18 August 2010

The Tale of ZombieSat

Braaaains!!! (Galaxy-15, Orbital Sciences)

The Galaxy-15 satellite seemed innocent enough. A simple communication satellite in geostationary orbit, it's only job was to sit in one place, receive signals (mostly for cable TV), amplify them, and beam them back to different places on the ground. It did that job with no trouble for about 5 years. 

Then, on April 5, 2010, Galaxy-15 malfunctioned, possibly due to a solar storm. Ground controllers found themselves unable to give the satellite commands. This was not unprecedented, plenty of satellites have been knocked out of commission by solar activity or other problems, to become pieces of space debris. Space debris needs to be monitored, but the risk of collisions with other satellites is small. Generally, a derelict satellite is not a big deal other than for the company that has to pay for a replacement. This event, however, was unique because Galaxy-15 was still functioning fine in most ways. It was receiving and broadcasting like normal, but would not respond to any commands. And this is important.

Satellites in geostationary orbits (always above the same point on earth) need frequent adjustments to stay in the same place, or they wander around, crossing paths with other satellites. And that's what Galaxy-15 started to do. It was at this point that the satellite gained its nickname: Zombiesat! It was wandering casually towards a gravity abnormality where dead satellites end up, cheerily doing what satellites do, relaying signals, but refusing to listen to any directions about how and where to do its job. The danger was (and still is) that its travels might take it past another satellite, where Zombiesat would steal the other's signal, and beam it off to who-knows-where before the correct satellite can receive it. 

So what were Orbital Sciences, controllers of what was now Zombiesat to do? Well, they first tried to reason with it, politely asking it to listen to their commands…200,000 times. When that didn't work, they did what anyone would logically do with any kind of zombie. They tried to kill it. On May 3, they sent it a strong signal which was supposed to cause the satellite's power system to malfunction and shut down. Zombiesat was unfazed. After that, ground controllers were out of options with Zombiesat as it drifted right into the neighborhood of another satellite, ready to mindlessly gobble up its signals.

What do you do if you are helpless and a zombie is headed your way? You get the hell out of there. So that's what the other satellite did. It moved out of the way as best it could while still relaying its signal. The procedure went well. Since then Zombiesat has drifted past three others without issue, and should pass a few more by the end of this month. At that point the satellite should lose power because its solar panels won't be pointed at the sun anymore. Then engineers may try one more time to get control. Basically they are now waiting for it to fall asleep and hoping to revive it with its memory intact. If that does not work, it will remain just a piece of space garbage, posing its satellite brethren little more danger after its three month drift of terror.

1 comment:

  1. This is a great story. Although it would be better if they had to shoot it in the head, that's probably not the most feasible with a million dollar machine.

    I wonder if there will be more zombie satellites.