Interesting Trajectory Problem

Charles Talleyrand wrote:
I'm sure you all remember Cavorite. It blocks the force of gravity.

In the book, our hero makes a space capsule of with Cavorite shutters.
He then closes the shutters between the capsule and the earth, blocking
the earth's gravity. He opens the shutters betwen the capsule and the
moon, allowingt the gravity of the moon to pull him towards the moon.

Consider how this will go in real life. You will get pulled towards where the
moon is, not where it will be. Therefore you end up in a curved trajectory

This is basically the exact same orbit you would follow if the earth did
not exist.

approaching the moon from the trailing side (the opposite of the side leading
the orbit). When you get close to the lunar surface you realize you are
moving too fast, and would like to slow down. Therefore you close the
shutters toward the moon, blocking it's gravity. You open the shutters
away from the moon. However, those shutters are pointed towards
empty space, and there's no gravity that way to help.

At any point, you can pick which of three (well) orbits you want.
Solar orbit, lunar orbit, or earth orbit.

Earth is moving (with regards to the moon) at some 300m/s.
The rotational speed of earth is slightly more than this, so simply
nullifying the earths gravity when the moon is nearly set (?)
gets you going directly toward the moon at some 30m/s or so. (at some
times of year)

The trick is then to make from the combination of segments of earth, moon,
and solar orbit, an orbit that intersects the moon at its diameter, and
with the same velocity as the surface of the moon.
The fact that everything is not quite in one plane makes this lots harder.

I suspect it can be done lots faster by using gravity assist manoevers.

First find a Cavorite mine.

"Ian Stirling" wrote in message
...
Charles Talleyrand wrote:
I'm sure you all remember Cavorite. It blocks the force of gravity.

In the book, our hero makes a space capsule of with Cavorite shutters.
He then closes the shutters between the capsule and the earth, blocking
the earth's gravity. He opens the shutters betwen the capsule and the
moon, allowingt the gravity of the moon to pull him towards the moon.

Consider how this will go in real life. You will get pulled towards
where the
moon is, not where it will be. Therefore you end up in a curved
trajectory

This is basically the exact same orbit you would follow if the earth did
not exist.

approaching the moon from the trailing side (the opposite of the side
leading
the orbit). When you get close to the lunar surface you realize you are
moving too fast, and would like to slow down. Therefore you close the
shutters toward the moon, blocking it's gravity. You open the shutters
away from the moon. However, those shutters are pointed towards
empty space, and there's no gravity that way to help.

At any point, you can pick which of three (well) orbits you want.
Solar orbit, lunar orbit, or earth orbit.

That's why there are shutters *all over*. In the above problem, you don't
open the shutters towards open space. You open the shutters towards the
earth and or the sun. You also bloody well pay attention to these sorts of
things and do your calculations ahead of time to know what shutter needs to
open and how much.
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"Ian Stirling" wrote in message ...
Charles Talleyrand wrote:
I'm sure you all remember Cavorite. It blocks the force of gravity.

In the book, our hero makes a space capsule of with Cavorite shutters.
He then closes the shutters between the capsule and the earth, blocking
the earth's gravity. He opens the shutters betwen the capsule and the
moon, allowingt the gravity of the moon to pull him towards the moon.

Consider how this will go in real life. You will get pulled towards where the
moon is, not where it will be. Therefore you end up in a curved trajectory

This is basically the exact same orbit you would follow if the earth did
not exist.

approaching the moon from the trailing side (the opposite of the side leading
the orbit). When you get close to the lunar surface you realize you are
moving too fast, and would like to slow down. Therefore you close the
shutters toward the moon, blocking it's gravity. You open the shutters
away from the moon. However, those shutters are pointed towards
empty space, and there's no gravity that way to help.

At any point, you can pick which of three (well) orbits you want.
Solar orbit, lunar orbit, or earth orbit.

Not so.

You can be pulled by the Earth, Moon or Sun in any combination. Further,
although you might only be currently feeling the pull of one of these
objects, your momentum might be wrong for the orbit and position
you currenly occupy.

Basically, I cannot imagine how to make a lunar landing using
Cavorite. Can anyone?

Charles Talleyrand wrote:

"Ian Stirling" wrote in message ...
Charles Talleyrand wrote:
I'm sure you all remember Cavorite. It blocks the force of gravity.

In the book, our hero makes a space capsule of with Cavorite shutters.
He then closes the shutters between the capsule and the earth, blocking
the earth's gravity. He opens the shutters betwen the capsule and the
moon, allowingt the gravity of the moon to pull him towards the moon.

Consider how this will go in real life. You will get pulled towards where the
moon is, not where it will be. Therefore you end up in a curved trajectory

This is basically the exact same orbit you would follow if the earth did
not exist.

approaching the moon from the trailing side (the opposite of the side leading
the orbit). When you get close to the lunar surface you realize you are
moving too fast, and would like to slow down. Therefore you close the
shutters toward the moon, blocking it's gravity. You open the shutters
away from the moon. However, those shutters are pointed towards
empty space, and there's no gravity that way to help.

At any point, you can pick which of three (well) orbits you want.
Solar orbit, lunar orbit, or earth orbit.

Not so.

You can be pulled by the Earth, Moon or Sun in any combination. Further,

Which was what the "well" was, though I should have been clearer.

although you might only be currently feeling the pull of one of these
objects, your momentum might be wrong for the orbit and position
you currenly occupy.

Can't be.
An orbit is any free-falling trajectory.
Take your current velocity and position.
Then, work out the gravitational accelleration vectors due to whatever nearby
bodies are.
You can now compose an accelleration from a sum of any part of these
three vectors.

Unfortunately, the resulting accelleration map is often going to look not
like a nice sphere, but a nearly flat triangle, or even a line.
This will vary with position and the orbits of the various bodies.


Basically, I cannot imagine how to make a lunar landing using
Cavorite. Can anyone?

Imagine what happens if you turn off earths gravity (and the moons) at a
given time and position on the earths surface. (latitude matters)
At some time, this will (I suspect) be a solar orbit that intersects
the surface of the moon at near zero velocity.
This is certainly not the fastest way.