Space Elevator Prototype Climbs MIT Building 422
Jackie O writes "According to an employee blog on the Liftport Group website, their prototype robot for the Space Elevator has just successfully climbed a 260-foot building (in a driving snowstorm, no less) at MIT. Now all they have to get it to do is climb over 60 thousand miles into space, carrying things. Good luck there." Update: 11/17 05:17 GMT by T : Liftport has posted some photos from the ascent, too. Thanks!
When? (Score:5, Insightful)
Umm.. (Score:1, Insightful)
Optimism? (Score:0, Insightful)
Never underestimate a stubborn genius. Besides, its the journey that holds the juice... imagine what they'd accomplish even getting half way there.
Re:When? (Score:3, Insightful)
And the fact that a rope and pully would do the same job faster just occured to me.
Should read 60 miles... (Score:1, Insightful)
Hmmm (Score:0, Insightful)
What's the point exactly? (Score:4, Insightful)
Re:Blog entry (Score:2, Insightful)
It's not all about 'just' having a ribbon that is strong enough - we've got to have climbers that can make the journey as well. This is one of those small steps.
I don't see this as very eventful or important. (Score:5, Insightful)
If I claimed that I can jump to the Moon, you'd look at me like I was crazy, because the laws of physics would be completely in opposition to my claim (for example bones would shatter long before you could exert the force to jump even 50 feet). Now if I showed you that I could jump 3 feet, would that really convince you that I'm making progress towards my claim of jumping to the Moon?
To get back to this space elevator idea, climbing 260 feet is no big deal at all using cables that we have today. It's simple work. However, making a cable that is 30,000+ miles and able to support its own weight plus the weight of the payload is impossible with these cables. They'd need a material that doesn't yet exist.
The real hurdle in this project is not making the robot climb the short conventional cables that are readily available, the real hurdle is getting a hold of cables of unbelievable strength made of a substance that doesn't yet exist.
Re:What's the point exactly? (Score:2, Insightful)
See M. Laine at the Bremerton office and bring a blueprint.
The first automobile wasn't supersonic, either. (Score:4, Insightful)
316,800,000 feet / 29 feet per minute = 20.77 years
And the first automobile didn't break the sound barrier either - though we now have an experimental model that has, and consumer-grade vehicles routinely cruise FAR faster than those early manufacturers considered.
Ditto trains. Ditto planes. Ditto ships.
Also: As you get farther up you can go faster for a given horsepower. Once you cross synchronous orbit (or when you go back down) you GAIN energy from going farther, and the limit (if you don't want to keep it as velocity) is how fast you can store or dump it.
chaos theory? (Score:1, Insightful)
Re:Umm.. (Score:4, Insightful)
Materials (Score:3, Insightful)
Or, slightly more verbosely, we can't build a space elevator because we can't construct a strong enough "ribbon". Carbon nanotubes are theoretically strong enough, but nobody has yet reported a macroscopic piece of material made from them that has the required tensile strength. While there is a lot of nanotube research going on, there's no guarantee that the right materials will be available soon. There's no guarantee that such materials will ever be available.
Don't get me wrong, I sincerely hope that the space elevator can be built. But until I can hold, in my hand, the requisite bit of unobtanium with enough tensile strength, I'll stifle my excitement.
Re:stop laughing - prototype - ... (Score:3, Insightful)
I know everybody's counting on exponential growth of nanotube-strength structures, but right now the longest nanotubes with the required strength are millimeters long. I once heard on Slashdot, "Once you can build a 40,000 millimeter bridge across a stream on campus, then we can start discussing a cable 40,000 kilometers long."
So I'll take that as my starting point. I'll stop laughing when I see that 40 meter horizontal bridge, that's still five orders of magnitude away. Then we can start talking about the remaining six orders of magnitude straight up.
So yeah, I'd believe it could be ten years from that point. How far are we away from that point? Well, I dunno, but I'm guessing that if it's ten years for the remaining six orders of magnitude it's probably the same 10 for the first six. In other words, I'll be laughing for another decade.
And a dollar per pound? I don't think you could ever see that. If my figures are right (.5 kg * 40,000 km * 9.8 m/s/s), that's about 10^11 joules = 30,000 kw-hours = 94 million BTUs. My last electric bill was for $.0045 per kilowatt-hour, or $135. In gasoline that's 755 gallons of gas (at 125K BTUs per gallon), or $1,500 where I live.
(As a check, that's about 1% of the current price.)
Yeah, the fuel is cheaper when you're buying it in bulk, but still, we're talking about two to three orders of magnitude more than a buck a pound. And that's just the energy cost; it doesn't amortize the cable itself, friction losses, and the other costs that always seem to add up. In other words, a buck a pound isn't going to happen without a separate revolution in energy production as well.
Re:What's the point exactly? (Score:1, Insightful)
1) The cars themselves have to be able to clamp onto the ribbon without deforming the structure and easy to get off.Remember you have anchors at both ends, you cant get the car off by just rolling to the end. If the clamp is too loose, the car will fall, if its too tight, you risk destroying the ribbon.
2) Its a moc-up. You look for failers, like getting the safety line caught in the rollers can be a hazzard.
3) It impresses investors. Try selling anything with just an idea on paper and no working demo. Heck, how quickly did Virgin jump onto Scaled Composits after their first transatmospheric flight?
4) To prove that the whole elevator idea is not a pipe dream and is a simple engineering project that could be built today. (Assuming materials are available.)
I would say that #3 has to be the big one. Mayhaps not to an engineer, but considering the amount of funds needed, I'm sure that it will help.
Re:That wouldn't work. (Score:5, Insightful)
Re:stop laughing - prototype - ... (Score:3, Insightful)
If you have a space elevator, then you can start building Solar Power Satellites for pretty cheap. Anchor one to the end of the elevator and beam down the power with a laser to a receptor on your climber. So yeah, you'll pay $135/lb (already > 1 order of magnitude better than current launch prices) for the first SPS and you'll pay a lot less thereafter. Even at your $135/lb estimate, we're talking about putting a grown man in GeoSynch for about $30,000. When you start taking into account life support, you're still talking only a few more times expensive than a transatlantic ticket on the Concorde. Once you've built an SPS to power it, your only (still significant) cost is maintenance.
Of course, you've still got the problem that it's single tracked. I mean how fast is this thing going to climb? 100Km/hr? 200Km/hr? 300Km/hr tops, once out of the atmosphere? So at least 130 hours or 5 days of climbing. If you can send one car a day (five cars on the line at once), that's 10 cars you miss to ship cars back down, best case. If 100km/hr is the top climb rate but you design the cable to have more cars on the line to compensate, then you could lose 30 trips. While you could run a geo synch switchyard so that you can send up multiple cars before you have to clear the line to send them back down, that still wastes a lot of ribbon time. Even assuming 300km/hr travel speed, you need between five and ten days to ship somebody down if there's a medical emergency requiring facilities not available in orbit.
You really want to build a second elevator a few dozen miles away and use it to return the elevator cars back down. Then you can probably get better throughput and a quicker maximum transit time.
That's UPS. You can still use rockets if you want Federal Express next-day but you'll pay through the nose.
Re:Materials (Score:4, Insightful)
Re:Space elevator practicalities (Score:3, Insightful)
I doubt you need to worry too much about resonance. The atmosphere can only apply forces over at most a few kilometers, a very small fraction of the ribbon's 40+Mm length, so you're extremely unlikely to get low node count resonances, especially when you consider the length of the cable and wave propagation time. Just adjusting a bit the speed of the elevator cars might be enough to damp out any resonances, though it might make for a bit of a bumpy ride. Don't forget your Gravol.
I agree with you about ads. This will be a space superhighway, not an information superhighway. There will be real physical products that will make this endeavor pay off. (But I just got off the space elevator and I'm going to Disneyland!)
As for birds, it's not the width that's the issue, it's the thickness. A bird could run into it edge on. Maybe paint the edges red for the first kilometer? Of course if both edges are red, you won't know which edge is pin 1.
Not that promising (Score:3, Insightful)
So, it has a energy-storage and a climbing-mechanism, none of which can climb to space, even with improvements. Instead both components will need to be made fundamentally different.
Most serious designs I've seen use energy from an external source, because if you are carrying your own energy on the climber, then you use most of your power to lift the energy-storage. (sorta like rockets are mostly lifting rocket-fuel) Ideas include powerful lasers shining on the thing from below, being converted to electricity by efficient photocells. (cells tuned to a single frequency like laser can be more efficient than full-spectrum cells) The laser will get weaker as the climber gains heigth, but so will gravity and thus the required energy.
For the actual climbing a non-contact method would be preferable, perhaps something involving magnetism. (essentially a vertical maglev) The trick is to manage that without making the ribbon itself much heavier. (and thus more expensive)
Re:Why do we need this? (Score:2, Insightful)
Re:chaos theory? (Score:1, Insightful)
The atmospheric effects of a nanotube space elevator would most likely be negligible. There might be some changes in local weather patterns, but large changes on any wider area are not really possible.
Re:Sixty THOUSAND miles into space? (Score:4, Insightful)
It's 60 miles to the beginning of space, and approximately 20,000 miles to geosynchronous orbit. The anchor for the space elevator needs to be at 3x geosynchronous orbit or approximately 60,000 miles out. They had that number right, but your comment emphasizes the Herculean nature of the task.
Re:Maybe not a good idea? (Score:2, Insightful)
Economic: A space elevator is a "cheap" way to get a ton of material into space, for which there is only a market for a few pounds.
Wear on the launch vehicle's rollers. Any roller is going to be designed to be softer than the cable proper, so that the tires wear out and not the cable. 60,000km is a long way to go on a set of tires. Too hard and you damage the cable. Too soft and you are riding rim partway up.
Chemistry. Carbon molecules have a high affinity for oxygen, especially in the presence of ionizing radiation. The paint required to properly protect the cable adds millions of tons to the mass of the project. Once the cable does start to corrode, it won't take long for a crack large enough to destroy the cable to appear.
Fire. With a conventional rocket, if something sparks out and a fire starts you only destroy the rocket. With an elevator, any fire that breaks out will damage the cable. Even if the cable itself does not burn, it will be exposed to intense heat which will alter the chemical bonds of the carbon molecules, turning your nice high-strength material to graphite.
Fatigue. Since we are operating on the edge of the material's tensile strength, almost any additional load we put on it is going to cause fatigue. And it you have never seen carbon thread fail, it is a nifty sight. All you need to do is score it in tension.
What you say? These are not impossibilities? True, they aren't to construction. But they are to operation. And if the thing ain't going to be operating long, why build it in the first place?