Wet, Carbonaceous Asteroids: Altering Minerals, Changing Amino Acids

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Wet, Carbonaceous Asteroids Altering Minerals,
Changing Amino Acids
Water
Aqueous alteration has substantially affected the
mineralogy of many carbonaceous chondrites.
An unaltered chondrule
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Amino Acids
Amino acids are characterized by the presence of
an amine group, NH2, and a carboxylic acid group,
COOH, joined to side chains (R). Two examples are
shown.
NASA /Mary Pat Hrybyk-Keith
Amino acids also can have symmetrical differences
in their structures, mirror images of each other.
Shown are L-isovaline and D-isovaline.
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Changes in the Amino Acid Mix with Aqueous
Alteration
Modified from Glavin et al., 2011.
Increasing alteration causes the abundance of
?-Alanine to increase, others to decrease.
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Changes in L/D with Aqueous Alteration
Graphic prepared with data from Glavin et al.
(2011).
Aqueous alteration appears to have enriched
isovaline in the L structure, suggesting that
this could have happened on the early Earth or
that carbonaceous chondrite asteroids added an
already asymmetrical mix to the Earth.