Friday, April 13, 2012

An Elevator to Space

The idea of an elevator to space has been around since the 1960's. It comes from an idea for a satellite attached to Earth by a strong cable. Vehicles could travel to and from the satellite along the cable. Unfortunately, there are problems with this idea.

The cable could not be pulled behind a space vehicle as it took off, as it would slow it down. So it would have to be lowered from space. If a heavy cable is lowered from a satellite, the satellite's center of gravity changes. The satellite must go higher in order to adjust. A cable lowered in this fashion would have to be very long. A good design for this estimates the cable will be about 90,000 km long. This is long enough to circle the Earth. Twice.

The cable would also have to be strong. Steel wouldn't work. Not even diamond fibres. However, carbon nanotubes would work. A cable made of these would be light and thirty times stronger than steel. This cable would also be incredibly thin. The original design was for it to be 100 times thinner than a piece of paper. The entire cable could weigh 20,000 kg. The cable would likely be anchored offshore.

There are still problems. The cable could easily be damaged. And we actually don't know how to make a cable like the one required. The longest rope we've made out of nanotubes is only a few centimeters long. And the elevator can't exactly be tested. We can't only go part of the way up, then a little further. The cost of such a venture would be more than ten billion dollars. If we can work past these problems, however, we might soon be taking elevators to space.

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