by Omnitir » Sun 08 May 2005, 07:17:52
The 400 Km figure is what I read at one site suggesting low orbit, but I now agree a high geosynch orbit at around 36000 Km would be needed.
Hmm, I wonder if the main problem here is the term space “elevator”, making people think of a traditional elevator reaching into space? Maybe it should be called an Earth-Orbit cable or something, so people don’t automatically assume its sci-fi?
$this->bbcode_second_pass_quote('ArimoDave', '
')O.K. You have attained a moderate near earth orbit, with your cable, now what?
I realise you were pointing out this needs to be in high orbit, which I agree, but assuming we have this cable reaching into high-orbit, what are the benefits now?
Well now we can send large payloads into space at a fraction of the cost. The possibilities are enormous. For one thing, goodbye jet airliners, hello “drop-ships” – for the price of the energy used to climb a cable a re-entry vehicle could go anywhere on Earth, low on fuel consumption and pollution. The trip may take a few days, but its much more sensible (and affordable) then modern jet aircraft (and much more fun!).
An even better and more obvious benefit is cheaply setting up
massive PV systems to harness the unfiltered solar rays for use on Earth – the answer to our energy crisis. Another benefit is the ability to get sensitive equipment into orbit that cannot currently be launched by conventional means, which would greatly enhance the abilities of satellites. Then there are the benefits of space exploration and colonisation. Getting from Earth obit to anywhere else in the system is easy once a cheap “launch” system exists.
The hardest part about doing things in space is getting into orbit. A cheap, slow ride up a cable is a much more realistic way to do it then blasting massive chemical rockets at breakneck speeds to escape Earth’s gravitational pull. It also more sensible then most standard forms of aviation (though probably slower).
The only thing stopping it from happening right now is a lack of an ultra light, ultra strong fibre to construct the cable with, which is what nanotubes will offer in a few years. The ten-year, $10 billion estimates of this project sound realistic. A space elevator project would actually be much more simple and affordable then many of the worlds more common (and more expensive) construction projects.
Here’s some quotes from physicist Bradley Edwards of Eureka Scientific in Berkeley, California, from
this article:
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')Even though the challenges to bring the space elevator to reality are substantial, there are no physical or economic reasons why it can't be built
…
I'm convinced that the space elevator is practical and doable. In 12 years, we could be launching tons of payload every three days, at just a little over a couple hundred dollars a pound," he said.
…
(About attaining the needed quantity of carbon nanotube fibres): That quantity of material is going to be around well before five years time. It's not going to take long,"
If budget estimates are correct, we could do it for under $10 billion.
And regarding the commercial fabrication of carbon nanotubes, here’s a press release from only two weeks ago:
')carbon nanotube composites are lighter than fiberglass and have the potential to be up to 100 times stronger than steel.
Opening a commercial production facility enables us to generate revenues in the shorter term by meeting the growing market need for this material. At the same time, it enables us to conduct research and development in this arena for our longer term goal of a commercial space elevator."