While it may have rued the one-year delay in completing its Global Xpress high-speed mobile broadband data constellation, mainly due to Proton launch failures, Inmarsat’s luck at least held for the Proton M/Breeze M launch of its own Inmarsat 5F-3 communications satellite. The launch, which was actually a return to service for Proton M after a launch failure in May, took place from the Baikonur Cosmodrome, near Tyuratam in Kazakhstan, at 1144 GMT on 28 August 2015. Despite the first burn of the Breeze M upper stage reported as being one second too short, and its second burn being one second too long, the launch was adjudged a complete success.
The flight was flown under International Launch Services (ILS), the commercial marketing arm of Khrunichev, the Proton’s main manufacturer. The five burns by the Breeze M upper stage put the spacecraft and Breeze M assembly, first into a circular parking orbit then into an intermediate orbit, followed by an initial transfer orbit. The spacecraft was finally released into a 65,000 x 4,341km, 26.75 degree inclination super synchronous transfer orbit 15 hours after launch. The remaining inclination will be removed by the spacecraft’s own apogee kick motor during manoeuvres to circularise the orbit into Geostationary Earth Orbit (GEO).
The satellite carries a communications payload of 89 Ka-band fixed beams and 6 steerable ones. In addition to its main communications payload, Inmarsat 5F-3 is carrying a hosted Ka-band and L-band payload for the US Government.
While three satellites will provide global coverage for the Global Xpress high-speed communications network, Inmarsat is planning to launch one more satellite into the system, Inmarsat 5F-4, which will act as supplementary satellite and as an in orbit back-up. All four satellites have been built by Boeing, using its BSS-702HP satellite bus design.
The spacecraft was insured for launch. Inmarsat is famous for “dodging bullets” as the only major satellite operator yet to have had an insurance loss.
