The Shuttle Radar Topography Mission (NASA SRTM v3, Color Index) layer is from the the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) Version 3 Shuttle Radar Topography Mission (SRTM) data product (SRTMGL1). This layer provides near-global, void-free, elevation information at 1 arc second (~30 meter) spatial resolution between 60° north and 56° south latitude. NASA SRTM data products result from a collaborative effort by the National Aeronautics and Space Administration (NASA) and the National Geospatial-Intelligence Agency (NGA), as well as the participation of the German and Italian space agencies. The purpose of the SRTM was to generate a digital elevation model (DEM) of 80% of the Earth's surface using radar interferometry. SRTM was a primary component of the payload on the Space Shuttle Endeavour during its STS-99 mission. Endeavour launched February 11, 2000 and flew for 11 days. On the default palette, white indicates the highest elevations, then brown, yellow and greens indicate low elevations.
References: LP DAAC - NASA MEaSUREs SRTM Version 3