Arianespace and ESA have issued an update on the launch anomaly that stranded two Galileo navigation satellites in the wrong orbits. The statement confirms that investigators are focused on an apparent problem with the Fregat upper stage of the Russian Soyuz ST launch vehicle.
The update provides no information about the fate of the satellites other than to say they are healthy and communicating with the ground. The European Commission has not issued an update since Friday, when it celebrated what it thought was a fully successful launch.
Space News reports that it is likely impossible to correct the error to make the satellites useful for navigation:
Among the first to pick up the U.S. military data was Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics, to announce the badly off-target injection data.
Climbing into correct position from a too-low perigee requires the use of fuel that would otherwise be used over the satellite’s life for regular maneuvers, but does not by itself mean the loss of the mission.
The inclination error, however, appears too serious to allow much, if any, use of the satellites, according to officials. Correcting the error likely would require more propellant than the satellites carry and, even if they did reach the correct position, they would arrive with propellant levels so low that the effort would be deemed useless.
McDowell speculated that the orbit left the two identical Galileo satellites with “not quite enough dV [delta V, or change in velocity needed to maneuver] to circularize their unplanned elliptical orbit.”
Meanwhile, the off-target launch is another black mark for Russia’s struggling space industry, which as suffered repeated launch failures over the past several years. Eight previous Soyuz ST from the European launch facility in South America had gone off without a hitch.
The statement by Arianespace and ESA follows.
On August 22, 2014, at 9:27 am local time in French Guiana, a Soyuz ST rocket lifted off with the first two satellites in the Galileo constellation.
The liftoff and first part of the mission proceeded nominally, leading to release of the satellites according to the planned timetable, and reception of signals from the satellites. It was only a certain time after the separation of the satellites that the ongoing analysis of the data provided by the telemetry stations operated by the European Space Agency (ESA) and the French space agency CNES showed that the satellites were not in the expected orbit.
The targeted orbit was circular, inclined at 55 degrees with a semi major axis of 29,900 kilometers. The satellites are now in an elliptical orbit, with excentricity of 0.23, a semi major axis of 26,200 km and inclined at 49.8 degrees.
Both the Fregat upper stage and the two satellites are in a stable condition and position that entails absolutely no risk for people on the ground. The residual propellants on the Fregat stage have been purged and the stage was depressurized normally.
According to the initial analyses, an anomaly is thought to have occurred during the flight phase involving the Fregat upper stage, causing the satellites to be injected into a noncompliant orbit.
Studies and data analyses are continuing in Kourou, French Guiana, and at Arianespace headquarters in Evry, near Paris, under the direction of Stéphane Israël, Chairman and CEO of Arianespace, in conjunction with the Russian partners in the Soyuz in French Guiana program (Russian space agency Roscomos and the manufacturers RKTs-Progress and NPO Lavotchkine), as well as Arianespace’s customer ESA and its industrial partners, to determine the scope of the anomaly and its impact on the mission.
“Our aim is of course to fully understand this anomaly,” said Stéphane Israël, Chairman and CEO of Arianespace. “Everybody at Arianespace is totally focused on meeting this objective. Starting Monday, Arianespace, in association with ESA and the European Commission, will designate an independent inquiry board to determine the exact causes of this anomaly and to draw conclusions and develop corrective actions that will allow us to resume launches of Soyuz from the Guiana Space Center (CSG) in complete safety and as quickly as possible. The board will coordinate its work with Russian partners in the Soyuz at CSG program.
“Arianespace is determined to help meet the European Union’s goals for the Galileo program without undue delay. We would like to thank ESA, the European Commission and CNES for the very productive discussions since becoming aware of the occurrence of the anomaly. While it is too early to determine the exact causes, we would like to offer our sincere excuses to ESA and the European Commission for this orbital injection that did not meet expectations.”