The CEOS Land Surface imaging (LSI) Virtual Constellation

The fundamental mission of the CEOS Land Surface Imaging (LSI) Constellation is to promote the efficient, effective, and comprehensive collection, distribution, and application of space-acquired image data of the global land surface, especially to meet societal needs of the global population, such as those addressed by the Group on Earth Observations (GEO) societal benefit areas (SBAs).
The LSI Portal is located at http://eros.usgs.gov/ceos/index.shtml

NOTE:
INPE recently coordinated the development of a new tool, the MS3Ortho, a significant contribution to the LSI Constellation and CEOS. MS3Ortho is a stand-alone command line orthorectification tool that implements two algorithms: the standard ortho process using RPC files and a rigorous model that uses ephemerides, attitude and the camera geometric model.  It supports all mid-resolution sensors that are available: Landsat, Resourcesat, and CBERS.  Click here to download MS3Ortho-4.7.1.