Taken By The Sky

Orbital Siphon Development

After the original 2D Java siphon simulation was produced in 1997, no further development of the orbital siphon was undertaken. Then, development restarted with the prospect of the presentation of a joint paper with Professor Colin McInnes at the 56th IAF Congress, Fukuoka, Japan, October 17-21, 2005, and again, with the concept developed a little further, in the Journal of the British Interplanetary Society, Vol. 59, No. 10, October 2006.

  1. A new 1D 'analytic' simulation was written. This roughly reproduced the original 250,000 km radius siphon, calculating inertial and gravitational forces on each mass in the tower, and demonstrating graphically the changes in tension, velocity, and acceleration along the length of the rising tower.

  2. Simple towers, which just pluck new bodies up from the Earth's surface, and release them at a given radial distance, were not always well-behaved: frequently they would develop growing instabilities, and tear themselves apart. In some simulations, like this example, radial oscillations became more and more and pronounced, with cable tensions growing, along with accelerations and speeds, to the point where some bodies would begin travelling back down the tower. Also when the numbers of bodies in the tower was increased, the propagation of forces up and down the tower slowed, and the towers would behave differently. Also, some towers had a propensity for bodies to collect near the top, moving relatively slowly outwards.
  3. A siphon on the asteroid Vesta was considered.
  4. The tension in a rising siphon reaches a maximum at synchronous. While Pearson's 1975 orbital tower was tapered to give a maximum cross-sectional area at synchronous, this isn't possible with a train of rising bodies. However, in principle, there may be at least one way to introduce additional tension bracing to a siphon.
  5. Since a the train of payloads in a siphon tends to accelerate, there needs to be some some sort of braking system at the base of a siphon, along with tension foundations. The brakes might be used to generate electricity.
  6. Some possible uses of a siphon are considered.
  7. A terminology is suggested for a variety of different types of towers, not very successfully. But there ought to be a naming convention, rather than just call things "towers" or "trains" or "strings of beads".
  8. Smooth siphon simulation. A siphon simulation with most radial oscillations removed.
  9. Free siphon simulations. Laterally unconstrained siphons.
  10. Cantilever Truss Simulation doodle.

Space Elevator Studies

In 1997, I only simulated a space elevator as a static tower, with nothing moving up and down it. Given that the coriolis forces exerted by rising payloads push back against the direction of rotation of a siphon, the same should be true of space elevators.

  1. Space Elevator motion study. The effect of coriolis forces from a rising stream of masses on a space elevator.
  2. A lift-engine-powered space elevator drives a tether loop.

  3. A numerical method for generating stationary nonequatorial towers is explored.

Other Studies

Solar system simulation Model uses Newtonian mechanics to model solar system motions from 1 Jan 1940. Includes variable time steps, zoom factors, barycentre location, siphon launch orbits, outline Earth map.

Artificial gravity in space stations can be generated by spinning a circular station. These can be simulated using a spinning chain of masses. One interesting notion I came across was the idea of a fountain on such a station.

  1. Simulation of a fountain on a rotating space station.

Totally Off-Topic

An online Scotoma Scanner.

An explanation of snooker kicks.

"Taken by the sky": Fleetwood Mac. Rhiannon.
-(Old Grey Whistle Test version)
Idle Theory

Chris Davis
First created: 19 Sep 2005
Last edited: Mar 2009