This post expands on the space-elevator-alternative launch system that uses an orbital electromagnetic track to catch a suborbital payload. A major shortcoming of the idea is the lack of an obvious momentum source for the track to regain the momentum it loses when picking up its payload.
For a while I have toyed with the idea of a full orbital ring that is interlocking with another orbital ring going in another direction. For nomenclature, we will mentally assume that the orbit it around Earth’s equator, thus we simply have West-moving and East-moving parts.
Basic sketch of the scheme I want to describe:
In those 2 arrows in the diagram, I mean that the full length of both of them is the catching track. The general steps go:
- Suborbital launch (with reusable booster) throws a payload with minimal magnetization coils and supporting equipment into a trajectory to come up just below the moving track
- The track then uses a computerized control system to adjust electrical connections such that a constant lifting force keeps the payload at the same relative vertical position, while accelerating it to orbital velocity
- That track electromagnetically interacts with a second orbiting track to regain the momentum it lost picking up the payload
The major insight that I didn’t have before is how to avoid collisions between the tracks while accommodating the catches. The best (and most obvious) answer seems to just don’t do catches when the tracks are passing by each other.
This still provides more time that one might expect. The acceleration phase should not last anywhere near as long as what an orbit takes. By the time a track passes by the other track, its last capture can be fully completed, with a go/no-go decision made with a comfortable buffer time.
Correspondingly, it should be obvious that both tracks will need to catch roughly the same amount of payloads. Even if the West-moving track just picks up rocks, I believe this would still be dramatically more energy-efficient that alternatives, such as using ion drives for station keeping.
Energy for the track-to-track interaction would need to come from a space-based source, realistically a large solar panel array mounted to the tracks. The benefit of this scheme relative to the ion drive option is that much less solar panels would be needed, and way less than the energy needed for an orbital rocket launch, due to the inefficiencies associated with the specific impulses available, which fall far short of orbital speeds.
