Close Planetary Flybys Cause Decompression, Boiloff.

[mikeemmert]

Dear All;<br /><br />This article:<br /><br />http://www.space.com/scienceastronomy/060111_hit_and_run.html<br /><br />appeared on Space.com today. It's about Mercury, an unusually dense little planet. The author's contention is that close flybys of planetary objects, even without contact, could cause large amounts of material to boil off through decompression:<br /><br /><font color="yellow">When two objects interacted, even in a near miss, the effects would have been dramatic.<br /><br />"As two massive objects pass near each other, gravitational forces induce dramatic physical changes—decompressing, melting, stripping material away, and even annihilating the smaller object," Williams said. "You can do a lot of physics and chemistry on objects in the solar system without even touching them."<br /><br />A smaller planet’s self-gravity, which holds it together, would depressurize in the sudden presence of a larger world.<br /><br />"It's like uncorking the world's most carbonated beverage," Williams said. "What happens when a planet gets decompressed by 50 percent is something we don't understand very well at this stage, but it can shift the chemistry and physics all over the place, producing a complexity of materials that could very well account for the heterogeneity we see in meteorites."<font color="white"><br /><br />The article did mention Pluto, where decompression effects will be acting on ices of various kinds.<br /><br />I wonder about the effects of a flyby or collision on the weird, recently discovered large KBO 2003 EL61, which has an unusually high density of about 3 grams per cubic centimeter? Effects of a collision on this object are prettty obvious in it's rapid spin, with a 3.9 hour day. Since the object has two moons, it's spin has to have slowed down considerably since it's formation. The large moon is about the size of the fifth largest asteroid in the main asteroid belt.<b></b></font></font>

 

[silylene old]

that's rather cool.<br /><br />here's a picture from the "glancing blow" simulation that formed Charon:<br /><br /> <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[yevaud]

Sure. I imagine the effects of torsional stresses via extreme gravity would really rock the place! <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[nacnud]

Its definiatly a neet way to bring things to the boil <img src="/images/icons/smile.gif" /><br /><br />

 

[yurkin]

Kinda like what happens to Io.

 

[CalliArcale]

That is very interesting! Especially applying it to Pluto/Charon, although the fact that they are mutally synchronous may mitigate most of the effect. <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>

 

[mikeemmert]

Right. Same forces involved. But the distances are much closer and the effects far more extreme and happen in a very short time frame.