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I know this is off-topic, forgive me. But it seems like a good time to bring this up.

If we are to spend hundreds of millions, maybe billions, of dollars in a multi-decade endeavor in name of science and profit, why not build a space elevator. The project isn't ready to begin yet, since we currently can't produce carbon nanotubes in sufficient quantity or quality, but with the research might of NASA and the heightened awareness of the goal we could create get a head start at the next space race. After which, the cost for all other space initiatives would be greatly reduced. The long term economic benefits of building the first space elevator could possibly outweigh the initial research and construction costs.

At the upcoming conference on the topic of space elevators, scientists will discuss the logistical, engineering, and political issues.

I know this is off-topic, forgive me. But it seems like a good time to bring this up.

If we are to spend hundreds of millions, maybe billions, of dollars in a multi-decade endeavor in name of science and profit, why not build a space elevator. The project isn't ready to begin yet, since we currently can't produce carbon nanotubes in sufficient quantity or quality, but with the research might of NASA and the heightened awareness of the goal we could create get a head start at the next space race. After which, the cost for all other space initiatives would be greatly reduced. The long term economic benefits of building the first space elevator could possibly outweigh the initial research and construction costs.

At the upcoming conference on the topic of space elevators, scientists will discuss the logistical, engineering, and political issues.

I know this is off-topic, forgive me. But it seems like a good time to bring this up.

If we are to spend hundreds of millions, maybe billions, of dollars in a multi-decade endeavor in name of science and profit, why not build a space elevator. The project isn't ready to begin yet, since we currently can't produce carbon nanotubes in sufficient quantity or quality, but with the research might of NASA and the heightened awareness of the goal we could create get a head start at the next space race. After which, the cost for all other space initiatives would be greatly reduced. The long term economic benefits of building the first space elevator could possibly outweigh the initial research and construction costs.

At the upcoming conference on the topic of space elevators, scientists will discuss the logistical, engineering, and political issues.

if we're really serious, we need to talk about building up a permanent presence in space. That means not just sending somebody to another planet to plant a flag. That means building a permanent infrastructure that will support continued expansion.

Amen! And since it hasn't been mentioned on /. for at least 3 days: the best way to do this is to build the space elevator, which may actually be easier, faster, and cheaper to develop than a rocket-based reliable high-capacity, high-orbit vehicle.

If they would just fund research on the Space Elevator They could have both the Moon and Mars!

You can bet that national governments not on friendly terms with the first owner will immediately band together to invest in their own elevator.

Maybe so - but do you currently see the US (or anybody else for that matter) rush to invest into recuperating the capability to build its own consumer electronics? If China ever were to pull the plug on that... but it's much cheaper to play nice with the Chinese than to try to compete on uneven ground (higher labor costs, etc.)

With the first space elevator up, you'll have the same situation: yes you can desperately try to play catch-up - or you can play nice with the elevator company and try to entice them to install one on your premises. Which is more likely, especially if the first space elevator is owned by an ideologically agnostic company rather than a government?

Playing catch-up is also going to be very, very hard. According to this schedule, by the time you've finally built your own renegade elevator, everybody who's played nice with the elevator company is already off colonizing Mars and mining the asteroid belt. It'll be like being a few years late for the gold rush, and all the good claims are already taken.

The carnage that such an event would wreak absolutely beggars the imagination.

The carnage would be non-existent. The proposed ribbon has the approximate shape, weight and composition of carbon paper (remember those?). All but the lowest few km would burn up in the atmosphere. The rest might land on your head with all the force of a fluttering sheet of newspaper.

Read Kim Stanley Robinson's Red Mars. Skip to the last few chapters if you just want the space elevator stuff.

The truth doesn't always make good fiction, and good fiction doesn't always tell the truth.

Check the bottom of this page. Of particular note:

In any analysis of the environmental impact the possibility of a falling cable and the damage it will cause must be compared to the alternative which is continued use of rockets. During rocket use both pollutants from the burning fuel and from the re-entry of the spent rockets must be considered. For example, each Titan IVB has a dry mass of 65,000 kg, much of which ends up re-entering and burning up in Earth's atmosphere. The Titan IVB also burns roughly 500,000 kg of propellant. Our proposed 20 ton capacity cable has a mass of 750,000 kg. A strictly mass comparison is far from the proper comparison to make but it gives a rough idea of scales of the environmental impacts we need to compare.

Space Elevator - Everything you needed to know

There ya go.

R.A.S.

I haven't seen any good ideas for something that will cheaply [make it above LEO].

Like this.

Here's Chapter 5 of Bradley Edwards' phase-I, NASA-funded study, which details such a low-initial-payload deployment strategy.

Actually, a SE makes a significantly better, safer and cheaper inter-solar-system-transportaion-system than dirty bombs. It's not just a tool to escape orbit - it can take us to other planets. That's what's so genious about the idea.

There are two reasons for making it 91000km long when all you technically need is 35000km.

One: because you need a very large and unfeasible mass at the top if you want to balance 35000km of cable hanging below GEO with a weight located, say, 1 meter above it. You need a significantly smaller weight at the top if you want to balance it at 91000km.

Two: (which brings us back to our point of discussion) If you go as far as 91000km, you can slingshot payloads as far as jupiter and its moons. If you build even higher, at 140000km you can get as far as pluto.

Of course, the first thing you'd want to send to your destination is a pre-fabricated and spooled SE to deploy there, so you can send stuff back...

The extra angular momentum is stolen from the Earth's rotation.

Unless they plan on catching everything they launch again, then we will slowly be slowing the earth down. (Things traveling up and down only have a net zero momentum balance; the issue is launching spacecraft) This will, over time, have way more adverse effects on the planet's climate than all the gasoline-powered cars, forest burning, and nuclear engines combined. I could care less about stuff falling, but I do care about longer days totally wacking out the distribution of temperatures across the planet!

You really should read up. Deploying a fully-rolled-up SE from up above is significantly easier than from down below.

The first SE'll be built by deploying a minimal strand from above, then sending up climbers that will thicken the ribbon, eventually reaching the desired strength. sending a fully-rolled-up SE using rockets is not feasible.

The second SE is a whole different matter. In a nutshell, you construct the second elevator completely on earth, spool it, send it up using the first elevator, and unspool it downwards.

Same goes for mars and moon cables. You'll be unspooling them from the top, hence they will pose significantly less problems than the first earth cable. If you look at the schedule in the NIAC stage I document, you'll see the mars cable design, delivery and installation was already seriously considered.

I hate when I see this arguement.

Look at some of the more recent space elevator designs.

Basically, the elevator would be made out of a ribbon so light and with such a surface area that it would fall to the earth like a peice of paper. At least that section of the ribbon that doesnt burn up while entering the atmosphere.

A space elevator isnt like the ones you read about in Kim Stanley Robinsons Mars trilogy.

I still think the Space Elevator will be the ticket for inexpensive space launches.

Well, carbon nanotubes do exist, just not in sufficient quantity or length yet.

elevators have limited life, tend to be cut by micrometeorites and space junk and are going to be more expensive than rockets

Space junk isn't such a huge problem if you design with redundancy; what are the odds of all, say, 3 ribbons being severed at the same time? And only the first elevator would cost an arm and a leg.

--

Climbers won't carry fuel. They'll run on electric motors with power beamed to them from one or more (probbably more) ground stations.

There's two existing technologies to do this - Microwave and Laser. MW gives you 0.5% power up top of what you spent beaming from the bottom. Laser gives you a whopping 2%. That's more than enough to get 20 tons (and later on even a Kiloton on the bigger 10^6 cables) 35 thousand klicks up. No additional breakthroughs needed on this end.

As another poster has pointed out, you are arguing on out-dated information. Let's look at each point in turn.

Even if they could make carbon nanotube strands longer than 10 microns

Individual CNTs have been manufactured up to lengths of several centimeters at least. This article is from May of last year, and progress has been made since then. This is not thousands of kilometers, of course, but it does not need to be, since we're going to be using CNT composite materials rather than pure CNTs.

and even if they could braid them in a fashion where they wouldn't slip

We have been able to manufacture CNT composite materials on the order of meters in length with strengths on the order of several GPa's now for a couple of years. Currently, steady progress is being made to increase the strength of the composites to the required ~100 GPa.

they'd still have to launch a few thousand tons worth of stuff into geosynch orbit

Try about 100 metric tons placed in LEO. (Here's a reference for an older deployment strategy that comes in at 122,000kg.) Hubble weighs 11. Mir was more...

And then they'd have to figure out how to avoid getting the tether cut by space debris

This is the hardest problem, but not insurmountable even within a couple of decades. The ribbon will be made very resilient to micrometeorite damage. (Not saying it won't take damage... just that it will continue to work fine in spite of some damage.) For larger debris, it becomes considerably less likely to collide with the ribbon, but active avoidance will be used to move the ribbon out of the path of larger pieces of junk. Also note that once one ribbon is up, the cost of raising a second one lowers dramatically. The first order of business for SE1 will be to raise the components for SE2...

There is some serious research going on here, and it's looking very encouraging. See LiftWatch.org for regular news, links to research and companies, discussion forums, images, etc.

1. China is laying down lots of money on its carbon nanotube research - they were mentioned as the 2nd most serious research after CNI.

2. They're beefing up their space program. Collecting the knowhow. Launching their own vehicles. Tackling the being-in-space problems on their own.

3. A little prophecy from the Space Elevator's Phase I NIAC paper:

"Let's consider two roughly equal entities (governments, private enterprise etc.). At year zero, entity one begins building a space elevator behind closed doors. The second is looking at building a space elevator and thinks it is important but has not begun building it yet. At year five the news gets out that the first entity is building the space elevator. The second now jumps into its program and starts building. At year ten the first entity has its first elevator operating and the second entity is 18 months from launch of its initial spacecraft. At year fifteen the first entity has six cables up including two 106 kg cables, has a manned station at geosynchronous, has recouped much of the construction cost through selling two cables and through hundreds of launches on its eight cables, and is beginning construction of a Mars cable. The second entity has up its first cable. Note that two additional entities also have cables now because of entity one's sales. At year twenty, entity one is making billions from the tens of cables it has produced, has a manned station on Mars, has a hotel at Geo station which now has a permanent population of over one hundred. Entities two, three, four, five,E each own a handful of cables and are trying to compete with entity one."

Is anyone adding this up?

Here's some ideas for future slashdot headlines:
2004: NASA announces new-and-improved winged-spacetruck candidate.
2009: NASA launches first new winged spacetruck
2015: NASA announces last shuttle of their new shuttle fleet has been delivered.
2015: NASA disassembles shuttle, sends it to space in pieces using chinese elevators to save up on launch costs.

We can all safely assume that one sixth the population of our planet would very much like it to happen _just like that_.
I'd be amused.

for current info on the space elevator click here

While the space elevator visionaries gathered in Santa Fe I feel it falls to me to point out a glaring hypocricy in the way that that conference was organised.

Despite the cost saving benifits of the elevator approach to accessing space, they are still advocating the ongoing use of shuttles as can be seen at the bottom of their about page.

There are several things to remember here:

1) The cable, like everything else, is not built to last forever. They were shooting for a 20-year operating lifetime.

2) Once the first cable is built, all the other ones are essentially free - probably on the order of multiple MILLION, rather than multiple billion. That's the improvement we're talking about in terms of launch costs.

3) Near the end of the elevator's lifetime (if not far before!), inevitably several new cables will be lofted to replace it.

OK, so losing the cable is not that big deal, but you may be quite skeptical that you could simply "replace it" if it broke, since from meteorites or other random stuff, you wouldn't have any warning. This is true - but again, once the first elevator's up, everything else is free. Most likely what would happen is that the first thing done would be to loft up a large amount of "spare cable" that in case of a break, the elevator could simply spool more cable down to keep itself in geosynchronous orbit.

Simple answer is that they have thought about this stuff, and meteor damage can be mitigated by making the elevator MUCH wider in the area where space debris is common (so it could survive more hits). Read here on meteor mitigation strategies.

Oh, and random point:
meteoroid: rocky object in space
meteor: rocky object burning up in the atmosphere
meteorite: rocky object from space that landed on Earth.

What you're concerned with is meteor damage, not meteorite damage.

...we can estimate the total weight of the cable at 18,311 x 380,800,000kg = 6.97 x 10^12. Seven gigatons...

Except that the GGB is make of steel and concrete, and the space elevator ribbon would be made out of a nanotube/epoxy material. Which, according to ISR, would weigh only about 7.5 kg per km.

If the space elevator is 36,000km - which is kinda short if I'm not mistaken, so let's be conservative and say it's 100,000km - would weigh only 750,000 kg... (about 850 emperial tons).

Following your math: 750000 x 0.5 x 50 x 50 = 937,500,000 Joules.

So you're only off by a factor of 4.5 million.

And not only is the TOTAL energy about 0.0000002 times what you thought it was, but such a relatively light (7.5 grams per meter! That's practically tissue paper...) and FLAT, THIN ribbon would have horrible aerodynamics and dissipate much of it's energy in churning the air. I'd say a conservative terminal velocity for this stuff would be no more than 5 m/s. So now it's kinetic energy drops by another factor of 100!

Here's an experiment, with Halloween not too far away... throw a roll of toilet paper so that it unwinds and watch how fast the ribbon of paper falls even with a heavy weight (remaining roll) on one end of it. Now imagine something that has about the same density but is at least five or six times wider (not thicker)...

Given that, whatever was out in space (no air resistance) will probably reach a speed fast enough to burn up, but the majority of it will probably make it to the ground. And when it does, I think the damage would be pretty minimal... ...you don't work for NASA, do you?
=Smidge=

Say the elevator is 1 kg / m

Disclaimer: I'm an undergrad physics student with a headache.

You are correct, however, the current proposals do not envision using a single nanotube, or even a nanotube rope. Rather, they intend to use a nonetube composite material, hence the 1m x 0.3m dimensions of the elevator "cable." The site formerly known as Highlift Systems is apparantly the ones behind the proposal that's being discussed, and their site has some interesting info on it. They describe the composite material as "..be[ing] composed of individual fibers 10 microns in diameter lying side-by-side. The fibers will be interconnected by tape sandwiches spaced every 10 cm along the length of the ribbon." Amusingly, they expect Japanese car manufacturers to invent the materials for them in the very near future.

The Institute for Scientific Research site has a bunch of good information about the space elevator including the initial report by NASA Institute for Advanced Concepts (NIAC).

The Institute for Scientific Research site has a bunch of good information about the space elevator including the initial report by NASA Institute for Advanced Concepts (NIAC).

The debris would resemble long hair and would probably be broken up in interactions with animals, plants, wind, fish and waves. In fiber form it would be much too large to inhale and would probably work its way through a digestive system unaffected. The only debris we have any concern about is if it were reduced to nanotube size. This we don't understand yet, so we will study this to see if there is a problem and then probably also design the ribbon to remain in larger pieces if it re-enters.

http://isr.us/spaceelevatorconference/

God Damnit... because of people like you Clarke once said "the elevator will be built 50 years after people stop laughing".

Would you please document yourself, make the appropriate research, concentrate for 2 seconds on the topic at hand before you open your hole and spill out the first fearful thought that comes to your mind?

- It would be built in the middle of the ocean on a floating platform
- If it broke, most of the 100,000Km would NOT fall to earth (junior high physics can tell you that), and most of the piece that would, would burn in reentry
- What remains would be much more harmless than your poisonous, unscientific whining.

You're like those people that hear the word "nuclear" and immediately thing BAD BAD BAD

The second annual Space Elevator Conference actually happens to be going on right now, in Santa Fe. Expect to hear more on this next week... By the way, this bill doesn't talk about getting from Earth to Orbit - Space Elevator may be the solution that makes all this possible and much less expensive.

From the ISR space elevator FAQ.

******************
What about conservation of angular momentum?

When an elevator ascends the ribbon, it must be accelerated eastward because the Earth's rotation represents a larger eastward velocity the higher you go. The required eastward force on the ascending elevator would have to be provided by a corresponding westward force on the ribbon.
If you go through the math quantitatively, the angular momentum for the climbers requires a pound or so of force over the one-week travel time, and we do that easily with our many tons of material in the anchor and the counterweight.

The quantities really are tiny, but just to be complete, a climber going up pushes the entire elevator slightly to the east, causing it to lean. However, the ribbon recovers for the same reason that it stays up in the first place. Centripetal acceleration is acting on the upper two-thirds 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.

***********

I don't have time or a good recollection of my college dynamics class to verify this, but it seems they have it worked out. I'd be more concerned with the part about "dodging a satellite every 14 hours."

This has been talked about a million times before.

There is some information here

Basically it says the area is too far from anything for "anything to sneak up on it".

Like this , in less than 20 years given adequate funding.

Ah, actually, the getting-lots-of-mass-up-there is quite feasible well within two thirds of that time.

What isn't is the price tag. Shouldn't they be busy seeing to employing their lot before getting back into the "my ___ is bigger" race?

Anyhows, _IF_ this will be up by, say, 2020 (including the martian side), and the Russians will be relying on American transport infrastructure, (is anyone counting the ifs here?) it _might_ actually be feasible.

But hey, people in the eighties would laugh at us if we told them what we're up to today. We shouldn't be laughing at ideas. Especially when they're technically doable.

Yep. And since they plan to stay there over a year, that'd be more than the 10 to 40 Billion we need to get an elevator up and running and trash the rocket engines concept altogether.

At least that was what the US government would be doing if getting people in space was what it really wanted to do.

Frankly, if I'd been ruling the world, I'd shift technology, research and humanity as a whole into high gear _BEFORE_ salvaging Iraq and removing Saddam's testacles, but hey, that's just me.

If Liftport is planning to give out that grant money, they may run into trouble if everybody has the same attitude you describe for NASA...they're hoping to receive lots of grants (check that 3-year plan). They're planning to hire their own scientists in year 3, if they can get the target $100 million.

On the other hand, while ISR is focused on doing their own research, Liftport is working on promoting the idea and working with universities, and maybe that's a better approach. And while I'm glad to see ISR's research commitment, I kinda lack faith that NASA and big aerospace have the cojones to actually follow through on this project. So while my initial investment in Liftport was smaller than it would have been if Edwards were still on the team, I'm rooting for them, and will put more in on the next round of funding if the team keeps hitting their targets.

On the other hand, Liftport has raised a million bucks in half the time they expected, and the gonzo attitude appeals to my Heinlein-educated sensibilities. I sent them a few hundred bucks yesterday, just in case.

On the other hand, Liftport has raised a million bucks in half the time they expected, and the gonzo attitude appeals to my Heinlein-educated sensibilities. I sent them a few hundred bucks yesterday, just in case.

I think we'll cultivate a lot more good will if we send "oreos" to Mars. Especially double-stuff.

A space elevator wouldn't hurt either.

I used to think the space elevator was a silly idea, or at least a not-any-time-soon idea, and that we should tinker with tethers or J. Storrs-Hall's space dock idea in the nearer term. But I started reading the info (most of the technical issues are treated in essays in the "Downloads" section of the website) and it's remarkable how thoroughly this guy has considered every possible aspect or risk of the system.

We don't need a lot of new science and technology to do this. We need better nanotube manufacturing and we need an automated system that can shoot down flying garbage in LEO. Aside from that, it's just money and politics. It would mean the end of shuttle disasters, and every space activity would be 10x or 100x cheaper than it is today.

Interestingly, the space elevator guy has recently taken a position at this think tank where he says he'll have the resources to really put up a space elevator. I hope things work out for him. If he succeeds, we'll all be better off.

Sorry for the failure to appropriately curb my enthusiasm. I'll try to do better next time.