[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

starship-design: Homochirality

Yeah, alien bacteria might be pretty nasty.  Unless the alien life was nearly
identical to Earth life we probably wouldn't have to worry about alien viruses,
though, which would be a good thing.

And maybe there's a 50% chance the bacteria wouldn't even be dangerous.  All
of our Earth-life amino acids are chiral, meaning their mirror-image isn't
the same as the original.  It's an outstanding puzzle how homochirality came
about on Earth, but if the process is random, then there's a 50% chance that
ALL the alien amino acids will be different; I think they all have to be 
either right-handed or left-handed.

But there was a recent paper that might be bad news for the random theory;
a meteorite's moledules were recently analzyed for chirality, and a slight
imbalance was found between the right- and left- handed versions.  And the
imbalance favored the same versions as Earth life.  So maybe it's not a
random process after all, and all alien life will have some duplicate aminos.
It's still an unresolved question, though.

As for the atmosphere on a planet around Tau Ceti...  Maybe we have no way of
knowing right now, but is there any way we could make a measurement without
actually going there?  I'm not sure what Deep Space Interferometry is
capable of, but anyone know what spectral signatures we might be able to
measure long-distance?  Water vapor?  Ozone?  CO2?  I know NASA is batting
around the idea, but I have no idea what the theoretical detection limits
are.  Especially with so much light coming from the star...

Ken Wharton