[SatNews] Launch from the Baikonur Cosmodrome in Kazakhstan took place on schedule at 11:44 GMT...
International Launch Services (ILS) is returning the Proton M rocket to flight with the launch of the Inmarsat-5 F-3 communications satellite—part of the Inmarsat Global Xpress (GX) system – on a multi-hour flight to its transfer orbit.
Proton M Mission:
The Proton booster launching the Inmarsat-5 F-3 satellite is 4.1 m (13.5 ft) in diameter along its second and third stages, with a first stage diameter of 7.4 m (24.3 ft). The overall height of the three stages of the Proton booster is 42.3 m (138.8 ft). I-5 F3 will cover the Pacific Ocean Region and will, together with Inmarsat-5 F1 and Inmarsat-5 F2, create the world’s first globally available, high-speed mobile broadband service, delivered through a single provider.
Following a successful launch readiness review I-5 F3 was cleared for roll-out from the final assembly building to the launch zone Pad 39 on 24 August. Every launch rollout at Baikonur is always scheduled at 06:30, in memory of the time Yuri Gagarin, the first cosmonaut, rolled out for the Buran shuttle launch in 1961.
Destination – geosynchronous orbit
The first three stages of the 58.2 m (191 ft) Proton rocket will place the orbital unit comprising the Breeze M upper stage and the I-5 F3 satellite payload into a sub-orbital trajectory less than 10 minutes after launch.
The Breeze M will then perform planned mission manoeuvres, through a series of five burns, to advance the orbital unit first to an circular parking orbit, followed by intermediate and transfer orbits, and finally into a super-synchronous transfer orbit.
Separation of I-5 F3 and release into geosynchronous orbit 35,786km (22,236 miles) above Earth is scheduled to occur 15 hours and 31 minutes after lift-off.
Once operational, I-5 F3 will deliver Global Xpress services to the Pacific Ocean Region, complementing I-5 F1 coverage in the Indian Ocean Region and I-5 F2 coverage in the Americas and Atlantic Ocean Region.
Together they will deliver Global Xpress, the world’s first globally available, Ka-band, high-speed broadband network connectivity service from a single, trusted operator – whether on land, at sea or in the air.
Inmarsat-5 F1 and F2 launches
The first Global Xpress satellite, I-5 F1, blasted off from the Baikonur Cosmodrome on 8 December 2013 followed by I-5 F2 on 1 February 2015.
Forty eight days and 12 million km (7.5 million miles) after launch, I-5 F1 reached its destination in geosynchronous orbit where it underwent a further four weeks of intensive payload testing before it began powering Global Xpress services on 1 July 2014.
I5-F2 is now in geostationary orbit and is due to arrive into its operational orbital slot shortly.
Inmarsat-5 satellites: the statistics
The I-5 body – at 6.98 metres (22.9ft), the height of a double decker bus
User beams – 89 Ka-band beams generated by two transmit and two receive apertures
Spot beams – six steerable spot beams to direct additional capacity where it is needed
Solar arrays – a wingspan of 33.8 metres (111ft)
Solar panels – five panels of ultra-triple-junction gallium arsenide solar cells generate 15 kW of power at start of service and 13.8 kW by end of life
Station-keeping thrusters – a xenon ion propulsion system (XIPS) handles in-orbit manoeuvring
Launch mass – 6,100kg
Mission lifespan – 15 years
