With an object in geostationary orbit, you could run a cable down to the Earth. Boom—there’s your space elevator. But wait! There are some problems. Can you imagine a cable that’s 36,000 kilometers long? That’s a LOT of cable. It’s so much that you’d also have to counterbalance the weight of the cable with some big mass a little past the geostationary level. This system would require a tension in the material that exceeds the maximum value for the strongest steel cables. It could only work with something like a carbon nanotube cable—which we don’t have (yet).