The first of three Inmarsat-5 Global Xpress (GX) satellites being built by Boeing has completed a key system life test, paving the way for it to launch later this year. The satellite performed as expected during the spacecraft thermal vacuum test, which simulated the cold, airless vacuum of space.

Housed in Boeing's 1 million square foot building in El Segundo, Los Angeles, California multiple tests were performed such as: giant ovens and anechoic test chambers that absorb radio waves some the size of two-story house.

Harsh conditions in orbit indicate that one side of the spacecraft can be freezing at -234 C while the other, facing the sun, reaches a super hot +199 C.

The satellite has also undergone violent vibration testing where it was shaken in all three axes at up to 30 times a second, and been subjected to low-frequency acoustic testing to simulate launch conditions during which it was blasted with noise louder than a jet engine at take-off.

Deployment of its massive solar panels has also been rehearsed, unfurling to their full 135ft – wider than the wingspan of a Boeing 737.

"We remain focused on continuing to complete crucial milestones to successfully deliver this series of satellites," said Craig Cooning, vice president and general manager of Boeing Space and Intelligence Systems. "The Inmarsat-5 series is built on our 702HP model of satellites, which is flight-proven with over 20 spacecraft in orbit."

When operational, the Inmarsat-5 satellites will support Inmarsat's Global Xpress network, the world's first high speed, mobile broadband service, providing vital data connectivity for government and commercial users on land, at sea and in the air.

The two remaining satellites, which will complete Global Xpress' global coverage, are currently in production at Boeing's Satellite Development Center.

Inmarsat GX has a global network that's owned and managed solely by Inmarsat, and covers all its clients. Purposely designed for mobility, it will provide a continuous, consistent service as traffic is handed seamlessly across each spot beam and from one satellite to another. Inmarsat GX will be complemented by the FleetBroadband service on the Inmarsat-4s. This is the only satellite network that combines both Ka- and L-band technologies to provide full global coverage.