Inmarsat F4 satellite launch

Image: Howard Slutsken

APEX Insight: I-5 F4, an advanced Ka-band satellite that completes Inmarsat’s Global Xpress (GX) constellation, launched from the Kennedy Space Center yesterday evening, carried by a SpaceX Falcon 9 booster. With full global GX coverage already provided by the first three I-5s, F4 will be an in-orbit spare, but can be tasked to provide additional capability to high-demand regions.

Inmarsat’s I-5 F4 satellite thundered into space yesterday evening, carried by a SpaceX Falcon 9 booster. In a picture-perfect evening liftoff, the rocket launched at exactly 7:21 p.m. (EDT), precisely at the beginning of the launch window. The Falcon 9 leapt from the historic Launch Complex 39A at the Kennedy Space Center, where Apollo and Space Shuttle astronauts had begun their journeys to space.

The satellite was deployed from the Falcon 9’s second stage 32 minutes after liftoff, after being inserted into a geo-stationary transfer orbit. Telemetry was received from F4 by Inmarsat’s operations center soon after, marking the completion of the successful launch.

I-5 F4 is an advanced Ka-band satellite that completes Inmarsat’s Global Xpress (GX) constellation, designed to provide optimal in-flight broadband connectivity. 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.

F4 was originally scheduled to be flown on a massive, three-core, 27-engine SpaceX Falcon Heavy, but development delays with that launcher drove Inmarsat’s decision to shift to the smaller single-core, nine-engine Falcon 9. Although SpaceX has successfully recovered the Falcon 9’s first stage during previous launches, the trajectory and mass of F4 required the use of all the booster’s propellant, and it was not recovered.

It will take F4 approximately two months to reach its geo-stationary orbit – more than 22,000 miles above the Earth’s equator. After testing, the satellite will enter service later this year.

“I-5 F4 … enables Inmarsat to provide guaranteed global connectivity to industries and governments worldwide.” — Rupert Pearce, Inmarsat

With full global GX coverage already provided by the first three I-5s, F4 will be an in-orbit spare, but can be tasked to provide additional capability to high-demand regions. “For Inmarsat, reliability and resilience are paramount,” said Rupert Pearce, CEO, Inmarsat. “Delivering global commercial services over the GX network, which we achieved at the end of 2015, was only the start of our Global Xpress project. I-5 F4 augments the capabilities of GX and, alongside our existing L-band constellations, enables Inmarsat to provide guaranteed global connectivity to industries and governments worldwide.” Each of the I-5 satellites has a 15-year mission life span, and were built by Boeing Satellite Systems in El Segundo, California.

With a program commitment of $1.6 billion, Inmarsat’s Global Xpress in-flight broadband service became fully operational with launch customer Lufthansa just two weeks ago, on May 2.

Howard has been passionate about aviation since he was a little kid, and is a pilot who loves to fly gliders and just about anything else with wings. He's a frequent contributor to aviation magazines and blogs.