UK Inmarsat begins Global Xpress roll-out

The Proton rocket carrying the first Inmarsat I-5 spacecraft leaves the misty Baikonur pad

The roll-out has begun for Britain's single biggest commercial space project.

The London-based Inmarsat company has launched the first spacecraft in what will be a new global telecommunications network for its on-the-move customers.


Inmarsat plans to launch up to three further spacecraft in its Ka-band Global Xpress (GX) system, representing an investment of £1bn ($1.6bn).

The initial I-5 F1 satellite was launched from Baikonur in Kazakhstan.

Its Proton rocket left the pad at 18:12 local time (12:12 GMT) on a long flight due to last over 15 hours.

Separation from the Proton's Breeze-M upper-stage on Monday (GMT) should put the I-5 in a supersynchronous transfer orbit that runs out to 65,000km above the planet.

The Boeing-built, 6.1-tonne satellite will then use its own electric propulsion system to circularise this trajectory and move itself into a "stationary" position at 63 degrees East, some 36,000km above the Indian Ocean.

Inmarsat has become the dominant force in the so-called Mobile Satellite Services (MSS) market.

Its principal customer base is the shipping sector, but the company also caters for any groups that need connectivity away from a fixed line.

These include oil and gas installations, the aviation sector, armed forces, aid agencies and NGOs in disaster areas, and TV news crews reporting from trouble zones.

Customers can use Inmarsat services to make phone calls, to transfer audio-visual material or simple data.

Traditionally, the company has served these customers using the L-band part of the radio spectrum.

However, the new GX constellation will operate in the higher-frequency Ka-band, enabling much higher bandwidth connections - up to 50Mbps download, and 5Mbps upload.

A total of four I-5s have been ordered from the Boeing manufacturer