The giant 7-metre tall, 6-tonne satellite is currently undergoing final radio frequency testing.
Once all tests are complete the first Global Xpress spacecraft will be flown from Los Angeles airport to the launch site at Baikonur in Kazakhstan on board a Russian Antonov cargo aircraft.
Visitors to the Boeing plant in El Segundo have to follow a strict dress code, as I found out.
You must wear clothes that fully cover your arms and legs, plus fully enclosed shoes – rocket fuel chemicals can be highly dangerous if they get on exposed skin.
You are also made to don a gown and head covering similar to a beret, making you look like a French artist.
There's no doubt – Boeing's clean room facilities are so clean you could eat your food off the floor.
I saw about a dozen engineers working on the I-5 satellite, taking measurements and making adjustments. A long list of successful satellite launches along one wall attests to their skill.
Everything about the facility is on an enormous scale, with giant ovens and anechoic test chambers – which absorb radio waves – the size of two-storey houses.
The I-5 F1 satellite has already passed through thermal testing, where it was placed in a giant vacuum chamber and subjected to the extremes of temperature it will experience in outer space.
The harsh conditions in orbit mean that one side of the spacecraft can be freezing at -234 C while the other – facing the sun – reaches a blistering +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.
These are supported on rails in the ceiling to try and simulate the weightless conditions in space. Huge helium-filled balloons are also used to support parts of satellite that would otherwise break off when subjected to Earth's gravity.
The solar panels will supply the 15 kW of electrical power that will both get the satellite into its final orbit and power its transponders.
The I-5 is currently scheduled for launch aboard a Proton rocket before the end of the year.
Once in its geostationary transfer orbit its solar arrays will be deployed and Boeing's revolutionary electrically-powered Xenon Ion Propulsion System – which is more full efficient than traditional rocket propulsion systems – will slowly move the satellite up to its final in-orbit location, taking around 35 to 40 days.
