Filling Space with non-colliding orbits
I also have an applet
description, a later page building Dyson swarms,
exploring gravitation with Java,
and a scale model of the solar
system.
Is there a set of orbits that:
- Guarantees that satellites do not collide at high speed (always
frowned upon)
- Keeps neighbors next to neighbors (you can't make maps otherwise,
indeed there is no sense of locality)
- Allows satellites to fill a 3-dimensional volume (there's all
that space there, it would be nice to be able to use it)
Yes, there is such a set of orbits. I'll attempt to describe it.
Start with a circular orbit (the blue circle) of period 1.000
circling the sun (the yellow circle). The applet on the right
demonstrates this.
| Click to Start
|
Make an elliptical orbit, also of period 1.000, in the same plane
as the circular orbit (the red ellipse).
|
|
These are the same orbits, viewed from an
angle, plus a third orbit (the grey ellipse). The grey ellipse also
has period 1.000, and is the same shape as the red ellipse, and its
major axis is in the same plane as the circular orbit, but the minor
axis is tilted out of the plane at about 30 degrees. The green lines
try to show the plane of the first two orbits and the angle at which the
third is tilted.
| Click to start
|
The green
ellipse is the circular orbit again, and the blue ellipses are copies
of the grey orbit. All the blue orbits have period 1.000, their major
axes are all in the same plane as the circular orbit (the major axes
are the green lines). The red shape is in a plane perpendicular to
the circular orbit. The red dots are where the various blue orbits
intersect that plane. By taking a single blue orbit and spinning its
major axis around the sun in the plane of the circular orbit, a
donut-shaped tube is formed, and the cross section of that tube
is the red shape. This entire surface can be covered with satellites
following blue orbits. Their periods are all 1.000, and neighbors
will remain next to neighbors.
|
|
The cross-section of
the tube is determined by the angle of the minor axis to the circular
orbit's plane, and by the eccentricity of the orbits. I don't know
exact formulas, but these equations are continuous, and it should be
possible to vary these two parameters to form a continuum of donuts,
one nested inside the other, with the circular orbit at the very
center. All the orbits will have period 1.000, so neighbors will stay
next to neighbors. They may get closer and further away at various
points in the orbit. The stretching is most amplified in the donuts
furthest from the central circular orbit.
| Click to start. Below is top view. Also, satellites
were given significant mass (1/10000 of sun).
|
Note that if you fill a donut of 3-space with satellites in such
orbits, then you can make a map of where the satellites are, and the
map does not change over time. The map could be a cylinder standing
on one if its circular ends, and any vertical line would represent an
orbit. The line down the center would be the center circular orbit.
This all falls apart if the satellites interact, say by having
serious mass.
There are several sets of telecommunications satellites in
low-earth orbits (GlobalStar, Iridium, GPS, Starlink, ...). Starlink has tens of thousands of
satellites in low earth orbit. They actually do follow this, to a
degree: the northward half the of the orbit differs in elevation
from the southward half by a few miles, guaranteeing no collisions.
How does a globular cluster work? Are
collisions very likely? Do stars interact
strongly with each other, or do they just orbit the overall center of
mass unhindered? Inquiring minds want to know. (It also makes
nice pictures.)
Itzu, or Crabs In Space
Why there are no perpetual
motion machines
Cryptographic Protocols
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