To keep its missile attack warning defences up to date, the US Air Force has awarded a US$2.9 billion contract to Lockheed Martin for the production of three Next-Generation Overhead Persistent Infrared (Next Gen OPIR) early warning satellites. They will be positioned in geosynchronous Earth orbit at circa 36,000km altitude and will be used to track “hot” ballistic missile plumes and hypersonic missile atmospheric wakes. They are the long-awaited successor to the SBIRS (Space Based Infrared System) early warning satellite constellation. The first launch of the Next Gen OPIR satellites will be in 2023.
It is thought that these three satellites will be transferred to the new US Space Force once it is up and running (assuming that the US Congress agrees to it).