On the 4 June 1783 the Montgolfier brothers were the first humans to break the surly bonds of Earth in their hot air balloon, and flight was born. We have come a long way in the two and a half centuries since.
Space flight of course, is only half a century old, so we have not advanced very far. In fact, we are still using rockets.
This is what Arthur C. Clarke meant when he said that hot air balloons were to flight what rockets were to space travel. He saw rockets as the first halting, primitive steps to space travel – soon to be left behind as hot air balloons were.
So what is the next step? Many people believe it is a space elevator.
The concept has been around since 1895, when this bloke suggested a humongous tower into space containing an elevator. This, of course, is impossible from an engineering standpoint because of its weight.
With the advent of travel and satellites a new possibility emerged. We currently have geostationery satellites that orbit the Earth in exactly the same position relative to be Earth, and they are used to bounce communication signals off. They stay in orbit because the force trying to pull them back to earth is exactly matched by the force attempting to fling them out into space.
So in principle if we dropped a cable from one of these down to earth we could simply climb it to get into space.
The problem with this is that the weight of the cable would be too great to be practical and it would break under its own weight, as well as pulling the satellite out of orbit.
But this problem has now been neatly sold by the advent of carbon fibre. This remarkable material is lightweight and strong, and as soon as someone works out how to make it in braids that are 100,000 km long, the space elevator will be viable.
Now, geostationary satellites are about 40,000 km above the Earth. So to counteract the weight of a space vehicle climbing a cable to it, there needs to be a counterweight. The counterweight of course has to extend further into space, out to 100,000 km. So the geostationary satellite then becomes the centre of balance, as it were, with balancing forces. as the space vehicle climbed from Earth the counterweight would have to move in the other direction, in just the same way as they do on the big sky scraper cranes that we see in the city.
A Japanese company intends to build one of these by 2050. And at an ascent rate of about 200 km/h, it would take about a week to get to the geostationary platform. Now, a week may sound like a long time for a trip, but just imagine the view.