PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT PUBLICATION_DATE = 2001-09-01 NOTE = "NEAR Mission Acronyms." END_OBJECT = TEXT END NEAR ACRONYM LIST This file contains a list of acronyms specific to the NEAR mission and are used by several of the documents on this volume. Acronym Description ------- -------------------------------------------------------- ACE Project Mission Controller (DSN) ACS Attitude Control System ADC Analog-to-Digital Converter AEC Automatic Exposure Control AGC Automatic Gain Control Ah Ampere-hour AIU Attitude Interface Units. There are two computers used for handling spacecraft commands, one of which is used (mainly for redundancy, in case one fails, there is a backup). There are also two Attitude Interface Units; they link the flight computer to the attitude (spacecraft pointing) control system, which includes gyroscopes, a star camera, accelerometers (for measuring how fast the spacecraft moves and turns in each direction) and the spacecraft thrusters. AIU Attitude Interface (Processor) Unit ANSI American National Standards Institute AOS Advanced Orbiting Systems (CCSDS); Acquisition of Signal APD Avalanche Photodetector Diode (sensor in the receiver of the NLR) APL The Applied Physics Laboratory in Laurel, Maryland. Part of the Johns Hopkins University. NEAR was built and managed by APL. APLNIS APL Network Information System ARQ Automatic Request for Retransmission ASIC Application-specific Integrated Circuit AU Astronomical Unit, the average distance from the Earth to the Sun. 149,597,870 km (92,955,808 miles). Astronomical Units are a common unit used for distances in solar system. b bit, binary digit (used as a suffix; e.g., 256b means 256 bits) B Byte, octet of bits (used as a suffix; e.g., 2MB means two megabytes) BC Bus Controller of the NEAR MIL-STD-1553 bus, located in the active CTP processor BCH Bose-Chaudhuri-Hocquenghem BCRTM Bus Controller/Remote Terminal/Monitor BER Bit Error Rate BGO Bismuth Germanate BIT Built-In Test BLF Best Lock Frequency BOA Beginning of (Acquisition) BOL Beginning of Life BOT Beginning of Telemetry BPS Bits per Second bps bits per second Bps Bytes per second BTE Bench Test Equipment BVR Block Five Receiver BWG Beam Waveguide C&DH Command and Data Handling. C/TP Command & Telemetry Processor (also CTP) CCD Charge Coupled Device CCSDS Consultative Committee for Space Data Systems CDU Command Detector Unit CLCW Command Link Control Word CLTU Command Link Transmission Unit CMOS Complementary Metal-Oxide Semiconductor COP Command Operation Procedure CPU Central Processing Unit CRC Cyclic Redundancy Check CSCI Computer Software Configuration Item CTP Command and Telemetry Processor dB decibel DIGSS Development and Integration of Ground System Software DLA Declination of Launch Azimuth DMD DSCC Media Calibration Subsystem DMR Detailed Mission Requirement DN Digital Number DOD Depth of Discharge DPCM Differential Pulse Code Modulation DPU Data Processing Unit DPW The PDS Data Preparation Workbook. DSAD Digital Solar Attitude Detector, used in the attitude control subsystem DSCC Deep Space Communications Complex DSM Deep Space Maneuver. DSN Deep Space Network, the JPL-administered network of interplanetary tracking stations in Goldstone, Calif.; Madrid, Spain; and Canberra, Australia. 34 meter is the diameter of the radio antenna used. high gain means that NEAR's 1-meter high-gain antenna is pointed at the Earth and used for the communication. DST Deep Space Transponder Earth Safe Mode In Earth Safe Mode, the spacecraft is placed in a power safe configuration with an emergency mode downlink. The solar panels are pointed directly at the Sun, and the medium gain antenna is placed on the Earth. The underlying assumption in Earth Safe Mode is that the Guidance & Control subsystem retains knowledge of the location of the Earth, and that the telecommunications subsystem is operational. ECL Emitter-Coupled Logic EDAC Error Detection and Control EDR Experimental Data Record. EEPROM Electronically-Erasable Programmable Read-Only Memory EOT End of Telemetry ER Eastern (Test) Range Eros An asteroid which is the destination of the NEAR spacecraft. Eros is one of the Near-Earth asteroids. ESB Earth Swingby, 23 Jan 98 FARM Frame Acceptance and Reporting Mechanism FC Flight Computer. NEAR has 2 flight computers. FIFO First In, First Out FOP Frame Operation Procedure FOR Field of Regard FOV Field Of View FPGA Field-Programmable Gate Array FVP Fine Velocity Control G&C Guidance and Control Ge Germanium GMT Greenwich Mean Time GSE Ground Support Equipment GSFC NASA/Goddard Space Flight Center GSS Ground Support System H&S Health and Status HEF High Efficiency HGA High Gain Antenna. This is the dish antenna on the NEAR spacecraft. HVCE High Voltage Control Electronics HVPS High Voltage Power Supply Hz Hertz, cycles or periods per second I&T Integration and Test I/F Interface I/O Input/Output IC Integrated Circuit IMR Interrupt Mask Register IMU Inertial Measurement Unit InGaAs Indium Gallium Arsenide IR InfraRed IREQ Interrupt REQuest ISS Interface Support Structure ITOGS Integration and Test Operations Ground Segment JHU The Johns Hopkins University JPL Jet Propulsion Laboratory, in Pasadena, CA. K suffix representing kilo, indicating 1024 (e.g. 2^10 ) keV kilo electron Volts KIPS thousands of Instructions Per Second LASER Light Amplification by Stimulated Emission of Radiation LED Light Emitting Diode LEO Low Earth Orbit LEOP Launch and Early Operations LFVC Large Fine Velocity Control LGA Low Gain Antenna LHC Left hand Circular LMC Link Monitor and Control LOS Loss of Signal LSb Least-Significant bit LSB Least-Significant Byte LSSP Launch Site Support Plan LSW Least Significant Word LVA Large Velocity Adjustment, as in LVA thruster. LVS Low Bus Sense (Voltage) MAG Magnetometer. One of the instruments on NEAR. MDA Metric Data Assembly MDT Mission Design Team MET Mission Elapsed Time MeV Mega electron Volts MGA Medium-Gain Antenna (Fan Beam) MIPS Millions of Instructions Per Second MLI Multi-Layer Insulation MOAT Mission Operations Analysis Tool Kit MOC Mission Operations Center. People, processes, and facilities for planning, control, and assessment necessary for conducting the mission. MOGS Mission Operations Ground Segment MOM Mission Operations Manager MOPDD Mission Operations Process Description Document MOPS Mission Operations. Acitivites of the MOC. MOR Mission Operations Review MOS Mission Operations System MOSES Model of Spacecraft, Environment, and Subsystems MOSO Mission Operations Systems Office MPP Maximum Power Point MRDF Material Review Disposition Form MRT Mission Readiness Test MSb Most Significant bit MSB Most-Significant Byte msec millisecond MSI MultiSpectral Imager (the main camera). One of the instruments on NEAR. MSW Most Significant Word mux multiplexer MVPS Medium Voltage Power Supply NaI Sodium Iodide NAIF Navigation and Ancillary Information Facility, a discipline node of PDS. NASCOM NASA Communications NASTIE NEAR Attitude System Test and Integration Environment NEAR The Near Earth Asteroid Rendezvous spacecraft, the first spacecraft launched in NASA's Discovery Program of low-cost, small-scale planetary missions. NEAR_Sim NEAR Simulation Program (for trajectory calculations) NGS NEAR Ground System NIS Near-Infrared Spectrometer . One of the instruments on NEAR. NLR NEAR Laser Rangefinder. One of the instruments on NEAR. nm nanometer NMOC NEAR Mission Operations Center NOCC Network Operations Control Center NOP Network Operations Plan NSSDC National Space Science Data Center. nT nanoTesla NTO Nitrogen Tetroxide (N2O4), a propellant gas OLS Orbital Launch Services OpNav OpNav stands for Optical Navigation, and means that images are obtained of Eros against the star background. These are measured (just like plates of asteroids and stars are measured to update asteroidal occultation predictions) to help determine where NEAR is relative to Eros, that is, to help navigate the spacecraft (since these observations are used in the overall orbit determination, based also on measurement of NEAR's radio signals, which is then used to plan thrusting maneuvers to target NEAR to Eros). OR Operations Requirement OWLT One-Way Light Time PCP Post Contact Processing PCU Power Converter Unit PDS The Planetary Data System. POCC Payload Operations Control Center POR Power-On Reset, an electrical signal that indicates to the FPGA in the NLR digital processor that power has recently been applied to the NLR instrument. Also, the digital sequence within the FPGA that immediately follows power-on. PPI Planetary Plasma Interactions, a discipline node of the PDS. PRF Pulse Repetition Frequency (ie Shot Rate), the reciprocal of PRI PRI Pulse Repetition Interval (ie Shot Period), the reciprocal of PRF PROM Programmable Read-Only Memory PSE Power System Electronics PSS Propulsion System Structure PSU Power Switching Unit R&QA Reliability and Quality Assurance R/T Real-Time RAM Random Access Memory RHC Right Hand Circular ROM Read Only Memory RS Radio Science, a NEAR experiment package. R-S Reed-Solomon (family of burst error correcting codes) RT Remote Terminal of the NEAR MIL-STD-1553 bus RTX Real Time Express RWA Reaction Wheel Assembly S/A Solar Array S/C Spacecraft SBN Small Bodies Node, a discipline node of the PDS. SDC NEAR Science Data Center, based at JHU/APL. SEC·DED Single Error Correction, Double Error Detection Hamming code SEP Sun-Earth-Probe angle SEU Single Event Upset SFVC Small Fine Velocity Control SIS Software Interface Specification. SOE Schedule of Events SPE Sun-Probe-Earth angle SPEC Static Phase Error, Coarse SPEF Static Phase Error, Fine SPICE A system of providing navigation and geometry data. S = Spacecraft, P = Planet, I = Instrument, C = C matrix, and E = Events. SR The PDS Standards Reference. SRAM Static Random-Access (read/write) Memory SRS Software Requirements Specification SSG Sensor System Group SSPA Solid State Power Amplifier SSR Solid State Recorder, used for storing data before it is transmitted back to Earth. NEAR has 2 SSRs. ST Star Tracker Sun Safe Mode In Sun Safe Mode, the spacecraft is placed in a power safe configuration with an unmodulated carrier downlink. The solar panels are pointed directly at the Sun, and the spacecraft is rotated to sweep the fan beam antenna through the hemisphere facing the Sun and Earth. Every 10 hours, redundant components of the telecommunications subsystem are exercised. TBD To Be Determined TBS To Be Supplied TC Telecommand TCM Trajectory Correction Maneuver. TCM-18 indicates the 18th trajectory correction maneuver that has been planned since NEAR was launched. TCU Telemetry Conditioning Unit TCXO Temperature-Compensated Crystal Oscillator TEC Thermo-Electronic Cooler TF Transfer Frame Time Systems of Time are discussed at http://tycho.usno.navy.mil/systime.html TLM Telemetry TOF Time Of Flight (e.g., duration of the laser pulse's round trip to the asteroid) UART Universal Asynchronous Receiver/Transmitter usec microsecond UTMC United Technologies Microelectronics Center V/T Voltage/Temperature VC Virtual Channel VC0 NEAR virtual channel for solid-state recorder data VC3 NEAR virtual channel for real-time telemetry data VCDU Virtual Channel Data Unit (CCSDS) VCO Voltage-Controlled Oscillator XGRS X-ray/Gamma-Ray Spectrometer. One of the instruments on NEAR. XPDR Transponder XRS/GRS X- and Gamma-Ray Spectrometer