Relic of ancient asteroid found

[michaelmozina]

http://news.bbc.co.uk/1/hi/sci/tech/4757545.stm<br /><br />I find it interesting that it contains less iron and nickel, and more uranium and sodium. I also find it intriguing that at least part of the meteorite survived the impact. <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[serak_the_preparer]

It's also here at:<br /><br />Meteorite survivor unearthed by Mark Peplow (Nature)<br /><br />10 May 2006<br /><br /><i>. . . The meteorite was found in the Morokweng impact crater in South Africa, which is more than 70 kilometres wide and thought to be some 145 million years old. The discovery is reported by Wolf Maier of the University of Quebec at Chicoutimi, Canada, and his colleagues in this week's Nature...</i><br /><br /><br />Fossil from space could tell ages-old secret (News Wales)<br /><br />10/5/2006<br /><br /><i>. . . Dr Adrian Boyce, of Glasgow University and Senior Research Fellow at the Scottish Universities Environmental Research Centre (SUERC), added: <br /><br />"This story has a further twist as the fragment shows some striking differences when compared with other meteorites - such as its absence of iron-nickel metal. The composition suggests that the asteroid came from a source not found in other objects reaching the Earth so far..."</i>

 

[tom_hobbes]

It's very intriguing. I see there is a rush to re-evaluate the kinds of asteroids that fell 140 million years ago and more recent examples, but doesn't it simply show that asteroid composition can be variable? Or is it even more significant than that? <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>

 

[CalliArcale]

To a layperson as me, it also seem to just be another example of how varied asteroids can be. I would expect variation; I mean, moons and planets vary, so why not asteroids? But I am far from an expert.<br /><br />In any case, it's really cool. <img src="/images/icons/wink.gif" /> <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>

 

[michaelmozina]

<blockquote><font class="small">In reply to:</font><hr /><p>It's very intriguing. I see there is a rush to re-evaluate the kinds of asteroids that fell 140 million years ago and more recent examples, but doesn't it simply show that asteroid composition can be variable? Or is it even more significant than that?<p><hr /></p></p></blockquote><br /><br />IMO on of the more interesting aspects of the article was the fact that at least part of the core survived the impact pretty much intact. That doesn't fit with most impact models. <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[tom_hobbes]

<i>I'm</i> confounded whenever a scientist expresses surprise at the failure of reality to live up to the model...<img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>

 

[tom_hobbes]

It certainly is cool! <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>IMO on of the more interesting aspects of the article was the fact that at least part of the core survived the impact pretty much intact. That doesn't fit with most impact models.<p><hr /></p></p></blockquote><br /><br />I thought most meteorites were basically intact inside? That's how they can draw conclusions about asteroids based on them. <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>

 

[michaelmozina]

<blockquote><font class="small">In reply to:</font><hr /><p>When a large impactor strikes the Earth, a colossal amount of heat is produced; and the asteroid material is believed to vaporise or fuse with the surrounding rocks. A 10-km-diameter impactor is thought to generate temperatures of between 1,700-14,000C.<p><hr /></p></p></blockquote><br /><br />Based on the quote from the article, I believe they make the assesment of what they expect to find after a massive asteroid impacts based on the estimated amount of heat generated at the point of impact. Evidently that simplistic way of calculating the energy at impact doesn't explain the physical process fully. At least part of the core survived the impact intact. <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[CalliArcale]

Massive asteroid impact -- there's a big crater here to prove there was a whopping huge amount of energy in teh impact.<br /><br />Sorry, I completely spaced out on that the first time I read this thread.....<br /><br />So yeah, that's weird. But cool! <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>

 

[tom_hobbes]

That's just the effect I have on women. Don't worry about it. <img src="/images/icons/wink.gif" /> <br /><br />Edit: It's the sensation of horror I evoke...<img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>

 

[serak_the_preparer]

<i>...doesn't it simply show that asteroid composition can be variable? Or is it even more significant than that?</i><br /><br />According to current theories concerning the formation of solar systems, the big stuff only lasts so long before it gets swept up into planetary bodies, captured by them, flung further out toward the edge of the system, settles into resonances with other objects, etc. The disk of material surrounding the young star thins out, with fewer and fewer mighty collisions occurring over time. So a lot of the big heavy stuff that would hit our Earth already has, with bombardment by big objects decreasing as the solar system evolves. Most objects this size - maybe 5 miles across (nearly as large as the Chicxulub impactor) - struck Earth earlier in her history, left no craters which survive to the present-day, and were completely destroyed by the heat of their own impacts. Like the thing found in the Yucatan at the K-T boundary, this one occurs at a geologic boundary (Jurassic-Cretaceous), when a major extinction of marine and reptile life took place.<br /><br />No intact piece of Chicxulub or any other very large impact object has been found so far. This is the first. So it is also the first time a detailed analysis of the actual composition of such an object is really possible, unaltered by the impact event or interaction with Earth materials.<br /><br />Why did it survive? Why is its composition a bit different from other space objects found on Earth?<br /><br />This isn't so much the case of a scientific model being challenged or overturned (though that could always happen). This is more about the questions above. Something is different here. Why?<br /><br />This asteroid may have come in slow at a very shallow angle to Earth's atmosphere - not as a single object but as something which broke up as it punched through the sky. This might allow the individual pieces to decelerate sufficiently for the Morokweng fragment to survive. While also produ

 

[tom_hobbes]

Speaking as an <i>entirely</i> ignorant layman.... I do agree.<br /><br />Why this piece survived is a very interesting question, I’m sure. About the answer though, I haven't the faintest clue. Your reply does throw up a number of intriguing possibilities although I'm not remotely capable of coming to any conclusion without help. I can for instance imagine scenario's whereby a large impactor does less damage to itself and the surrounding impact site due to relative velocity, etc. For instance if a large asteroid impacts by coming up on the earth, not too fast, from behind, or at a shallow angle as you suggest, it might not destroy itself entirely in the process. Could it in this way, simultaneously leave a sufficiently wide crater <i>and</i> leave pieces of it's core behind? I don’t know.<br /><br />As for composition there is an interesting question as to it’s apparent different ingredients. But I’m sure there are many exotic bits and pieces riding the gravity well right now that we have never seen, and have no idea about. I’m sure we’re still scratching the surface when it comes to our knowledge of how the solar system developed, what remains to be discovered out there, where all the material in our solar system came from, etc. I’m absolutely sure that there are many big surprises to come.<br /><br />As for your final point, I can’t see any reason why some agglomerations of matter can’t be far, far older than others...<br /><br />But there must be some more knowledgeable chaps out there willing to speculate!<br /> <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>

 

[serak_the_preparer]

<i>Why this piece survived is a very interesting question, I’m sure. About the answer though, I haven't the faintest clue...</i><br /><br />A clue:<br /><br />Meteorite impacts on space rock theories (AFP)<br /><br />Thursday, May 11, 2006<br /><br /><i>Researcher Wolfgang Maier, of the University of Quebec in Chicoutimi, says more work is needed to see if there could be other meteorites around the world that match this unusual signature.<br /><br />But the implication is that the composition of space rocks that have reached the earth differs over the time scale of impact.<br /><br />This, in turn, raises the question that there may be a bigger than suspected variety in the chemistry of rocks circling the sun...</i>

 

[dmjspace]

The solar nebula hypothesis for asteroids and comets--the preferred model for most astronomers--suggests that the two entities are pristine remnants of solar system formation.<br /><br />A better predictive model, the "exploded planet hypothesis (EPH)," suggests that meteorites are chunks of larger, planet sized parent bodies.<br /><br />The key difference between the solar nebula and EPH models is that the latter insists that meteorites should show evidence of significant differentiation, chemical evolution and variety--the kind we know exists in planet sized bodies.<br /><br />The meteorite in question does not fit the model of a primitive remnant. Rather, it fits the model of a chemically diverse chunk of an evolved body, which is why scientists are up in arms over its discovery.<br /><br />Unfortunately, to patch up the solar nebula theory, astronomers are going to have conclude that something unknown happens to asteroids as they float through space, when a simpler solution would suffice: the chemically diverse rocks were created in a planet sized body, according to well known physical laws.

 

[serak_the_preparer]

<i>Unfortunately, to patch up the solar nebula theory, astronomers are going to have conclude that something unknown happens to asteroids as they float through space, when a simpler solution would suffice: the chemically diverse rocks were created in a planet sized body, according to well known physical laws.</i><br /><br />Why can't there be an overlap between these theories? The nebular theory posits a proto-solar cloud of gas and debris out of which the solar system forms. If the sun of a previous solar system exploded in a supernova, why couldn't the planets of that solar system suffer destruction as well? The nebula of leftovers then becomes the birthplace of Sol and perhaps other stars, too.

 

[torino10]

It occured to me that the exploded planet hypothesis does seem like a likely possibility. It has been a genarally accepted consensus that the moon was formed by the impact of a planetoid sized body.<br /><br />Could this meteorite have been a remanant from that earlier collision? This might explain why it has such a different composition as well as giving it similar orbital charecteristicts as the earth resulting in a more 'soft' type of landing.<br /><br />Then again it may just have broken up right before impact due to it's different composition.<br /><br />Anyways it is interesting.