> Chris, > Just so you know. When you look at the time and date of my posts you will see > they are from Thursday. They are often delayed by several days. I don't know > why they take so long to post to the list. I have not had time yet to read > your references but I certainly will very soon. > You make entry sound so dramatic with your TNT figures but those amounts are > gibberish to most of us non-scientists. > What makes me curious relative to those scary numbers you state, is the > simple fact that we have been shuttling space ships and rockets for quite > some time in and out of this atmosphere with relatively few TNT scale > catastrophes. That said it seems that if we can do it so can a smooth rock. > Even if you look at photos we have of asteroids they are very smooth > themselves. Not jagged or non-aerodynamic. Makes you wonder why that is? Is > there some mechanism that makes them smooth that we have never addressed yet? > So, my presumption is that they have had millions of years of experience > with space travel. Some we have even observed entering our atmosphere and > then actually exiting without ever falling to Earths surface. These it seems > to me that those rocks would be extra touch for the next go round. Because > they now already must have a tough fusion crust which might be even better > designed than our space shuttle tiles. And therefore should slip through our > atmosphere with the greatest of ease. > So, keeping all of this in perspective , Sterling says the range is actually > from 14%-100% is lost. This figure makes much more sense but it seems to me > that some meteoroids MUST be equally as aerodynamic as our space shuttle and > therefore can not be discounted from the equation. And therefore must make it > through with little loss. > Just my humble common sense here. without math. Thanks again. Carl > -- > Carl or Debbie Esparza > Meteoritemax > > > ---- Chris Peterson <c...@alumni.caltech.edu> wrote: > > To get a visceral sense of why so little material survives entry, we can do > > a simple back-of-the-envelope calculation that lets us ignore messy details > > like entry angle, composition, and ablation physics. > > > > A very slow meteoroid (12 km/s) entering the atmosphere is carrying a > > kinetic energy of 72 MJ/kg. That's the equivalent of 17 kg of TNT per kg of > > meteoroid. Usually, all of that energy is dissipated in at most a few > > seconds (for our purposes, any surviving meteorites can be considered to > > have zero kinetic energy). > > > > A meteoroid that enters at 26 km/s (still slow enough for meteorites) gives > > up 338 MJ/kg, or 80 kg TNT per kg. > > > > Not hard to see from this just how rough a ride those meteoroids > > experience. > > The energy is what it is; the primary factor that determines survival is > > how > > long the energy is allowed to dissipate. That's why long lasting fireballs > > are much better candidates for meteorite producers than shorter ones. > > > > Chris > > > > ***************************************** > > Chris L Peterson > > Cloudbait Observatory > > http://www.cloudbait.com > > > > > > ----- Original Message ----- > > From: <cdtuc...@cox.net> > > To: "Richard Kowalski" <damoc...@yahoo.com>; "meteoritelist" > > <meteorite-list@meteoritecentral.com> > > Sent: Thursday, December 03, 2009 9:32 PM > > Subject: Re: [meteorite-list] How much survives entry? > > > > > > > Richard, > > > Very nice show tonight. I recorded it so I can watch again. You were very > > > very good! You are (the) ultimate meteorite hunter. Congrats. > > > I'm pretty sure it has been stated on this list that the amount burned up > > > in passage through the atmosphere depends on so many different factors > > > that any guess might be right. > > > Anyway, Congrats again. > > > Carl > > > > ______________________________________________ > > http://www.meteoritecentral.com > > Meteorite-list mailing list > > Meteorite-list@meteoritecentral.com > > http://six.pairlist.net/mailman/listinfo/meteorite-list
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