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Latest MODIS Image

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MODIS Direct Broadcast
NASA/GSFC Ground Receiving Station

About MODIS Direct Broadcast
One of the unique features of the MODIS instrument is its Direct Broadcast capability. Generally, spacecraft collect data and then store it on board until it passes over a ground station set up to receive the data, at which point it transmits the data in one large batch. This avoids losing data taken when the spacecraft is out of sight of any ground stations, such as when it is over the ocean.

MODIS does store data on board for later download, but it also broadcasts the raw data it collects immediately, on the chance that someone on the ground below is listening. This is called Direct Broadcast of the data. NASA/GSFC has the antennas and other equipment necessary to receive and process MODIS Direct Broadcast data whenever the spacecraft is above the horizon. The Overpass Predictor can be used to determine when there will be a Terra or Aqua spacecraft overpass of NASA/GSFC (Greenbelt, MD) or any other location that may have a MODIS Direct Broadcast receiving station.

About the Direct Broadcast images
The MODIS instrument takes data by scanning from side to side as it passes over the earth. The instrument points straight down, and "sees" up to 55 degrees to either side. Because of this, the image is most accurate down the centerline of the image, and becomes more distorted (compressed) towards either side. This is a combination of the angle MODIS is viewing the ground at and the curvature of the Earth.

The images are built from MODIS bands 1 (red), 4 (green) and 3 (blue). The images shown have a resolution of 1 kilometer per pixel at nadir (the picture centerline). For higher resolution versions of the images shown, please browse our Image Gallery.