MUMBAI: What happens when a DTH satellite turns rogue?
Well, it has to be sent to the graveyard or junk orbit, which is 300 km above the geostationary orbit (35,786 km above the earth). That’s exactly what the AT&T-owned direct to home service provider DirecTV is dealing with. One of its satellites Spaceway-1 - located at 138.4 degrees west and built by Boeing - has developed a malfunction in its batteries, which has put it in danger of exploding.
The Boeing 702HP model spacecraft was functional from 2005 and had been providing high-definition TV services to US subscribers of DirecTV. It was later demoted to the status of a backup satellite. (Normally communications satellite have a life span of 14-16 years.)
AT&T has now written to the Federal Communications Commission (FCC) seeking permission to allow it along with Boeing and Intelsat to deorbit and decommission the satellite between now and 25 February when the satellite would go into earth’s shadow or eclipse.
It has told the FCC that “Spaceway-1 suffered a major anomaly in December that resulted in significant thermal damage to its batteries.”
The harm to the batteries is grievous enough to not support the pressure that would come on them were they to be switched on during the eclipse phase (the period when it enters the earth’s shadow and does not receive sunlight to charge its solar panels; currently the satellite is in the sunlight phase). However, AT&T confesses it cannot avoid switching on the batteries when it enters the eclipse phase as the satellite will not have enough power to be totally deorbited and decommissioned then. And if they are turned on there is a possibility of an explosion, which could possibly damage other satellites in the vicinity.
AT&T has also informed the FCC that just raising the satellite to the graveyard orbit will take 21 days leaving it with just 7 days to vent out 73 kg of its propellant fuel which is nigh impossible. (For a satellite to be decommissioned it needs to discharge its fuel and normally, it takes two to three months for the task when the spacecraft reaches the end of its life.) Within the time period available to Spaceway-1 only a nominal portion of the fuel will have been removed. Hence, it has sought the FCC’s permission to waive off the complete propellant fuel venting requirement. “Authorising DirectTV’s emergency de-orbit operations will facilitate disposal of Spaceway-1 as safely as possible,” AT&T has pleaded.
Obviously, AT&T and DirecTV are racing against a deadline. And the clock is ticking away. Hopefully, the Spaceway-1 will find its way to its final resting place in time.
