Zubrin citisism

> You're thinking 2 dimensionally!

Good point. With orbits you often can, but no need to this time.

> It's a bit inefficient of delta-v, but if you're high up in a
> gravity well to start with, it doesn't matter quite so much.

Hey, the whole idea in this application is to burn off the delta-v
without messing with your orbit.

If I'm visualizing right (this time, for a change) it shouldn't
depend on the angle being 90 degrees. Any plane change and its
reversal half an orbit apart should work. In the case of launching
payloads from a colony without using reaction mass or messing with
the colony's orbit, the impulses are going to be small relative to
the colony's momentum. Roughly speaking, it seems as though you
ought to be able to launch at will in the direction perpendicular to
the plane of the orbit, and as long as launches happen at randomly
scattered points in the orbit it will all cancel out.

But having to launch in a single direction is a significant
constraint, so being able to get a component in the plane of the
orbit (with a solution to my 2D problem) would still be of value.

--- In spacesettlers@yahoogroups.com, Ian Woollard
wrote:
>
> On 11/4/05, Dan Wylie-Sears wrote:
> > You're right that I visualized it wrong. I don't know whether
> > there's a solution for what I was trying to do. I wanted to
find a
> > pair of impulses in the same direction that will cancel each
other
> > out. To have zero net effect on angular momentum, they have to
be
> > on opposite sides of the primary.
>
> You're thinking 2 dimensionally! (Insert geeky quote from Wrath of
Khan here)
>
> What you could do is arrange the initial orbit on a plane at 90
> degrees to the final direction... That way the two kicks actually
> cancel each other out perfectly... (It's a trick due to Bob Forward
> AFAIK).
>
> It's a bit inefficient of delta-v, but if you're high up in a
gravity
> well to start with, it doesn't matter quite so much.
>
> --
> -Ian Woollard
>
> "People are brilliantly stupid, and stupidly brilliant"-Robin
Abrahams