Lockheed Martin has received a follow-on contract to continue to sustain and upgrade the US Air Force's (USAF) Global Positioning System (GPS) satellite constellation's ground control system. The performance period of the USAF GPS control segment sustainment II (GCS II) contract runs through 2025 and follows the GCS contract awarded to the company in 2013. As per terms of the GCS II contract, Lockheed Martin will continue modernisation of the GPS architecture evolution plan operational control segment (AEP OCS). This sustainment and upgrade will support GPS III satellite on-orbit operations such as positioning, navigation and timing missions, developed under the GPS III Contingency Operations (COps) programme. Furthermore, the latest contract will support critical troop capability, operational M-code. It is currently being developed under the M-code Early Use (MCEU) contract and will be deployed next year.