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1. The counterweight is in geosynchronous orbit. It is "held up" by its absurd speed like any other satellite. 2. One of the reasons you need a very strong mat

1. The counterweight is in geosynchronous orbit. It is "held up" by its absurd speed like any other satellite. 2. One of the reasons you need a very strong material. The tether will be in tension, but probably will have quite a bit of movement to it. The tether dynamics are not a solved problem. 3. Most plans suggest that power will be beamed from the ground to the climber, either as microwaves or visible light. Some plans might use a paired tether to carry electricity. In either case, no onboard fuel is needed, which us pretty nice, as that's a lot of weight you don't have to pull against gravity. There have been several competitions in this area already.

kamaal 13y ago
Yes, sorry the centripetal-centrifugal force balance thing was completely off my mind when I asked that question. But with all the remaining two points look in the domain of SciFi to me. I'm sure tether dynamics are going to a materials engineering problem like never seen in history of mankind. Plus the energy problem is still by and large a very problem. Sending electricity down the tether looks very inefficient give the article says it will 62K miles long. In short we are still may be what, say 50 years away from this?
- Sharlin 13y ago
  Solar power satellites would most likely beam the power to Earth using microwaves.
- jccooper 13y ago
  Quite possibly. I'm not concerned with power transmission so much; that's just engineering, and the tiny Centennial Challenge teams were doing well enough over a few years that it seems quite soluble. We will probably have UAVs flying on beamed power regularly within a few years. The tether materials are obviously the long pile in this tent. We have theoretical materials that will work, which is great, but we really need practical materials. The day you can go buy nano tube thread you can formulate an actual timeline for a space elevator. Until then, its only a dream.
Sharlin 13y ago
The center of gravity of the whole system must be in the geosynchronous orbit (36000 km up) so that the thing stays up. This means that half its weight (not mass!) must be above 36000 km; in the modern proposals there's no separate counterweight, but the ribbon itself extends to ~100000 km up. In practice, the CoG must be a bit above 36000 km so that payloads going up don't pull the ribbon down.

kamaal 13y ago

Yes, sorry the centripetal-centrifugal force balance thing was completely off my mind when I asked that question. But with all the remaining two points look in the domain of SciFi to me. I'm sure tether dynamics are going to a materials engineering problem like never seen in history of mankind. Plus the energy problem is still by and large a very problem. Sending electricity down the tether looks very inefficient give the article says it will 62K miles long. In short we are still may be what, say 50 years away from this?

Sharlin 13y ago
Solar power satellites would most likely beam the power to Earth using microwaves.
jccooper 13y ago
Quite possibly. I'm not concerned with power transmission so much; that's just engineering, and the tiny Centennial Challenge teams were doing well enough over a few years that it seems quite soluble. We will probably have UAVs flying on beamed power regularly within a few years. The tether materials are obviously the long pile in this tent. We have theoretical materials that will work, which is great, but we really need practical materials. The day you can go buy nano tube thread you can formulate an actual timeline for a space elevator. Until then, its only a dream.

Sharlin 13y ago

The center of gravity of the whole system must be in the geosynchronous orbit (36000 km up) so that the thing stays up. This means that half its weight (not mass!) must be above 36000 km; in the modern proposals there's no separate counterweight, but the ribbon itself extends to ~100000 km up. In practice, the CoG must be a bit above 36000 km so that payloads going up don't pull the ribbon down.