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A-train (satellite constellation)
Encyclopedia
Satellite constellation
A group of artificial satellites working in concert is known as a satellite constellation. Such a constellation can be considered to be a number of satellites with coordinated ground coverage, operating together under shared control, synchronised so that they overlap well in coverage and...
scheduled to have seven Franco
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
-American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
Earth observation satellite
Earth observation satellite
Earth observation satellites are satellites specifically designed to observe Earth from orbit, similar to reconnaissance satellites but intended for non-military uses such as environmental monitoring, meteorology, map making etc....
s in sun-synchronous orbit
Sun-synchronous orbit
A Sun-synchronous orbit is a geocentric orbit which combines altitude and inclination in such a way that an object on that orbit ascends or descends over any given point of the Earth's surface at the same local mean solar time. The surface illumination angle will be nearly the same every time...
at an altitude
Altitude
Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
of 690 kilometers above the Earth.
They are spaced a few minute
Minute
A minute is a unit of measurement of time or of angle. The minute is a unit of time equal to 1/60th of an hour or 60 seconds. In the UTC time scale, a minute on rare occasions has 59 or 61 seconds; see leap second. The minute is not an SI unit; however, it is accepted for use with SI units...
s apart from each other so their collective observations may be used to build high-definition three-dimensional
Three-dimensional space
Three-dimensional space is a geometric 3-parameters model of the physical universe in which we live. These three dimensions are commonly called length, width, and depth , although any three directions can be chosen, provided that they do not lie in the same plane.In physics and mathematics, a...
images of the Earth's atmosphere and surface.
Active
The train consists of the following active satellites:- AquaAqua (satellite)Aqua is a multi-national NASA scientific research satellite in orbit around the Earth, studying the precipitation, evaporation, and cycling of water. It is the second major component of the Earth Observing System preceded by Terra and followed by Aura .The name "Aqua" comes from the Latin word...
, lead spacecraft in formation, launched on May 4, 2002 - CloudSatCloudSatCloudSat is a NASA Earth observation satellite, which was launched on a Delta II rocket on 28 April 2006. It uses radar to measure the altitude and properties of clouds, adding to information on the relationship between clouds and climate in order to help resolve questions about global warming...
, runs 2 minuteMinuteA minute is a unit of measurement of time or of angle. The minute is a unit of time equal to 1/60th of an hour or 60 seconds. In the UTC time scale, a minute on rare occasions has 59 or 61 seconds; see leap second. The minute is not an SI unit; however, it is accepted for use with SI units...
s and 30 secondSecondThe second is a unit of measurement of time, and is the International System of Units base unit of time. It may be measured using a clock....
s behind Aqua, launched with CALIPSO on April 28, 2006 - CALIPSOCALIPSOCALIPSO is a joint NASA and CNES environmental satellite, built in the Cannes Mandelieu Space Center, which was launched atop a Delta II rocket on April 28, 2006. Its name stands for Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations...
, follows CloudSat by no more than 15 seconds, launched on April 28, 2006 - AuraAura (satellite)Aura is a multi-national NASA scientific research satellite in orbit around the Earth, studying the Earth's ozone layer, air quality and climate. It is the third major component of the Earth Observing System following on Terra and Aqua...
, lags Aqua by 15 minutes, crossing the equator 8 minutes behind due to different orbital track to allow for synergy with Aqua, launched on July 15, 2004
Past
- PARASOLPARASOL (satellite)PARASOL is a French-built Earth observing research satellite. It carries an instrument called POLDER which studies the radiative and microphysical properties of clouds and aerosols....
, launched on December 18, 2004; moved to other (lower) orbit on 2 December 2009
Failed
- OCOOrbiting Carbon ObservatoryThe Orbiting Carbon Observatory is a NASA satellite mission intended to provide global space-based observations of atmospheric carbon dioxide . The original spacecraft was lost in a launch failure on February 24, 2009, when the payload fairing of the Taurus rocket which was carrying it failed to...
, destroyed by a launch vehicle failure on February 24, 2009, and would have preceded Aqua by 15 minutes - GloryGlory (satellite)The Glory satellite was a planned NASA satellite mission that would have collected data on the chemical, micro-physical and optical properties—and the spatial and temporal distributions—of sulfate and other aerosols, and would have collected solar irradiance data for the long-term climate record...
, failed during launch on a Taurus XL rocket on March 4, 2011, and would have flown between CALIPSO and Aura