Tag Archives: Space elevator

Space Elevators as Launch Platforms

It is not widely appreciated that Arthur C. Clarke’s idea for a “space elevator” is not just useful to reach Earth orbit: it can become a way to launch probes and people around a large part of the solar system with little fuel consumption.

In fact the elevator’s end at geostationary level (36,000 km) moves at 11,000 kph, that is 3 km/sec. At that height, the Earth escape velocity is 4.23 km/sec, so a relatively small “nudge” is needed to leave Earth.

That is not all. If the elevator is extended to 46,000 km, the “terminal” velocity equals the escape velocity (3.8 km/sec): therefore making launches even simpler and cheaper, more or less “free”.

The maximum theoretical limit is the L1 point between Earth and Moon, where their gravitation pulls equal each other. Situated around 260,000 km away from the Earth’s surface, an elevator terminal that far would travel at 20 km/sec, more than enough to reach Mars. And that, without allowing for various techniques that could make the launch speed even larger.