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Europeanized Soyuz Delivered Galileo Satellites to Useless Orbit
PONTE VEDRA, Florida – The Aug. 22 launch of the first two fully operational Galileo positioning, navigation and timing satellites, initially cheered as a success, will now be registered as a failure of the Europeanized Soyuz rocket’s Fregat upper stage, which left the satellites in a useless orbit, government and industry officials said Aug. 23.
As of mid-afternoon Central European Time Aug. 23 – 24 hours after launch and 20 hours after the Fregat stage inserted the satellites into orbit – launch-service provider Arianespace and the European Space Agency said they were still investigating the injection anomaly and could not conclude what, if any, effect it would have on the two satellites’ functionality.
In what must be felt as a bitter irony in Europe, it was the U.S. Defense Department’s Space Surveillance Network -- which publishes initial orbital parameters, known as two-line elements, of recently launched satellites – that first disclosed the problem Aug. 22.
Among the first to pick up the U.S. military data was Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics, to announced the badly off-target injection data.
The Soyuz-Fregat was supposed to deliver the two satellites into a circular orbit 23,222 kilometers in altitude, inclined 56 degrees to the equator. As McDowell noted, the rough two-line elements produced by the U.S. surveillance network showed the satellites in an elliptical, not circular, orbit with an apogee of 25,922 kilometers and a perigee of 13,700 kilometers.
The worse news: The inclination was 47 degrees instead of 56.
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 signal 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, if they did arrive in correct position, would leave them 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."
The satellites launched Aug. 22 were the first of a 22-satellite order to satellite builder OHB AG of Bremen, Germany. The next two Galileo satellites are scheduled for launch, also on a Soyuz-Fregat operating from Europe’s Guiana Space Center spaceport, in December.
ESA and the European Commission, which owns Galileo, had counted on four more Soyuz-Fregat launches (each carrying two Galileo satellites) and three heavy-lift Ariane 5 vehicles (each with four satellites) to complete the current Galileo satellite order.
That left four more satellites to build to complete the planned constellation of 30 satellites in orbit. Now the minimum next order will be for at least six satellites, not four. The loss of the two spacecraft is unlikely to have any material effect on Galileo’s in-service schedule.
ESA and the European Commission, like most governments, have elected not to insure the Soyuz launches, preferring instead to invest in satellite hardware rather than in commercial insurance policies.
The investigation into the Aug. 22 failure will focus on the Fregat upper stage, built by NPO Lavochkin of Russia. Fregat is capable of being re-ignited in orbit some 20 times. For the Galileo launch, only two burns were used before separation. Then a third motor firing was planned to place the stage into a higher orbit, out of the medium-Earth orbit traffic lanes, to mitigate its threat to other satellites as orbital debris.
The Jupiter Control Room at Europe’s Guiana Space Center, located on the northeast coast of South America, receives much of its information from Moscow, where the Soyuz vehicle is monitored.
The question is what information, in the form of telemetry signals, did Fregat send to Russia, and then on to the European center, at the moment the stage released the satellites?
One official said initial conclusions are that Fregat acted as though it was at the correct orbital-injection location, and said as much to ground teams, leading to the applause in the Jupiter Control Room and a series of speeches by European government and industry officials celebrating a launch success.
But somewhere in that same control room was an engineer looking at a screen showing data not from Fregat, but from the down-range ground stations that were evaluating the satellites’ actual position and receiving satellite telemetry.
Enough early telemetry was received to show the satellites were healthy and sending signals. But warnings that the orbit was wrong likely would have arrived soon enough.
A close analysis of Arianespace’s habitual video sweep of the Jupiter center after the cheering began might show at least one control team member still hunched over a screen in a pose not normally associated with a celebration.