ILS Proton Delivers Inmarsat’s Second Global Xpress Satellite to Orbit
PARIS — An International Launch Services (ILS) Proton rocket on Feb. 2 successfully placed the Inmarsat 5 F2 Global Xpress Ka-band mobile broadband satellite into a supersynchronous transfer orbit fifteen and one-half hours after launch from Russia’s Baikonur Cosmodrome in Kazakhstan.
London-based Inmarsat and satellite builder Boeing Space and Intelligence Systems of El Segundo, California, both confirmed the satellite’s successful in-orbit placement and its signal strength.
For Reston, Virginia-based ILS, which is owned by Proton builder Khrunichev Space Center of Moscow, it was the first of a planned five or six campaigns set for 2015, including the third and final Inmarsat Global Xpress satellite in the ILS manifest. That launch is scheduled to occur this spring. The Russian government plans to use Proton for five or six of government missions in 2015.
Russia’s Proton rocket and its Breeze-M upper stage dropped Inmarsat 5 F2 into a supersynchronous transfer orbit, with an apogee of 65,000 kilometers rather than the 36,000-kilometer drop-off point often used for telecommunications satellites. From its drop-off point, Inmarsat 5 F2 will be maneuvered to remove the high inclination relative to the equator resulting from a launch from Kazakhstan. The perigee was 4,341 kilometers, ILS said.
ILS said the supersynchronous orbit saves about 200 kilograms in propellant that would otherwise be needed for a satellite placed in conventional geostationary transfer position. The weight savings can be used to extend the satellite’s service life or to add payload capacity.
Inmarsat said the satellite’s antennas would be deployed by the end of February, at which point its electric-power propulsion would begin moving it into final circular geostationary 36,000 kilometers over the equator. Testing of the Ka-band payload should begin in April, the company said.
The 6,070-kilogram satellite is designed to deliver 13.8 kilowatts of power to the Ka-band payload at the end of its contracted 15-year service life.
Inmarsat originally ordered three identical Global Xpress satellites from Boeing – all three for launch on ILS Proton vehicles — and then added a fourth to be able to rebound from a launch failure or, if all three were successfully put into service, to be able to augment capacity.
The fourth satellite is scheduled for completion in 2016. Inmarsat has signed several launch options with SpaceX of Hawthorne, California, but has not yet specifically assigned the fourth Global Xpress satellite to a SpaceX Falcon rocket.
The first Global Xpress satellite, which entered service in July 2014, seven months after its Proton launch, and covers Europe, the Middle East, Africa and parts of Asia. The second spacecraft will cover the Atlantic Ocean region, with the third to operate over the Pacific Ocean.
Once the second satellite is in operation, Global Xpress will cover 98 percent of the world’s population and two-thirds of the Earth’s surface. Boeing and Inmarsat are both involved in commercializing Global Xpress, with Boeing handling busuiness with the U.S. government.
Inmarsat views its Global Xpress constellation as a complement to the U.S. Defense Department’s Widband Global Satcom constellation of Ka-band satellites.