NOAA-21

NOAA-21 was launched on November 10, 2022, aboard an Atlas V 401 rocket from Vandenberg Space Force Base in California. It is the second operational satellite in the Joint Polar Satellite System (JPSS) series, following NOAA-20 which launched in 2017. NOAA-21 joined NOAA-20 in a similar afternoon sun-synchronous polar orbit.

NOAA-21 carries five major instruments, including the Visible Infrared Imaging Radiometer Suite (VIIRS), the Cross-track Infrared Sounder (CrIS), the Advanced Technology Microwave Sounder (ATMS), the Ozone Mapping and Profiler Suite (OMPS), and the Clouds and the Earth's Radiant Energy System (CERES). VIIRS provides high-resolution global imagery across 22 spectral bands. Together these instruments provide comprehensive atmospheric, oceanic, and environmental data.

NOAA-21 operates in the same sun-synchronous afternoon polar orbit as NOAA-20, separated by approximately 180 degrees, effectively doubling the frequency of observations. Together they replaced the aging Suomi NPP satellite's role in the afternoon orbit. The JPSS program is a partnership between NOAA and NASA, with NASA managing the build and launch while NOAA operates the satellites.

NOAA-21 operates in a sun-synchronous polar orbit at approximately 824 kilometers altitude, crossing the equator in the early afternoon local time. This orbit ensures consistent lighting conditions for imaging and near-global coverage. The satellite circles Earth approximately every 100 minutes, completing roughly 14 orbits per day.