The Lunar Elevator System

Now that you mention it it does bring to mind one of the benefits of
the lunavator concept over rocket transportation to and from the
moon, and that is that the lunavator, with a low delta-v orbit
requirement, can more significantly take advantage of the m * v
relationship, whereas the rocket equation must follow the m * v2
relationship. Is this what you're referring to?

Thanks for taking this thread in a new direction.

--- In spacesettlers@y..., Lynn Olson wrote:
>
> This is an excellent post. I do have a quibble with the statement
that an
> ion thruster would not work for momentum replacement.
>
> It's true that ion engines require a lot of time to deliver
significant
> delta v because the thrust to mass ratio for a spacecraft is
small.
> However, in the case of the rotovator, we need only match the
payload and
> so do not need to deliver a large delta v to the rotovator.
>
> For example, if we have ion thruster producing an acceleration of
> .1cm/sec^2, the delta v gained in 132 minutes is approximately 8
> meters/sec. If the mass ratio is 20 and the payload delta v is 1.6
> meters/sec, the payload pickup delivers 80 meters/sec to the
rotovator,
> which is ten times what the ion engine delivers in one orbit.
However, if
> we increase the mass ratio by ten while maintaining the same
acceleration,
> the ion engine and payload delta v's will be the same. In
practice the
> acceleration should go up because a higher percentage of the
rotovator will
> be devoted to propulsion. Two way traffic will also improve the
picture
> because then only the difference in momentum needs to be made up.
>
> Whether it will be done this way depends on the economics, with a
tradeoff
> between the capital cost of the propulsion units versus the
propellant
> savings from using high specific impulse. I suspect the first
ones will