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Skyhook Robot Passes 1000 Foot Mark
JhohannaVH writes "MSNBC.com is running a story about yesterday's successful test of the Space Elevator!! Maybe it will become a reality after all." From the article: "This week's testing involved a 12-foot (4-meter) diameter balloon. Safety lines held by team members kept the balloon from floating away. The ribbon dangling from the balloon was made of composite fiberglass, with the robot lifter running up and down the tether ... During the day, the highest altitude reached by the balloon/ribbon/robot combination was 1,000 feet (305 meters). 'It gives us complete confidence that the mile goal is well within reach,' Laine said. Laine said that the Federal Aviation Administration has been very supportive and helpful in orchestrating their test flights. "
117,407,136 to go
1000 feet? Nice, a "space elevator" (circa 2005) almost two-thirds the way to the top of the Sears Tower (circa 1973).
This makes my launch of my Estes Andromeda a successful test of intergalactic travel.
Centripetal acceleration
It's kinda annoying to see every space elevator article attract a swag of ill-informed comments that get modded as insightful. Please go read question 4 of the FAQ.
the ribbon recovers for the same reason that it stays up in the first place. Centripetal acceleration is acting on the counterweight pulling it outward, and the lost angular momentum is replaced very quickly (essentially as fast as it is lost). The ribbon will never lose enough angular momentum to even deflect a single degree, let alone fall. The extra angular momentum is stolen from the Earth's rotation; we will have to worry about this effect slowing down the Earth and making the day longer if we ever decide to ship Australia into space.
How we know is more important than what we know.
Thrusting from the bottom is expensive. It requires extra weight to be carried as fuel (or a Big Friggin' Laser). You could instead adjust the counterweight position at the top so that it begins to move away from the Earth by itself. There is some fine-balancing involved, naturally.
"To an extent, Mr. Swartz is correct: As payloads are moved up and down the elevator, the ribbon is distorted, and it would move the counterweight. Nevertheless, looking at the travel time and the relative masses of the climbers, the ribbon, and the counterweight, we find that the distortion is extremely small and would be quickly corrected because of the forces that are felt by the ribbon and the counterweight. The rotating Earth supplies the needed angular momentum through the anchor and the ribbon. The rotation also provides all the restoring forces required--no rockets are needed to move the counterweight. The best way to look at this may be to think of the space elevator as a pendulum. If you pull the ribbon from its normal position--rising straight up from Earth--the forces will always pull it back."
--Brad Edwards
I have been following the progress of research concerning space-elevator for some time now. The LiftPort Group of companies working towards a space-elevator are making a great deal of progress. See here and here for more LiftPort specific information. Slashdot reported on the faa approval of their high altitude tests several days ago -- refer to that thread for some interesting discussion. Check here and here here for several reports concerning the viability of the elevator -- be sure to check the NIAC pdf. Also, Blaise Gassend has a great collection of information. Finally, though carbon nanotubes are still in their infancy (its been a little over 12 years since they were discovered) - their theoretical tensile strengths are perfect for use in the construction of a space elevator tether. This recent development spells a rosy future, and many innovations yet to come.
...Stairway To Heaven was looping on the Muzak. Frickin' annoying!
Yes, why not? In theory you just need to go a short distance past Geosynchronous orbit, which is about half that, but only if you have a very heavy counterweight.
By increasing the distance they reduce the counterweight mass.
http://michaelsmith.id.au
"This lifter is much smarter than our previous versions. It's our 18th version..."
...
...?
Version 1 Logic: Go up.
Version 18 Logic: Go up.
aoeu
I've been editing the video from the 1,000-foot robot test. Since I've been busy lately with grant writing etc., I wasn't involved in activities like making the ribbon. So it wasn't until I was watching the video that I noticed the sentence written in block letters on the 2-inch wide ribbon (which alternates color in 50-foot strips of bright yellow and fluorescent orange) near the top:
ATTENTION PILOT: IF YOU CAN READ THIS, YOU'RE TOTALLY SCREWED.
Our sense of humor (or at least Nyein's) may not (or it may) be visible from far away, but it's there.
Comment forecast: Bits of genius surrounded by a sea of mediocrity.
Look ma, I made it across the pool in an inner tube. I'm going to try the Pacific next!
As I understand it, most of the fuel that you expend in a standard launch is there to make sure that the rest of the fuel can make it high enough to finally push the payload into orbit.
With a space elevator, you're no longer required to accelerate several dozens of tons (>90% of which is just fuel) up to 7 miles/second just to get a 500lb satellite in orbit. The cost savings would be huge.
Now granted, you'll still have to haul some fuel up the elevator, but it's like the difference between climbing the stairs to reach the top of the Empire State Building vs. jumping to the top from street level in one bound.
As I understand it we're talking about a carbon fiber composite ribbon. You certainly couldn't run an entire circuit through it. If it were pure carbon fiber you could probably run half the circuit through it, but the polymers holding the fibers together would probably make this impractical.
The weight and resistance of a wire are proportional to it's length. The resistance of a wire is inversely proportional to its weight.
You understand this thing is going to be, perhaps 30,000 miles long, right? That's a 60,000 mile circuit when the lifting vehicle is at the far end (as for a moon or Mars mission).
Weight and line loss would be two problems.
-Peter