[AR] Re: Freeman Dyson, RIP

  • From: Peter Fairbrother <peter@xxxxxxxxxx>
  • To: arocket@xxxxxxxxxxxxx
  • Date: Wed, 4 Mar 2020 00:07:28 +0000

On 03/03/2020 18:39, William Claybaugh wrote:

Henry:

It looks to me that this scheme does not require a stupid mistake to create a runaway chain reaction.  It appears to initiate upon *any* mistake, ever.

Kinda looks like a bad bet to me....

For a single ring (lots of objects spaced out in the same orbit, so the objects are essentially stationary to each other in terms of the orbit) the cascade effect could be self-limiting.

Eg suppose a comet comes in and smashes into one object, which breaks up into say 10 bits with <1/10th the k.e of the comet; two of these bits hit other objects, they break up into 20 bits with <1/100th of the comet's k.e. - impact with which the objects can survive intact.


For rings of objects in orbits of different inclinations, where the k.e. of the collision is also dependant on the relative inclination and the average distance from the Sun, things are harder, especially where orbits cross at large angles.

At Earth distance from Sol the maximum closing speed of objects would be 24.8 miles per second, not good.

For a "sphere" in the habitable zone of a blue giant however (if we are going to make a sphere, let's make a BIG one) the maximum closing speed would be about 600 mph if I got my numbers right. That might be engineerable.


Perhaps you could make the objects out of ice, with reflective sunsides, so that any broken bits would evaporate?

Peter F



Bill

On Tue, Mar 3, 2020 at 11:36 AM Henry Spencer <hspencer@xxxxxxxxxxxxx <mailto:hspencer@xxxxxxxxxxxxx>> wrote:

    On Tue, 3 Mar 2020, William Claybaugh wrote:
     >       The "sphere" is not a solid shell but a collection of objects
     >       orbiting at the same approximate distance but different
     >       inclinations. That is commonly misunderstood.
     >
     > I've always wondered why this scheme does not result in a runaway
    chain
     > reaction leading to a massive debris field.

    The orbits are coordinated and controlled, not left to drift at random.
    People who are active enough in space to build such a thing should long
    since have gotten past the stupid-mistakes stage that we're still
    struggling to emerge from.

    Henry



Other related posts:

  1. Home
  2. arocket
  3. Archive
  4. 03-2020