Fuel that froze on the Russian Soyuz rocket is what caused two satellites from Europe's troubled Galileo navigation system to be sent into the wrong orbit in August, an investigation revealed Wednesday.
The freeze was caused by a problem in fuel feeding pipes on the rocket's fourth, Fregat, stage -- "a design flaw" that can be easily fixed, launch firm Arianespace's chief executive officer Stephane Israel told AFP of the findings.
The orbiter pair, intended as the first fully operational satellites in Europe's troubled satnav alternative to America's GPS, were launched from Kourou in French Guiana in August.
But they were placed in the wrong orbit, and experts have said it is unlikely they could be repositioned and used.
A commission set up by Arianespace, the European Space Agency and the European Commission has found that the problem arose about 35 minutes after launch.
Hydrazine propellant froze, which starved the altitude control thrusters of fuel, causing a loss of power and a misorientation of the Fregat upper stage.
"We know what we need to fix this very quickly," said Israel.
"This means that we can envisage returning Soyuz to service from Guiana in the month of December."