‘Zombie’ satellite still a threat
October 19, 2010
Intelsat’s uncontrolled Galaxy-15 craft is still posing a threat to broadcasting satellites which are in its path. Galaxy-15 was probably affected by a solar flare back in April and cannot be controlled from the ground. It is drifting steadily – and predictably – along an orbital arc and while there is little chance of collision there are very real headaches for the satellites whose path Galaxy-15 will cross.
The problem is one of interference because Galaxy-15 is very much switched ‘on’, and automatically re-broadcasting any incoming signals that it collects en-route. When the incident happened Intelsat said they expected the rogue satellite to lose its momentum control around August.
The theory was that with momentum control lost the craft would then lose its ability to point its all-important solar arrays towards the sun, and thus lose its power source. Then, it was thought, its batteries would run down and the satellite would become inert. At that point the engineers would attempt one last exercise which is to ‘re-boot’ the satellite and kick-start it back into normal life.
This window of opportunity is tiny. Leave the intervention too long and the risk is that the satellite’s remaining fuel would freeze as would other critical components.
Galaxy-15 is 7 years old, and despite this grave malfunction, is proving to be a robust craft. Intelsat’s engineers admit that Galaxy-15 predicament is quite unprecedented. The past months have seen it transit the official orbits of SES’ AMC-11 craft, a handful of other Intelsat-owned satellites since June, and on its route now are a Mexican satellite, a pair of Canadian and three additional SES Americom craft.
However, according to reports, Intelsat and the satellites builders Orbital Sciences, remain optimistic that the satellite can not only be kick-started back into life but could then be put to work for the best part of its remaining 7-8 years of planned life. And if this doesn’t happen then the craft will eventually end up in a satellite graveyard.