Are there any man-made orbits more stable than God created?

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newtonian

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Are there any man-made satellites that are more stable than either earth's orbit around the sun or the moon's orbit around the earth?<br /><br />Do any man-made satellites receed in orbit extremely slowly comparable to our moon's receeding in orbit around the earth?
 
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priusguy

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No man-made satellite recedes from Earth. In order to do so, a satellite must be large enough to cause tides*. Every satellite that ever comes within 500-600 km of Earth's surface suffers from atmospheric braking and will some day re-enter.<br /><br />So if there are any satellites around Earth in more or less circular orbits at 50,000-100,000 km, they may well be more stable than the Moon. Farther away, and the influence of the Moon itself becomes felt, possibly elongating the orbit over millenia and causing the perigee get dangerously close to the atmosphere. However, I am not aware of any satellites in such orbits. A circular orbit in 50K-100K km range is not terribly useful.<br /><br />Geosynchronous orbit (36K km from the surface) is not stable over geological times because unevenness of Earth's surface eventually warps it. Same bulges in Earth's sphere pass under the satellite every day at the same point of its orbit, gradually elongating the latter. In fact, geosynchronous comsats require active station-keeping to stay in their "fixed" positions above equator.<br /><br />* Also to be outside geosynchronous orbit -- a moon that orbits its planet faster than the planet itself rotates <i>loses</i> energy via tidal interaction and eventually crashes into the planet.
 
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newtonian

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Priusguy - Was that a No?<br /><br />OK, while I am at it - are there any planetary moons with a more stable orbit than our moon?<br /><br />And what is the longest predicted earth orbit for a man-made satellite not course corrected?
 
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Saiph

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I don't imagine so, considering the amount of mass and inertia that are involved in such systems.<br /><br />It takes far far more to mess with such a system than any man-made orbit. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>
 
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vogon13

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Technically, the earth only exerts 42% of the pull on our moon that the sun does.<br /><br />Since there are no massive nearby perturbing bodies, the moon isn't going to do much except continue to recede very slowly, but the moon is not all that 'securely' in earth's 'grip'.<br /><br />Satellites such as Io and Mimas, are enormously more 'attracted' to their primaries than the distant sun and thus would be relatively harder to 'snag' than our moon would be. (not that that is very likely in any event)<br /><br />Google 'Hill sphere' for more info on this sort of thing.<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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priusguy

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I guess the answer is "No, to the best of my knowledge" <img src="/images/icons/smile.gif" />
 
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willpittenger

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I need to disagree with you on several points.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>No man-made satellite recedes from Earth.<p><hr /></p></p></blockquote><br />Incorrect. Any orbit from the geosynchronous orbit out will recede because the Earth is slowing down. This is why the Moon recedes. Eventually, all satellites that are not below geosynchronous orbits will end up geosynchronous orbits. This is what happened to the the Pluto/Charon system.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>In order to do so, a satellite must be large enough to cause tides<p><hr /></p></p></blockquote><br />Actually, every satellite in Earth orbit creates tides. Just remember that not all of these tides are measurable.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Also to be outside geosynchronous orbit -- a moon that orbits its planet faster than the planet itself rotates loses energy via tidal interaction and eventually crashes into the planet.<p><hr /></p></p></blockquote><br />I think you are talking about orbits inside geosynchronous orbit. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>
 
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CalliArcale

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<blockquote><font class="small">In reply to:</font><hr /><p>Any orbit from the geosynchronous orbit out will recede because the Earth is slowing down. This is why the Moon recedes.<p><hr /></p></p></blockquote><br /><br />The Moon isn't receding because the Earth is independently slowing down. The same thing is causing both. The tidal interactions between the Earth and the Moon are significant, so that means that over time, the primary will transfer rotational energy to the secondary -- causing Earth to slow, and the Moon to recede. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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CalliArcale

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<blockquote><font class="small">In reply to:</font><hr /><p>OK, while I am at it - are there any planetary moons with a more stable orbit than our moon?<br /><br />And what is the longest predicted earth orbit for a man-made satellite not course corrected? <p><hr /></p></p></blockquote><br /><br />There is one moon with a more stable orbit: the Pluto-Charon relationship has reached equilibrium. It's kind of an odd question in some respects, though; a great many natural satellites have orbits that should remain indefinitely, and the biggest effects on many orbits aren't due to the relationship with the primary but with other secondaries. Io, Europa, and Ganymede, for instance, are in orbital resonances with one another. And there are lots of Trojan satellites in the Saturn system.<br /><br />The longest predicted Earth orbit for an existing man-made satellite with no course corrections? Indefinite. Objects in geostationary orbit should stay in orbit forever, assuming they don't run into anything. Most Earth satellites in decaying orbits are decaying not due to orbital interactions but due to atmospheric drag; they're essentially aerobraking over a very long period of time. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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nexium

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I don't know of any man made objects in more stable orbits than Earth's orbit around the Sun, but that is partly because no manmade objects have even a trillionth the mass of Earth. Earth's orbit is so stable we don't know if Earth's orbit is becoming more circular or less circular, nor do we know if our average distance from the Sun is increasing or decreasing. One poster was of the opinion that Earth will be perhaps one percent farther from the sun a billion years from now, but comparitively few experts agree. Neil
 
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CalliArcale

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Part of the trouble is that the Earth's orbit does vary -- but in both directions! It's very very difficult to figure out the net change in the Earth's orbit over a long period of time, because we're not in a two-body system. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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willpittenger

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<blockquote><font class="small">In reply to:</font><hr /><p>There is one moon with a more stable orbit: the Pluto-Charon relationship has reached equilibrium.<p><hr /></p></p></blockquote><br />I would still expect Charon to slowly recede. Charon is probably causing Pluto's rotation to slow down.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Objects in geostationary orbit should stay in orbit forever, assuming they don't run into anything.<p><hr /></p></p></blockquote><br />Not quite. They need to use fuel to remain there. When a geosynchronous satellite runs out of fuel, it slowly drifts away. That is why I read that it was "polite" to use the last bit of fuel to move the satellite to a safe orbit farther out.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Most Earth satellites in decaying orbits are decaying not due to orbital interactions but due to atmospheric drag; they're essentially aerobraking over a very long period of time.<p><hr /></p></p></blockquote><br />The other common effect is the tidal effect from Earth's gravity. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>
 
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Saiph

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The mechanism between pluto and charon that would cause either orbit or rotation periods to change is now gone. Both objects face eachother at all times, pluto's day is the same as charon's orbit (and vice versa). As such tidal forces can no longer transfer angular momentum between the two...and they are in equilibrium.<br /><br />Objects in geosynchronous orbit do not require fuel to stay there. You may have this mistaken with the the 1st, 2nd, and 3rd lagrange points in a two body system.<br /><br />Tidal forces acting on man-made satellites are insignificant, and do not affect the orbit if the satellite is not rotating w.r.t. the surface of the earth (as is very common). <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>
 
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willpittenger

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<blockquote><font class="small">In reply to:</font><hr /><p>Objects in geosynchronous orbit do not require fuel to stay there. You may have this mistaken with the the 1st, 2nd, and 3rd lagrange points in a two body system. <p><hr /></p></p></blockquote><br />From Wikipedia: Circular geosynchronous orbits at the equator are known as geostationary orbits. A perfect stable geostationary orbit is an ideal that can only be approximated. In practice the satellite will drift out of this orbit (because of perturbations such as the solar wind, radiation pressure, variations in the Earth's gravitational field, and the gravitational effect of the Moon and Sun), and thrusters are used to maintain the orbit in a process known as stationkeeping. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>
 
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Saiph

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touche. <br /><br />Here we are talking about various perturbations that can mess with ideal orbits...and I go and forget about them. Geesh, I need sleep! <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>
 
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CalliArcale

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The geosynchronous satellites aren't moving due to tidal interactions, though. It's other factors that cause them to drift. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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plutocrass

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What about electron orbitals? Aren't they trying to fuse nucleii together to get super heavy elements, eventually marching past the radioisotopes and into a region where the stability of the heavy man-made atoms are more stable than anything God created? <br /><br />"Get your own dust." He said.<br /><br /><br /><font color="yellow">Physics World - Superheavy elements<br />Feature: July 2004<br /><br />The recent discovery of elements 113 and 115 will tell us more about the structure of the nucleus and the possible existence of the "island of stability". </font><br /><br />
 
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steampower

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this question is actualy somewhat erronious, it assumes that naturaly occuring orbits are somehow unusualy stable, but thats purely because all the unstable orbits decayed or caused collisions billions/millions of years ago, and as we know from places like Barringer crater or even Tungsta (maybe), there are still objects in the solar system with unstable orbits, so to assume that natural orbits are somehow blessed with some extra stability is in error.<br /><br />with our modern equipment we can detect peturbations in orbits down to miniscule amounts that make the natural drift of (say) Earth look crude and innacurate, if we can detect errors in timing that apear to our instrumentality to be gross then it is obviously possible that we could fine tune the orbit of an artificial object to a higher precision than anything else in the solar system, so we can surpass any natural orbit easily, and probably have with something like Gravity probe A.<br /><br />Geostationary com satelites such as those used for TV etc tend to get pulled out of their designated places by the variations in gravity as the month progresses and the moon tries to adjust their orbit, that plus air drag (V slight but there), the sats have to be in the right point of the sky cos thats where your dish is aimed, so they need to stationkeep within 30 miles or so of their intended position, plus if the satellite turned by one degree the microwave horn feeding the sports channel to your TV dish would be pointed at the wrong spot on the earth (they all have tightly controled "footprints"), so due to air resistance and lunar/solar pull (mainly) the operators need to keep em on station with reasonable precision with the odd manual "tweak"<br /><br />all this tweaking is nothing to do with the innacurracy of the satellites orbit, but due to the operators wanting it to follow an un-natural orbit that is unaffected by anything else in the solar system (and atmospheric drag). so that you can use a fixed dish to point
 
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plutocrass

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hi steve, thanks for your response. <br /><br />i understand those factoids about electron orbitals, i think we all learned about them in grade school, a few of us got to read about them in college, where would organic chemistry be without them? i suppose "would college students be without organic chemistry" is a more entertaining question.<br /><br />my answer was posted because i saw how mistakenly placed was this question, so i thought to put a creative 'spin' on it. your bohrish response will remind me not to provide creative responses to a scientific thread.
 
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newtonian

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stevehw33 - Yes. electrons are not in orbit - they are in orbitals - these are more or less stable than orbits?<br /><br />BTW - this is off thread theme if orbitals are not in orbit - but why are they called orbitals - are electrons travelling at very high speed - is there angular momentum involved?<br /><br />I sort of agree - but I don't know why exactly.
 
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newtonian

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willpittenger - Thank you for the wikipedia quote.<br /><br />So what effect does the solar wind have on earth's and moon's orbits?<br /><br />Ditto radiation pressure?<br /><br />Ditto changes in solar and earth magnetic fields and other magnetic fields [e.g. the ionizatilon of the IGM].<br /><br />Please note that my impression is that earth and moon are in unusually stable orbits now because that is part of God's purpose - albeit changes is earth's orbit during red giant phase is still rather up in the air in my research.<br /><br />Certainly extrasolar planets show a tendency to be unstable - of course there is a bias since that instability makes these planets easier to observe by gravitational effects (as in highly elliptical and hence perturbing other planetary orbits.)
 
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newtonian

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Saiph - good and humble posts respectively.<br /><br />See above - what are the perturbation effects on earth and moon (my primary concern - but in comparison with all other orbits - notably man-made ones.).
 
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newtonian

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Calli - Thank you for your responses.<br /><br />I agree orbits can remain forever, albeit I'm not sure about this without sustaining power (e.g. from God).<br /><br />You posted:<br /><br />Objects in geostationary orbit should stay in orbit forever.<br /><br />As you note from later posts, this is often not the case.<br /><br />However, I expect some orbits will remain forever.<br /><br />Some questions on this:<br /><br />Has God created a perpetual motion machine? (compare Isaac Newton's motion model of the solar system.)<br /><br />I.e. - is our universe in perpetual motion?<br /><br />Will earth and moon eventually reach orbital equilibrium like Pluto and charon - say in a quintillion years?<br /><br />How about our sun in galactic orbit - how stable is that orbit and are we receeding at all from galactic center of gravity (and supermassive black hole, etc.)?<br /><br />I know it will be very hard do predict the exact effects of our sun's orbit caused by the Andromeda-Milky Way merger a few or several billion years from now. <br /><br />Is it just coincidence that the sun is predicted to enter red giant phase about the same time as Milky Way begins to interact with Andromeda?
 
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Saiph

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thing is newt, the earth-moon system isn't more stable than any other given orbit.<br /><br />Taken individually, the earth and/or moon are actually more perturbed by the fact that you could almost classify the system as a binary planet (center of mass is almost outside the earth's crust).<br /><br />as a system, it isn't any more stable than the other planets. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>
 
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