Military communications satellites
Astrium was both the prime contractor and payload contractor for the UK Ministry of Defence’s Skynet 4 satellites. Derived from Astrium’s previous-generation OTS and ECS satellites, Skynet 4 satellites are three-axis stabilised with an initial on-orbit mass of slightly less than 800 kg. The spacecraft power is 1.2 kW and solar array span 16 m. The communications payloads include three X-band transponders and two UHF transponders.
A variety of spot and global beams enables the Skynet 4 satellites to serve a widely dispersed and extensive inventory of Earth stations on land, sea and in the air, ranging from small man-portable radio sets and aircraft terminals to rugged systems on naval vessels and submarines and large anchor stations on land.
Skynet 4A, 4B and 4C were launched between 1988 and 1990, and Skynet 4D, and 4E and 4F in 1998, 1999 and 2001. The NATO IVA and IVB satellites were launched in 1991 and 1993.
All provide secure communications for government establishments and all three services throughout the world. Originally owned by the UK MoD, the Skynet 4 constellation is now owned and operated by Paradigm Secure Communications, a subsidiary of Astrium.