'Zombie' Satellite Returns To Life 98
realperseus writes "The American telecommunications satellite Galaxy 15 has been brought under control after spending most of the year traversing the sky and wreaking havoc upon its neighbors. The satellite is currently at 98.5 degrees west longitude (from 133 west). An emergency patch was successfully uploaded, ensuring that the conditions which caused it to 'go rogue' will not occur again. Once diagnosis and testing have been completed, Intelsat plans to move the satellite back to 133 west."
Re:Traversing the sky? (Score:5, Informative)
If it was perturbed into a slightly lower orbit then it would orbit the Earth in less than 24hrs. If it ended up in a slightly higher orbit then it would orbit the Earth in slightly more than 24 hrs.
I don't want to commit to which way this satellite has gone (because I'm bound to get it backwards) but it's now about 2 hours displaced from where it should have been. That's an error in its orbit of about 0.02% or about 20 seconds per day.
Tim.
Triaxiality (Score:5, Informative)
Except for two stable points at 75 and 255 degrees east longitude, any geostationary satellite suffers an East-West (or West-East) perturbation due to the earth not being a perfect sphere [wikipedia.org]. This is called "triaxiality" by experts in the field.
The result is that without correcting maneuvers the satellite longitudinal position oscillates around those two stable points, even if the orbit is exactly at the geostationary altitude.
Re:Out of control from April 5th to Dec 23rd? (Score:2, Informative)
From what I understand they were on it all the time but there was simply nothing they could do. The satellite's systems did not respond to commands so they basically had to wait for it to drain its batteries and have the emergency system kick in and reset it autonomously. That just happened, so now they can actually work on it again.