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]

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