By-Pass the Moon?

On Feb 14, 2008, at 12:04 PM, John Frazer wrote:
> And the point about NEAs is that even with longer distance, you land
> several times the tonnage on an NEA than on Luna, you can lift off
> nearly 100 times the tonnage that you could from Luna, and you do it
> all with higher efficiency rockets since you don't need the sudden
> high
> thrust to get off the Moon. Going to the NEAs gets you more of
> everything you want, especialy since the resources are
> _so_much_better_
> than on Luna.
>
All true, but the logistics are awful. Trip times ranging from
months to years instead of days, and literally *ranging*, even for
the same site, so only certain launch windows are available (and
don't recur for years). Bad news if anybody gets in trouble on such
a trip, or if you get a little behind schedule and miss your window.
The Moon is dramatically easier, and given our record in the last 40
years, I think we should be sticking to whatever path toward progress
is easiest.
> He bases everything, like the "Mars Direct" plan was based, on
> eliminating everything but right to Mars because with the perpetually
> anemic budget, you have to starve one child to feed the other.
>
And because he's unreasonably obsessed with making (short-lived!)
footprints on Mars.
> If we've
> got to wait until the LunOx plant is providing useful amounts of O2 in
> Earth orbit to fuel Mars expeditions, then the price tag for the Lunar
> infrastructure gets tagged onto the eventual Matrs expedition, causing
> sticker shock over the high price of getting to Mars.
>
Only if you bother to mention Mars at all. This is probably the one
thing that Bush did right in his entire tenure; in his Moon speech,
he mentioned Mars only in passing, along with "and other
destinations." That's as it should be. Sure, somebody our thriving
space infrastructure will let us get to Mars and other destinations,
far more cheaply and safely than we could now, but Mars itself is not
the point.
> It also means
> that much longer before we can fund any R&D into manned Mars travel
> until the Lunar effort is "finished" and in the clear (which may be
> never, it may be struggling for a long time).
>
Again, as it should be.
> This means that every
> time a pundit or politician opens their mouth about it, they want to
> cut costs, and since Mars is so far down the line, it gets cut first.
>
Even pundits and politicians do something sensible now and then.
> Like the LunOx scheme, the NEA fuel scheme is put ahead of Mars
> travel,
> and in fact, IMO, it puts Lunar travel behind NEA fuel (since you
> still
> need upper stage fuel, and the upper stage oxidiser iss ~45% of the
> tonnage lifted to LEO, if you're going to GEO or anywhere further).
> It won't be popular with either the Mars camp or the Luna camp, but
> the
> main point is the infrastructure in place, in the water mine at the
> NEA
> and the orbital depot is there for Lunar & Mars travel, and what it
> allows is more tonnage to be lifted from Earth, and more
> reliability in
> sending to deep space, since remotely opening solar & radiator
> arrays &
> antennae are a common failure point, since everything is lifted on
> expendable boosters.
>
Yes, but just think how much more we could lift if we added fairy
dust too! :) Sorry, cheap shot, but I think the point is valid: NEA
resources are beyond our capabilities to obtain in the near future.
The Moon is dramatically simpler, and a good cislunar infrastructure
will make reaching NEAs more achievable.
> Since we can never fund Mars travel until the Moon is "Finished", and
> Mars fans want to delete the Moon, the NEAs might be a compromise,
> since it gives us leverage to anywhere, including SPS and orbital
> habitats.
>
But it's not doable. It would mean another 40 years of accomplishing
nothing at all, for trying to accomplish too much.