The Earth Observing System Data Gateway (EDG) software provides a "one-stop-shopping" standard interface for exploring and ordering Earth-science data stored at geographically distributed sites. EDG enables a user to do the following:

  • Search for data according to high-level criteria (e.g., geographic location, time, or satellite that acquired the data);
  • Browse the results of a search, viewing thumbnail sketches of data that satisfy the user's criteria; and
  • Order selected data for delivery to a specified address on a chosen medium (e.g., compact disk or magnetic tape).

EDG consists of (1) a component that implements a high-level client/server protocol, and (2) a collection of C-language libraries that implement the passing of protocol messages between an EDG client and one or more EDG servers. EDG servers are located at sites usually called "Distributed Active Archive Centers" (DAACs). Each DAAC may allow access to many individual data items, called "granules" (e.g., single Landsat images). Related granules are grouped into collections called "data sets." EDG enables a user to send a search query to multiple DAACs simultaneously, inspect the resulting information, select browseable granules, and then order selected data from the different sites in a seamless fashion.

This program was developed by Robin Pfister of Goddard Space Flight Center and Joe McMahon, James Amrhein, Ed Sefert, Lorena Marsans, Mark Solomon, and Mark Nestler of Global Science & Technology, Inc. For further information, access the Technical Support Package (TSP) free on-line at under the Software category. GSC-14938-1

NASA Tech Briefs Magazine

This article first appeared in the October, 2006 issue of NASA Tech Briefs Magazine.

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