Boomerang meteorite may be the 1st space rock to leave Earth and return

[Admin]

Scientists are puzzled by an unusual rock that might've once launched from our planet into space before coming back home in one safe piece.

Boomerang meteorite may be the 1st space rock to leave Earth and return : Read more

 

[Unclear Engineer]

My first thought when I read this was to wonder if this meteorite could be from the Moon, rather than from Earth. It would be much easier for an asteroid strike on the Moon to send a chunk of the Moon to Earth than vice versa. But, then I read near the end that a meteorite that is believed to be from Earth was found on the Moon by NASA astronauts.

However, that seems to be a major stretch. The link in the article says about the bit of Earth found on the Moon:
". . . a 0.08-ounce (2 grams) fragment composed of quartz, feldspar and zircon, all of which are rare on the moon but common here on Earth. Chemical analyses indicated that the fragment crystallized in an oxidized environment, at temperatures consistent with those found in the near subsurface of the early Earth . . ."

"The available evidence suggests that the fragment crystallized 4.1 billion to 4 billion years ago about 12 miles (20 kilometers) beneath Earth's surface, then was launched into space by a powerful impact shortly thereafter.

"The voyaging Earth rock soon made its way to the moon, which was then about three times closer to our planet than it is today. The fragment endured further trauma on the lunar surface. It was partially melted, and probably buried, by an impact about 3.9 billion years ago, then excavated by yet another impact 26 million years ago, the researchers said."

Or, maybe we don't know that much about the Moon to begin with. If something unexpected was found in the small amount of lunar material the Apollo astronauts brought back, it is hard to claim that it is really "rare" on the Moon. And, to have it undergo a history of being disturbed by 3 impacts seems to imply that there should be a lot more of the same thing on the Moon, both scattered on its surface and buried well under the surface.

So, back to the meteorite found in the Sahara that is thought to be from Earth, could that be a piece of the Moon that is similar to the piece of moon that is thought to be from the Earth? It seems like a piece of the Moon floating to Earth over a few thousand years after a large impact on the Moon would be much more likely, considering we have no visible impact crater on Earth that fits the calculated parameters to launch this rock from Earth, while the Moon is full of undated craters.

 

[skynr13]

Could this be a piece of the Earth that broke off when the Moon was formed over 4 billion years ago and now has returned? It could be compared to the rock from Earth found on the Moon to detect how much they are alike. It should as least be dated to determine it's age, other spectral analysis should also be performed. Why should NASA now go all the way to the Moon to determine the origin of the Moon when they can do it right now here on Earth!

 

[Unclear Engineer]

The argument for the Sahara meteorite is that the amount of changes to the isotopic composition indicate only thousands of years exposure to cosmic rays, not 4 billion years of exposure. So, even if it was some part of Earth that somehow ended up on the Moon after the theorized impact between proto-Earth and "Thea" 4 billion years ago, it still would have had to be buried on the Moon until an impact there sent it out into space for several thousand years of effects from cosmic rays before it came down to Earth in the Sahara.

 

[skynr13]

I actually wasn't sure how long it had been exposed to Cosmic rays. When they say thousands, sometimes they mean thousands and thousands! It could have been inside a meteor that mostly came apart as it's core, or most of the exposed surface burned up in the atmosphere. Still, how would it have gotten into space and only been there a thousand years? You read how large they said the initial meteor crater would have to be to eject it past the Karman line!

 

[Unclear Engineer]

The linked article also has a puzzle for me: It says that the bit of Earth thought to be in the Apollo moon sample crystalize in an oxidized environment about 4 billion years ago about 12 miles below the Earth's surface. That was about 1.5 billion years BEFORE the "Great Oxygenation Event" on Earth, so the "oxidized environment" on Earth 4 billion years ago was not a product of biology. So, why couldn't the Moon have some sort of oxidized environment some depth below its surface 4 billion years ago, too? And, although "quartz, feldspar and zircon, all of which are rare on the moon but common here on Earth" are not common on the Apollo samples, do we really have enough samples or other data to say that it is not present on the Moon at depth, or at other surface sites? We are only talking about a 0.08 ounce fragment in about 100 pounds of Moon surface rocks.

 

[slicksister]

The boomerang meteorite article mentioned it contained Helium-10. I was surprised that Helium could contain so many neutrons (8) and looked up the isotopes of Helium on wikipedia. It indeed exists, but appears to have a half-life measured in yocto-seconds, 260 ys or 2.6*10^-22 seconds. That's so short they also supplied a resonance figure of 1.76 MeV. How ever could the authors detect this Helium-10??? Makes me question the entire article.

 

[Unclear Engineer]

Well, Beryllium-3 is an impossibility, because, to be beryllium, it needs to have at least 4 protons, not to mention some neutrons.

So, I think this is just a typo (or brain fart) that should have been He-3 and Be-10.

 

[slicksister]

Well, Beryllium-3 is an impossibility, because, to be beryllium, it needs to have at least 4 protons, not to mention some neutrons.

So, I think this is just a typo (or brain fart) that should have been He-3 and Be-10.

thanks. makes more sense. (I should've caught the Be-3 goof as well!)