I am a chartered structural engineer, and an...
Space elevators are a permanent infrastructure that will reach from the ground to high orbit. I believe that they could be built cost-effectively within a century, and pay for themselves within just a few years.
Taking lightweight structures to new frontiers, a space elevator is a cable with its centre of gravity at or just above geostationary orbit (an orbit such that the satellite remains over a fixed point on the Earth). The cable would extend down to the Earth, with a similar amount of cable above to balance the system.
I’m referring to a ‘cable’, but it would actually be more like a flat ribbon. And it would need to be made of a material that could hold its own weight in this situation, something like graphene or carbon nanotubes. There is the small problem that at present we cannot manufacture the quantity or length of the carbon nanotubes this would require. But I’m confident we will soon be able to.
Why bother considering such seemingly far-fetched ideas? Because the only way we currently have to get into orbit leaves a lot to be desired. It basically involves sitting on top of a vast quantity of high explosives and hoping for the best; despite the best efforts of engineers, space rockets can sometimes go tragically wrong. And a successful launch is incredibly expensive. Accurate figures are hard to come by, but according to NASA low-earth orbit costs $10,000/kg while geostationary orbit might cost $50,000/kg. In 2013 alone, 260 satellites and probes were launched at a cost of over $40 billion.
An elevator should reduce the cost of getting into space to about $220/kg for an estimated build cost of $20 billion. It is difficult to predict how much of a difference a reduction of two orders of magnitude on the launch costs will make to the space industry and society, but it is likely to be as significant. Today the aerospace industry carries over three billion passengers and $6 trillion of goods a year. This means that the cost of a space elevator is about the same as one day’s air freight.
The space industry has already given us countless improvements to our lives, from small ones like Velcro and non-stick frying pans, to much bigger ones like global weather forecasting and satellite navigation. Cheap space flight would accelerate this innovation, and bring even more benefits in the form of lunar and asteroid mining, as well as an expansion of the human race comparable to our ancestors first leaving Africa or the discovery of America.
I’m not the only one who thinks space elevators could soon be viable. NASA is researching and promoting enabling technologies such as the power beam and tether climb challenges and the Tokyo-based Obayashi Corporation has announced plans to build an operational space elevator by 2050. There are also plans by Liftport, an American company, to build a smaller elevator on the Moon by 2025.
While we have not quite got all the technology in place, and there are still engineering challenges to be overcome, the space elevator has nearly arrived.