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Going Up? 567

Posted by michael
from the keep-arms-inside-the-car dept.
jmiyaku writes "The National Post is reporting that NASA has given a Seattle company a $570,000 grant to continue its investigation into constructing a space elevator. Coupled with some production-grade technology from a Japanese car company (carbon nanotube composites), this elevator could be a reality within 15 years..." The Highlift website has some more information.
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Going Up?

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  • Environmental impact (Score:2, Interesting)

    by lonely (32990) on Tuesday August 13, 2002 @09:31AM (#4060908)

    One thing that worries me about orbital towers is the impact on the weather and the local environment. Something that big must affect local rain patters in some way...


    Also what about the risk of it falling down? An orbital tower will wrap about the earth more than once if it falls. The description in Red Mars was particularly though provoking.

  • fifteen years? (Score:3, Interesting)

    by s20451 (410424) on Tuesday August 13, 2002 @09:34AM (#4060926) Journal
    According to this BBC article [bbc.co.uk] covering the same story, a fifty year timeline is more likely.
  • by pgpckt (312866) on Tuesday August 13, 2002 @09:35AM (#4060934) Homepage Journal

    Well, Yucca Mountain leaves a whole lot to be desired. I suppose the best thing to do would be to shoot the radioactive waste into the sun. You could lanuch self-guiding ships full of the stuff straight into the sun...the sun sure wouldn't care. But how do you get the stuff in space safely?

    Perhaps this space elevator? I think it should be safe(r). Use the elevator to take the radioactive waste top the space station, then build a craft to launch the waste into the sun. No more radioactive waste problem! And it would probably be cheaper than the current proposed solution, plus it would be really great for the space program and scientific development. Is this a good idea?
  • Elevator vs. Launch (Score:3, Interesting)

    by chaidawg (170956) on Tuesday August 13, 2002 @09:37AM (#4060943)
    Does it seem to anyone else that this is less like a space elevator and more of a really large launch facility? Clark envisioned a true elevator, with cars coming up and down. With this proposal explained as it is, you still have to worry about craft that can deal with reentry and landing, instead of a simple elevator ride down.
  • short circuit (Score:2, Interesting)

    by the_Bionic_lemming (446569) on Tuesday August 13, 2002 @09:45AM (#4061006)
    I seem to remember someone commenting that a space elevator would act like a bridge between the ionosphere and the earth - Making a giant "short circuit" - does anyone have a link to the article that was posted?
  • Re:Easy target? (Score:2, Interesting)

    by csimicah (592121) on Tuesday August 13, 2002 @09:46AM (#4061013)
    Based on what the article said, the "crash" would be somewhat like a sheet of newspaper falling to the ground. Not too worrisome unless a large piece landed on your windshield while you were driving, perhaps blinding you.
  • by Christopher Thomas (11717) on Tuesday August 13, 2002 @09:51AM (#4061043)
    Also what about the risk of it falling down? An orbital tower will wrap about the earth more than once if it falls. The description in Red Mars was particularly though provoking.

    I used to think that this would make space elevators impractically dangerous. However, this turns out not to be the case.

    The energy gained by the falling cable will be at most its gravitational potential energy, which is within a factor of two of conventional high explosives (per unit weight). Pick a maximum yield on impact, and you have a maximum cable weight. Use a thin enough cable to meet this weight restriction, and you have an adequately disaster-proof elevator (it'll make a mess, but not wreck the world's climate).

    My own calculations with a 10 kT yield/cable weight came up with something that could reasonably be used for space travel and would pay for itself if you could keep the cargo moving.

    The biggest problem is figuring out how to move cargo fast enough. I'd be leery of having induction motors mess with the cable itself, and if its a nanotube bundle they won't conduct in the right direction anyways. Winches are much too slow. Sheathing the cable with metal would only be practical for a very thin layer, which ends up being too thin to support the required currents without boiling off (I think). It's an interesting design problem.
  • by barawn (25691) on Tuesday August 13, 2002 @09:51AM (#4061047) Homepage
    Yah, but reentry's easy! It's simply an issue of falling into a gravity well, rather than climbing out of it. You've got all that atmosphere to brake you down!

    Think about it, really: the Shuttle is really a very advanced glider on its downward trip - that's all you really need. I imagine you could probably send a few reentry gliders or capsules up the space elevator if you need to.

    Anyway, getting up is the important part. We've pretty much got the "getting down" part pretty down pat. Getting up's much harder. Once it's in place, you could start shuttling things upward to build a space station at the top, and then work on downward-bound cars.

    First step is to get off this rock. :)
  • Uhm... (Score:1, Interesting)

    by Dark Lord Seth (584963) on Tuesday August 13, 2002 @10:04AM (#4061131) Journal

    Is it in any existing flight paths?
    One of the nice things about our anchor site is that it is in the middle of nowhere, approximately 400 miles from shipping or plane routes.

    So how are they going to get stuff over there? Drive it through the middle of nowhere on a truck? I'm pretty sure equatorial conditions (high temp, high humidity) aren't the best thing that could happen to any satelite or other object bound for space. Besides, wouldn't a nice 20 Billion USD worth satelite be a nice target to attack? Once simple ambush with a 100 USD rocket launcher and poof goes 20 billion bucks. Are they going to provide every transport military cover all the way to the anchor site? Same thing applies to shipping and I don't think airplanes would be allowed near the anchor site... How do they intend to secure it all?

    Are they going to set up massive defences at the anchor site? SAM batteries against air attacks? Will they station ground forces at the anchor station? If so, who will provide these forces? The US goverment? NASA? ESA? Or an independent body?

    Also, suppose it all does work out after all, how are we going to deal with things in space? Is everybody going to do his thing or are we going to learn from history and immediatly develop some standards for cargo storage up there like container size, weight and capabilities?

  • I don't buy it (Score:3, Interesting)

    by khendron (225184) on Tuesday August 13, 2002 @10:52AM (#4061468) Homepage
    I LOVE the idea of a space elevator. Reading "Fountain's of Paradise" is what got me into the engineering field in the first place.

    However, I still do not buy the argument that getting into space will cost virtually nothing once a space elevator is built. Sure, in pure energy, the costs are low. But what about the entire support infrastructure?

    Right not it would cost me about $100 to take the train from Ottawa to Toronto, a 4 hour trip. With a space elevator we are talking about a trip 100 times farther and 50 times longer. Applying some hand waving math, we would be looking at $10K to $20K for a trip up the elevator. Maintenance costs for the elevator are going to be a *lot* more than those for a strip of train track, so it would not be unreasonable to multiple this estimate by a factor of 10.

    Yes, that is a lot less than $1,000,000 but also far from virtually nothing.
  • by ldopa1 (465624) on Tuesday August 13, 2002 @11:33AM (#4061768) Homepage Journal
    The space elevator has been featured in a lot of books, most recently David Gerrold's [amazon.com] "Jumping off the Planet" [amazon.com].

    This is a great idea, but it has one big problem. It isn't energy - The idea of generating energy by dangling something into the atmosphere from space has been explored and proven that it will work [nasa.gov].

    The problem is this: With every gram of matter you chuck into space (or even lift from the surface), the rotation of the Earth slows in direct proportion to the cargo's mass relative to the mass of the Earth. In other words, every time we throw something in to space,the Earth will slow down just a bit, no matter how small the load. Proving yet again that there's no such thing as a free lunch.

    Fine, you say. It'll take a TREMENDOUS amount of mass to be lifted into space to stop the rotation of the Earth. I completely agree. However, if the Earth slows .000001%, (about 9 hundredths of a second, enough to win/lose a car race) then the days will get measurably longer unless we bring an equal amount of mass down.

    Just to sate your curiosity, the earth weighs about 5.98 X 10^24 kilograms (or, 5,980,000,000,000,000,000,000 tons, metric, roughly speaking. Source. [enchantedlearning.com]). That said, it would just take us lifting 59,800,000,000,000 trillion tons into space to affect the aforementioned change. Again, a tremendous amount, right?

    Consider this: New York city alone produces 13,000 tons of residential waste a DAY, and they've run out of places to put it (Again, Source [fathom.com]). That's 4.7 Million tons a year. And they're currently paying PA to dump is for them. There are other cities with the same problem. Exactly how long do you think it will take for someone to decide to move the waste even farther away? Like Space? And that's just residential.

    That's only one example. Let's add Yucca Mountain's 77,000 Metric tons of waste and 100,000,000 gallons of high level radioactive waste water (Call Claire at the Yucca Mountain Project (dept. of civilian radioactive waste mgmt. for more info -Link [ymp.gov] or 1-(800) 225-6972). Okay, lets add the "extra" garbage of all of the other states, countries, provinces etc who have run out of places to put their waste. It adds up REALLY quickly.

    And that's not including the actual mass of the elevator itself, including it's anchor.

    Mind you, I still think we should build it, I just don't think we should use it as a tool to get rid of our problems that's we're too stupid to fix, but smart enough to move out of sight.
  • by Guppy06 (410832) on Tuesday August 13, 2002 @11:39AM (#4061813)
    Everytime this has come up on Slashdot I've posted how foolish an idea this is (especially after 9/11), but nobody seems to listen to me.

    1.) If it falls, bad things will happen. As I type this there are probably at least 10 posts to this article moderated way up that point out how "safe" this thing would be coming down. Every single one has two flaws:
    • It treats the beanstalk as a series of point particles as opposed to one connected strand
    • It neglects the fact that gravity is stronger towards the bottom of the beanstalk than the top
    What does this mean? It means that, as the bottom comes down, the top will be yanked down faster than it would be by gravity alone. Want an analogy? Extend a tape measure to its full length. Let go and let it wind itself back up. Try not to cut your hand. And you want to build this on a large scale?

    2.) People will now respond to this post saying that it won't fall down because the top will be in orbit. In order to keep the bottom of the beanstalk from whipping around the circumference of the earth every 90 minutes, you must be talking about putting the center of gravity into geostationary orbit. I've done the math. If you want to put the center of gravity of a cable with uniform density into geostationary orbit, it puts the top of your beanstalk well beyond lunar orbit (inverse square againt). And when the moon snaps off that top guess what happens.

    To sum up: Not on my planet!
  • Re:Think About It (Score:3, Interesting)

    by dbrutus (71639) on Tuesday August 13, 2002 @11:40AM (#4061823) Homepage
    Actually, I think it would be much more likely that loaded return trips would be made. Why haul around all that expensive re-entry weight when you have the perfect mechanism to come back down on the elevator itself. It's elegant, it's cheaper, and it's likely to be much less riskier than re-entry which can and has gone wrong in the past.
  • by ldopa1 (465624) on Tuesday August 13, 2002 @12:02PM (#4061972) Homepage Journal
    "When you throw that bag of garbage straight up, directly away from the center of the earth, it's going to exert a force on you in return directly toward the center of the earth. This won't affect Earth's rotation at all (no torque)."

    As long as you throw it, not lift it, which is the principle behind the space elevator. That also true as long as you don't let go (which is why a figure skater goes faster when she/he brings her arms back in). To make the space elevator concept work, you'd have to bring down an = amount of trash/rock/whatever to make the lift work economically. Nobody is going to trade trash for rock. With trash, we'd be letting go. Goodbye rotational energy.

    The 12 quintillion figure is for NY's trash alone. Like I said, let's add everyone elses trash, plus payloads, etc and it adds up quickly. And again, you're talking about stopping the earth entirely, not slowing it down for the .09 seconds I was talking about.

    Did you actually think that people were concerned about global warming before they started chucking billions of tons of pollutants into the atmosphere, some 50 years ago?
  • by Guppy06 (410832) on Tuesday August 13, 2002 @12:11PM (#4062055)
    "The energy gained by the falling cable will be at most its gravitational potential energy,"

    Isn't that cute... but it's WRONG!

    The top of the cable has something much more powerful acting on it than gravity alone: the bottom of the cable. The top will be moving just as fast as the bottom, accellerating downward just as much as the bottom. So you have a miles-high structure coming towards the earth at a relatively steady 9.8 m/s/s. This is far worse than mere gravity alone.
  • by patiwat (126496) on Tuesday August 13, 2002 @12:20PM (#4062123)
    Although Highlift devotes considerable technical detail into estimating the operating cost of the space elevator, nowhere do I find any detai of how he gets his $7-10 billion cost of initial investment. This of course, is the whole problem. It doesn't matter if the elevator works on solar power and requires no infrastructure or maintenance - the key barrier to its construction will be the magnitude of investment. This penny-wise and dollar-foolish approach of engineering is very frustrating for someone like me who really wants to see a working space elevator in my lifetime.

    To put things into perspective, Europe's Ariane 5 launch vehicle cost nearly $10B in development over a decade. If his $10B estimate is correct, then the Highlift space elevator isn't a project that any single country (besides the US) can undertake. Another perspective: Boeing's Sea Launch projeect, which involved a platform in the equatorial Pacific, a fueling and operations ship, and considerable infrastructure, cost less than $1B (considerably cheaper than Ariane 5 because it didn't involve a new launch vehicle).

    I want to see the elevator happen, I really do. But to see it happen, these guys have got to get out of their "this is really cool on paper" engineering mode and get into a hard nosed "how are we going to make money out of this and make this really happen" mode.
  • by Enigma2175 (179646) on Tuesday August 13, 2002 @02:32PM (#4063260) Homepage Journal
    the power source is a laser shot from the platform, aimed at collectors on the bottom of the car. There, it's converted to electricity, and drives motors with wheels on the cable.

    That is an idiotic design. If you use conventional conductors in the cable, then we can also use the cable as a big powerline from space. We can have a large solar array in space and get the power back to earth via the elevator cable. Proposals in the past for powering earth from space have suggested using microwave transmission, the elevator cable would be a much safer alternative. In addition, if you have a powered cable you can use energy return brakes on the climber, so when it comes back down the motors function as generators, returning power to the system. With the aforementioned solar array, the elevator can be an energy producer rather than an energy consumer. Not to mention the fact that it is terribly inefficient to convert the electricity to light (laser) then back to electricity on the climber. It would be much more efficient to run power in the cable itself.

  • by mesocyclone (80188) on Tuesday August 13, 2002 @03:33PM (#4063835) Homepage Journal
    Sigh... it's the old "we are running out of space for garbage" myth again.

    Just a nit in this discussion, but there is not any problem at all in terms of space for waste. I forget the figures, but basically you could put all the waste generated in the US for a century into a spot something like 10mi x 10mi. I live in the middle of a desert where the nearest large city outside of the one I live in (Phoenix) is 120 miles away! LOTS of room for rubbish. For that matter, we have huge retired open pit copper mines around here. We can use the rubbish to restore the scenery (although open pit mines are pretty cool to look at, and the Arizona town of Bisbee is built in one).

    Other than that, I'm glad at least someone did the math so I didn't have to.

  • by barawn (25691) on Tuesday August 13, 2002 @05:03PM (#4064657) Homepage
    Did you read the FAQ? Honestly, most of the objections are dealt with in there. After that point, read the NIAC paper, there are actual numbers in there to alleviate any concerns.

    The ribbon is 1 cm width from 0-10km, because that's where the atmosphere is important (winds) and it reduces wind drag. Everything higher than that is much thicker. It isn't important being thin at that point because it doesn't need to withstand impacts (the atmosphere shields it) and you don't need to worry about it burning up on reentry (as it's only 10 km).

    As for the mass issue, look, this is trivial, and it's been done. Check out the FAQ, check out the proposal. It's 100,000 km long, and the top counterweight is only about 30,000 kg. Carbon nanotubes are reaaaallly light and strong. They rule.

    As for the windspeed issue, at height, the air density is less as well, therefore the actual amount of force they place on the ribbon will be minimal.

    Regarding your numbers, you have to remember that everyone's planning on tapering this thing: it doesn't have a constant density. Without a counterweight, a tapered ribbon would need 144,000 km to work - not the distance to the moon.They're planning on putting up a counterweight which is of order the size of the ribbon, bringing that down to 91,000 km. The density profile of the ribbon they want to use is pretty complicated: it'd take a bit of work to calculate it out, but go ahead: you'll find that they're right.

Faith may be defined briefly as an illogical belief in the occurence of the improbable. - H. L. Mencken

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