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Why hasnt been artificial satellites torn apart?

  1. Jan 24, 2011 #1
    Do you think that the artificial satellites of earth revolve inside the Roche limit? If
    inside, why are they not breaking apart? Are there any specific reasons?

    Sorry if am asking sill doubts but pls answer me as am really a Beginner :)
  2. jcsd
  3. Jan 24, 2011 #2

    D H

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    Google and wikipedia are your friends. The answer is in the wikipedia article on the Roche limit.
  4. Jan 24, 2011 #3


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    Aww, was going to reply. Let's see if pranathi can figure it out from the wiki article though.
  5. Jan 24, 2011 #4


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    Interesting - is tensile strength also the main reason why objects don't explode in vacuums?
  6. Jan 24, 2011 #5


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    Only if there is gas inside the object. Otherwise it won't want to explode, as there is no force putting pressure on the inside. It doesn't take that much strength to keep about 1 atmosphere pressurized in space. A common household air compressor would be overkill if thats all you wanted to do. What's more important is that the object has the strength to survive launch and manuevering.
  7. Jan 25, 2011 #6
    Some real satellites, both natural and artificial, can orbit within their Roche limits because they are held together by forces other than gravitation. Jupiter's moon Metis and Saturn's moon Pan are examples of such satellites, which hold together because of their tensile strength.

    :shy: This is what I could get from wiki.....So is the tensile strength alone, reason for this or are there any other factors? Can you please give me in brief , sir :)
  8. Jan 25, 2011 #7

    D H

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    Tensile strength is all that is needed to explain why satellites can orbit within their Roche limits. The Roche limit describes the point at which a rubble pile will be torn apart. All that holds a rubble pile together is gravitation itself, and gravity is a very weak force.

    Imagine astronauts taking trips to a rubble pile versus a rocky asteroid of more or less the same mass and density. Escape velocity from an asteroid is very, very low. The astronauts will have to take care not to jump to hard lest they jump right off. An astronaut on a rubble pile could pick up one of the little rocks that form the rubble pile and give it a toss that puts it on an escape trajectory. Astronauts could do the same on a rocky asteroid, but first they would have to chip off a piece of the asteroid. Rocky asteroids are bound together chemically as well as gravitationally.

    Put that rubble pile in orbit about a planet within the Roche limit and gravity gradient from the planet's gravity field will tear the rubble pile apart. It would take a lot more effort to tear apart a rocky asteroid, and even more to tear apart a metallic artificial satellite.
  9. Jan 25, 2011 #8
    Umm... thank you Sir :)
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