When the late Neil Armstrong and the crew of Apollo 11 went to the Moon, they did so sitting atop a rocket the size of a skyscraper that blasted out jets of smoke and flame as it hurtled skyward. For over half a century, that is how all astronauts have gone into space. It’s all very dramatic, but it’s also expensive. Wouldn’t it be cheaper and easier to take the elevator? That’s the question that Michael Laine, CEO of LiftPort in Seattle, Washington, hopes to answer with the development of a transportation system that swaps space-rockets for space-ribbons.
Rockets have done sterling service in launching satellites and astronauts into orbit. The trouble is, they’re inefficient and therefore expensive. Putting a payload into orbit means that the rocket must not only lift the payload, it has to carry the payload, the fuel to lift it and the rocket, the fuel to lift the fuel, the rocket and the payload, the fuel to lift all that and so on. The space elevator is based on the idea of cutting out the middleman and just lifting the payload. It does this by way of a tower of mind-boggling height – from sea level at the equator, clear up to geosynchronous orbit 35,800 kilometers (22,238 mi) up with an elevator for going up and down it like it was the Seattle Space Needle.
The idea even predates liquid-fueled rockets. It was first proposed by Russian space pioneer Konstantin Tsiolkovsky in 1895. Inspired by the Eiffel Tower, he had the idea of building what came to be known as the “Tsiolkovsky Tower.” He saw the advantage of a tower tall enough that launching satellites would be a matter of simply releasing them like pigeons, but The tower wasn’t remotely practical because no conceivable self-standing structure could be built so high and not collapse under its own weight.
For decades, the idea languished and was largely forgotten, until is was reinvented in 1959 by another Russian scientist, Yuri N. Artsutanov. His new design remained unnoticed as well because his paper was not published in English until many years later, so the space elevator was reinvented twice again by American scientists in 1966 and 1979. The cycle might have continued if Sir Arthur C. Clarke hadn’t made the construction of a space elevator the plot of his 1979 novel Fountains of Paradise. Sir Arthur was very keen on the idea and liked to predict that the elevator would be built “ten years after everyone stopped laughing.”
By the 1970s, the basic design of a possible future space elevator had been refined. Tsiolkovsky’s tower was replaced by a ribbon suspended from a space station in geosynchronous orbit over the equator. Those two points are important because at that distance and at the equator, the station remains over the same spot on the Earth at all times. Above the station at a distance of 144,000 kilometers (90,000 miles – nearly the halfway point to the Moon) is a gigantic counterweight that holds up the ribbon and the station by centrifugal force, which the Earth’s gravity counters and balances.
This system doesn’t envision the use of an actual elevator. A 35,800 kilometer-long cable isn’t exactly practical and the counterweight needed for the thing would be the size of a small mountain. Instead, it uses a self-propelled car that climbs the ribbon. How the car is powered varies from electricity carried by the ribbon to lasers beamed from the ground and the station. The car itself would be a high-tech affair and is often imagined as a climbing robot or something equally exotic.
The space elevator is simple in concept, but nearly impossible in execution. The main problem is that no material known to science is strong enough to make the ribbon. Steel and titanium are much too weak. In fact, the ribbon needs to be 60 to 200 times the strength of steel if it isn’t going to snap under its own weight. Quartz fibers and even diamonds have been considered and recently carbon nanotubes seem promising, but engineers are still a long way from answering that basic question of what the heck to make it out of.
Other problems include the cold in the upper atmosphere, which plays havoc with lubricants, materials and electronics – not to mention the danger of ice building up on the ribbon. Then there’s inclement weather buffeting it. Above the atmosphere, satellites and space debris whizzing by pose their own challenges.
LiftPort – heading for the Moon
LiftPort ultimately wants to build a space elevator on Earth, but the company isn't planning on doing it in one go. Instead, Laine and his team are settling for a more modest goal – building an elevator on the Moon by 2020. This is much easier. For one thing, there’s no air on the Moon, so no icing problems. Also, the lower gravity means that no unobtanium is needed for the ribbon. Kevlar is strong enough for the job. And finally, there’s very little in the way of satellites or debris to contend with. LiftPort’s goal in its Kickstarter funding campaign is a modest US$8,000, which it has already surpassed. This may seem like chicken feed for such an ambitious program, but Laine intended it as a way of sparking public interest. The ultimate goal is to raise $100,000 to $3 million with the first round of funding to be used to continue a preliminary study of the system.
"The study will include characterization of materials; analysis of required rocketry and robotics; and evaluation of landing sites and methods of anchoring to the Lunar surface," says Laine. "Additionally, Ribbon spooling, infrastructure deployment, and micrometeorite mitigation techniques will be explored."
If all goes well, Laine believes construction of the lunar elevator could begin by 2020. The LiftPort lunar elevator would be deployed from lunar orbit with a spacecraft lowering a lander on the ribbon. On contact with the surface, the lander will anchor itself. After that, landing on the Moon will be as simple as docking with the craft in lunar orbit, transferring to the climber car and reading a book on the way down.
The immediate goal, however, will be to test the system on an elevator only two kilometers (1.24 mi) high, which would be suspended from balloons. LiftPort plans to build a robot climber capable of scaling the ribbon. In order to test this, the team will construct a sort of “vertical treadmill” for the robot to climb before taking on the real thing.
Further money raised will be used to develop better sensors, increase the height of the suspended ribbon to 5 km (3.1 m), develop a new robot and then go on to climbs of 30 km (18.6 m) and, finally, a full feasibility test of the system, which Laine hopes to carry out next year.
Laine sees a number of applications for such space elevators beyond launching spacecraft and giving tourists a restaurant with one fantastic view. He sees the elevator as being the tallest line-of-sight radio tower possible, which would be a tremendous boon to communications. Also, even the technology for suspending the ribbon from balloons opens the potential for quickly deployable emergency communications/surveillance towers.
But part of the attraction for Laine is simply adrenaline-raising fun. Anyone for the ultimate bungee jump?
The video below depicts how a lunar elevator would be deployed.
Sources: LiftPort (Kickstarter page) via Cosmic Log
