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Forum » SpaceEngine » Science and Astronomy Discussions » Asteroids, meteors, and meteorites (Everything related to space rocks.)
Asteroids, meteors, and meteorites
midtskogenDate: Monday, 25.03.2013, 08:45 | Message # 76
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I didn't take that photo. I should perhaps been cleared, but the there is a watermark in it. It was taken by Olav Søla. It's a pity if people copy it and remove the watermark.

I've calculatd the path of the meteor and written a bit about it here. It entered the atmosphere in a shallow angle, less than 10 degrees, travelled almost 300 km before disintegrating at least 50 km up. No meteorites. And far from land anyway.





NIL DIFFICILE VOLENTI


Edited by midtskogen - Monday, 25.03.2013, 08:48
 
WatsisnameDate: Monday, 25.03.2013, 08:57 | Message # 77
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How does one determine if a meteor was likely to drop meteorites? Is it primarily by the minimum altitude at which it was visible?




 
midtskogenDate: Monday, 25.03.2013, 17:38 | Message # 78
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Quote (Watsisname)
How does one determine if a meteor was likely to drop meteorites? Is it primarily by the minimum altitude at which it was visible?

Short answer, yes, for typical fireballs (I'm sure there are many factors and much that can be said, but I'm no expert and currently I don't have a proper keyboard to type on anyway and my internet connection is pretty unstable... I'm in pretty rural parts of the eastern Czech republic this week).

An audible bang is a good sign. Or at least that it was still visible below 30 km.





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WatsisnameDate: Monday, 25.03.2013, 21:09 | Message # 79
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That's a good enough answer for my purposes, thanks!

There was a bright (about magnitude of full moon) fireball over the east US coast last Friday. Alas, I missed it, but a friend of mine saw it. He was wondering if it may have dropped some stones. From the reports it sounds like it may have dropped a few, but if so they're all probably in the Atlantic ocean. sad





 
midtskogenDate: Tuesday, 26.03.2013, 07:07 | Message # 80
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Quote (Watsisname)
There was a bright (about magnitude of full moon) fireball over the east US coast last Friday. Alas, I missed it, but a friend of mine saw it. He was wondering if it may have dropped some stones. From the reports it sounds like it may have dropped a few, but if so they're all probably in the Atlantic ocean. sad

Possibly. You need at least two accurate observations from different places to estimate the altitutude. But brightness wise, full moon is bright enough for meteorites. Or rather, if it's not -10 or so, don't expect any meteorites The fireball in the picture that I posted was described as full moon in brightness, It was reported that the landscape was illuminated 400 km away, so it was bright enough, but since it was nowhere close to reach below 30 km, it's safe to say that there were no meteorites.





NIL DIFFICILE VOLENTI


Edited by midtskogen - Tuesday, 26.03.2013, 07:12
 
SolarisDate: Saturday, 30.03.2013, 02:20 | Message # 81
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Itokawa rotates under Hyabusa(535 by 294 by 209 meters in size). The images are actually from three separate rotations.


Processed by Øyvind Guldbrandsen
 
WatsisnameDate: Tuesday, 02.04.2013, 09:15 | Message # 82
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Wow, that really emphasizes the 'rubble pile' appearance of those asteroids.

In other news, some meteorite researchers believe that a certain class of meteorites may originate from the planet Mercury, which would be the first of their kind known. (Their paper can be found here.)

I think the evidence for this, though compelling, is far from conclusive. The authors themselves emphasize this and say more study is required before we can know for sure. As it stands right now, the evidence consists of:

-low magnetic field strength (like Mercury)
-low iron content (like Mercury's surface, and which also suggests it came from a differentiated body.)
-~4.56GY age (therefore a remnant of an original body in the early solar system and mostly unaltered since then)
-composition rich in refractory elements (which implies an origin in the inner solar system)

This evidence is confounded somewhat by some elemental ratios that are similar to Mercury surface rocks, but others that are way off the mark. I am also confused by the claim about its magnetism (do we know that Mercury did not have a strong magnetic field when it was very young?) Regardless, the point remains that overall these meteorites are very dissimilar to any other known meteorite class, so it does seem like we're looking at a unique origin for them. And if they are not from ancient Mercury itself, it appears very plausible that they may be from a protoplanet that was in the same neighborhood, which is still extremely interesting. smile





 
NovaSiliskoDate: Tuesday, 02.04.2013, 09:18 | Message # 83
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Quote (Watsisname)
Wow, that really emphasizes the 'rubble pile' appearance of those asteroids.


Pff, here's a close-up

 
HarbingerDawnDate: Tuesday, 02.04.2013, 09:23 | Message # 84
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Quote (NovaSilisko)
here's a close-up

Now that would be an interesting place for an EVA





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WatsisnameDate: Tuesday, 02.04.2013, 09:33 | Message # 85
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Of course, it is rubble on all scales. I just think the full-view with rotation showing the gargantuan chunks sticking off of it is most impressive. happy

Quote (HarbingerDawn)
Now that would be an interesting place for an EVA


I'd love to try this in KSP. wacko







Edited by Watsisname - Tuesday, 02.04.2013, 09:34
 
NovaSiliskoDate: Tuesday, 02.04.2013, 09:36 | Message # 86
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I imagine if you flew too quickly towards it and impacted at a few m/s, the whole thing would just shatter.

Then again, meteoroids do that all the time and it's still more or less intact, so I suppose it's clumped together tightly enough that it can withstand impacts.


Edited by NovaSilisko - Tuesday, 02.04.2013, 09:38
 
HarbingerDawnDate: Tuesday, 02.04.2013, 09:40 | Message # 87
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Quote (NovaSilisko)
I imagine if you flew too quickly towards it and impacted at a few m/s, the whole thing would just shatter.

Don't forget about the mass of that object. You'd have to hit it with something pretty big - or fast - in order to really disrupt it. Also, since it is a rubble pile rather than a monolith, the energy of an impact would affect it differently.





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NovaSiliskoDate: Tuesday, 02.04.2013, 09:48 | Message # 88
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Hmm. I wonder if a sufficiently sturdy impactor could just end up going straight through it?
 
WatsisnameDate: Tuesday, 02.04.2013, 10:10 | Message # 89
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The gravitational binding energy of the asteroid (given the parameters on wikipedia) is a hundred million joules or so. An empty space shuttle could shatter it with a speed of only 50m/s. smile

(Though that would of course crunch the shuttle in the process) tongue







Edited by Watsisname - Tuesday, 02.04.2013, 10:14
 
NovaSiliskoDate: Tuesday, 02.04.2013, 10:13 | Message # 90
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It's impressive that these things manage to even exist for very long, then... Of course, they do present quite a small target.
 
Forum » SpaceEngine » Science and Astronomy Discussions » Asteroids, meteors, and meteorites (Everything related to space rocks.)
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