| Class: Earth. Type:
Weather. Destination: Sun-synchronous orbit. Nation:
USA. Agency: NASA. Manufacturer: Ball Aerospace.
CloudSat was selected as a NASA Earth System Science Pathfinder
satellite mission in 1999 to provide observations necessary to
advance our understanding of cloud abundance, distribution,
structure, and radiative properties. CloudSat flew the first
satellite-based millimeter-wavelength cloud radar, that was more
than 1000 times more sensitive than existing weather radars.
CloudSat was co-manifested with the Calipso (Cloud-Aerosol Lidar
and Infrared Pathfinder Satellite Observations) satellite for launch
aboard a Delta II rocket. CloudSat and Calipso joined three
satellites already in orbit ( Aqua, Parasol, and Aura) to form a
constellation of satellites known as the A-Train. The satellites
flew in a nearly circular orbit with an equatorial altitude of
approximately 705 km. The orbit was sun-synchronous, maintaining a
roughly fixed angle between the orbital plane and the mean solar
meridian. CloudSat maintained a close formation with Aqua and a
particularly close formation with Calipso, providing
near-simultaneous and collocated observations with the instruments
on these two platforms.
Science leader for CloudSat was Graeme Stephens of Colorado State
University. NASA's Jet Propulsion Laboratory provided project and
mission management and developed CloudSat's instrument, the Cloud
Profiling Radar.
CloudSat's primary mission was scheduled to continue for 22
months after launch, in order to allow more than one seasonal cycle
to be observed, although radar lifetime data indicates that the
radar was expected to operate for three years with a 99 percent
probability.
The Cloud Profiling Radar (CPR) was a 94-GHz nadir-looking radar
which measured the power backscattered by clouds as a function of
distance from the radar. The CPR was developed jointly by NASA/JPL
and the Canadian Space Agency (CSA). The overall design of the CPR
was simple, well understood, and had strong heritage from many cloud
radars already in operation in ground-based and airborne
applications. Most of the design parameters and subsystem
configurations were nearly identical to the Airborne Cloud Radar,
which had been flying on a NASA DC-8 aircraft since 1998.
CPR System Characteristics:
- Nominal Frequency: 94 GHz
- Pulse Width: 3.3 microsec
- PRF: 4300 Hz
- Minimum Detectable Z*: -26 dBZ
- Data Window: 0-25 km
- Antenna Size: 1.95 m
- Dynamic Range: 70 dB
- Integration Time: 0.3 sec
- Vertical Resolution: 500 m
- Cross-track Resolution: 1.4 km
- Along-track Resolution: 2.5 km
- Data Rate: 15 kbps
Mass: 848 kg (1,869 lb).
Cloudsat Chronology
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