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 .  .p126 Rare Earth Hypothesis "assumes too much", when much is uncertain
 .p127 Jupiter effect - clears asteroids, also destabilizes them
 

Astrobiology - A Brief Introduction

Kevin Plaxco, Michael Gross; Multco Central 576.839 P721A 2011

I was looking for information about the stabilization of RNA by borate minerals on Mars, referred to by Peter Ward in one of his books (attributed to Joe Kirschvink, IIRC). Skimmed, not read cover-to-cover.

Page 94 mentions a paper by Steven Benner at U. Florida suggesting calcium borate (borax and colemanite):

  • p94-95: Borate, it turns out, can react with two neighboring hydroxyls of a sugar such as ribose to form a cyclic boron "ester" -- a ring-shaped molecule with boron bridging the oxygens of the former alcohol groups. As this renders the sugar unreactive, formation of the sugar terminates the formose reaction at ribose. Of course, while this pushes up the yield of robose, it does nothing to stabilize ribose once the free sugar is released from the boron (the reaction is easy to reverse -- just add water). And the chemical half-life of ribose remains quite short relative to the required lengths of time we'd expect for the prebiotic chemistry to build up useful quantities of life's precursors.
    • No direct references in this book

The "information first" process starts with the sculpting and replication of molecules, evolving through RNA to DNA. The "metabolism first" process, which seems more plausible to me, starts with autocatalytic collections of molecules in naturally occuring compartments (like serpentine rock or lipid bubbles).

Astrobiology - A Very Short Introduction

David C. Catling, Multco Central 576.839 C365a 2013

  • p22 Al26 ratios to Fe60 ratios in Vesta-sourced meteorites, probably Wolf-Rayet star rather than supernova

  • p38 Chirality, enantiomirs molecules that are mirror images

  • p39 earliest life; maybe Isua Greenland sedimentary graphite with "lifelike" isotope ratios, 3.8 Ga
    • or fossil stromatolites near "north pole", north-western Australia, 3.5 Ga, Roger Buick
  • p74 chemoautotrophs, life from fixing carbon powered by organic compounds
    • chemoheterotrophs, animals
    • photoautotrophs, plants
    • photoheterotrophs, energy from sunlight, carbon from other microbes
  • p80 extremophiles, 62C for eukariotes, 95C for bacterial and 122C for archaea
  • p83 Life candidates in solar system, Mars, Ceres,
    • Jupiter moons: Europa, Ganymede, Callisto, Saturn moons Enceladus, Titan, Neptune moon Triton, Pluto
  • p126 Rare Earth Hypothesis "assumes too much", when much is uncertain
  • p127 Jupiter effect - clears asteroids, also destabilizes them

Astrobiology (last edited 2019-10-07 05:14:30 by KeithLofstrom)