https://www.eaglespeak.us/2010/02/war-in-future-satellite-alternatives.html
EagleSpeak: War in the Future: Satellite Alternatives and More
Very interesting discussion here about some alternatives to GPS satellites upon which the U.S. military (and, in point of fact, a whole lot...
in the futuresatellite alternativeswar
https://www.space.com/505-alternatives-landsat-satellite-imagery-challenge.html
Alternatives to Landsat Satellite Imagery Still a Challenge | Space
Nov 1, 2004 - More than a year after a government land remote sensing satellite was crippled by technical malfunctions, users of the data it produces are still searching for...
alternatives tosatellite imagerylandsatstillchallenge