3 ms·

But then you have to put solar sails or ionic propulsion into the shade. BFR could deploy a completely passive sail directly into such a sun-synchronous ellipt

• Retric 8y ago
  Anything that blocks that much light is going to be a huge solar sail and need a lot of station keeping. The only reason ionic propulsion might be considered is the they are already going to be solar panels. If you make a large chunk of them from solar panels you then have crazy energy for space based industry and plenty of energy for ionic propulsion. Also, with that much mass in orbit you are going to want some way do move dammaged segments.
  • elihu 8y ago
    Supposing you can re-orient parts of the "huge solar sail" then wouldn't it become rather like the sail of a ship or the wing of a plane, and be usable as a control surface for maneuvering? I'd imagine that in the neighborhood of L1 you would try to find some equilibrium point a little closer in to the sun so that the force of the solar wind matches gravitational pull to the sun. If you start drifting in to the sun, you expose more surface area, and if you're drifting towards the Earth, you re-orient the sail to absorb less solar wind.
    • Retric 8y ago
      That's the idea I was going with. You let the sun counteract most of the force from your solar sail, but that requires you to constantly to make minor adjustments because unlike a normal orbit it's not even close to stable over time. But, while not necessarily difficult it does prevent a lot of the more simple designs as you can't just toss out a bunch of reflective beach balls with very low pressure or other 'simple' means of blocking sunlight.