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Great! What does the paper say about overcoming some of the problems that seem to make it tough, like the radiation that humans will receive riding up, or avoid

by kornork 13y ago

Great! What does the paper say about overcoming some of the problems that seem to make it tough, like the radiation that humans will receive riding up, or avoiding space debris? I'm assuming problems like building a rope strong enough to hold its own weight will be overcome, as well as developing the technology to climb the elevator.

aunty_helen 13y ago
The fragile humans could still hitch a ride on a (reusable) rocket and extraplanetary garbage collection is something that is currently being proposed and could be a good source of materials too.
eru 13y ago
Why should radiation be much more of a concern than for rockets? (Couldn't you just add shielding?)
- mullingitover 13y ago
  The rocket ride is shorter.
  - lutorm 13y ago
    That just means you get to the high-radiation regions faster...
    - briandw 13y ago
      No, you will spend more time in the http://en.wikipedia.org/wiki/Van_Allen_radiation_belt http://en.wikipedia.org/wiki/Van_Allen_radiation_belt with a space elevator.
      - eru 13y ago
        There's an interesting proposal for reming that radiation belt (https://en.wikipedia.org/wiki/Van_Allen_radiation_belt#Proposed_removal https://en.wikipedia.org/wiki/Van_Allen_radiation_belt#Propo...). But shielding seems to be doable with pretty thin layers of metal.
mahranch 13y ago
Radiation is only a minor concern, astronauts in the space station experience similar radiation doses. I assume if it's cheaper to get things into orbit [with the elevator], it's also cheaper to shield the entire contraption. Climbing isn't much of a concern either, they've already run a bunch of tests and NASA has already awarded their prizes out for the challenge. The real issue is mass producing the carbon nanotubes. It's like saying "Warp drive is possible" then saying all you need to do is build a ship that can manipulate the fabric of spacetime. Well of course that's all you need to do. Sure, producing carbon nanotubes is easy. I've seen them make the it in a lab. It's making the tubes to spec and making thousands of miles of the stuff that is the hurdle. It's the equivalent of asking computer engineers in the 60s to mass produce 22nm CPUs with billions of transistors. Can it be done? Sure. In about 50 years.
- mcv 13y ago
  > Radiation is only a minor concern, astronauts in the space station experience similar radiation doses. Why would they be similar? The space station is only in LEO. That's not remotely comparable to geostationary orbit, or the Van Allen belts. Fortunately, shielding is a lot cheaper than on anything a rocket carries.
cgrubb 13y ago
Early in the book: The first few years will enable 20ton payloads without humans [radiation tolerance an issue for the two week trip]... From Finding 7-5: Radiation is not a problem for tether climbers, as the designers will incorporate this threat into the design requirements and ensure operational success through any radiation environment. Historic precedence supports this conclusion as the space community runs spacecraft in all regions where the space elevator will be operating. However, when people are included in the tether climb [after some years of robotic success], the radiation problem becomes an order of magnitude more difficult. There are many ways to reduce the radiation and shorten the trip, which will have to be incorporated when the human element is added. Although the authors envision eventually using the elevator for transporting humans, I don't see any discussion about how to speed up the trip or increase the shielding. There is a fairly long section on debris. The authors note that significant debris only exists in low earth orbit. They think the chance of collision is small, but large enough that the situation needs to be monitored. They think debris can be tracked and that if a collision were forecast, the cable could be moved. Also, they think space faring nations should be tasked with removing some of their junk from orbit.

by kornork 13y ago

aunty_helen 13y ago

The fragile humans could still hitch a ride on a (reusable) rocket and extraplanetary garbage collection is something that is currently being proposed and could be a good source of materials too.

eru 13y ago

Why should radiation be much more of a concern than for rockets? (Couldn't you just add shielding?)

mullingitover 13y ago
The rocket ride is shorter.
- lutorm 13y ago
  That just means you get to the high-radiation regions faster...
  - briandw 13y ago
    No, you will spend more time in the http://en.wikipedia.org/wiki/Van_Allen_radiation_belt http://en.wikipedia.org/wiki/Van_Allen_radiation_belt with a space elevator.
    - eru 13y ago
      There's an interesting proposal for reming that radiation belt (https://en.wikipedia.org/wiki/Van_Allen_radiation_belt#Proposed_removal https://en.wikipedia.org/wiki/Van_Allen_radiation_belt#Propo...). But shielding seems to be doable with pretty thin layers of metal.

mahranch 13y ago

Radiation is only a minor concern, astronauts in the space station experience similar radiation doses. I assume if it's cheaper to get things into orbit [with the elevator], it's also cheaper to shield the entire contraption. Climbing isn't much of a concern either, they've already run a bunch of tests and NASA has already awarded their prizes out for the challenge. The real issue is mass producing the carbon nanotubes. It's like saying "Warp drive is possible" then saying all you need to do is build a ship that can manipulate the fabric of spacetime. Well of course that's all you need to do. Sure, producing carbon nanotubes is easy. I've seen them make the it in a lab. It's making the tubes to spec and making thousands of miles of the stuff that is the hurdle. It's the equivalent of asking computer engineers in the 60s to mass produce 22nm CPUs with billions of transistors. Can it be done? Sure. In about 50 years.

mcv 13y ago
> Radiation is only a minor concern, astronauts in the space station experience similar radiation doses. Why would they be similar? The space station is only in LEO. That's not remotely comparable to geostationary orbit, or the Van Allen belts. Fortunately, shielding is a lot cheaper than on anything a rocket carries.

cgrubb 13y ago

Early in the book: The first few years will enable 20ton payloads without humans [radiation tolerance an issue for the two week trip]... From Finding 7-5: Radiation is not a problem for tether climbers, as the designers will incorporate this threat into the design requirements and ensure operational success through any radiation environment. Historic precedence supports this conclusion as the space community runs spacecraft in all regions where the space elevator will be operating. However, when people are included in the tether climb [after some years of robotic success], the radiation problem becomes an order of magnitude more difficult. There are many ways to reduce the radiation and shorten the trip, which will have to be incorporated when the human element is added. Although the authors envision eventually using the elevator for transporting humans, I don't see any discussion about how to speed up the trip or increase the shielding. There is a fairly long section on debris. The authors note that significant debris only exists in low earth orbit. They think the chance of collision is small, but large enough that the situation needs to be monitored. They think debris can be tracked and that if a collision were forecast, the cable could be moved. Also, they think space faring nations should be tasked with removing some of their junk from orbit.