Is there a cheaper and more efficient way to put humans, equipment and materials into space than by using powerful rocket engines?
Since the beginning of space flight in the late 1950s, we’ve relied upon thrust to enable satellites and manned vehicles to reach space. Escape velocity is the physics term for achieving enough kinetic energy to break free of a gravitational field. The precise escape velocity varies depending upon the mass of the planet or moon that you’re trying to take off from; on our particular planet, it’s necessary to fly at a speed of 25,038.72 miles per hour. (If, by chance, you’re an extraterrestrial planning to depart soon from another planet besides Earth, here’s a handy escape velocity calculator that will calculate what velocity you’ll need to attain.)
For a space vehicle to achieve that speed, of course, requires a lot of rocket power, and that’s expensive. The massive Ares I rocket, which have put the cancelled Constellation manned craft into space, would have cost a breathtaking $1.6 billion per flight, according to this analysis on Spacepolicyonline.com. As you can imagine, that eventually would start to add up to some serious money.
That’s why space scientists have been taking a new look at an old idea that’s so simple that it sounds almost like something a child would dream up. What if we put a satellite into geosynchronous, had it drop a really strong, flexible weighted cable down to Earth, and then attached that tether to the ground and used it to haul an elevator into orbital space?
The notion of a space elevator has been around for a long, long time. Back in 1895, Russian space-travel visionary Konstantin Tsiolovsky, who may have been the first to envision using rockets for space travel, also contemplated a tower tall enough that an elevator could travel up it into space. The idea was revived in the 1960s by a Soviet engineer named Yuri Artsutanov, and by scientists the Scripps Institute of Oceanography, who proposed tethering a satellite using a thin wire. In the mid-1970s, Jerome Pearson published an engineering analysis of the space elevator concept. Pearson’s description was so compelling that science fiction author Arthur C. Clarke used the idea in his novel The Fountains of Paradise
, which depicted a fictional effort to build such an elevator that utilized a cable made of a filament fashioned from diamond crystal.
In 1999, NASA scientists and engineers actually discussed the construction of such an elevator at a space infrastructure conference, and based upon their work, David Smitherman Jr. of the Marshall Space Flight Center authored this 2000 paper on the feasibility of space elevators. The scientists envisioned a super-strong, super-flexible cable connecting a satellite and a tower built on the Earth at a spot around the Equator. The elevator car wouldn’t actually be hauled in the conventional fashion; instead of wheels and pulleys, it would float upward along a track attached to the tower and cable, using electromagnetism. Such a vehicle would not only be super-efficient, energy-wise, but it also would be much faster than a conventional elevator and its parts would be subjected to less wear and tear. NASA scientists envisioned creating such a space highway in the distant future, but in a followup 2003 report funded by NASA’s Institute for Advanced Concepts, author Bradley C. Edwards ventured that an elevator could be built by 2018 at a cost of just $10 billion on a man-made floating base (either a ship or an oil platform in the tropics.
Perhaps the major problem encountered by space elevator visionaries has been finding a sufficiently high-performance material from which to make the cable. The 2003 NAIC report proposed using one made from carbon nanotubes, which basically are threads of pure carbon that are among the strongest materials known.
Additionally, the elevator’s power supply would be provided by a ground-based laser that would beam energy into space. Amazingly, birds and aircraft could fly through the beam without being harmed.
Advocates of the space elevator concept continue to gather new research data and to make the case that it’s something we not only could build, but should. The key group is the International Space Elevator Consortium, which sponsors an annual conference that will be held in August at the Microsoft Conference Center in Richmond, WA.
In an era when government budget woes are endangering rocket-powered space flight, a space elevator might be a way to sustain the space program without arousing the ire of austerity-conscious taxpayers and politicians.
Here’s a 2008 article on space elevators from the Spaceward Foundation, and a recent article from National Geographic magazine.