-Z- (Z@Gundam.Com)
Sun, 09 Apr 2000 18:13:24 -0700


At 23:55 4/8/2000, you wrote:
>-Z- wrote:
>> "Bunch" may simply be a made-up word or a Japanese word applied in a
>
>Would it make more sense if Bunch refers to a political entity rather then
>physical organization?

There are already established political entities for each Side -- Zahn
(Side 1), Hatte (Side 2), Munzo or Zeon (Side 3), Moore (Side 4), Raum
(Side 5), Riah (Side 6) and Noah (Side 7) -- that are named, like states or
provinces. If Zeon is any indication, the names are those of historical
figures, not unlike the American states, counties and cities named for
Washington, Jefferson and Lincoln. Bunches, on the other hand, are
numbered, like police precincts or school districts. In Gundam ZZ, the
numbering was clearly tied to order in which the colonies were built -- the
Shangri-la colony is the first colony ever built, Bunch 1 in Side 1.

Note that the colonies each have names in addition to their Bunch number,
the naming convention being for locales on Earth, fictional as well as actual.

>> As to the orbital dynamics, each cylinder spins on its long axis, which is
>> always in a straight line pointing at the Sun. Gyroscopic action keeps it
>> in this orientation. The spinning cylinders travel in a near-circular
>
>If I understand gyroscopes correctly, the spinning of the cylinder will
>actually keep it pointing at the same stars, not at the sun. If a certain
>cylinder is pointing at the Sun in December (Sagittarius), then it should
>point at the Sagittarius all year, in July, it should be pointing exactly
>away from the Sun. To keep it pointing at the Sun, there must be a torque
>applied to the cylinder, costing expensive propellent. Did I screw up
>some reasoning? Or O'Neil had a different answer?

You're assuming that the plane of rotation is the same as the ecliptic
plane, as it would be for a planet orbiting the Sun, or the Moon orbiting
the Earth (about 5 degrees off the ecliptic plane proper). Remember, the
colony is in an orbit around a Lagrange point in the Moon's orbit, not in
the Moon's orbit proper. Objects in the halo orbit have the same period
around the Lagrange point as the Lagrange point has about the Earth, but
they are two distinctly different orbits. Here, the plane of rotation is
that of the halo orbit, and that plane is perpendicular to the axis of
rotation, which is a line toward the Sun. The cylinders are kept in
alignment with the Sun by gyroscopic inertia, which acts to keep the
cylinder rotating in the same plane about the same axis in space.

That being said, it's not a free ride, as noted in the 1975 NASA/Ames Space
Settlement Design Study:

"The basic conclusion is that massive objects placed in the vicinity of L4
and L5 would orbit these points with a period of about one month while
accompanying the Earth and Moon around the Sun. At the price of the
expenditure of some propulsive mass, objects could be maintained near the
other libration points rather easily. The cost of such station keeping
needs to be better understood before the usefulness of these other points
for space colonies can be evaluated. ... The availability of resources for
use by colonists is closely related to the properties of space. The colony
should be located where station-keeping costs are low, where resources can
be shipped in and out with little expenditure of propulsion mass, and where
the time required to transport resources and people is short. These three
criteria, minimum station-keeping, minimum propulsion cost, and minimum
transportation time cannot be satisfied together. Some balance among them
is necessary. In particular, time and effort of transportation are
inversely related."

So, yes, the colonies would have to expend propellant to maintain their
orbits, but not because to maintain their orientation. That become
problematic only when the cylinder's rotation begins to slow down, causing
it to lose gyroscopic inertia and the resulting "rigidity in space" that
comes with it.

>> My understanding, never confirmed, is that is was in orbit around the
>> Moon. The name was thus a double pun: the moon of the Moon and the "moon"
>> belonging to the Moons. The Moons were supposedly Sun-worshippers, so
Moon
>> Moon was in an orbit that kept it always on a line between the Sun and the
>> Moon ... or so the story goes. I don't think that such an orbit is
>> possible without orbital correction. A polar orbit around the Moon's
>> terminator, precessing as the Moon rotates so that Moon Moon's parabolic
>> mirror always points Sunward, would be much more likely and not require
any
>> orbital corrections.
>
>Ugh, rather weird. If it's going around the Moon, how can it evade
>detection all these years? That's why I flavoured the highly ellipitic
>orbit, perhaps normal to the eclipic plane, this will take it (for many
>years) out of all the human traffics around Earth and out to the Jupliter.
>Anyway, I am sure many people would much rather forget about Moon Moon.

Please note that the Lunar orbit theory is unconfirmed -- I read it many
years ago and could not now produce the source. It could be fannish
invention. That being said, your question as to how it could "evade
detection all these years" presumes that someone is [a] looking for
anything in the general vicinity [b] looking for Moon Moon in
particular. The minimum-energy Hohmann double-tangent transfer orbits are
all bound to the ecliptic plane, so a polar Lunar orbit would, for all
intents and purposes, be outside the Earth Circle (a much better
description than Earth Sphere, although that has the added political
statement re Earth's sphere of influence) for 99.99999% of its period.

Matching orbits with such a body from the "standard orbit" when you're
already in transit to another destination would require an insane amount of
delta-V, though. But that's true for any deviation from an established
trajectory -- you can't just change course any time you want. You're
committed to a limited number of options from the moment you launch and
those options become more and more limited as you go.

-Z-

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