Space Elevator Options

[EMac]

While the idea certainly isn't new, the material basis for it is somewhat interesting. I like the graphic...makes it seem like a geosynchronous orbit is nearby versus over 3 times further than the diameter of the earth. I'd like to see the process they'll use to make 26k mile diamond cables.

Space elevator article

[fenixsmom]

That is pretty brilliant actually. Imagine if they could create the boron-nitrate nanochain in the labs. The applications coud be endless!
I understand there are plenty of problems to solve before the elevator became a reality. One I would imagine would be electricity. Would solar panels be the best option as opposed to say the mundane copper wiring? Could said panels be protected easily from space fodder flying around? What about solar storms?
Very interesting thought: our own stairway to heaven. Zeppelin would be so proud!

[fenixsmom]

Another query, could either nanochain withstand the temperature of space? I kinda doubt it's a balmy 72 degrees up there!

[fenixsmom]

Forget my silly questions. I found an article that dumbed it down for me. http://science.howstuffworks.com/space-elevator5.htm

[EMac]

Forget my silly questions. I found an article that dumbed it down for me. http://science.howstuffworks.com/space-elevator5.htm

Your question is a really good one, and would have to be part of the design considerations. A material's coefficient of thermal expansion (CTE) is a very real consideration even at sub-orbital altitudes (at 35k ft, -30 to -60C is common). There will frequently be significant thermal deltas going from the sun-facing side of a satellite to the dark side. For satellites, we can use heaters, heat pipes, vents and insulation to keep things humming along. For an elevator the support cables would be exposed to all the various temperatures at once, and a pod traversing the cables would have to account for the entire temperature range as it makes the journey. Considering diamond is an extremely good conductor of heat, it would be interesting to see what happens and how the designers would deal with it. I'd also be interested to see if tribo charging would be an issue. Here we see CTE is problematic with relatively minor temperature fluctuations on the earth's surface with train tracks (although hot rolled steel has a much higher CTE):


There are so many technical challenges with such an endeavor, that I'm somewhat skeptical we'll see one in my lifetime. Imagine the chain breaks 120 miles up from the ground because a tiny piece of the tons of space junk floating in LEO hits the cable at 17,000mph. How much crap crashes back down to earth over how long, and how much additional debris would this put in orbit? How fast would a pod climb the cables, and how would it be powered? Solar is a good idea, but you get a design tradeoff of speed vs drag vs panel size vs stiffness while still in the atmosphere. Power transmission via cable has its own challenges as well besides the aforementioned thermal concerns. What's the lift capacity, and how would you transfer lifted materials to an ISS or other orbiting platform? What happens when the pod breaks down with people on board 100 miles up? Are there multiple tracks to ascend and descend simultaneously? Soooo many questions about how to do this successfully...

Although...if this group is successful, might be fun to run a few buckets of moon rocks to see if there's any color: Lunar Elevator

[fenixsmom]

All those brilliant questions we pondered are explained in the article. Who would have thought of injecting a gas into the cables to create electricity! Actually, that isn't that remarkable. Or the fact it will have an 18 ton payload with the carriage weighing in at 30 tobs! Also that they will retract the elevator when finished and use sensors ro move the ocean bouy away from incoming debris!

[EMac]

Those are very much pie in the sky ideas that will have to be proven with real technology. You can read about what they're able to accomplish now at small scale here (translated from the Japanese site, so it reads strangely): Japan Space Elevator Association

These guys seem committed to producing something, but like the other article, the technology doesn't currently support these design goals (i.e. they can only produce 3cm nanotubes at the moment): Obayashi article on CNET

It's interesting to me that in the CNET article they quote the guy at $200 per kilogram of payload, but in the Space.com article they can't give an overall price. I'm not sure how they can quote a price per kilogram without knowing how much it would cost to design, build, deploy and operate.

[CP]

Very interesting idea for sure and I've wondered the same Emac, how do they know how much transport costs could be with out knowing how to build or deploy one successfully yet.
Another scary thought would be if there are cables stretching from ground to orbit some several hundred miles, if one were to break and begin swinging out of control from the upper end or platform....YIKES! That's one long whippin' nanochain that could do exstensive damage to things from ground level through air space for planes and assumedly, the geo sync sat orbits as well, reaching hundreds of miles in any direction!

[Caveman]

I'm sure that they would have some sort of destruct capability for just that sort of scenario. If not - WTF? That cable is as long as twice the circumference of the Earth!

That equals one hell of a lawsuit!

[fenixsmom]

I'm sure they would have plenty of safety SOP in place with a cable that long. Back up cables and support cables just to name a few. They are talking about planting it in the middle of the ocean. They are also betting that every super power will have military patrols safeguarding it from terrorists.

Could you imagine it only being $100 per pound for tourists? Little people like me would be cheap to take up :D

[EMac]

Another scary thought would be if there are cables stretching from ground to orbit some several hundred miles, if one were to break and begin swinging out of control from the upper end or platform....YIKES! That's one long whippin' nanochain that could do exstensive damage to things from ground level through air space for planes and assumedly, the geo sync sat orbits as well, reaching hundreds of miles in any direction!

2 orders of magnitude more distance....several 10s of thousands of miles of cable! The designs I've seen are putting the anchor around 60k miles from earth: almost 3 times the distance to the geo orbit (~26k miles). The thought of that thing coming back down is scary. The thought of being trapped up there after an anomaly is horrifying.

I'm sure that they would have some sort of destruct capability for just that sort of scenario. If not - WTF? That cable is as long as twice the circumference of the Earth!

That equals one hell of a lawsuit!

Noodling on this is interesting as well...i.e. how could a self-destruct protocol be done safely? Charges placed every 100m or so (this would mean close to a million charges)? Frangibolt style mechanism (like used to separate payloads from carrying rockets)? Cutting mechanisms similar to an ADD used in skydiving? A rocket attached to the anchor along with a cutter at a set distance so that the majority of the chain goes into orbit around the sun vs earth? How much weight would this add, and how would they be triggered? Would the chain burn-up on re-entry (I'm skeptical if it's diamond, particularly if it's still a long chain given diamond's thermal properties)? It not, that just creates new hazards for future space travelers. The chain is ostensibly static too meaning it can't maneuver out of the way or incoming debris. Considering the velocities from orbiting objects, it doesn't take a huge asteroid to cause massive damage: SWRI & ESA

How do we even lift the chain? If it has to be a continuous strand, 60k miles is 9,656,064,000cm. Assuming ~1cm cubes of diamond stacked, and using 3.51g per cubic centimeter of diamond, this translates to a 33,892,784kg chain. I can't find a simple calculation of weight by volume of carbon nanotubes, but a chain of this material is likely quite massive at these lengths.

If it's not continuous, how will they find the chain's ends in orbit, much less bond the chain's sections together (weakest link in the chain concept), and how many launches will it take just to deploy the chain? How will they keep it under tension? Will the anchor have fuel on board to perform orbital maneuvers (similar to how gliders remove slack in a tow line)?

What kind of electrical effects will need to be accounted for? Depending on the type of chain material chosen, this could make for some interesting experimentation. Towards the sun, the chain will extend past the magnetosphere and a significant portion (~20k miles) will be subjected to the full force of stellar winds. On the back side, it will be encompassed by the field, and will always pass through the ionosphere (conductive). What kind of electrical potentials are developed in such a system? Fenixsmom is onto something with solar storms...massive currents are developed in the ionosphere during these, particularly during strong storms that break the field on the backside (from 100kA nominal to over 1MA during severe storms...how GICs are able to fry EHV transformers). The materials in question, diamond and carbon nanotubes, can serve as insulators (non-doped or non-conductive doped diamond) to semiconductors (boron doped diamond and nanotubes).

...and why did Ogre from Revenge of the Nerds just pop into my head? NERDS!!!!

[fenixsmom]

Couldn't they use a remote controlled quick connect as opposed to detonation charges?

Thanks, I have moments of brilliance. Like a neurological solar storm. :)

[fenixsmom]

Another question sparky, i know very little about solar storms, aside from the fact they can potentially cause a lot of harm. So bear with me.

Is it possible for a solar storm to positively or negatively charge a object? Or even swapthe polarity of a proton or neutron?

Excuse my stupid questions, i rarely have anyone around that is smart enough to stretch my brain muscles out with.

[Caveman]

...and why did Ogre from Revenge of the Nerds just pop into my head? NERDS!!!!

Suffice it to say, given the infrastructure problems, space debris, solar events, not even mentioning near pass asteroids, tropical storms, and gravitational anomalies from the orbiting moon - this thing will not happen in our lifetime. Ain't chaos theory great?

[Rockyrat]

Wikipedia has a decent page on the subject. It should have enough technical detail to keep most people's heads spinning.


http://en.wikipedia.org/wiki/Space_elevator