To help humanity explore the universe and spread to the stars, we first need to escape the gravity well of planet Earth. The only way to do that right now is to ride a rocket - which takes an enormous amount of energy and money, especially if you want to send anything bigger than a mobile phone into orbit. Rockets are useless for the kind of offworld commuter solution we'll need if we're going to become an interplanetary civilization - let alone an interstellar one. That's why an international team of scientists and investors are working on building a space elevator. Using very little energy, these 100,000km-high elevators could carry travelers out of the gravity well and up to a spaceship dock.
If you want a glimpse of tomorrow's morning commute, you need to know about the space elevator.
Top image by Michael Evans
What is a space elevator?
A space elevator is a fairly simple concept. It would be made of an ultra-strong metal ribbon that stretches from a mobile base in the ocean at the Earth's equator, up thousands of miles into space, attaching at its other end to an "anchor" in geostationary orbit. Robotic climbers rush up the ribbons, pulling cars full of their cargo - human or otherwise.
Because the space elevator pulls cargo out of our gravity well, rather than pushing it using combustion, it would save a lot of energy and be capable of bringing far more materials offworld quickly. It would also be sustainable, making one or more runs per day. That it's reusable already makes it many thousands of times cheaper than the one-time-use Soyuz rockets that bring supplies to the International Space Station, only to destroy themselves in Earth's atmosphere.
Why will it save energy and money?
NASA says that each Space Shuttle launch runs about $US450 million. A lot of that money goes to fuel, and to storing enough of it to make the whole trip up and back down to Earth. But a space elevator won't need rocket fuel.
According to How Stuff Works:
The lifter will be powered by a free-electron laser system located on or near the anchor station. The laser will beam 2.4 megawatts of energy to photovoltaic cells, perhaps made of Gallium Arsenide (GaAs) attached to the lifter, which will then convert that energy to electricity to be used by conventional, niobium-magnet DC electric motors.
Groups working on space elevator plans believe this system could reduce the cost of transporting a pound of cargo into space from today's $US10,000 price tag to as little as $US100 per pound.
Getting rid of our dependence on rocket fuel will reduce carbon emissions from rocket flights bringing everything from satellites to astronauts into orbit. And it will also cut down on water pollution from perclolrates, a substance used in making solid rocket fuel, and which the Environmental Protection Agency in the U.S. has identified as a dangerous toxin in our water supplies.
What it be made of?
The biggest question about space elevators is how we'll make that 100,000km-long ribbon stretching between Earth and a counterweight. The short answer is: A substance that doesn't exist yet, but which we're very close to creating in many labs devoted to nanoscale engineering and materials science. Essentially we need a way of knitting together carbon atoms to produce a light, flexible, ultrastrong metal that robots can grip with their climbing treads. Most of the time, the ribbon will be there as a guide rail rather than serving as a big ladder - in other words, it won't always need to bear a lot of weight. But it will need to withstand being stretched tight, and to resist being torn apart by winds and other wear and tear you'd expect in the upper atmosphere and space.
LiftPort, a company that's trying to develop materials to make such a ribbon, believes that it will be made from carbon nanotubes because they'll be light enough to transport easily into space:
The space elevator could be built using existing stronger/lighter-than-steel materials such as Spectra or Dyneema or even Kevlar. The problem is the excessive mass of material that would be needed to support it's own weight. Even with 60 GPa material strength an initial starter ribbon will require multiple heavy lift rocket launches to get started. These rocket launches will be very expensive. Any decrease in strength results in an exponential increase in required mass. Spectra would take well over 100 shuttle sized launches. The problem at this point becomes financial.
The other question is what the anchor will be made of. Ideally, it would be an asteroid or other chunk of rock from our local volume of space. But more likely it will be a human-made platform of some type. Maybe we can even make it out of all the space junk that's orbiting the planet right now. Who doesn't want a recycled space elevator dock?
Who is working on building one?
There have been two large Space Elevator Games events, much like the X-Prize, where inventors competed for large cash prizes for their viable models of space elevator climbers and ribbon structures. Here you can see a small-scale version of what a space elevator would look like from the 2006 games.
ISEC, the International Space Elevator Conference, is a group that holds annual conferences and prize giveaways for inventors and investors to explore novel materials and methods we could use to build a space elevator. They're associated with groups in Europe, Japan, and America that are working on space elevator engineering.
The Space Engineering and Science Institute puts on an annual conference about space elevator design (this year it's in August at Microsoft). Not surprisingly Google has also tossed around the idea of putting money toward a space elevator, and several years ago the Google Earth blog even featured a conceptual design for one based on Google satellite imagery.
Entrepreneurs like the LiftPort group are trying to develop materials for the ribbon, while LaserMotive (the company behind the mosquito-killing lasers) is attempting to create the laser energy beam that would fuel the robot climbers.
And, most importantly: Where can I see space elevators in science fiction?
Usually when you see them, they're being destroyed: Most memorably, the evil alien forces called the Covenant destroy Earth's Mombassa space elevator in the game Halo 3: ODST. Because obviously that's much more fun to look at than a fully functioning space elevator. In Kim Stanley Robinson's novel Red Mars, there's an incredible description of building a space elevator using one of the Martian moons as a counterweight. Unfortunately, it's destroyed in a war and we get an amazing account of what happens when thousands of miles of burning carbon wraps itself multiple times around the planet. There is also a terrific chase scene on a space elevator in Ken MacLeod's novel Night Sessions.
The space elevator is one of those rare engineering dreams that has made more headway in the scientific community than in the science fictional one. They're not as big in pop culture as jet packs and flying cars, but they're far more likely to happen and they'll be much more useful. Many space elevator groups are shooting to have working prototypes in twenty years.