Comments on: Danish turnover meteorites

By: Eric Palmer

Eric Palmer — Wed, 16 Sep 2009 04:39:28 +0000

Well, I talked with Dr. Haack at this year’s Meteoritical Society meeting in France. He let me look at the data which was pretty cool. The meteorite is a CM chondrite and has the features that are characteristic of CM chondrites. They found the typical kamacite grains which are exclusive to meteorites. The meteorite also had the characteristic oxygen isotope ratio that defines CM meteorites. Earth rocks have a different ratio of 17O, 18O, 16O. Oxygen isotopes are an excellent way to identify classes of meteorites, lunar rocks or Earth rocks. The meteorite also contained cronstedtite and tochilinite, two minerals that are rare on Earth, but are excessively common in CM chondrites.

In terms of the rock pile, when Grau found the meteorite, it was in one piece. The first thing he did was touch a magnet to it (meteorites are usually magnetic due to the large amounts of kamacite). When he did, the rock fell apart.

In terms of longevity, CM chondrites are very susceptible to terrestrial weathering – i.e. they are too fragile in the highly corrosive environment. Haack expects that any other pieces of meteorite would be destroyed by now.

By: astrodoc

astrodoc — Sun, 22 Mar 2009 15:11:47 +0000

Excuse me, but there is a really small probability for the rocks to be found all in one pile.

By: =)

=) — Tue, 17 Mar 2009 16:17:16 +0000

wooooooowwwww….

By: castletonsnob

castletonsnob — Tue, 17 Mar 2009 06:50:14 +0000

Shouldn’t that read “Danes turn over meteorites?” Or was the original some kind of pun?

By: Daniel Fischer

Daniel Fischer — Tue, 17 Mar 2009 00:34:33 +0000

Grau – whom you can see in this TV clip reporting on the Danish success – is pretty famous in the German meteor(ite) community because he has found ways to triangulate strewn fields mostly from eyewitness interviews, something thought impossible until recently. Normally you need several good videos or all-sky images of a fireball to narrow down the impact area enough for a search to make sense.

By: matt

matt — Tue, 17 Mar 2009 00:21:26 +0000

is that the all connected if it is then it is possible and if not then not possible

By: Torbjörn Larsson, OM

Torbjörn Larsson, OM — Mon, 16 Mar 2009 23:16:45 +0000

When put together in a test tube, these components spontaneously formed into functional ribosomes.

And just before that, a pair of scientists succeeded in making a tree analysis of ribosome parts. This shows how ribosomes grew successively to todays complexity by reusing parts. It is showcased on Talk Rational [Bokov, K. and Steinberg, S.V. (2009) A hierarchical model for evolution of 23S ribosomal RNA. Nature, 457, 977-980.] :

The scheme of dependencies presented in Fig. 2b can help us to elucidate some details of the evolution of the large ribosomal subunit after the emergence of the proto-ribosome. Our analysis shows that stabilization of the proto-ribosome tertiary structure was a major aspect of the 23S rRNA evolution in the post-proto-ribosome era. [...] Our results also demonstrate that, despite its visible complexity, the structure of 23S rRNA follows a rather simple principle and could have evolved in a relatively short time on the evolutionary scale. Each new insertion emerged randomly and was accommodated only if it made the ribosome more stable and effective as a transpeptidase. At early stages of evolution, the ribosome existed exclusively as an RNA body. Later, when the ribosome functioning became sufficiently effective to produce proteins, the latter started playing an important part in the ribosome structure. [My bold.]

They manage to show the growth from the original proto-ribosome (the peptidyl-transferase centre) adding 59 parts, all the while with selection for increased functionality, including accommodation for the smaller subsidiary ribosome units. That is an origami in the higher school!