NOAA’s JPSS-2 satellite was successfully launched from Vandenberg Space Force Base on Nov. 10 at 1:49 a.m. PST. This week it was officially named NOAA-21.

The Joint Polar Satellite System (JPSS) series of satellites provides the latest advances in observations collected from polar orbit. Previously, in NOAA’s polar orbit, each satellite was assigned a letter (-A, -B, -C, etc.) when they were designed, built, and launched. Then, as each satellite reached orbit, they were renamed and given a number. For example, the polar orbiting satellite NOAA-H was launched on September 24, 1988. When it reached polar orbit, it was known as NOAA-11.

The satellites in this latest series (JPSS-1, -2, -3 and -4) are slightly different. Instead of letters, they are marked with numbers during their development and publication phase. However, they will still become NOAA-20, -21, -22, and -23 when they reach orbit, respectively.

The current JPSS system consists of two satellites – the NOAA-NASA Finland National Polar-orbiting Partnership (Suomi-NPP) satellite and NOAA’s NOAA-20. Launched in 2011, Suomi-NPP began as a research satellite and has served as a model for the JPSS series, revolutionizing the making of long-term forecasts and the monitoring of long-term climate changes. Its sister satellite NOAA-20 (formerly JPSS-1) was the first of NOAA’s newest generation of polar satellites, launched in 2017. Still in orbit, Suomi-NPP and NOAA-20 continue their cooperation.

When fully deployed and operational, NOAA-21 will fly about 50 minutes, or half an orbit, ahead of NOAA-20. Suomi-NPP circulates between the two, approximately 25 minutes away from both. NOAA-21 will be the main satellite, NOAA-20 will be the backup satellite, and Suomi-NPP will be the third satellite in the JPSS constellation.

NOAA’s polar orbiting satellites pass 512 miles above Earth and travel at 17,000 miles per hour. Like its predecessor, NOAA-21 circles the globe from pole to pole, crossing the equator 14 times a day to get a full view of the globe twice a day. Below, the important data they collect about the land, oceans, and atmosphere helps scientists better understand our environment and improves both daily weather forecasting and extreme weather forecasting.

As the JPSS satellites are designed to last approximately seven years and the current fleet is aging, NOAA-21 will ensure that we have a robust and sustainable constellation of polar-orbiting weather satellites for years to come.

Why do their names change from “JPSS” to “NOAA”? The change is intended to maintain consistency in the naming conventions NOAA has followed since 1978 for polar orbiting satellites. NOAA satellites are typically built in sets or arrays, with the exception of Suomi-NPP, which was developed as a joint research mission and was therefore not renamed as a numbered NOAA satellite after entering orbit.

NOAA-21 is the 21st polar-orbiting NOAA satellite, ensuring a continuous set of global weather data to ensure a “weather-ready” Earth.