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'Zombie' Satellite Returns To Life

Posted by Soulskill on from the it's-a-trick,-run dept.

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."

12 of 98 comments (clear)

  1. 133 west by circletimessquare · · Score: 5, Funny

    aka 133t status

    --
    intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
  2. Drat by JustOK · · Score: 4, Funny

    Drat! Foiled again.

    --
    rewriting history since 2109
  3. Technically... by mandark1967 · · Score: 4, Funny

    It wasn't a Zombie satellite. Zombies remain dead. Plus, it didn't incessantly transmit the message, "BRAINS! It's what's for dinner!"

    --
    Sig Follows: "Suppose you were an idiot. And suppose you were a member of Congress. But I repeat myself." -- Mark Twain
  4. Re:Traversing the sky? by locofungus · · Score: 4, 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.

    --
    God said, "div D = rho, div B = 0, curl E = -@B/@t, curl H = J + @D/@t," and there was light.
  5. Nuke it from the ground by Stele · · Score: 5, Funny

    It's the only way to be sure.

  6. Amsat-OSCAR 7 by Gordonjcp · · Score: 5, Interesting

    It's worth comparing it with the venerable AO-7 satellite, which was launched in 1974 and eventually "died" when its battery failed dead short in 1981. A little over ten years later, the failed battery failed again, this time going *open* circuit and allowing the satellite to run entirely off its solar panels. So, while the satellite is illuminated by the Sun it works fairly reliably. You need to keep the power down, because it has a linear transponder so the more power you put in the more comes out - until you exceed the tiny amount produced by the solar cells. It works, though, and people communicate across the world on it every day.

  7. Nice story submission! by swordgeek · · Score: 4, Insightful

    Seriously, three short lines which clearly convey the entire summary of the story, contains lots of links to both story and background, AND doesn't contain terrible typos! Also, geeky and interesting. This is what slashdot needs more of.

    --

    "People who do stupid things with hazardous materials often die." -- Jim Davidson on alt.folklore.urban
  8. Just like that? by Thapa · · Score: 4, Interesting

    What impresses me most is that you can just upload patches to orbiting satellites. Sounds like a party for the next DEFCON...

    1. Re:Just like that? by Cylix · · Score: 4, Insightful

      Not too long ago the norm was actually for transponders to simply be open.

      Meaning if you had a means to send a signal to a particular frequency it would be easy to bounce from that transponder and relay back down. Now, if the NOC (or SOC really) caught an open transponder being used as a relay they would eventually shut it down if you were not paying for the air time.

      This became a big deal during the initial war in Iraq as there were a good deal of hijack broadcasts spewing forth from across the sea. In response, they eventually began shutting down transponders until they were scheduled to be used. Either out of interest or trying to lock a particular bird I would find them at random times.

      Somehow I doubt the mechanisms used on the old satellites were more obscurity then security to prevent updates.

      --
      "You should always go to other people's funerals; otherwise, they won't come to yours." -- Yogi Berra
  9. Windoze on Board? by Identita · · Score: 4, Funny

    "We have placed Galaxy 15 in safe mode, and at this time, we are pleased to report it no longer poses any threat of satellite interference to either neighboring satellites or customer services," Intelsat officials announced." Unknown to anyone, the last shuttle launch had a secret space walk in order to hit CTRL-ALT-DEL on the sat's terminal.

  10. Triaxiality by mangu · · 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. 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.

    1. Re:Triaxiality by mangu · · Score: 5, Insightful

      I have worked with geostationary satellite control for over twenty years, so I know a bit about this. The masses on the earth aren't distributed evenly, the higher density of the rock in some parts pull the satellite to the east or the west.

      You are right in that the perturbation caused by the moon is several orders of magnitude larger than the one caused by this slight longitudinal asymmetry. It's only for satellites that are either in geostationary orbit or in 12 hour period orbits that this effect becomes significant.

      For other orbits the pull in one direction is compensated by a pull in the opposite direction when the satellite comes around the earth. For geostationary orbits, however, the perturbation is always in the same direction, because the satellite is always in the same position with respect to the mass asymmetry, so the effect adds up in time.

      Typically a geostationary satellite needs correcting East-West maneuvers every couple of weeks or so. These maneuvers consume about 10% of the total fuel budget for station keeping, inclination maneuvers consume the other 90%. This goes to show how stronger the perturbations caused by the sun, moon, and earth's ellipsoid shape, which cause the inclination of the orbit to increase, are compared to the triaxial density asymmetry.