* Astronomy

Sixty two minutes after lift-off, Calipso separated from the rocket's second stage. CloudSat followed 35 minutes later. Ground controllers successfully acquired signals from both spacecraft, and initial telemetry reports show both to be in excellent health.
Over the next six weeks, system and instrument checks will be performed.
The two satellites will eventually circle approximately 705 kilometres above Earth in a sun-synchronous polar orbit.


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The launch of CloudSat and Calipso satellites from Vandenberg Air Force Base, California.
Credit: Boeing/Thom Baur

Each spacecraft will transmit pulses of energy and measure the portion of the pulses scattered back to the satellite. CloudSat's Cloud-Profiling Radar is more than 1,000 times more sensitive than typical weather radar. It can detect clouds and distinguish between cloud particles and precipitation. Calipso's polarisation lidar can detect aerosol particles and distinguish between aerosol and cloud particles. Lidar, similar in principle to radar, uses reflected light to determine the characteristics of the target area.
The data can then be rendered into three-dimensional maps of clouds that identify the location and form of water molecules.

The satellites will fly in formation as members of NASA's "A-Train" constellation, which also includes NASA's Aqua and Aura satellites and a French satellite known as Parasol, for Polarisation and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar. Lidar uses pulses of shorter wave energy - in the infrared and visible part of the spectrum - fired down into the atmosphere to obtain a different, but complementary, set of data from Cloudsat's.

The Cloudsat and Calipso missions have a number of objectives:

* Together, the satellites will provide the first statistics on the vertical structure of clouds. Scientists will be able to see clouds from their tops to their bottoms - like getting a CT scan of clouds from space
* Cloudsat and Calipso will give researchers the first indirect but validated estimate of how much clouds and aerosols contribute to the vertical distribution of atmospheric warming
* Cloudsat will provide the first global estimates of the percentage of Earth's clouds that produce rain
* Cloudsat will afford scientists the first vertically sliced picture of how much water and ice are in Earth's clouds
* Cloudsat will provide the first ability to detect snowfall from space
* Cloudsat will offer the first estimates of how efficiently the atmosphere produces rain from condensates
* Calipso will provide the first statistics on the global vertical distribution of aerosols and aerosol types
* Calipso will reveal for the first time how often "sub-visible" cirrus clouds - very thin clouds invisible to the naked eye - occur, and whether they change with the seasons.

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