How satellites are made

Form the structure

Beams and panels make up the frame that carries everything else. Aluminum is favored for being light and fairly cheap, and the Spacebus design from Thales Alenia uses carbon fiber around a composite honeycomb.

Build the subassemblies

Equipment boxes are built in-house or by subcontractors, each packed with hundreds of parts. Every component is tested to prove it will perform in space, even if it is headed into a subassembly. Flight computers must cope with space, run largely on their own and tolerate faults.

Outfit the payload

On some designs the payload is developed apart from the bus and fills its own panels. Transponders go on communications satellites, and observation satellites carry cameras or radar. The finished panels travel to the integration site to join the bus.

Join with cable and waveguide

Subassemblies are brought together into a single system. Hundreds of units are linked by miles of electrical wiring plus radio frequency waveguides or coaxial cable.

Fit power and heat control

External panels take the solar arrays and engine, and batteries store the power. Radiators, insulation and heaters hold the equipment at working temperatures, since in space heat moves mainly by radiation and conduction.

Weigh and balance

In clean rooms, crews check the craft and unfold its solar arrays in a deployment test. A dedicated rig measures its center of gravity and moments of inertia against the design.

Run the thermal vacuum

A large chamber lined with temperature-controlled panels has its air pumped out. Heat flow between zones inside the craft cannot be reproduced in normal air, so this test matters. The UK's chamber is seven meters across and 12 meters long.

Shake it

Mounted on a shaker table, the craft is vibrated to mimic launch, which lasts roughly 30 minutes. A blanket laid underneath catches tie wraps, bolts or screws, and the team must trace where each one came from.

five to 200 Hz in three axes at one UK facility

Blast it with sound

Huge speakers in an acoustic chamber recreate the noise inside a rocket during the first seconds of launch. The speakers are close cousins of those used at rock concerts.

typically 147 adjusted decibels at one UK facility

Check radio emissions

After the mechanical tests come radio frequency checks in an anechoic chamber shielded from outside interference. Near-field scanners can also measure how the antennas perform.

Ship and fuel

The craft is airlifted in a shipping container to the launch base and retested for transit damage. Crews in protective gear then load propellant, a hazardous job, and any contamination could spoil thruster performance. Finally it is sealed inside the rocket's fairing.