The Proton rocket used to orbit Inmarsat 5 F3. Photo: Khrunichev

[Via Satellite 08-31-2015] Inmarsat’s third satellite in its Global Xpress (GX) High Throughput Satellite (HTS) constellation launched on Aug. 29 aboard an International Launch Services (ILS) Proton rocket from the Baikonur Cosmodrome in Kazakhstan. The mission successfully delivered the satellite to Super-Synchronous Transfer Orbit (SSTO) — the fifth such mission for ILS — after a 15-hour, 31-minute mission. According to ILS, SSTO missions provide increased heavy-lift performance over Geostationary Transfer Orbit (GTO) mission designs, maximizing potential spacecraft operational lifetime.

Inmarsat 5 F3 (I-5 F3) is built on Boeing’s 702 High Power (HP) platform carrying 89 Ka-band fixed beams and six steerable spot beams. With a mass of 6,070 kg, the satellite is designed to generate approximately 15 kilowatts of power at the start of service and approximately 13.8 kilowatts at the end of its 15-year design life. Over the coming weeks, the Inmarsat operations team will raise I-5 F3 to its final orbit, deploy its solar arrays and reflectors, and undertake payload testing. Once these operations are complete, I-5 F3 will join the first two GX satellites, Inmarsat 5 F1, launched in December 2013, and Inmarsat 5 F2, launched in February 2015. The third satellite links together GX as a global system — something Inmarsat sees as an inflection point for new revenue.

“We have been working towards this day ever since we announced plans to create the Global Xpress constellation in 2010. I am delighted that we now have three Global Xpress satellites in orbit, enabling us to provide global GX services by the end of the year,” said Rupert Pearce, CEO of Inmarsat.