for National Geographic News
Spouting a long flame that lit up the predawn sky, a Delta II rocket rose from California's Vandenberg Air Force Base this morning carrying two highly specialized weather satellites with unprecedented powers to examine the Earth's cloud layers.
The two satellites are the final components of the biggest space observatory ever built: the "A-Train," a string of international satellites racing over the Earth's poles in closely matched orbits to aid in climate study.
One of the two newcomers to the A-Train is CloudSat, a NASA platform whose powerful radar will be able to probe even dense clouds top to bottom with sensitivity a thousand times that of standard ground-based weather radar.
The other is CALIPSO, a joint French-American satellite whose laser-beam, or lidar, reflections will provide measurements of dust and other small aerosol particles in clear air and in thin clouds.
Aerosols are key players in energy transfer in the atmosphere and in the processes that form clouds.
CloudSat's radar should provide the most dramatic new portraits of the atmosphere in action.
It will be equivalent to a cloud x-ray, able to see the detailed distributions of rain and snow forming inside clouds.
"Today we can't even tell how much of a cloud is making precipitation," said Graeme Stephens, the principal investigator for CloudSat, before launch.
Being able to make such detections will provide a key part in the puzzle of the atmosphere's overall flow of energy and water, he said.
The launch at 3:02 a.m. PDT this morning was timed almost to the second to allow the satellites to join the three satellites already in formation.
To reach their final position may take a month or more of adjustment in orbit.
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