Orbital rings are extremely similar to launch loops, but have some differences.

They have the following advantages:

They have the following disadvantages:

The following things are notable, but are similar to launch loops

Keith writes:

Good points.

Note that orbital rings cannot be started up from the surface, because there is no circular path with uniform height around the earth to start them from. Curving them over mountains will require complicated paths and higher deflection forces, leading to larger magnets that somehow have to be removed while the system is brought up to speed. Of course, you will be changing from ground motors to at-altitude motors as well. The deployment of launch loops from the ground is difficult, but much more difficult with orbital rings.

All these systems need tracks and control cables. With only periodic deflection structures, a few millimeters per second radial velocity error at a deflection structure translates to large "miss distances" at the next deflection structure, perhaps beyond the control distance of that structure. Vehicles will be a large source of deflection error.

"Orbital rings" may be a misnomer, since building more than one is problematic. All rings will need to run in parallel planes - they can't be deployed in different inclinations, or they will intersect at some point during deployment or powerdown. When one ring fails, it may take out other rings - without a ground-based rotor dispersal system, the pieces of a failed ring stay in orbit and eventually may hit something, including a replacement ring.

Debris is indeed a problem, which is why the loop is located at 80 kilometers altitude and not higher. The launch path may have "meteor bumpers" spaced a few tens of centimeters to the sides (where most of the orbiting manmade debris will come from) to deflect some of the debris, but we are counting on the atmosphere to bring down material most likely to impact it.

It is interesting to speculate about systems that would raise or lower the track a few tens of centimeters to avoid tracked debris chunks. I doubt the chunks would follow a predictable trajectory when they are in 80 kilometer atmosphere, so I've ignored that speculation, though it is common among orbital ring and space elevator aficionados.

OrbitalRings (last edited 2010-06-24 16:18:53 by KeithLofstrom)