The Earth Observing System (EOS) Clearinghouse, or ECHO refers to a system that was used by the National Aeronautics and Space Administration (NASA) to spatially, temporally and otherwise index the petabytes of data that NASA's Earth Science projects collect.[1] It does not hold the data itself, but serves as a search engine that other applications can access via a web service based interface. While ECHO has been set up to support both data and services, as of mid-2008, data is well represented and services are yet to be focused on.[2]
In the late 1990s, NASA recognized that the emerging internet technologies would facilitate a democratization of the access to data. NASA began the ECHO effort as a prototype, using web technology to allow the public extensive access to data previously only available to researchers. Access was initially through an application programming interface, not a graphical user interface.
In 2017, the Common Metadata Repository (CMR) replaced ECHO as a high-performance, high-quality, continuously evolving metadata system that catalogs all data and service metadata records for NASA's EOSDIS. CMR will be the authoritative management system for all EOSDIS metadata.[3]