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Comment by zain | Hacker News Reader

I had a crazy idea too, and I'll probably get ridiculed, but what the hell.

I think it is fairly straightforward to get something tiny to the moon. The challenge comes in making it broadcast back to earth. For wireless transmissions, you need considerable bulk and you add a lot of cost.

Wouldn't it be cool if, instead, it was connected to earth by a ridiculously long insulated wire? Then you might even be able to cut down the size to well under a pound for the rover itself (not including the fuel needed to get there). It shouldn't have problems transmitting as long as the wire is insulated well enough, right?

Some back-of-a-napkin calculations lead me to believe that you wouldn't need more than 60 cubic miles to store enough wire to reach the moon (200,000 miles long, 1 inch thick).

what do you think? flame away :)

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Wouldn't it be cool if, instead, it was connected to earth by a ridiculously long insulated wire?

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

Another way to quote specific strength is breaking length, also known as self support length: the maximum length of a vertical column of the material (assuming a fixed cross-section) that could suspend its own weight when supported only at the top. For this measurement, the definition of weight is the force of gravity at the earth's surface applying to the entire length of the material, not diminishing with height.

According to that article, the breaking length of steel is 26 miles, of kevlar 256 miles, and of carbon nanotube 4,716 miles.

Would that (the longer tube) take into effect the diminishing force of gravity on each additional mile?

Would that (the longer tube) take into effect the diminishing force of gravity on each additional mile?

No. From the description I quoted:

For this measurement, the definition of weight is the force of gravity at the earth's surface applying to the entire length of the material, not diminishing with height.

Sorry. Stupid.

So IF you could find a wire long enough and insulated enough, how would your wire deal with the rotation of the earth? :)

the trans-equatorial railway express, of course, ol chap!

but, uh, (slightly) more seriously, if one big transmitter is the problem, then isn't the solution multiple small transmitters in the the same orbit, repeated at increasingly closer-to-earth orbits? then you could just run a wire up to a transmitter in geostationary orbit.

Sounds like the space elevator. The problem's that the moon and earth move back and forth too far, and space debris would kill it. You need a string made out of nano-carbon or another material harder than diamond.

I think there'd be a problem with extreme temperature conditions as well as the fact that the moon is not in geosynchronous orbit

Interesting idea, but wouldn't the weight of that much wire be more than the weight of a transmitter? Also, resistance in something that long would probably be an issue

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