In 2009 a helicopter hovered 900m above the Mojave Desert, Andrew Petro was watching. Beneath the helicopter was a steel cable tethered to the ground, as he watched a small, square robotic device rose upwards, racing towards the helicopter along the cable, at 600m it slowed to a crawl and then stopped. At the base of the cable was a tripod-mounted laser pointing at the robotic device, no longer powering it upwards, the limits of its power had been met. On behalf of NASA, Andrew Petro handed the semi-successful team behind the robotic square a cheque for $900,000 – they had just won a competition for the future of space travel.
Getting to space is expensive, but it becomes a lot cheaper when you don’t use rocket fuel. How to do that though. The answer involves a powerful laser, a cable 8 times the diameter of the earth, a large steel ball and finally a very big metal box. It was first described in 1895 as a ‘celestial castle’ attached to earth by a tether on the top of something like the Eiffel tower. It was more accurately presented in 1979 by Arthur C. Clarke’s ‘The Fountains of Paradise.’ The way to reach space, is with a Space Elevator.
The competition was the 2009 Space Elevator Games, a NASA-run competition to encourage innovation that could lead to more advanced prototype space elevators. The reasons for the sudden interest and investment are two-fold. In 1990 the first carbon nanotubes were successfully manufactured; and high-strength lasers are rapidly increasing in power. The thing is becoming possible. So now, it seems, the space elevator concept could finally be getting off the ground.
The concept is as follows, out in space is a large steel ball. Attached to this large mass is a tether which reaches along the 60,000 miles to earth. As Earth spins around the steel ball tries to fly off into space, this force keep the tether taut. On the tether, an elevator, which bears loads and proceeds to elevate them. It does this in the same way as a ski lift, a series of rollers attached to the tether which pull the elevator up.
This large elevator would be a revolution, once built, goods could be transported to space for the cost of the electricity to power the elevator. More regular space-visits and it can be made at any size. The smallest length is eight times the earth in diameter, we could make one stretch out to Mars. The problem being that this isn’t possible. Yet.
The first is the tether, it would need to support its own weight plus up to 20 tons of space-bound goods or people. There is only one material that can make a suitably strong tether. Carbon nanotubes; 180 times stronger than steel and much lighter. To get an elevator to space would require a single cable only 6.5 millimetres across. Something too difficult to make today, but many expect it to become possible in the next 20 years. It would be an engineering feat; the Spaceward Foundation says it would be like a:
“thin black line, almost like the trace of a film-scratch on a picture. The tether reaches straight up and quickly disappears from view into the clear blue sky.”
The next problem is power. If you used batteries, you would not get enough power out of them to lift their own weight. So the solution is power beaming. In essence you fire a big laser at a big solar cell. This, and power from the sun allows the elevator to elevate. We just need bigger, better and more efficient lasers.
Infeasible would be the most appropriate word at the moment, however hope is at hand. Progress must go on, that is its sole function. In addition to NASA the Japanese Space Agency, JAXA, is looking into developing their own large prototype. The Spaceward Foundation expects at least one Space Elevator to be functional by 2025, with a commercial, possibly even tourist one in place by 2035. They expect the journey to take several days. It will cost $10 per pound going to space and the whole experience shall be a sedate journey as the elevator rises. Well technically the elevator doesn’t rise, it is falling, upwards. On Earth it is upside down, but that shouldn’t matter.
There are grand plans for the elevator, the Spaceward Foundation predicts the first Space elevator will mainly carry up parts for the first zero gravity factories for nano-machines and space hotels where space tourists shall enjoy their space holidays, which will obviously be in space. Also they see another use. If you had the space elevator, swinging wildly out in space, what if you let go?
If done accidentally it would be a new kind of problem, but if you aimed, the whole system would fly out into space, maybe heading for the Moon, or Mars perhaps.
A mixture of the familiar and the bizarre. One is tempted to wonder how it would go. Settlers with the belongings arrive in a large corporate building. They file into a large, cylindrical chamber and the select their seats. A last wave to friends assembled then they reach for the buttons. A wandering finger passes by the numbers and pauses, before firmly prodding the button labelled ‘Space.’ A slight whirr and they set off upwards, first out of the rather tall building, past the clouds and Earth. When they reach the end of their tether they simply let go of Earth and are flung into space. Several weeks later they step, rather ruffled, out of the crash-landed elevator and onto Mars. Among them, a confused office worker who got into the wrong lift.
Of course this would not happen, current proposals suggest the base building for the tether would be 50km high. The rest, may be accurate. With the push of a button and the firing of a laser you can reach space. So removed from the spectacle and furore of a rocket launch that it is a wonder they lead to the same place. The appeal of the idea is that it would be both safe and easy, a combination which lifts the spirit.
Space would finally seem not just possible, but attainable. Then perhaps we could all gaze down at the blue marble of the earth, stretched out beneath our feet. Space will become a place now. An oversized elevator could be the start of a new story, one starting very soon. Just don’t expect to spot the ‘Space’ button in an elevator any time soon.
- NASA article on the 2009 Space Elevator Games
- NASA article on the Space Elevator concept
- Good.is article on the JAXA Space Elevator plans
- The Spaceward Foundation