Differences between revisions 2 and 3
⇤ ← Revision 2 as of 2012-05-12 14:04:57 →
Size: 1778
Editor: KeithLofstrom
Comment:
← Revision 3 as of 2012-05-12 14:06:02 → ⇥
Size: 1781
Editor: KeithLofstrom
Comment:
Deletions are marked like this. Additions are marked like this.
Line 28: Line 28:
 . My heating recovery calculations:
  . Solar Shielding/reflector at 0.95 A.U., 10 grams per meter squared, 3e16 m^2^, 3e14kg
  . 12 km/s delta V, 20% efficiency, 100 year mass replacement rate, --> 36 Terawatts		   . My heating recovery calculations:
  . Solar Shielding/reflector at 0.95 A.U., 10 grams per meter squared, 3e16 m^2^, 3e14kg
   . 12 km/s delta V, 20% efficiency, 100 year mass replacement rate, --> 36 Terawatts

The Life and Death of Planet Earth

Peter D. Ward and Donald Brownlee 2002 0805067817

booknotes

  • I learned a lot from Ward&Brownlee's Rare Earth (2000), and Ward's Under a Green Sky (2007)

    • I didn't see "Life and Death" until 10 years after publication, hence much of the contents are old news
  • Subject: Long term climate change in a world without geoengineering
  • Reiterates that we live at a time suited for intelligence, rare in Earth's very long history
  • More glaciations due

    • Root cause, weathering of Himalayas and abnormally low CO2

    • Previously warmer, wetter
  • Future heating due to sun heating
    • Solar heating because helium hotter at same pressure and density
    • Denser hotter core means faster fusion
    • Sun expansion at 7GY from now (not 10 as I remembered) oopsie
  • Earth in old age - mostly because sun heating limits life span

  • Claims animal life possible only ± 500MY from now

  • Dismisses space technology
    • yes, rockets are expensive, book assumes forever
    • Moving to Mars
      • Who needs another (too small) planet?
    • Moving earth with repeated cometary encounters
      • 100 km diameter comet, go to mars orbit, would lose moon
      • 2001 Don Korycanscky, Gregory Laughlin, Fred Adams

        • http://arxiv.org/abs/astro-ph/0102126 Feb 2001

        • 300 AU semimajor axis, 1e18 kg every 6000 years, 1 million times
        • my note: how about ten 500 tonne objects a second? Or 1 million 5 kg objects a second?
    • My heating recovery calculations:

      • Solar Shielding/reflector at 0.95 A.U., 10 grams per meter squared, 3e16 m2, 3e14kg

      • 12 km/s delta V, 20% efficiency, 100 year mass replacement rate, --> 36 Terawatts

      • 1e-13 of solar output

LifeAndDeathOfPlanetEarth (last edited 2012-05-12 14:06:02 by KeithLofstrom)