A new era in space exploration may soon begin. Traditionally, spacecraft have relied on the combustion chemical fuel to propel them out of our atmosphere and through the solar system. Nearly every craft we have so far launched, manned or unmanned, has relied on this method of propulsion. The only other propulsion method we have ever used in spacecraft are ion thrusters, which lack the force needed to lift a craft out of the Earth’s gravity well, are unable to operate in the atmosphere anyway, and are only used to maneuver in deep space.
This isn’t for lack of imagination, however. Numerous propulsion systems have been proposed over the years, from NASA’s practical but unpalatable nuke-propelled project Orion, to the theoretically possible but technically infeasible Alcubierre Warp Drive. So far, our ability to exploit these propulsion techniques is only limited by our level of technology or our concern for safety, but soon, one of these fantastic-sounding visions may become a reality. Enter the Tokyo-based Obayashi Corp., which announced on Feb. 22nd that they are working on plans to create an elevator capable of lifting people and cargo into space.
The idea of a “space elevator” is not new. The basic concept dates back more than 100 years, to a Russian scientist named Konstantin Tsiolkovsky. Inspired by the recently constructed Eiffel Tower in Paris, Tsiolkovsky had the idea for a huge, stationary tower reaching 22,238 miles above sea level into space. Over the past 60 years, however, physicists have refined this idea into something more practical. Rather than a standard tower, relying on compression forces to hold it up, recent ideas of space elevators have instead focused on the idea of tensile forces holding the structure up. Essentially, the idea is that a large counter-weight would be placed into space above geostationary orbit, with a cable snaking down to a spaceport on the ground. An elevator “car” would then be attached to the cable so it can climb up into orbit and back down to the ground again.
The advantages of such a system are obvious. Once the structure is built, ferrying people and cargo into orbit will be much cheaper than with conventional chemical rockets, and the ride promises to be a little smoother. On the other hand, building the structure in the first place will be extremely expensive. Until recently, the idea was not even possible, due to the enormous forces exerted on the cable. Conventional materials would not be able to handle the stress, or if they could, they are much to heavy to be practical. Obayashi Corp. plans on using newly-developed carbon nanotubes in the construction of their elevator cable, however, which should be light and strong enough to work. However, the current going rate for carbon nanotubes is $95 – $500 per gram. The cable Obayashi Corp plans to build will stretch 60,000 miles from Earth’s surface (one quarter of the way to the Moon) into space. It doesn’t take a rocket scientist to figure out that at a minimum of $95 per gram, that is one expensive tether.
Obayashi plans on finishing their space elevator sometime by the middle of the century, so don’t pack your bags just yet. But as we reap the benefits of venturing into space more and more, technologies like this one will become indispensable. Throughout history, we have invested in transportation projects that seem too big for us at the time, but quickly become necessary for society. The Roman Empire’s road network, the transcontinental railroad, and the Moon landing are all examples of this. Once this enormously expensive project is complete, it will likely begin paying for itself right away. Let’s just hope they pick a better selection of music than they do for conventional elevators.