Post by Rocketman on Aug 22, 2005 13:56:49 GMT -6
The A-Train
The so-called A-Train is a flotilla composed of the Aqua, Aura, CloudSat, PARASOL, and CALIPSO satellites flying in formation in low polar orbits 438 miles (705 km) above Earth at an inclination of 98 degrees. Together, their overlapping science instruments give a comprehensive picture of Earth weather and climate. The satellites are referred to as the A-Train because the caravan has been said to resemble a train of satellites flying around Earth.
However, the railroad metaphor doesn't give an accurate picture. The satellites do not follow each other in single file. Rather, they fly independently and cross over the equator a few minutes apart starting just after 1:30 p.m. local time.
The A in A-Train also stands for "afternoon" because the satellites cross the equator shortly after noon. Aqua leads the train. It is the largest satellite in the group and the first to cross the equator each day (about 1:40 p.m. on ascending passes), and night (at 1:40 a.m. on descending passes).
The spacecraft travel around the planet at more than 15,000 mph. Ground controllers maintain their orbits within 15 minutes of the leading, and trailing satellites. CloudSat, and CALIPSO fly within 15 seconds of each other, they can measure the same clouds at the same time.
Terra (not shown in the above graphic), the first Earth Observing System satellite was launched aboard an Atlas-Centaur IIAS expendable rocket from Vandenberg Air Force Base, California, at 1:57 p.m. EST on December 18, 1999.
Aqua (formerly EOS PM-1), the second EOS satellite, was launched aboard a Delta II expendable rocket from Vandenberg Air Force Base, California, at 5:55 a.m. EDT on May 4, 2002. Aqua is studying EarthÕs water cycle with an imaging spectrometer, two radiometers, infrared, and microwave sounders.
Aura (formerly EOS Chem), the third EOS satellite, was launched aboard a Delta II expendable rocket from Vandenberg Air Force Base, California, at 6:01 a.m. EDT on July 15, 2004. It's sounders measure air quality, stratospheric ozone, and climate change.
PARASOL (Polarization & Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar) was launched aboard an Ariane 5 at 1626 GMT on December 18, 2004, from the European Space Agency's (ESA) launch complex ELA3 at Guiana Space Center at Kourou, French Guiana. PARASOL is a project of the French space agency Centre National d'Etudes Spatiales (CNES). Its radiometer studies the atmosphere by measuring the direction, and polarization of light reflected by clouds, and aerosols.
CloudSat, and CALIPSO are to be launched together aboard a Delta 2 expendable rocket from Vandenberg Air Force Base, California, no earlier than October 26, 2005. CloudSat, and CALIPSO complement each other in providing a 3-D view of clouds, and aerosols showing how they form, evolve, affect weather, and climate. CloudSat is a U.S.-Canadian project using radar to measure thick ice, and water in clouds. CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations), a U.S.-French mission, has a lidar, infrared, and visible imagers to measure thin clouds, and aerosols over the globe.
OCO (Orbiting Carbon Observatory) will join the A-Train in 2008. OCO will be placed 15 minutes ahead of Aqua, and will measure the concentration of carbon dioxide in the atmosphere.
The so-called A-Train is a flotilla composed of the Aqua, Aura, CloudSat, PARASOL, and CALIPSO satellites flying in formation in low polar orbits 438 miles (705 km) above Earth at an inclination of 98 degrees. Together, their overlapping science instruments give a comprehensive picture of Earth weather and climate. The satellites are referred to as the A-Train because the caravan has been said to resemble a train of satellites flying around Earth.
However, the railroad metaphor doesn't give an accurate picture. The satellites do not follow each other in single file. Rather, they fly independently and cross over the equator a few minutes apart starting just after 1:30 p.m. local time.
The A in A-Train also stands for "afternoon" because the satellites cross the equator shortly after noon. Aqua leads the train. It is the largest satellite in the group and the first to cross the equator each day (about 1:40 p.m. on ascending passes), and night (at 1:40 a.m. on descending passes).
The spacecraft travel around the planet at more than 15,000 mph. Ground controllers maintain their orbits within 15 minutes of the leading, and trailing satellites. CloudSat, and CALIPSO fly within 15 seconds of each other, they can measure the same clouds at the same time.
Terra (not shown in the above graphic), the first Earth Observing System satellite was launched aboard an Atlas-Centaur IIAS expendable rocket from Vandenberg Air Force Base, California, at 1:57 p.m. EST on December 18, 1999.
Aqua (formerly EOS PM-1), the second EOS satellite, was launched aboard a Delta II expendable rocket from Vandenberg Air Force Base, California, at 5:55 a.m. EDT on May 4, 2002. Aqua is studying EarthÕs water cycle with an imaging spectrometer, two radiometers, infrared, and microwave sounders.
Aura (formerly EOS Chem), the third EOS satellite, was launched aboard a Delta II expendable rocket from Vandenberg Air Force Base, California, at 6:01 a.m. EDT on July 15, 2004. It's sounders measure air quality, stratospheric ozone, and climate change.
PARASOL (Polarization & Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar) was launched aboard an Ariane 5 at 1626 GMT on December 18, 2004, from the European Space Agency's (ESA) launch complex ELA3 at Guiana Space Center at Kourou, French Guiana. PARASOL is a project of the French space agency Centre National d'Etudes Spatiales (CNES). Its radiometer studies the atmosphere by measuring the direction, and polarization of light reflected by clouds, and aerosols.
CloudSat, and CALIPSO are to be launched together aboard a Delta 2 expendable rocket from Vandenberg Air Force Base, California, no earlier than October 26, 2005. CloudSat, and CALIPSO complement each other in providing a 3-D view of clouds, and aerosols showing how they form, evolve, affect weather, and climate. CloudSat is a U.S.-Canadian project using radar to measure thick ice, and water in clouds. CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations), a U.S.-French mission, has a lidar, infrared, and visible imagers to measure thin clouds, and aerosols over the globe.
OCO (Orbiting Carbon Observatory) will join the A-Train in 2008. OCO will be placed 15 minutes ahead of Aqua, and will measure the concentration of carbon dioxide in the atmosphere.
