WASHINGTON — DirecTV’s Spaceway-1 satellite has been retired to a graveyard orbit 500 kilometers above the geostationary arc, eliminating the risk of the malfunctioning satellite exploding in an orbit populated by active satellites.
Ground-based observations from ExoAnalytic Solutions’ network of space surveillance telescopes show that Spaceway-1 has been moved out of harm’s way and deactivated.
“Its light curve indicates that it’s no longer stabilized,” Bill Therien, ExoAnalytic’s vice president of engineering, said Feb. 14 by email. Satellites like Spaceway-1 rely on attitude control systems to maintain a stable orientation in orbit. Without power or propulsion to keep it stable, a satellite will begin to tumble.
Fleet operator Intelsat, which flew Spaceway-1 on behalf of DirecTV, notified satellite trackers this week that the 15-year-old satellite had been successfully decommissioned “well above the threshold for the GEO graveyard orbit,” according to T.S. Kelso, a senior research astrodynamicist at Analytical Graphics Inc.
Therien said that Spaceway-1, which operated from geostationary orbit some 36,000 kilometers above the equator, had by Feb. 10 completed its 500 kilometer climb to a graveyard orbit. Its new orbit is high enough to keep the defunct satellite circling the globe for millions of years.
DirecTV, which was using Spaceway-1 as a backup satellite for television broadcast services, notified the U.S. Federal Communications Commission last month that the satellite could explode if it wasn’t moved to a graveyard orbit and shut down by Feb. 25.
The Boeing-built 702 series satellite had been relying exclusively on power generated by its solar arrays after an unexplained anomaly caused “significant and irreversible damage” to its battery in December.
Risk of explosion was minimal as long as the battery remained powered down, but operating on direct solar power would no longer be possible starting in late February when several weeks of eclipses in Spaceway-1’s geostationary orbit would require the satellite to periodically pass through shadow.
Spaceway-1’s operators began maneuvering the satellite into its graveyard orbit in late January.
DirecTV originally planned to leave Spaceway-1 at 300 kilometers above the geostationary arc — a common disposal orbit for retired satellites — but decided later to increase that altitude to 500 kilometers, possibly to consume or vent more fuel. The company originally told the FCC it would not have time to deplete all of Spaceway-1’s approximately 73 kilograms of remaining bipropellant because of the urgency of the satellite’s battery issue.
Daphne Avila, Jim Greer and Kate MacKinnon, spokespersons for DirecTV’s parent company AT&T, did not respond to multiple requests for comment from SpaceNews regarding Spaceway-1.