs using a variety of administrative approaches.
The SCaN Office was established by direction of Griffin in a Memorandum entitled “Establishment of a Space Communications and Navigation Office,” dated July 19, 2006. SCaN operates as a central organization within the Space Operations Mission Directorate (SOMD):
The Ground Network (GN) has since been renamed the Near Earth Network
.
, with a selection of spectra, modulation, and encoding methods, enumerated below.
The Deep Space Network communicates with spacecraft using S-band, X-band, and Ka-band.
of the carrier frequency
.
The Reed-Solomon method is used as the initial error-correcting block code
prior to the selected secondary encoding scheme.
NASA
The 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...
space communications networks, Space Network
Space Network
Space Network is a NASA program that combines space and ground elements to support spacecraft communications in Earth vicinity. The SN Project Office at Goddard Space Flight Center manages the SN, which consists of:...
(SN), Near Earth Network
Near Earth Network
The Near Earth Network provides orbital communications support for Near-Earth orbiting customer platforms via various NASA ground stations.NASA's NEN consists of ground stations in:...
(NEN) (previously known as the Ground Network or GN), and the Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...
(DSN), under one Management
Management
Management in all business and organizational activities is the act of getting people together to accomplish desired goals and objectives using available resources efficiently and effectively...
and Systems Engineering
Systems engineering
Systems engineering is an interdisciplinary field of engineering that focuses on how complex engineering projects should be designed and managed over the life cycle of the project. Issues such as logistics, the coordination of different teams, and automatic control of machinery become more...
umbrella. It was established in 2006. It was previously known as the Space Communications & Data Systems (SCDS) Program.
History
Before NASA's administrator Michael D. GriffinMichael D. Griffin
Michael Douglas Griffin is an American physicist and aerospace engineer. From April 13, 2005 to January 20, 2009 he served as Administrator of NASA, the space agency of the United States...
created SCaN to direct an integrated networks program, different organizations at NASA Headquarters have managed the Agency’s space communications capabilities and functions under separate Programs using a variety of administrative approaches.
The SCaN Office was established by direction of Griffin in a Memorandum entitled “Establishment of a Space Communications and Navigation Office,” dated July 19, 2006. SCaN operates as a central organization within the Space Operations Mission Directorate (SOMD):
The Ground Network (GN) has since been renamed the Near Earth Network
Near Earth Network
The Near Earth Network provides orbital communications support for Near-Earth orbiting customer platforms via various NASA ground stations.NASA's NEN consists of ground stations in:...
.
Services
SCaN is viewed as a service provider supporting interfaces and performing a standard set of functions, including:- Forward data transfer (uplinkUplinkA telecommunications link is generally one of several types of information transmission paths such as those provided by communication satellites to connect two points on earth.-Uplink:...
to spacecraft) - Return data transfer (downlink from spacecraft to ground)
- Dissimilar voice communications
- Emergency communications
- Post-landing communications
- Radiometric measurement
- Time correlation
- Service monitoring
- EphemerisEphemerisAn ephemeris is a table of values that gives the positions of astronomical objects in the sky at a given time or times. Different kinds of ephemerides are used for astronomy and astrology...
exchange - Operational coordination
- Service scheduling.
Communications schemes
Communications with spaceborne platforms is performed by RFRadio frequency
Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...
, with a selection of spectra, modulation, and encoding methods, enumerated below.
Spectra
The Space Network communicates with spacecraft using S-band, Ku-band, and Ka-band with planned laser/optical communications.The Deep Space Network communicates with spacecraft using S-band, X-band, and Ka-band.
Modulation
SN uses Phase Shift Keying and Phase ModulationPhase modulation
Phase modulation is a form of modulation that represents information as variations in the instantaneous phase of a carrier wave.Unlike its more popular counterpart, frequency modulation , PM is not very widely used for radio transmissions...
of the carrier frequency
Carrier wave
In telecommunications, a carrier wave or carrier is a waveform that is modulated with an input signal for the purpose of conveying information. This carrier wave is usually a much higher frequency than the input signal...
.
Encoding
The Space Network (used for near-Earth communications) supports the following encoding schemes:- BPSK
- QPSK/SQPSK
- 8PSK
- Rate 1/2 convolutional codingConvolutional codeIn telecommunication, a convolutional code is a type of error-correcting code in which* each m-bit information symbol to be encoded is transformed into an n-bit symbol, where m/n is the code rate and...
- SQPNPhase-shift keyingPhase-shift keying is a digital modulation scheme that conveys data by changing, or modulating, the phase of a reference signal ....
- PN codingPseudorandom noiseIn cryptography, pseudorandom noise is a signal similar to noise which satisfies one or more of the standard tests for statistical randomness....
- used to reduce power spectral density for low bit rate signals, and for time transfer.
The Reed-Solomon method is used as the initial error-correcting block code
Block code
In coding theory, block codes refers to the large and important family of error-correcting codes that encode data in blocks.There is a vast number of examples for block codes, many of which have a wide range of practical applications...
prior to the selected secondary encoding scheme.
See also
- Space NetworkSpace NetworkSpace Network is a NASA program that combines space and ground elements to support spacecraft communications in Earth vicinity. The SN Project Office at Goddard Space Flight Center manages the SN, which consists of:...
- Deep Space NetworkDeep Space NetworkThe Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...
- Near Earth NetworkNear Earth NetworkThe Near Earth Network provides orbital communications support for Near-Earth orbiting customer platforms via various NASA ground stations.NASA's NEN consists of ground stations in:...
- Indian Deep Space NetworkIndian Deep Space NetworkThe Indian Deep Space Network is a network of large antennas and communication facilities that supports the interplanetary spacecraft missions of India. It is located at Byalalu, a village about 100 km from Bangalore, India. It was officially inaugurated on 17 October 2008 by ISRO chairman...
- Tracking and Data Relay SatelliteTracking and Data Relay SatelliteA Tracking and Data Relay Satellite is a type of communications satellite that forms part of the Tracking and Data Relay Satellite System used by NASA and other United States government agencies for communications to and from independent "User Platforms" such as satellites, balloons, aircraft,...
- Eastern Range