..Yeh, I'm Otis...but we don't need no elevators in Mayberry.
Posted on 08/19/2002 8:09:11 PM PDT by Brett66
Going Up? Private Group Begins Work on Space Elevator
By Leonard David
Senior Space Writer
posted: 07:00 am ET
19 August 2002
SEATTLE, WASHINGTON -- The world's space programs are vertically challenged. What's needed is a revolutionary low-cost way to move payloads and people into Earth orbit and then outward to the asteroids, Mars and beyond.
Now an upstart company of enterprising engineers and investment strategists want to tackle the ultimate high-rise project for the 21st century: the space elevator. They are on the ground floor of putting calculations to paper and wrestling with the toughest challenges.
The message from the First International Space Elevator Conference, held here August 12-13, is that the concept is an idea whose time has come…well almost. World-class specialists in diverse fields -- from materials science, bridge building, and aerospace technology to law, business, and financing -- contend the project is on the up-and-up.
Simple physics
"This is a vertical railroad," said Brad Edwards, co-founder Seattle-based HighLift Systems, a privately held, Seattle-based firm established this year. "The space elevator has long been the stuff of science fiction. We're turning a concept into a reality," he told SPACE.com.
Edwards is a driving force behind the space elevator project. The work has been spurred into being by funding through the NASA Institute for Advanced Concepts (NIAC) program.
When you hear the details, it's clear no small thinking is allowed. Yet the proposed structure is steeped in simple physics.
At the heart of the space elevator is a ribbon that stretches some 62,000 miles (100,000 kilometers) from Earth to space. This high-wire act would be anchored to an offshore sea platform floating near the equatorial line in the Pacific Ocean. At the other end, high above Earth, the elevator is tipped by a counter weight.
Returning to down-to-earth physics. Just like a ball on a string that's swung round and round over your head, the twine stays straight. Hold onto that thought.
"What we're doing here is using the Earth's rotation. Because of that rotational acceleration, a space elevator cable is pulled outward. It has an upward tension, with gravity pulling down on the bottom. The cable is balanced and it hangs there…stable and vertical in space," Edwards said.
Electrically powered "climbers", energized by laser beam, would make their way up and down the ribbon, Edwards said. These automated devices are built for the long haul; they ride the length of the ribbon topped by spacecraft, construction materials, and eventually passenger-carrying pods.
Wanted: unobtainium
Making the difference in designing a true space elevator is finding a critical building material for the ultra-lengthy tether, cable, or ribbon - whatever you want to call it.
Fact is that many writers in the past that pondered the building of a space elevator just chalked up the mysterious super-substance to "unobtainium".
That changed in 1991, thanks to Japanese researcher Sumio Iijima, an electron microscopist for the NEC Corporation. He is discoverer of what are now called nanotubes. Additional research has shown that carbon nanotubes posses incredible properties. One of those attributes is having a tensile strength 100 times stronger than steel at one-fifth the weight.
The nanotube research community sees super composites having wide application in automobile manufacturing and other high-tech vehicles to even ski poles and bikes.
Edwards said it appears that the unobtainium material for a space elevator has been found.
Out of the lab
"Carbon nanotubes are essentially a super-material," Edwards said. "They have tensile strengths already measured that are much stronger than anything else that's out there. Their promise is considerable. They are now more than a laboratory curiosity," he added.
This exotic substance can be utilized in creating a composite material that, in turn, is ideal for creating lengths of ribbon. "These actually have the strength, at least theoretically, to produce a space elevator," Edwards explained.
Margaret Roylance, a materials engineer for Foster-Miller, Inc., Waltham, Massachusetts, said the jury is still out on how best to fashion carbon nanotubes for use in a space elevator. "The technology to achieve the target strength on a larger scale is still not with us," she noted.
Roylance said, however, that the movement from lab testing of the material to commercially feasible product is underway. Higher production rate of carbon nanotubes is moving apace too. Nanotubes have "great potential" for the space elevator cable, she said.
"A significant scale up [of carbon nanotube production] is necessary to meet the space elevator quantities. But this is in progress and looks quite promising," Roylance said.
Heavenly heights
As envisioned by HighLift Systems, building the space elevator begins by positioning a special purpose spacecraft in geosynchronous orbit. From that spot the craft reels out a cable fashioned from carbon nanotube composite material.
While this cable is played out, the spacecraft floats outward. Once the end of the cable reaches Earth it is then anchored. Automated climbers then shimmy up and down the long cable, carrying more of the strand material, strengthening and shaping the overall cable in the process.
Any early version of the space elevator would be modest contrasted to follow-on versions. Space elevators can traffic up tons of satellites, dropping them off into low-Earth orbit through geosynchronous orbits. Larger capacity elevators could support a bustling business of shipping tourists into space, even sling payloads across interplanetary distances.
But the project has a purpose…and a bottom line. That is, dramatic reduction in the expense of lifting objects up into space, perhaps down, eventually, to just a few dollars per pound.
No need for klutzy chemical rockets. Forget the bone jarring controlled explosion that is a space shuttle hop to the heavenly heights.
Like a long ocean-going voyage, it's slow going to get to the top floor of the space elevator. It takes 7.5 days to get to geosynchronous orbit and the same amount of time to get back down.
Killer woes
Officials of HighLift Systems suggest that the first space elevator could be literally up and operating toward the close of next decade.
"It's a 15 year effort that started yesterday," said Michael Laine, president and CEO of the company during the second day of the meeting. "We're trying to build something stronger than any thing ever built," he said.
The first space elevator could possibly be constructed at a price tag of between $7 billion to $10 billion, said HighLift Systems staff member, Eric Westling. "If we get away costing less, then we're looking really good," he said.
"It's the best estimate of what it takes…we've tried to nail it down as best we can," said Edwards, a former research scientist with Los Alamos National Laboratory in New Mexico.
Edwards does not shy away from an array of daunting issues that haunt the space elevator plan. "If nobody mentions problems, nobody will come up with solutions," he said.
Lightning, wind, the degrading effects of atomic oxygen on the cable, radiation, wearing down of the ribbon by sulfuric acid droplets drifting in the upper atmosphere - all these and other uncertainties are being dealt with.
Then there's the worry of meteoroid hits, pings from the shooting gallery of space junk, and collisions with satellites. Even the threat of a terrorist attack on a space elevator is being assessed. So too are public health risks of using tiny carbon nanotubes, so ultra-small in size that the effects of ingesting the substance into the lung calls for detailed study.
Research into these problem areas, one by one, is ongoing. No killer problems have been identified to date. Nonetheless, solid engineering of the space elevator is critical to success of the endeavor.
Reasonable future
"The team is good and dedicated. They are covering all the major technical issues, said Robert Cassanova, Director of the NASA Institute for Advanced Concepts in Atlanta, Georgia. "It boils down to having materials available for the filament to go into space. There are going to be challenges. There are going to be surprises. It's going to take a lot of very good, very careful engineering design and development," he told SPACE.com.
Lane of HighLift Systems said "there's a ton of milestones ahead," with step-by-step work on tap that's dedicated to answering technical issues, raise research funds, and broadening support for moving out on the elevator to space.
Furthermore, exposing carbon nanotube samples to simulated space plasma is slated in the near-term. Wear and tear tests on elements of the space elevator climbers are under review. Next year an Earth-tethered high altitude balloon experiment is scheduled to judge the viability of key elevator components.
"A lot of work is yet required prior to construction," Edwards said.
That comment conjures up an observation made in the late 1970s by space visionary and writer, Arthur Clarke. Asked when the space elevator would become real, he responded: "The space elevator will be built about 50 years after everyone stops laughing."
"We're getting our team together. We believe we can have a viable, usable system in the reasonable future," Edwards concluded.
Going up? Space elevator wins support U.S. company builds on Russian idea
This one was more interesting though.
Sounds relatively cheap, as major space programs go. Anybody happen to know what the GPS project cost?
The military implications would be enormous — which probably means they could get the government funding to make it happen.
..Yeh, I'm Otis...but we don't need no elevators in Mayberry.
Chemical rockets are very, very inefficient.
When you run out of tether, drop mass back to Earth and you can reset the counterweight.
So, we need a regular supply of mass at the top of the tether. Fire it off the Moon with a magnetic railgun, again at very low cost (about 15 cents per kg in raw energy - yes, energetically high Earth orbit is much, much closer to the Moon).
Personaly I think the twine will wrap around and around.
John, you are right... and you are wrong.
While the energy accumulated in the object lifted to orbit will be the same, the amount of energy expended per DELIVERED pound will NOT be the same. Since the MODE of lift is not self-contained, it is unnecessary to lift fuel, tanks, guidance, etc. along with payload. Lifting 10,000 lbs to geosynch orbit would no longer require lifting 1,000,000 lbs of vehicle and fuel off the ground and throwing 99% of it away in the process. Nor would great speeds like 25,000 MPH escape velocity be required. Reusable 'cars' with no internal fuel or energy supplies would do the job climbing the cable at 10 - 1000 mph.
Using a "space elevator", electrical power could be supplied to a "car" which would use electric motors and gripping mechanisms to 'climb' the 'tower'. Much of this power could be reclaimed when the "car" descended by using electomagnetic braking to retard the fall down the 'tower'... for greater efficiency, make it a double track system and have a descending car come down while an ascending car is raised to minimize power draw from the grid.
Most designs I have seen would incorporate a "counter weight" extended beyond the geosynch point and use 'centripetal force' to provide stability and offset the effects of added weight of cars and opposite reaction forces imparted by the cars 'climbing' the cable. Several different modes have been suggested for fine tuning this counterbalance as cars are added, climb and descend. Once the materials are created, the rest is merely engineering... and legal entanglements.
Power the system with solar power antenna arrays at the space side geosynch 'anchor' and I bet it could be a net profit center... supplying earthside power TO the grid.
The technology and design exist... the only things really holding back such a construction are economics and the 'unobtainium' material to make the cable (it has to withstand its own weight, the counterbalance force, support the weight of electrical cabling... AND the weight of cars and freight as well as the forces moving them... and withstand the varied environments.
I doubt the carbon tubes described in the article are up to the task... 100 times stronger than steel is probably not strong enough. 1000 times might be.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.