RE: [meteorite-list] Re: Scientists Find Mars Met. (NWA 1950)
Really, can you imagine making an announcement like that and typo such important dating? Your question is really a good one, and I have always thought that there MUST be some terrestrial meteorites misclassified as being of extraterrestrial origin. I also would like to hear a good reason why they are missing from the find records. Regards, CharlyV -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Sunday, January 04, 2004 4:29 AM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: [meteorite-list] Re: Scientists Find Mars Met. (NWA 1950) SNC meteorites are extremely rare - fewer than 20 confirmed examples have been discovered - and are believed to all come from the same body of rock. They are distinguished by their relative youth, being at most 1.3 million years old, compared to 4.5 million for other meteorites. From Scientists find Mars meteorite From Gerard Sevestre in Paris January 04, 2004. Hum, 1.3 million, 4.5 million? Not 1.3 billion and 4.5 billion? fewer than 20 confirmed examples??? Regards, Fred Hall What was Earth's atmosphere like 1.3 Billion years ago? I'm sure Earth had hydrated basaltic rocks then, right? Is there any possibility that some of the SNC's (lava meteorites) are not from Mars, but Earth? Isn't there an Earth meteor crater that formed around 1.3 billion years ago? I have yet to hear a good reason as to why we have not found an Earth meteorite. Some scientist out there, please set me straight as to why we have found some 25+ Mars meteorites and not one Earth meteorite. Thanks
Re: [meteorite-list] Re: Scientists Find Mars Met. (NWA 1950)
I've alway had that exact same question: Where are the Earth meteorites? The answers I have contemplated are, which only plug the curiosity, and I apologise if this is basic stuff published in some texts, as I have yet to read and meteorite reference materials except "Find a Falling Star": Tektites are a form of Earth Meteorites that didn't make escape velocity. And we have plenty of them. >From a collision with the Earth, by an impacting stone or iron, anything which DID obtain escape velocity from the Earth would do just that: escape. It would go any direction AWAY from the earth. The gravity of Earth is much greater than the minimal gravity of the asteroids, and also greater than Mars or the Moon. So a much greater escape velocity is required to remove material from Earth. Additionally, Due to the atmosphere Earth has, at least atmospheric density in the last X millions of years, a hot stone propelled from Earth would have to be fairly large to have it not dampened and returned to Earth. Thus, all small stones would be quenched , by the atmosphere, medium stones exploded and quenched. That leaves very large stones... All the potential meteorites that have returned to Earth during the provolking impact events timing have degraded and blended in with the surrounding rock, except for some impact glasses, as glass as we all know is nearly indestructable for millions of years. So it would have to be a rock returning during the last few dozen thousands of years. If Earth material is ejected in an orbit coincidentally similar to Earths, in a few years the Earth will alter its course and sweep it up. Thus only very massive rocks sent AWAY from Earth's orbit would be potential meteorites. To actually become a meteorite on Earth, that big body would have to later suffer a collision and be once again propelled towards Earth's orbit. The case with Mars is different since this material not swept out by Mars may settle into near Earth's orbit over astronomical scales. Table: Escape velocity; Atmospheric density vs. Earth Earth 11.2 km/sec (25,000 mph); 1.00 Venus 10.4 km/sec (23,200 mph); 90 Mars 5.0 km/sec (11,200 mph); 0.01 Luna 2.4 km/sec (5,400 mph); 0.00 Vesta 0.39 km/sec (870 mph); none So you can see why there are no Venusian meteorites found yet -- ther atmosphere is 90 times thicker than Earth's, similar gravity and escape velocity (you weigh 90% your Earth weight on Venus) and just as meteorites usually reach free fall velocities when hitting Earth, to escape Earth, its the same in reverse. One must ask, when was the last meteorite we know of that hit Earth at more than free fall velocity? Perhaps Siberia (1908, the largest fall in the last 2000 years, probably 400,000,000 Kg stone, known to have blown a man into a tree forty feet away hundreds of km from impact, who later died of the injury) ... no not even that one...it couldn't handle the atmosphere!!! So, the small fragments upon an Earth impact typically would be blown to smitherines recaptured and fall immediately due to the atmospheric damping. And if they are Earth rocks, unless it is a fresh fall, one will never know as all but tektites disintegrate rapidly (less than a million years - excepting very special preservation circumstances). If you look at my table atmospheres, you will see that the moon has none, and Mars only 1% of Earth's. Add that to the fact that Escape velocity is less than half for Mars, and for the Moon, almost down to a fifth, then mix in that within 1,000,000 years, the Earth and Moon will sweep out virtually all of the rocks that pass by its orbit, or change their orbit. In the case of Mars, the expulsion is more random from our point of view, and although it is still unlikely, it is quite believable that some mass could be orbiting, around, further modified by Jupiter and impacts in the asteroid belt that can find its way to Earth. In the case of the Moon they should be much more common, except for the fact of the sweeping, they get cleaned out quickly on an astronomic scale. If you still don't believe me, ask yourself (if you believe in Tektites): What is the largest known tektite? That should make things clearer as to what happens to the resulting particles of a big impact, of the type necessary to make Earth meteorites, after the secondary shocking of atmospheric passage. Anyone have a one kilo tektite? And hot SiO2 I would guess is more cohesive (= larger fragments) than other "typical" Earth rocks. Those are the arguments I can come up with for the lack of Earth parented meteorites. Of course, they are statistical, and a single rock doesn't follow statistics, just what happens to it...so don't give up looking for Earth meteorites. PS I would expect the Moon to have conserved some Earth meteorites, and perhaps some of the fresh Howardites contain ancient Earth meteorites. Saludos, Doug Dawn Mexico En un mensaje con fecha 01/04/2004 8:04:48 AM Mexico Standard Time, [EMAIL PROTECTED] escribe: Really,
Re: [meteorite-list] Re: Scientists Find Mars Met. (NWA 1950)
Well, at the moment its belived, that the moon has separeted the earth after a collision with a Mars-sized body. So in fact all lunar ones are "earth meteorites" ... And in fact the moon is the biggest "earth meteoroid". Hope it will stay on its orbit anyway, prefer a bit smaller ones to my back-yard...;- pekka s [EMAIL PROTECTED] wrote: I've alway had that exact same question: Where are the Earth meteorites? The answers I have contemplated are, which only plug the curiosity, and I apologise if this is basic stuff published in some texts, as I have yet to read and meteorite reference materials except "Find a Falling Star": -- Pekka Savolainen Jokiharjuntie 4 FIN-71330 Rasala FINLAND + 358 400 818 912 Group Home Page: http://www.smartgroups.com/groups/eurocoin Group Email Address: [EMAIL PROTECTED]
Re: [meteorite-list] Re: Scientists Find Mars Met. (NWA 1950)
Hello Pekka, Perhaps Copernicus didn't go far enough... :) If you want to go into the details, you will also find at the moment it is also more correct to call the Moon-Earth System is a binary Planetary system, and Luna a Planetoid, not a "Meteoroid", so we are just the third "rocks" in plural from the Sun. So a meteorite from the Moon is no more significant than a handful of dirt from Finland sent to Australia, although I guess Suomen Posti Oy's rate might be a bit higher. I remind you that the oldest of a few Apollo sample Moon rocks have been dated to nearly 4.5 billion years old, and Allende is considered to be 4.56 billion years old. On the other hand following the logic we can consider other protoplanetary impact events, and we are mostly part of the Solar nebula, so we would all be Solar meteoroids, and that includes that freckled runt, Jupiter... Anyway, you are right, without the phases of the Moon it would be unfortunate to have it land in the back yard... Saludos Doug Dawn Mexico En un mensaje con fecha 01/04/2004 5:07:17 PM Mexico Standard Time, [EMAIL PROTECTED] escribe: Asunto: Re: [meteorite-list] Re: Scientists Find Mars Met. (NWA 1950) Fecha: 01/04/2004 5:07:17 PM Mexico Standard Time De: [EMAIL PROTECTED] Para: [EMAIL PROTECTED] CC: [EMAIL PROTECTED] Enviado por Internet Well, at the moment it´s belived, that the moon has separeted the earth after a collision with a Mars-sized body. So in fact all lunar ones are "earth meteorites" ... And in fact the moon is the biggest "earth meteoroid". Hope it will stay on it´s orbit anyway, prefer a bit smaller ones to my back-yard...;- pekka s [EMAIL PROTECTED] wrote: I've alway had that exact same question: Where are the Earth meteorites? The answers I have contemplated are, which only plug the curiosity, and I apologise if this is basic stuff published in some texts, as I have yet to read and meteorite reference materials except "Find a Falling Star": -- Pekka Savolainen Jokiharjuntie 4 FIN-71330 Rasala FINLAND + 358 400 818 912 Group Home Page: http://www.smartgroups.com/groups/eurocoin Group Email Address: [EMAIL PROTECTED]
Re: [meteorite-list] Re: Scientists Find Mars Met. (NWA 1950)
Hello Pekka, I believe the Moon is in large part composed of the impactor material, the remainder is material from the Earth's early composition. David Pekka Savolainen wrote: Well, at the moment it´s belived, that the moon has separeted the earth after a collision with a Mars-sized body. So in fact all lunar ones are earth meteorites ... And in fact the moon is the biggest earth meteoroid. __ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Re: Scientists Find Mars Met. (NWA 1950)
Yes, Doug, you have right... Its just funny to have a bit more "philosophic" view time to time. If we follow the same logic a bit further, we all are the dust from Solar nebula, as you say, and because our Sun is a second-generation star, it seems, we all are material from the same supernova explosion...and so on until the singularity... Well, think in this way I was none the wiser for it, so perhaps its better to aggree, the Earth is the Earth and the Moon is the Moon, and a binary planetary system, as you say. Know, the too "philosophic" attitude can easily lead me to the nice, round, padded room. Perhaps this have something to do with the origin of the word lunatic...;- And in fact I have spent quite a lot of time and money for my collection, so it doesnt feel very nice to think it just as an ordinary dust, but in fact couldnt help that. The logical result of this seems to be, Im collecting dust...hmmm, perhaps a time to buy a new vacuum-cleaner...;- take care, pekka s [EMAIL PROTECTED] wrote: Hello Pekka, Perhaps Copernicus didn't go far enough... :) If you want to go into the details, you will also find at the moment it is also more correct to call the Moon-Earth System is a binary Planetary system, and Luna a Planetoid, not a "Meteoroid", so we are just the third "rocks" in plural from the Sun. So a meteorite from the Moon is no more significant than a handful of dirt from Finland sent to Australia, although I guess Suomen Posti Oy's rate might be a bit higher. I remind you that the oldest of a few Apollo sample Moon rocks have been dated to nearly 4.5 billion years old, and Allende is considered to be 4.56 billion years old. On the other hand following the logic we can consider other protoplanetary impact events, and we are mostly part of the Solar nebula, so we would all be Solar meteoroids, and that includes that freckled runt, Jupiter... Anyway, you are right, without the phases of the Moon it would be unfortunate to have it land in the back yard... Saludos Doug Dawn Mexico En un mensaje con fecha 01/04/2004 5:07:17 PM Mexico Standard Time, [EMAIL PROTECTED] escribe: Asunto: Re: [meteorite-list] Re: Scientists Find Mars Met. (NWA 1950) Fecha: 01/04/2004 5:07:17 PM Mexico Standard Time De: [EMAIL PROTECTED] Para: [EMAIL PROTECTED] CC: [EMAIL PROTECTED] Enviado por Internet Well, at the moment its belived, that the moon has separeted the earth after a collision with a Mars-sized body. So in fact all lunar ones are "earth meteorites" ... And in fact the moon is the biggest "earth meteoroid". Hope it will stay on its orbit anyway, prefer a bit smaller ones to my back-yard...;- pekka s [EMAIL PROTECTED] wrote: I've alway had that exact same question: Where are the Earth meteorites? The answers I have contemplated are, which only plug the curiosity, and I apologise if this is basic stuff published in some texts, as I have yet to read and meteorite reference materials except "Find a Falling Star": -- Pekka Savolainen Jokiharjuntie 4 FIN-71330 Rasala FINLAND + 358 400 818 912 Group Home Page: http://www.smartgroups.com/groups/eurocoin Group Email Address: [EMAIL PROTECTED] -- Pekka Savolainen Jokiharjuntie 4 FIN-71330 Rasala FINLAND + 358 400 818 912 Group Home Page: http://www.smartgroups.com/groups/eurocoin Group Email Address: [EMAIL PROTECTED]
Re: [meteorite-list] Re: Scientists Find Mars Met. (NWA 1950)
Hi, What the computer models which lead to the big-impactor theory of the Moon's origin show is that the Moon ends up being composed of most of the impactor's mantle, and that portion of the Earth's mantle that is blown off by the impact. The impactor's denser core material mostly remains with, or falls back to, the Earth, and some of the impactor mantle is also incorporated in the Earth's crust. This is why the bulk density of the Moon is identical to the bulk density of the Earth's crust, since both are a mixture of the crustal material of the two original bodies before impact. This fortuitous correspondence was the chief argument for the old theory that the Moon was spun off from the Earth's Pacific basin. This theory, formulated by Darwin (no, not that Darwin, but a nephew or grandson), was still being vigorously supported by some as late as 1963! Sterling K. Webb --- David Weir wrote: Hello Pekka, I believe the Moon is in large part composed of the impactor material, the remainder is material from the Earth's early composition. David Pekka Savolainen wrote: Well, at the moment it´s belived, that the moon has separeted the earth after a collision with a Mars-sized body. So in fact all lunar ones are earth meteorites ... And in fact the moon is the biggest earth meteoroid. __ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
