<3_4cm>|3 or 4 centimeters: Approximately 1 to 2 inches.
<4cm>|4.0 centimeters: Approximately 1.6 inches.
<4.3cm>|4.3 centimeters: Approximately 1.7 inches.
<5cm>|5 centimeters: Approximately 2 inches.
<10cm>|10 centimeters: Approximately 4 inches.
<20cm>|20 centimeters: Approximately 8 inches.
<30cm>|30 centimeters: Approximately 12 inches.
<32cm>|32 centimeter: Approximately 13 inches.
<50cm>|50 centimeter: Approximately 20 inches.
<84f>|84 degrees Fahrenheit: 29 degrees Celsius.
<5gsc>|5 grams per square centimeter: Equivalent to approximately 1.14 ounces of force at nominal gravity per square inch.
<2169.4kg>|2169.4 kilograms: Equivalent to approximately 4782.7 pounds of force at nominal gravity.
<2388.4kg>|2388.4 kilogram: Equivalent to approximately 5265.5 pounds of force at nominal gravity.
<2600kg>|2600 kilogram: Equivalent to approximately 5,732 pounds of force at nominal gravity.
<1km>|1 kilometer: Approximately .62 miles.
<1336km>|1336 kilometer: Approximately 830 miles.
<20200km>|20,200 kilometer: Approximately 12,600 miles.
<1.3m>|1.3 meters: Approximately 4.3 feet.
<1.5m>|1.5 meters: Approximately 4.9 feet.
<2.5m>|2.5 meters: Approximately 8.2 feet.
<2.6m>|2.6 meters: Approximately 8.5 feet.
<3m>|3 meters: Approximately 10 feet.
<3.3m>|3.3 meters: Approximately 11 feet.
<5.5m>|5.5 meters: Approximately 18 feet.
<6.6m>|6.6 meters: Approximately 22 feet.
<8.89m>|8.89 meters: Approximately 29.2 feet.
<10m>|10 meters: Approximately 33 feet.
<11.5m>|11.5 meters: Approximately 37.7 feet.
<58m>|58 meters: Approximately 190 feet.
<15mps>|15 meters per second: Approximately 49 feet per second or 33 miles per hour.
<1n>|1 newton: Approximately .225 pounds of force.
<22n>|22 newtons: Approximately 4.95 pounds of force.
<29.4sqm>|29.4 square meters: Approximately 317 square feet.
<accuracy>|accuracy: The measure of how close an instrument's readings are to the true value.
<algor>|algorithm: A series of steps used to process data.
<alt>|altimeter: A device for measuring distance. For TOPEX/Poseidon, the height of the spacecraft above the surface of the ocean.
<altimetric>|altimetric: Pertaining to measurements made by an altimeter.
<ah>|ampere-hour: The quantity of electricity carried past any point of a circuit in one hour by a current of one ampere.
<glossa>|annotated glossary link: When you roll over an annotated glossary link, the annotation appears in the visual window. When you click on an annotated glossary link, the definition of the term appears in this window.
<anom>|anomaly: A deviation from what is expected or predicted.
<aspace>|Arianespace: A company owned by the French government responsible for building and operating the Ariane launch vehicle.
<atmos>|atmosphere: The mass of air surrounding a planet. For the earth, the mass per unit area of the atmosphere is approximately 10,200 kg/m(squared). This is equivalent to an atmosphere with a thickness of 8.4 km and uniform density of 1.21 kg/m(squared).
<attitude>|attitude: The orientation of a spacecraft relative to the earth.
<bgc>|biogeochemical: Chemical composition of and chemical changes in the solid matter of the earth and how these changes relate to plant and animal life.
<bow>|bow: The forward part of a ship or spacecraft.
<buoy>|buoy: A free-floating or moored instrument platform at sea that provides measurements that may include tides, currents, wind, salinity, etc.
<canted>|canted: Set at an angle.
<atmoscirc>|circulation: The flow of a fluid that follows a circuit and eventually returns to its staring point. For the earth, the oceans and atmosphere circulate due to heating and cooling effects and to the rotation of the earth.
<cnes>|CNES: France's space agency, the Centre National d'Etudes Spatiales.
<concentric>|concentric: Having a common center.
<consume>|consumables: Resources, such as propellants, aboard a spacecraft which are depleted during a mission and cannot be replaced.
<cubes>|corner-cube: A geometrical shape consisting of the corner of a cube. Light entering the face reflects off the inner surfaces of the cube and exits along the same path that it entered.
<doppler>|Doppler shift: A change in the frequency of waves (usually sound or radio) from a given source when the source and the observer are moving with respect to each other. The frequency is higher than normal as they approach each other and lower as they part.
<doris>|DORIS: Doppler Orbitography and Radiopositioning Integrated by Satellite.
<dsn>|Deep Space Network: A set of 26 meter antennas used to observe earth satellites. The primary DSN stations are located in Goldstone California, Madrid Spain, and Canberra Australia. The locations of these 3 stations allow uninterrupted tracking of spacecraft regardless of its location.
<df>|dual-frequency: Using two separate radio frequencies.
<eb>|electromagnetic bias: A term used to describe the fact that electromagnetic waves, in this case the radar signal, appear to be reflected from a surface that is lower than sea-level. The bias gets larger as the ocean waves get higher and the winds stronger.
<ed>|electrostatic discharge: Discharge of built up static electricity.
<ephemeris>|ephemeris: Position and velocity of planets and satellites at a particular time.
<freelect>|free electrons: Electrons that are not bound to a nucleus.
<geocentric>|geocentric: Measured as if observed from the earth's center.
<geodesy>|geodesy: A branch of applied mathematics concerned with the determination of the size and shape of the earth and the exact positions of points on its surface with respect to the geoid.
<geodetic>|geodetic: Relating to or determined by the size and shape of the earth and the exact positions of points on its surface with respect to the geoid.
<gd>|geodynamics: A branch of mechanics that deals with forces within the earth and their relation to the motion and equilibrium of the solid earth.
<geoid>|geoid: Average sea-level of an ocean at rest.
<geophys>|geophysical: Dealing with the physics of the earth including the fields of meteorology, hydrology, oceanography, seismology, volcanology, magnetism, radioactivity and geodesy.
<ghz>|gigahertz: One billion cycles per second.
<gimbal>|gimbal joint: Joints that allow rotational movement around one axis (much like an elbow joint).
<grav>|gravitational: Information relating to gravity.
<gg>|greenhouse gas: Gasses, primarily water vapor, in the atmosphere that trap infrared radiation and thereby increase the earth’s temperature.
<ground>|ground track: The trace of a satellite's nadir path on the earth's surface.
<gyro>|gyro: A device consisting of a heavy spinning disk mounted on gimbals which allow it to remain in a fixed orientation, regardless of the orientation of the spacecraft.
<hydra>|hydrazine: A highly toxic liquid fuel typically used in attitude control thrusters on spacecraft. Hydrazine is typically not ignited to produce thrust, but rather is rapidly decomposed in a chemical reaction.
<hg>|hypergolic: Propellants that will ignite upon contact of their components without external aid such as a spark.
<inc>|inclination: The angle between the satellite orbit plane and the earth’s equatorial plane.
<iono>|ionosphere: The part of the earth's atmosphere beginning at an altitude of about 30 miles and extending outward 300 miles or more. The ionosphere contains a large quantity of positively and negatively charged particles or ions (a neutral plasma). 95% of the ionoshpere is below the orbit of the TOPEX/Poseidon spacecraft.
<id>|ionospheric delay: The apparent increase in the path length of an electromagnetic signal due to the slowing of the signal in the ionosphere.
<jpl>|JPL: NASA's Jet Propulsion Laboratory.
<kbits/s>|kb/s: One thousand bits per second.
<laser>|laser beam: A coherent beam of light.
<limb>|limb: The outer edge of the apparent disk of a planet or satellite.
<litho>|lithosphere: The outer part of the solid earth, composed of rock, and considered to be about 50 miles in thickness.
<lg>|low-gain: A radio-antenna system which has a low efficiency relative to a directional or "pointable" system. The advantage of a low-gain system is that the antenna does not need to be aimed at a receiver. The disadvantage is that since the radio signal is transmitted in all directions, most of the power is lost.
<mtb>|magnetic torquer bars: Electromagnets used to push against the magnetic field of the earth, causing the spacecraft to turn.
<mag>|magnetometers: An instrument used to detect the presence of a metallic object or to measure the intensity of a magnetic field.
<magnitudes>|magnitude: Brightness quality of a star according to an established scale.
<mp>|mantle processes: Activities occurring in the part of the interior of earth that lies beneath the lithosphere and above the central core.
<margin>|margin: Extra capability allowing for contingencies or special situations.
<models>|mathematical models: A set of equations and boundary conditions used to simulate the natural environment.
<mb>|Mb: Megabits - One million bits.
<meteo>|meteorologists: Individuals who study the atmosphere and its phenomena, especially weather and weather forecasting.
<ms>|microwave signal: A comparatively short electromagnetic wave, about 1 millimeter to 1 meter in length.
<mms>|MMS: Multimission Modular Spacecraft.
<monop>|mono-propellant: A rocket propellant containing both the fuel and the oxidizer in a single substance.
<nadir>|nadir: The direction pointing from the satellite to the center of the earth, directly opposite the zenith.
<nadircol>|nadir column: A cylinder of air extending from the satellite to the surface.
<nasa>|NASA: National Aeronautics and Space Administration.
<ot>|ocean topography: The difference between the sea-surface height and the ocean geoid.
<ogers>|oceanographers: Individuals who study the oceans.
<ogic>|oceanographic: Pertaining to the measurement of oceanic processes.
<ogy>|oceanography: A science that deals with the oceans including the delineation of their extent and depth, the physics and chemistry of their waters, and the plants and animals contained in them.
<omni>|omnidirectional: In all directions.
<omm>|orbit maintenance maneuvers: Controlled variation in the velocity of the spacecraft with the purpose of correcting orbit decay and restoring the satellite to the nominal reference orbit.
<parabolic>|parabolic dish: Bowl shaped.
<payload>|payload: Spacecraft equipment related directly to the purpose of the flight as opposed to equipment necessary for its operation.
<gloss>|plain glossary link: When you click on a plain glossary link, the definition of the term appears in this window.
<port>|port: The left side of a ship or spacecraft looking forward.
<precision>|precision: The measure of an instrument's ability to obtain consistent readings.
<proton>|protons: A positively charged elementary atomic particle which, along with neutrons, is a constituent of all other atomic nuclei.
<pyro>|pyrotechnic device: Explosive mechanical mechanism usually used to release a deployable appendage.
<radial>|radial position: The location of the spacecraft with respect to the center of the earth.
<radiation>|radiation: The process of emitting radiant energy in the form of waves or particles.
<mr>|radiometer: An instrument for measuring the intensity of electromagnetic radiation.
<rangedelay>|range delay: Delay observed in the radar signal path. The apparent increase in the path length of an electromagnetic signal.
<safe>|safe-hold mode: Backup state of the spacecraft. A spacecraft will usually switch itself to a safe-hold, or protected state if a fault is detected. Various levels of backup states have been defined to cover different situations.
<ssh>|sea-surface height: The height of the sea surface relative to the center of the earth.
<sshumid>|sea-surface humidity: Humidity of the atmosphere at sea level.
<seq>|sequences: An ordered set of commands transmitted to a spacecraft that provide instructions for functions to be performed, such as observations or maneuvers.
<sf>|single-frequency: Using one frequency channel.
<skewed>|skewed: Set at an angle to all three of the major axis of the spacecraft.
<slr>|SLR: Satellite Laser Ranging.
<ss>|solid-state: Relying on solid semiconductors instead of electron tubes.
<srb>|SRB: Solid Rocket Booster.
<starboard>|starboard: The right side of a ship or spacecraft looking forward.
<stern>|stern: The back end of a ship or spacecraft.
<subtrop>|subtropical: Near but not in the tropics.
<tdrss>|TDRSS: Tracking Data Relay Satellite System.
<telemetry>|telemetry: Data and system-health related information transmitted by radio from a satellite to a ground system.
<tidegage>|tide gauges: Instruments used to measure the alternate rising and falling of the surface of the ocean. These changes are primarily due to the gravitational interaction of the sun and moon with the fluid earth.
<tts>|time-tagged signals: Transmissions from satellites that include a time reference used to calculate the difference between the time the signal is sent and when it is returned.
<tlc>|TLC: Tender Loving Care.
<topo>|topographic: Height variations in the earth's surface, usually reckoned to the geoid.
<trans>|transponder: Transmitter and receiver aboard the satellite that receives and re transmits the ground signal for purposes of tracking the satellite.
<trop>|tropical: Within the region of the earth bounded on the north by the Tropic of Cancer (23.5 N latitude) and on the south by the Tropic of Capricorn (23.5 S latitude).
<td>|tropospheric delay: The apparent increase in the path length of an electromagnetic signal due to slowing of the signal through the air.
<w>|watt: The amount of energy, in joules, expended per second. The typical incandescent light bulb is rated at about 100 watts.
<zenith>|zenith: The direction pointing from the center of the earth upward through the satellite, directly opposite the nadir.
<zenhem>|zenith hemisphere: The area above and directly to the sides of the spacecraft.
