Going Up! Next Stop, Earth Orbit

September 23, 2008

One of my favorite fairy tales from childhood is Jack and the Beanstalk, where the untouchable clouds can be reached by shimmying up an oversized vine.

The Arthur C. Clarke 1979 novel The Fountains of Paradise, describes the space age incarnation of this fairy tale: the construction of a space elevator that whisks people up to Earth orbit without the need of rocket ships.

This idea goes as far back as the Russian physicist and theoretical father of rocketry, Konstantin Tsiolkovsky, of a century ago.

When I mention this concept among friends they give me a quizzical look as if I was really talking about something as absurd as climbing a beanstalk.

A space elevator is essentially a very long super strong cable extending from Earth’s surface high into space.  The elevator capsule would carry cargo and passengers to a tethered space station in geostationary Earth orbit (GEO), at 22,300 miles altitude.

To keep the cable taunt, it would be attached to a large counterbalance mass beyond geostationary orbit, perhaps a captured near Earth asteroid. The GEO gateway station would be at the center of balance of the cable.

Yes, The concept of a space elevator sounds utterly fantastic. You can just imagine the buttons: “9 millionth floor please.” Kids would be banned. They’d push all the buttons!

Nevertheless the promise of a space elevator is every bit as tantalizing as it is seemingly improbable. I do believe it will be a matter of when not if, when this daunting super-engineering dream is finally realized.

Why? Because from a vantage point only three miles from the launch pad, I’ve watched several NASA space shuttles roar skyward atop Promethean flames. The raw power of the 7 million pounds thrust is as terrifying as it is awesome to behold. 

In that back of your mind you think there must be a more civilized way to get into space instead of strapping yourself to two oversized skyrockets that are nearly one-third the height of the Washington Monument.

Just as terrifying is the though of screaming back into Earth’s atmosphere at 25 times the speed of sound. Your vehicle glows red hot, as it has to bleed off as much energy as it used to get into space.

Two fatal space shuttle accidents – one while going up and one while coming down – underscore the extreme aerodynamics and extreme physics in operating such a space transportation system.

In recent years NASA has offered a $400,000 prize for teams that can build an energy beam-powered space elevator model that can ride 200 feet up a ribbon of material. In a second competition NASA offered a prize for the team that could come up with their best formulation for an ultra-light, ultra-strong ribbon material that survives grueling tug-of-war stresses. So far there have been no winners.

Last week Japan announced that a consortium of scientists and industrial firms has formulated a plan to build a space elevator for $9 billion.

At the heart of concept is a three-foot wide carbon nanotube ribbon. IN the coming years nanotube technology is expected to reach the tensile strength required to fabricate a 75,000 mile-long ribbon. The strength of nanotubes materials has increased a hundredfold in just the last five years.

Elevators attached to the ribbon would crawl up and down powered by electricity, a laser beam, or electromagnetic propulsion. The elevator would drastically reduce the cost of moving people and cargo into orbit. Rocket payloads can cost $10,000 per pound.  The space elevator could drop costs to $100 per pound say some experts. Orbital transportation vehicles like the space shuttle would be remembered as the Hindenburg of the space age.

It’s easy to imagine a sort of second-generation space race where the world’s major powers compete to see who can be the first to establish a permanent space presence by constructing a space elevator.
It would be a resource of national pride and a status symbol of technological prowess. You could imagine a string of international space elevators stretching out from the equator like spokes radiating from the hub of a bicycle wheel.

However, the elevator would be as "choke point", as characterized in military language. Destroy the slender ribbon and you cut off a nation’s access to space.

The Earth platform for the elevator would be a prized target for enemy nations as well as terrorists. What’s more, it would have to be located outside a country’s boundaries and near the equator. One prime anchor location is in the Pacific Ocean, roughly 1000 miles west of the Galapagos Islands where interference by lightning, hurricanes, strong winds, and clouds is minimal.  But It would have to be surrounded by several concentric defense perimeters to ward off attacks.

The space elevator would not only make sense on Earth but on Mars too. Colonists would reach Mars’ surface by docking with the elevator’s orbiting station node and pressing the down button. I described in an earlier blog that Mars is very problematic for making safe rocket landings. The thin atmosphere makes it much more treacherous than landing on the moon or Earth.

Advanced space faring civilizations elsewhere in the galaxy may have already reached the space elevator era. Regrettably even this sort of macro engineering around a star is not detectable from Earth. A circumequtorial ring of space colonies might give a terrestrial planet a slightly anomalous infrared excess. But this would easily be explained as a dusty slender ring system rather than the handiwork of an advanced intelligence.

artwork credit: Pat Rawling/NASA