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> because new technology will magically solve all our problems. Well, if you call putting 10 million tons of diffractive moondust into orbit at L1 “magical”, t

• mpoteat 6y ago
  How much fuel would lifting 10 million tons of dust into high orbit require? Probably more than we have the ability to access. Sounds magical to me!
  • unchocked 6y ago
    Impossible until it’s inevitable. The material is available at low deltaV from near-earth asteroids. Though it’s better fabricated into a giant solar sail of a sunshade.
  • Geezus_42 6y ago
    Considering it's moondust and thus has to come from the moon, also assuming rocket engines have gotten more efficient since we last sent people to the moon and taking into consideration the much lower gravity of the moon. I would hazard to guess that it would take about the same or less fuel than an Apollo mission. Also, once the container was launched from the serfice of the moon you could probably propel it using a light sail and some sort of solar powered beam thus only needing fuel for take off and deceleration. But that's all just guesses based on unbacked assumptions.
    • Causality1 6y ago
      Exactly what thought process leads you to believe we can put 10 million tons of dust into solar orbit for the same amount of fuel we used to send 1/222,222 of that mass to the moon?
      • Geezus_42 6y ago
        You don't need to lift it from earth gravity therefore less fuel is required.
        • Causality1 6y ago
          You do have to lift from earth gravity since there's no fuel on the moon. Even if there were, 1/6 earth's gravity makes lifting easier but not two hundred thousand times easier.
    • titzer 6y ago
      So you want to use a solar sail to move something closer to the Sun?
      • Geezus_42 6y ago
        A light sail would have probably been a better term. A solar powered base station could emit a beam that would propel it.
  • zaroth 6y ago
    If you were to launch it all from Earth it would be about 100 tons of cargo for every million kg of methane. A million tons a year to orbit (10,000 launches) equates to 600 billion cubic feet of methane, or about 2% of total US annual production. But the actual plan would involve manufacturing the “mirrors” from moondust and propelling them to L1 using railguns powered by lunar solar panels. So you don’t need nearly so much methane.
• Causality1 6y ago
  Even if you had a magical fuel plant on the moon to produce infinite fuel for free, what would be the effects of reducing the amount of light earth receives? It's not just turning down the AC. It's fundamentally altering a variable that features in almost every biological and meteorological system on earth. On top of that, you have Poynting–Robertson drag stopping you from putting dust into stable solar orbit in the first place.
  • zaroth 6y ago
    I consider it a feature that whatever you put up there won’t be in a perfectly stable orbit. That means whatever you do will require upkeep one decade to the next or else it will just revert back to normal. And you can start out at whatever scale you feel comfortable with. E.g. If 1 million tons of material had an overall effect of 0.1% reduction in TSI. The sun’s output isn’t perfectly constant over time naturally. On average we get about 1361W/m2 (TSI). But sunspots can show short-term variance up to 0.3%, overall TSI has been varying about 0.04% per decade based on modern measurements, and TSI is believed to have increased about 40% overall over the last few billions of years. Estimates are that reducing TSI by 1% would reduce global average temperatures somewhere between 0.6°C to 1.6°C. I think the most interesting impact of being able to set the world’s temperature would be countries arguing over the thermostat at a global scale. It’s bad enough when my wife and I can’t agree in our own house! https://climate.nasa.gov/news/2659/four-decades-and-counting-new-nasa-instrument-continues-measuring-solar-energy-input-to-earth/ https://climate.nasa.gov/news/2659/four-decades-and-counting...