• The I-5 F4 launch on Monday. The fourth and final satellite provides a layer redundancy to the Inmarsat global Ka-band Global Express network. Credit: SpaceX via Flickr
    The I-5 F4 launch on Monday. The fourth and final satellite provides a layer redundancy to the Inmarsat global Ka-band Global Express network. Credit: SpaceX via Flickr
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Katherine Ziesing | Florida

Known as I-5 F4 (Inmarsat’s 5th generation, number four in the series), the fourth and final satellite provides a layer redundancy to the global Ka-band Global Express network which went live in 2015.

Though the Boeing-built satellite was originally planned to be a ground-based test article, Inmarsat decided to launch the six-tonne satellite to provide greater bandwidth in support of the growing demand for speed worldwide. The three existing satellites provide global coverage with 89 steerable spot beams each and the fourth will eventually be likely positioned in the Indian region, Inmarsat CEO Rupert Pearce told media in Cocoa Beach.

Pearce explained that the final satellite completes the $1.6 billion program, complementing over a dozen other Inmarsat satellites on various bandwidths already in orbit.

I-5 F4 is the heaviest launch (watch here) on record for SpaceX and Inmarsat, and the Falcon 9 two-stage launch vehicle was used from the Kennedy Space Centre’s launch pad 39A. Launch Complex 39A has an impressive history dating back to the early days of the Apollo program; it was from here that Apollo-11 took off in July 1969 to become the first manned mission to land on the moon. The first of the I-5 series, F1, was launched in 2013 from the Baikonur Cosmodrome in Kazakhstan, atop a Proton booster. The next two satellites, F2 and F3, followed in 2015, also on Protons.

I-5 F4 was deployed approximately 32 minutes after launch at 7:21pm local Florida time on May 15, when it came under the command of the Boeing and Inmarsat satellite operations teams based at the Boeing facility in El Segundo. From here I-5 F4 will be manoeuvred to its geostationary orbit, 35,786 kilometres above Earth, where it will deploy its solar arrays and reflectors and undergo intensive payload testing before beginning commercial service later this year.

Chief Technology Officer for Inmarsat Michele Franci explained that the satellite would take roughly 50 days to each its geosynchronous orbit.

Note: Katherine Ziesing travelled to Florida as a guest of Inmarsat.

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