Space Elevator: Momentum Building
Envoi de e-ngo le 14 Octobre 2004 23:12:09:
http://www.space.com/businesstechnology/technology/space_elevator_040629.html
Space Elevator: Momentum Building
By Leonard David
Senior Space Writer
posted: 07:00 am ET
29 June 2004
Leading experts are meeting this week to take a longing look at the idea of
a space elevator. The idea is a stretch, no doubt, with plenty of work to do
before travelers have push-button, top floor access to space.
For one, what's needed, advocates explain, is a super-tough ribbon that does
an about face in thinking. It hangs from the ground and falls into the
sky -- thanks to the Earth's spin and centripetal force.
Anchored in space a ribbon 62,000 miles (100,000 kilometers) long would be
made of carbon nanotubes. A "climber" would haul cargo, as well as passenger
modules up and down the length of ribbon. Those are the basics. Of course,
money is a key lubricant in this high-wire balancing act of technology.
At the third annual international conference on the space elevator being
held in Washington, D.C., scientists and engineers are tackling hurdles that
must be overcome for the concept to, quite literally, get off the ground.
Challenges ahead
"It's a mega project.things are moving about as quickly and as well as could
be expected," said Bradley Edwards, Director of Research for the Institute
for Scientific Research (ISR), based in Fairmont, West Virginia. He is a
leading authority on the space elevator concept, and is moderator for this
week's event.
Edwards is quick to run down what's up on the space elevator challenges,
from carbon nanotube technology, power beaming, climber hardware to space
debris impacts on the ribbon, health and safety issues, as well as cost,
politics and regulations.
At this week's gathering, leading scientists delving into carbon nanotubes
are detailing the fast-paced nature of their work in this arena. Different
methods of producing carbon nanotubes are moving forward, even to the point
of a new process that spins the material in similar fashion to how rope is
made, Edwards told SPACE.com.
The discovery of carbon nanotubes and the ongoing development to form them
into a composite material is central to space elevator viability being
achieved in the coming years.
Major advancements are underway in carbon nanotubes, Edwards said. That goes
for competitive production ideas, as well as churning them out in
ever-stronger batches and at costs far cheaper than before. Purchasing grams
of the material in the past has turned into buying kilograms today, and for
a greatly reduced price tag, he said.
Space elevator 101
Blue-sky thinkers like Edwards envision the space elevator as a
revolutionary way of getting from Earth into space. The primary system is a
ribbon attached at one end to Earth on a floating platform located in the
equatorial Pacific Ocean. The other end of the ribbon is in space, beyond
geosynchronous orbit.
Once operational a space elevator could ferry satellites, spaceships, and
various structures into space using electric lifts clamped to the ribbon.
Research points to a space elevator capable of lifting five-ton payloads
every day to all Earth orbits, the Moon, Mars, Venus or the asteroids - in
15 years after formal go-ahead.
The first space elevator would reduce lift costs immediately and
drastically, as compared to current launch costs. Additional and larger
elevators, built utilizing the initial design, would allow large-scale
activities in space and reduce lift costs even more.
Admittedly, years of research are required to turn this pipedream into
actual space hardware. Nevertheless, major organizations are taking the
notion seriously. That is clear from the list of sponsors for this week's
meeting: Los Alamos National Laboratory, NASA's Marshall Space Flight
Center, NASA Institute for Advanced Concepts, as well as the National Space
Society.
"There's a broad range of issues.but we're trying to hit the biggest issues
we can," Edwards said.
Straightforward exploration
Being on top of the space elevator has its downside, Edwards noted. "I get a
lot of 'this is crazy' kind of comment," he said.
But remember the early mariners who dared to build ships that sailed around
the globe. Recall how going to the Moon was thought impossible, expressed by
well-known experts at the time, Edwards countered.
"People have to take the time to look at the engineering that's been done,"
Edwards explained, "then make an informed decision. That's what we've been
pushing."
Edwards said NASA's new reach back to the Moon, onward to Mars and beyond
would become a very clear-cut undertaking - given high-strength material to
fabricate a space elevator.
"The risk of a Challenger or Columbia shuttle tragedy is basically removed.
You don't have the large energy transfer type events of a rocket launch or
reentry. No need for heavy-lift vehicles. You can eliminate a lot of the
other development risks," Edwards concluded. "The whole space exploration
program could be very straightforward and become successful pretty quick."
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