The National Polar-orbiting Operational Environmental Satellite System (NPOESS) was to be the United States' next-generation satellite system that would monitor the Earth's weather, atmosphere, oceans, land, and near-space environment. NPOESS satellites were to host proven technologies and operational versions of sensors that are currently under operational-prototyping by NASA. The estimated launch date for the first NPOESS satellite, "C1" or "Charlie 1" was around 2013. Issues with sensor developments were the primary cited reason for delays and cost-overruns.