Following rigorous testing in France and Germany, a new type of dispenser designed to carry four navigation satellites into orbit at once is now in French Guiana, in place for Galileo’s first Ariane 5 launch later this year.

The dispenser is an essential element of launch success, with a double role to play. It first must hold the quartet of satellites securely in place during the stresses of liftoff, and then the nearly four-hour long flight to medium-Earth orbit.

Then, once the Ariane 5 EPS upper stage reaches its target altitude of 23,222 kilometers , the dispenser will release the four Galileo satellites using a pyrotechnic release system triggered by separate igniters, each one firing half a second after the other.

The separated satellites are then pushed away from the dispenser in separate directions using a spring-based distancing system.

The 447-kilogram dispenser, designed by Airbus Defence and Space, must support a satellite mass of 738 kilograms each – nearly three tons total.

Made from a combination of metal and composite materials for maximum stiffness, the dispenser has undergone very comprehensive testing at Airbus Defence and Space near Bordeaux, France, and the IABG testing centre in Ottobrunn, Germany – using both Galileo engineering models and an actual flight satellite, including fit, shock and separation testing.

A four-satellite dispenser for Ariane 5 Galileo launches with engineering models attached for test purposes.
Copyright: CNES/ESA

The test campaign met all objectives, reports the ESA, confirming the behavior performs as predicted, after which the dispenser was shipped to Europe’s Spaceport in French Guiana.

This fall, four Galileo satellites will be launched together for the very first time on a specially customized launcher — the Ariane 5 ES Galileo.

In development since 2012, the new launcher variant has evolved from the Ariane 5 ES (Evolution Storable), used to place ESA’s 20,000-kilogram ATV supply vehicle into low-Earth orbit.

This launder has to carry a lower mass payload – four fully fuelled 738-kilogram Galileo satellites plus their supporting dispenser – but needs to take it up to the much higher altitude of medium-Earth orbit, approximately 23,222 kilometers up.

The target orbit is actually 300 kilometers below the Galileo constellation’s final working altitude, which leaves the Ariane’s EPS upper stage in a stable “graveyard orbit,” while the quartet of Galileos maneuver themselves up to their final set height.

Once the Ariane 5 ES Galileo flight is complete, there should be 18 Galileo satellites in orbit.