200 nanosats for global coverage, they may need replace 100 every year if nanosats lifespan 1-2 years?
“Low cost and a tolerance of less-stringent standards allow multiple nanosats to be built faster. This allows for a higher risk of failure. Nanosats have a relatively short life, which might be no more than a year or two in low-Earth orbit before re-entering the atmosphere and burning up. Planet Labs, for one, expects to replace some of its nanosats with new versions every year.” http://www.economist.com/news/techn...e-smartphones-and-other-consumer-technologies
Cost maybe higher than you expected. Planet Labs founded in 2010, planned to launched 100 nanosats for global imaging coverage, it raised more than $160 mil USD from 2010-2015. http://techcrunch.com/2015/01/20/planet-labs-95m/