Direct Broadcast

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The EOS spacecraft Terra and Aqua provide direct broadcast services, similar to operational NOAA satellites. Starting in 1999, the Terra spacecraft has broadcasted selected portions of the MODIS instrument data to X-Band reception facilities. The broadcast is continuous with the following exceptions: 1. During the time spacecraft is dumping its play-back data which lasts about 15 minutes, once per orbit; 2. When the spacecraft is in the line-of-sight of NASA Deep Space Stations (Goldstone, Canberra, and Madrid).

Starting in 2001, the Aqua spacecraft has broadcasted all of its instrument data to X-Band reception facilities. The instrument suite includes AIRS, AMSU-A, HSB, AMSR-E, MODIS and CERES. With a more extensive filtering capability on its transponder, Aqua broadcasts almost all the time except during the ground contact time over the Poker Flat, Alaska, and Svalbard, Norway. Interruption lasts about 5 minutes, once per orbit.

The Direct Broadcast service is particularly useful to people who need science data quickly (sooner than the normal 24-hour availability through the EOS Data and Information System, EOSDIS). It requires, however, a sophisticated ground station to receive and process those data. More details on the EOS Direct Broadcast and information on Direct Readout processing software are available at: http://directreadout.gsfc.nasa.gov/index.cfm

The International MODIS/AIRS Processing Package (IMAPP) developed by CIMSS, allows any ground station capable of receiving direct broadcast from Terra or Aqua to produce calibrated and geolocated MODIS radiances (Level 1), along with a select group of science products (Level 2). IMAPP is derived from the operational MODIS processing software developed at NASA GSFC, and is modified to be compatible with direct broadcast data. For more details and how to get the package, see: http://cimss.ssec.wisc.edu/imapp/
It is expected that the Level1b AIRS direct broadcast preprocessing package will be available in early 2003.