Beamed Power

Wired News has a story today mentioning a fresh examination of beamed power.  Most of the piece is about a $500 billion project to generate power on the moon and then beam it back to Earth (oy), though it does mention the space elevator eventually.  NASA is partnering in set of Centennial Challenges aimed to promote development of technologies such as beamed power, strong tethers, and climber robots.

Going UP

Here are the first few paragraphs of my chapter for the Liftport Space Elevator Book (Official Title TBA), which will be published in summer 2005.  Loads of info and more documents at The Space Elevator Reference.

Construction and Operational Hazards to the Space Elevator
Robert Carlson

Climbing a narrow ribbon of carbon seems a tenuous means of reaching for the stars.  Like the horse hair suspending the sword over Damocles’ head, reminding him of the precarious nature of political power, the thin thread of the Space Elevator will constantly remind us of our fragile freedom from Earth’s gravity well.  The primary argument for building the elevator can be derived in a few lines on the back of an envelope; the energy cost of putting 1 kg in geosynchronous orbit on the elevator is approximately 1% the cost using rockets.  We then must determine whether the 100,000 km long structure is theoretically plausible to build and operate.
    Even in theory, the sheer size of the elevator inspires both awe and fear in the form of unknowns that appear overwhelming at first glance.  Fortunately we have accumulated many person-years of operational knowledge of the environments the ribbon will experience.  Moreover, all of the technology required to build the elevator has already been independently demonstrated, save the completed ribbon itself.  This means we can apply existing engineering know-how to evaluate whether the elevator is a feasible project and what risks may arise during construction and operation.  And the ribbon is far from being “unobtanium”.  There appears to be only one known material suitable for building the ribbon, carbon nanotubes (CNTs).  The amount of progress made in understanding both the construction and properties of long carbon nanotubes is quite remarkable given our mere 15 years of experience.  Many critical properties of the ribbon, and its constituent adhesives and CNTs, can already be measured or estimated. 
    Still, the history of human engineering and construction is full of hubris confronted by physics.  The devil is definitely in the details for this project.  The few engineering details available are compiled in two NASA Institute for Advanced Concepts (NIAC) reports and a book, all written by Bradley Edwards.
    The purpose of this chapter is to explore what could go wrong with the deployment and operational plans, and what might be done about it.  Much of those plans are determined by the seemingly unavoidable requirement of launching an initial full-length ribbon and then lowering it from orbit to the Earth’s surface.  As related in Brad Edwards' reports (Phase I, Phase II, book at Amazon) for NASA, this deployment strategy appears a happy confluence of economic and design factors.  The numbers, remarkably, work out quite nicely...

I'll post publication details for the book when they are finalized.