Re: Calipso satellite with green and infared lasers set for Launch on Apr 20

From: Tony Beresford (
Date: Sat Apr 01 2006 - 07:47:45 EST

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    At 19:42 1/04/06, Kevin Fetter wrote:
    >The Calipso satellite which has a 532 nm and 1064 nm laser on it, will be launched along with
    >Cloudsat on Apr 20 at around 10:02 UTC ( Apr 20 )
    >Once they are in the proper orbit, calipso will follow cloudsat by roughly 15 seconds.
    The orbit for both is part of the "A-train", following the Aqua satellite by a minute or two.
    This is of course in a sun=synchronous orbit, whose afternoon ascending node is at 1330 local
    time. A little playing with Aqua predictions on Heavens-above shows the the descending path
    crosses 50N latitude around 3:30am local time. So first chance to observe will, given the
    distribution of observers, be the japanese members of the list. Aqua enters shadow
    at 0204 JST (1704UT),almost Due N of Japan. From an arbitrary observer at 40N, 136E,
    this is at an elevation of 40 degrees.
    Here is a description of the 'A-Train'
    The Afternoon or "A-Train" satellite constellation presently consists of three satellites flying in formation around the globe (NASA's Aqua and Aura satellites and CNES' PARASOL satellite). The CALIPSO and CloudSat satellite missions will be inserted in orbit behind Aqua later this year. A sixth spacecraft, OCO, is planned for launch in 2008 and will be placed ahead of Aqua.
    Each satellite within the A-Train has unique measurement capabilities that greatly complement each other. For the first time, near simultaneous measurements of aerosols, clouds, temperature, relative humidity, and radiative fluxes (the change of radiation in a layer) will be obtained over globe during all seasons. This ensemble of observations will allow one to understand how large scale aerosol and cloud properties change in response to changing environmental conditions. It will further allow one to determine how changing cloud and aerosols distributions influence our climate with greater clarity than possible before.
    For much of its life, the A-Train will be maintained in orbit within 15 minutes of the leading and trailing spacecraft while traveling at over 15,000 miles per hour. CloudSat and CALIPSO will be controlled to an even finer requirement, within 15 seconds of each other, so that both instrument suites will view the same cloud area at nearly the same moment. This capability is crucial for studying clouds, which have lifetimes often less than 15 minutes.
    The different instruments on each platform are described in Table 1: A-Train Instruments. <>+ View Table 1
    CALIPSO will be flown as part of the Aqua satellite constellation (or A-train), which consists of the Aqua, CloudSat, CALIPSO, PARASOL, and Aura satellite missions. The constellation has a nominal orbital altitude of 705 km and inclination of 98 degrees. Aqua will lead the constellation with an equatorial crossing time of about 1:30 PM. CloudSat and CALIPSO will lag Aqua by 1 to 2 minutes and will be separated from each other by 10 to 15 seconds. 
    For the first 2 years of the mission, the nadir track of CALIPSO and CloudSat will be offset eastward from the Aqua nadir track by approximately 215 km at the equator. This shift permits comparisons with MODIS aerosol products in regions that would have been otherwise masked by sun glint during the northern hemispheric summer. During the third year of the mission, the current plan is to allow CALIPSO to precess westward across the swath of MODIS and CERES to view aerosol and cloud properties at a variety of viewing angles.
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