Space Elevator?

June 27, 2008

First, a shout-out to reader Imperator D, who turned me on to this idea with his comment about a previous blog on the question of whether NASA should go back to the moon or straight to Mars. Imperator wrote that

“The priority for low and high orbit human endeavors is to build a space elevator. This would make construction of a large vessel easier.”

Sounds perfectly logical, huh? Except that you may be wondering: What in the Robert Heinlein is a space elevator? 

Allow me to explain. For most of the space-faring era, humans have relied upon powerful rockets to put satellites, probes and manned spacecraft into space. The Space Shuttle, for example, is propelled at liftoff by a pair of 650-ton solid rocket boosters that are jettisoned, retrieved and refilled with fuel for reuse in a future mission. For the next generation of missions to the moon and beyond, NASA is developing the massive Ares V cargo launch vehicle, which it hopes to have in ready in time for a manned lunar mission in 2020.

While big rockets are a proven technology, they have a major downside, in that they’re incredibly expensive. Even though the $350 million to $500 million Ares V vehicle is also designed to be reusable, by one estimate the cost of each launch will come to a staggering $1.5 billion. Since it might take a dozen or so Ares V launches to transport the hardware needed for a moon base, Congress and taxpayers may wince more than a little when they get the bills. One prominent space scientist, Steven Howe, director of the Center for Space Nuclear Research at the Idaho National Laboratory, has proposed saving some money by using nuclear power instead of chemical rockets, which might allow NASA to attach bigger payloads to each vehicle and thus reduce the number of launches. But even so, we’re still looking at a cash sink.

But maybe there’s an even cheaper, more efficient way to get men and materials into space. What if we simply put a satellite in geosynchronous orbit, used it to lower an immensely long cable back down to the Earth’s surface, and then attached an electric motor and an elevator car to it so that it could haul stuff into the sky?

In some ways, the concept dates back to the Book of Genesis, in which Jacob dreams of a ladder reaching to heaven.

In 1895, Konstantin Tsiolkovsky, the 19th- and early 20th-century Russian scientist who pioneered the idea of using rockets for space travel, was inspired by the recently constructed Eiffel Tower to propose an even more outré structure that reached into space, consisting of a 35,790-kilometer-long cable attached to an orbiting “celestial castle.” (Here’s an animated graphic of how it might look.)
Tsiolkovsky’s tower had one very significant flaw: It would have been impossible to build, since even the strongest steel available in his time wouldn’t have been tough enough to withstand the forces to which it would be subjected. In a 1975 paper on the concept of building a space elevator, space scientist and engineer Jerome Pearson described the challenge:

Three problems stand in the way of building the orbital tower. First, any tower 35,800 km high would seemingly buckle unless it were hundreds of kilometers in diameter. Second, even if it were prevented from buckling, the stress at the base due to the weight of the material above would apparently exceed the strength of any known material, and it would collapse. Third, if the tower elastic modes were in resonance with the tidal excitations of the moon, they would be amplified and the tower would be destroyed.

Nevertheless, believers in the space elevator concept persisted. Pearson’s work inspired another visionary, science fiction author Arthur C. Clarke. His 1979 novel The Fountains of Paradise depicted fictional engineer Vannevar Morgan’s effort to create a space elevator using “hyperfilament,” a substance fashioned from diamond crystal that was microscopically thin but incredibly strong. Indeed, that would have been the ideal solution, except that hyperfilament was a product of Clarke’s fertile imagination.

Since then, however, space elevator supporters have become enamored of a real-life material that might actually be up to the task: fibers made of carbon nanotubes, those cylindrical molecules that are hundreds of times stronger than carbon steel. A few years ago, NASA’s Marshall Space Flight Center  joined forces with the private nonprofit Institute for Scientific Research to study the idea of tethering a geosynchronous satellite to Earth with a nanotube fiber ribbon 100,000 kilometers long, several meters in width and the thickness of a sheet of paper. Here’s a NASA scientific paper describing the technological requirements, and from ISR, a video showing how the space elevator would work:

Not surprisingly, space elevator advocates are all over the Internet these days. One of my faves is retired software engineer Ted Semon’s Space Elevator Blog, which is a great source of news about the latest developments. And if you’re looking for something to do the weekend of July 18-20,
Microsoft’s Redmond, Wash., headquarters is hosting the Space Elevator Conference 2008, a three-day event that will look at the science/technical, political/social, legal and economic issues involved in building a space elevator.

If NASA could somehow get this to work, the benefits to the exploration and commercialization of space would be incredible. Space scientist and entrepreneur Bradley Edwards has estimated that the cost of transporting material into orbit would be reduced from $10,000 a pound on space shuttle missions to just $100 a pound, so that sending stuff into space someday could become nearly as routine and affordable as using Federal Express is today. Additionally, reaching space and returning to Earth afterward would become much, much safer, because the elevator could move at speeds much slower than conventional spacecraft. Space tourism would no longer be restricted to business moguls with $20 million to spare. And if we built multiple space elevators, they could become conduits for electricity generated by solar panels on the satellite tethers.

What are the potential pitfalls? In a 2003 report, Bradley noted that a space elevator might face potential risks such as extremely high winds or collision with existing satellites. I haven’t seen any discussion of the potential environmental impact of erecting such a structure. And I have to wonder how we would protect it from a missile launched by a rogue dictator or a bomb planted by terrorists.

So, what do you think about building a space elevator? Express your opinion below.

Picture: Courtesy of Lifeport Group

Comments

[Astroboy]

But big rockets are WAY more fun!

[Grunge Bob]

I think it's a good idea, but there are additional issues to be concerned about. Here's a point from a CBC news article http://www.cbc.ca/news/background/space/spaceelevator.html

For people going up the space elevator the ride will take more than a week and they will spend days passing through a belt of heavy radiation before reaching the top. So that's another problem. The passenger car must be designed to shield travellers from those deadly radioactive beams.

[Caffeine Driven Stress Magnet]

This sounds like space travel for wimps.

[Harry]

I'm convinced that a space elevator eventually will be built, because there is so much interest from scientists and engineers in this concept. For example, here's an interesting design paper written by MIT students http://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-170Fall-2005/10350948-E85B-4D47-932E-F3EF6C8C4FD4/0/lec20.pdf

[Skeptic]

What about lightning and hurricanes? Wouldn't they destroy a space elevator?

[Lance]

Instead of building an elevator from the bottom up, how about top to bottom? Without touching the earths surface, just a floating hanger to fly to with a elevator going straight up to the space station. Sounds good, but is it?

[SynGen]

The space elevator is a great idea. We can't hope to always use rocket fuel to get to space, its to costly and not enough people in the world are willing to throw in the tax dollars to do it all the time to go to another planet. A space elevator would bring cheaper costs to space exploration, and make it easier to build a BETTER station in space. Not like the ISS is bad, but as human beings and so far as we know, the only intellegent beings in the universe(which i doubt), we are capable of building something far better. For centuries humans have looked up at space in wonder, and now is our chance to immerse ourselves into it.

[Brad Lewis]

While a space elevator seems like a great idea... I have trouble wrapping my mind around this concern... When the satillite is in orbit and lowers the "strap" and a heavy object is then attached WHAT keeps the lower object from "reeling" in the satillite from space instead of the reverse?

[Traveler]

Here's what Wikipedia says:

The most common proposal is a tether, usually in the form of a cable or ribbon, spanning from the surface near the equator to a point beyond geosynchronous orbit. Neglecting perturbations, it would be possible to design such a tether to barely touch the ground while remaining in orbit. All proposals however have additional ballast placed at the two ends to provide stability. As the planet rotates, the inertia at the upper end of the tether counteracts gravity, and keeps the cable taut.

[Berkeley Barb]

My initial attempt to post this didn't seem to work, so here it is again...

Someone wrote: Instead of building an elevator from the bottom up, how about top to bottom? Without touching the earths surface, just a floating hanger to fly to with a elevator going straight up to the space station. Sounds good, but is it?
---------------------------------------------
Aha! There is indeed an alternative proposal to the space elevator, called the skyhook, that would do just this. Carnegie-Mellon University's Hans Moravec, better known for his work in artificial intelligence, wrote a paper proposing this idea back in 1976.
http://www.frc.ri.cmu.edu/~hpm/project.archive/1976.skyhook/papers/scable.pox

[Lance]

Skyhook sounds like a good name for it lol, and I've read that link Berkeley Barb posted and I think it might work.

[Pablo]

Lance, I think you're onto something, man. Great minds think alike, I guess. :)

[Ted Semon]

Thanks for the nice comments about my blog and thanks also for the plug for the upcoming Space Elevator Conference.

I don't know if we (USA) will be the first ones to build an earth-based Space Elevator or not, but at the end of the day it doesn't matter. Once someone (Dubai & India?) builds one and proves the concept, I think we'll see a lot of them. And then we'll have the cheap access to space that we want and need.

[online computer repair service]

This seems like the most comprehensive blog on this niche