Inmarsat launches fourth I-5 satellite for GX Aviation service

Inmarsat's I-5 F4 satellite for GX Aviation lifts off from Florida aboard a SpaceX Falcon 9. Image: SpaceX
Inmarsat’s I-5 F4 satellite lifts off from Florida aboard a SpaceX Falcon 9. Image: SpaceX

Inmarsat’s fourth I-5 (I-5 F4) Ka-band satellite for its GX Aviation inflight connectivity service has been launched from NASA’s Kennedy Space Center in Florida, USA.

The launch of the SpaceX Falcon 9 rocket took place on Monday 15 May at 19.21 EDT.

This was the first launch of an Inmarsat satellite with SpaceX and its two-stage Falcon 9 rocket delivered the satellite to a Geostationary Transfer Orbit (GTO).

This was the heaviest payload lofted by a Falcon 9 into GTO so far.

The aim was to launch I-5 F4 as high as possible to cut down on the amount of in-orbit manoeuvring that will done using the satellite’s Xenon-ion electric thrusters.

For this reason the Falcon 9 was not recovered back to the launch site and its boosters dropped into the Atlantic.

The satellite was deployed approximately 32 minutes after launch when it came under the command of the Boeing and Inmarsat satellite operations teams based at the Boeing facility in El Segundo near Los Angeles.

The I-5 F4 satellite will be manoeuvred to its geostationary orbit, 35,786km (22,236 miles) above Earth, where it will deploy its solar arrays and reflectors and undergo intensive payload testing before beginning its GX Aviation commercial service.

Inmarsat GX Aviation

Like the other three satellites in its fifth generation fleet, I-5 F4 was built by Boeing in El Segundo, California as part of Inmarsat’s investment of approximately US$1.6bn.

The 6,100kg satellite is approximately seven metres tall – bigger than a double decker bus – and has a wing-span of 40.6 metres (wider than a Boeing 737). The payload has 89 Ka-band fixed spot beams and six steerable spot beams to direct additional capacity where it is needed.

It will join the three other Inmarsat I-5 satellites that circle the world.

But where exactly is it going to be placed?

At the Aircraft Interiors Expo in Hamburg last month Inmarsat President of Aviation Leo Mondale wouldn’t be drawn on the ultimate orbital position for the fourth I-5 satellite.

He said then it was a secret for commercial reasons, but was widely expected to be somewhere over the Asia-Pacific region. Mondale said it would be placed where the extra capacity was needed.

Update: The official line this morning is: “I-5 F4 has a currently expected geo-stationery location providing service to Europe, the Middle East and the Indian sub-continent. Its final location will be advised in due course.

“The fourth satellite adds further capacity to the GX network, as well as in-orbit redundancy that further upgrades the reliability and resilience of Inmarsat’s service offerings.”

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