From NEO to GEO --- an SPS scenario

>
> Consider the delta-V required to go from LEO to L4 or L5 with Lunar assist.
> Is this more or less than the delta-V required to escape Earth completely
> from LEO?
>

Actually now that I think some more about it, I am not sure if it is
more or less. It is about the same, maybe slightly more, maybe
slightly less.

The difference is small enough that other factors will be a lot more
important.

In particular, the main problem with a NEO is the lack of launch
windows, they can be several years apart.

On the other hand, we can shuttle back and forth between LEO, GEO and
Lunar L-4/5 any time we want to.

So for ease of logistics and planning (which includes financial
planning) the modus operandi should be to send as little as possible to
the NEO, because the dominant problem will be getting ROI as quickly as
possible to keep the investors happy. Rather than save a few percent
in propellant, they would much rather get their ROI a couple of years
sooner.

Hence the following scenario would be more attractive than sending
everything to a NEO in one shot (that would require a huge up front
investment and tie the money up for a long time):

1) Finance, develop and build a NEO propulsion system.
Select one or more target NEO's, and send the propulsion system(s)
there.
Grab all or part of each NEO and send it to lunar L-4/5.

In parallel to 1) :

2) Finance, develop and build manufacturing facility at Lunar L-4/5.
This can proceed asynchronous to the NEO recovery mission allowing for
improved flexibility in planning and fundraising. This project could
be started after the propulsion unit is on its way to NEO, and thus
spread out the time over which money must be invested. This will be a
lot easier than trying to raise all the money up front.

Also, the L-4/5 facility can be fed by multiple NEO objects, so we are
not locking ourselves into having our manufacturing facility being tied
up on a single NEO which could take several years to return to Earth.

====

We can send multiple propulsion units to multiple NEO's and set up a
steady stream of payloads to arrive at L-4/5. All feeding a single
manufacturing facility.

We can also use other sources of feedstock. A manufacturing facility at
L-4/5 can use spent rocket stages in Earth orbit as rich feedstock. A
space tug in LEO can use precession to drift towards different orbital
planes (same inclination, different ascending node) over periods of
time, and then rendezvous and grab each stage and take it to L-4/5 via
luanr flyby. Then a subsequent lunar flyby at apogee can be used to
change the inclination. Most of the propellant can be oxygen extracted
from NEO or lunar material.