Skynet 5Edit
An artist's impression of a Skynet 5 satellite
Skynet 5 is the next generation of satellites, replacing the existing Skynet 4 Stage 2 system. It has been contracted via PFI to a partnership between Paradigm Secure Communications and EADS Astrium, a European spacecraft manufacturer. EADS Astrium were responsible for the build and delivery of Skynet 5 satellites in orbit, whilst subsidiary company Paradigm will be responsible for provision of service to the MoD. Paradigm have also been contracted to provide communications services to NATO using spare capacity on the satellites.
The Skynet 5 satellite is based on the Eurostar E3000 bus design, weighs about 4,700 kilograms (5.2 short tons), has two solar panels each about fifteen metres long, and has a power budget of five kilowatts. It has four steerable transmission dishes, and a phased-array receiver designed to allow jamming signals to be cancelled out. They will also resist attempts to disrupt them with high-powered lasers.[17]
The first of the constellation of Skynet 5 vehicles (Skynet 5A) was launched by an Ariane 5 rocket at 22:03 GMT on 11 March 2007, in a launch shared with the Indian INSAT 4B civil communications satellite, and entered full service on 10 May 2007.[18] The launch was delayed from 10 March due to malfunction of a launch pad deluge system.[19] Skynet 5A successfully separated from its launch vehicle and Telemetry was acquired by its dedicated Control Centre approximately 40 minutes after launch.
The second Skynet 5 UK military communications satellite (Skynet 5B) was launched at 22:06 GMT on 14 November 2007, from Kourou in French Guiana, aboard an Ariane 5 ECA rocket. This launch was delayed from 9 November due to problems with the electronics on one of the Solid Rocket Boosters, and 12 November due to a fueling problem with the launch pad. At time of launch the Ariane 5 ECA launcher set a new record on this mission, deploying a total payload of more than 8,700 kg.[20]
The third Skynet 5 UK military communications satellite (Skynet 5C) was launched at 22:05 GMT on 12 June 2008, from Kourou in French Guiana, aboard an Ariane 5 ECA rocket.[21] The launch had been delayed twice. Originally scheduled for 23 May, more checks were carried out on the launch vehicle and the launch was rescheduled for 30 May.[22] A problem with the launch software during pre-launch checks led Arianespace to reschedule the launch for a second time to 12 June.[23][24]
The fourth Skynet 5 UK military communications satellite (Skynet 5D) was launched at 21:49 GMT on 19 December 2012, from Kourou in French Guiana, aboard an Ariane 5 ECA rocket.[25]
The programme marks a change of approach in the UK from traditional defence procurement methods to a services-based contract which also includes provision of leased ground terminals, Reacher vehicles, the Satellite Communications Onboard Terminal (SCOT) for ships, and the associated baseband equipment.
Initially two Skynet 5 satellites were to be built, with insurance covering any launch loss; the MoD later decided to have a third satellite built in advance, and later still to have the third satellite launched to serve as an on-orbit spare.[26]
Technical specificationsEdit
The fleet of military X-band satellites have been specifically designed to support smaller, low powered, tactical terminals. Each Skynet 5 satellite is equipped with:
High power 160W TWTAs on all transponders, giving 56 dBW peak EIRP in each transmit spot beam and 41 dBW peak EIRP in each global beam per transponder.15 active transponders ranging in bandwidth from 20 MHz to 40 MHzUp to 9 UHF channelsMultiple fully steerable downlink spot beamsOn Board Active Receive Antenna (OBARA) capable of generating multiple shaped uplink beamsFlexible switching capability allowing connectivity between any uplink beam and at least two downlink beamsNuclear hardening, anti-jamming countermeasures and laser protection[