Technical problem may lead to postponement of Galileo satellite launches

The failed August launch of two European Galileo navigation satellites may have delayed a planned launch of two new satellites in December. The probable cause of the launch failure has now also been identified.

Investigations into the launch failure by Arianespace revealed that a fuel line in the final stage was positioned too close to a line filled with liquid helium. The very cold helium froze the fuel line filled with hydrazine, with the result that the engines of the so-called Frigate-trap could not do their job. This put the two Galileo satellites into orbit thousands of kilometers too low. The angle of inclination also turned out to be wrong.

The Russian NPO Lavochkin has built the rocket stage. The company is said to have applied the failing design to a quarter of the Fregat stairs manufactured. According to the rocket builder, the design can be adjusted quite easily.

It is not yet clear whether the changes can be implemented in time. Another launch of two Galileo satellites with a Soyuz Fregat rocket is planned for December, but the EU may also decide to launch these satellites in spring or summer along with two other Galileo rockets. These must be raised with an Ariane 5 rocket. The latter choice would give the ESA more time to subject the satellites to additional tests.

The two satellites that went into too low orbit in August have not yet turned out to be completely useless. For example, the artificial moons can be controlled via a ground station. It is being examined whether the satellites currently moving in an elliptical orbit can still be used. However, the two Galileo satellites will have to deal with more radiation due to their orbit, which will shorten their lifespan. The signal of the two built-in clocks may also be disturbed. Because the amount of fuel is limited, the artificial moons can only be moved into other orbits with difficulty.