US spy satellite re-entry

Discussion in 'Astronomy, Exobiology, & Cosmology' started by blobrana, Jan 26, 2008.

  1. madanthonywayne Morning in America Registered Senior Member

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    Is a date/time set for the missle launch?
     
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  3. blobrana Registered Senior Member

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    I can work out optimum times, (after the shuttle lands on, or after, 20th Feb).
     
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  5. draqon Banned Banned

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    this all reminds me of Cosmos 954
     
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  7. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I noticed that the missle will be fired from an Aegis ship. APL/JHU where I worked for few months shy of 30 years, has developed the Navy's "Standard Missle," SM, self-defense system* into a mobile ocean-based Anti ABM sustem using the vertical lunchers of the Aegis Ships. It is amazing but they now have such good guidance and final-stage target incercept ability that they can hit the target and do not use any war head - only a "kinetic kill."

    Elimination of the wearhead allows for even faster accelerations. About year ago in the APL News, which I still receive as I was "senior staff," there was an update on the program progress. - They had made direct hits on 7 of 8 tries against targets rockets at IBM altitude and speeds. I bet they nail that sucker on the first try, but to be sure, perhaps will launch two anti-ABM versions of the SMs a few seconds apart.


    BTW: before taking over NASA, Mike Griffen was high up leader in the Space department at APL/JHU. I am sure his concerns are real, but bet he is happy that APL/JHU will get some exposure shooting it down. APL/JHU invented the proximaty fuse which saved the Pacific Fleet (from the Kama Kazi attacks) in WWII. Ever since then APL/JHU has lead the way in keeping the Navy's ships safe with the technological advances needed. Few have even heard of them so sure Mike will be happy if more do.
    --------------
    *And the Aegis radar system which can simultaneously track many targets as the no-motion phased-array electronics forming the radar beam is jumping to all track locations in mill seconds to keep tracks, while still making 360 dregree full scans to look for new threats.
    BTW "aegis" was the name of a Greek god's magic/ perfect shield, but I forget which.
     
    Last edited by a moderator: Feb 18, 2008
  8. Echo3Romeo One man wolfpack Registered Senior Member

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    Cool. I didn't know JHU was behind the SM-3. That thing is amazing. I love it how the designed service ceiling is 160km or so, but the weapon is capable of so much more that 160km is just the limitation programmed into the software.

    "What's that? You want that satellite destroyed? Hang on...

    <keystrokes>

    Okay, try it now."
     
  9. blobrana Registered Senior Member

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  10. Syzygys As a mother, I am telling you Valued Senior Member

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    I was thinking what if they end up with a fiasco? Trying to hit it and miss? That would be some fun...
     
  11. sandy Banned Banned

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  12. Echo3Romeo One man wolfpack Registered Senior Member

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    Yeah, I'm amazed, but apparently the engineers think it stands a chance of hitting its target. The software limitation does make sense though. I know the SPY-1D radar used on the newer AEGIS ships can track satellites and meteorites with the software filters off, but it normally doesn't because the combat system's track database is limited to 256 tracks at a time and they don't like it getting saturated.
     
  13. K.FLINT Devil's advocate :D Registered Senior Member

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    space trash

    The reason we do not want to do this is because causing an explosion in orbit puts debris there that could cause problems for future use of that part of space and would make even passing through more dangerous. The less debris the better.

    The people who design these things would be better off adding a
    sub-system that would push a satellite out into deep space when it senses communication failure or device failure that leads to an unrecoverable decay in its orbit.
     
  14. blobrana Registered Senior Member

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    Optimum times
    Time: 03:20 UT
    Time: 13:04 UT
    Orbit: 253 x 247 km

    @K.FLINT
    Yes, the worry is that there will be a lot of debris created that it may even endanger the ISS or other satellites.
    But it is in such a low orbit that most debris will only make a few orbits before they burn up; so no long term problem hopefully.
     
  15. Nasor Valued Senior Member

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    It would take waaay to much fuel. You would basically have to have a whole other rocket with a substantial amount of fuel attached to your satellite, which would require a bigger rocket to launch initially and cost a lot more.
     
  16. blobrana Registered Senior Member

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    Most of the satellite debris is predicted to make one to three orbits before it renters the Earths atmosphere (If you live in northern Canada look out for shooting stars 10 - 15 minutes afterwards).
     
  17. BenTheMan Dr. of Physics, Prof. of Love Valued Senior Member

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  18. Orleander OH JOY!!!! Valued Senior Member

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    Is it gonna look like a meteor shower when it re-enters or are all the parts gonna be too small?
     
  19. Chatha big brown was screwed up Registered Senior Member

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    Something very fishy about that story, even communication sattelites don't just fall out of orbit.
     
  20. D H Some other guy Valued Senior Member

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    Nothing fishy at all. Communications satellite are in geosynchronous orbit, so they won't "fall out of the sky". Satellites in low Earth orbit (i.e., where this satellite is) are still in the Earth's atmosphere. To a person, the air at 200 km would seem little different from a hard vacuum, but there is still air up there, and that thin air makes things in orbit fall. The atmosphere extends up to 10,000 kilometers above the surface of the Earth.

    As an example, the International Space Station falls about 100 meters per day because of aerodynamic drag. One of the jobs of vehicles that go to the Station is to lift it back up to a higher orbit.
     
  21. Janus58 Valued Senior Member

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    Communication satellites are placed in geosynchronous orbits with altitudes of 38,000 km. Photo reconnaissance satellites are placed in orbits between 100 and 150 km in altitude. Variations in the height of the atmosphere due to Solar activity is enough to cause the drag needed to eventually bring down such a LEO satellite.
     
  22. D H Some other guy Valued Senior Member

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    Not that low! Atmospheric drag would take down a satellite orbiting at that low of an altitude in no time flat. Even at 200 km, satellite orbits don't last much longer than a day or so.

    A brief primer on space junk:

    Countries are also supposed to (but not required to) "play nice" in space. Part of playing nice is carrying enough fuel on a LEO satellite to make it ends its life with a controlled re-entry -- i.e., in the middle of some ocean. Most LEO satellites do carry that suicidal dose of fuel. However, bad things sometimes happen, as is the case with the vehicle to be "shot down" in a few hours. The fuel is there but the vehicle is dead.

    Playing nice in geosynchronous orbit means carrying enough extra fuel to move a GEO satellite to a graveyard orbit at the end of its life. Most GEO satellites do not carry their dose of suicide fuel. Using every bit of fuel for orbit maintenance extends the life of the vehicle by months or years. Only about a third of GEO satellites "play nice".

    GEO now has quite a bit of uncontrolled junk flying through it. When a GEO satellite runs out of fuel without moving to a graveyard orbit, it does not remain perfectly geostationary. Solar radiation pressure, Earth's non-spherical gravity field, and third body effects (Moon and Sun primarily) change the orbit slightly. This makes dead GEO satellites a hazard to every functional vehicle up there. I won't be surprised if someday soon we lose a big chunk of TV broadcasts because of a collision in GEO.

    This Parliamentary Office of Science and Technology note is a bit dated, but is well-written and provides some very nice charts and tables on amount of stuff in orbit, orbit lifetimes, Earth impacts, and the Space Treaty.
     
  23. draqon Banned Banned

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    hey dudes...they shot it won
     

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