Talk:Space elevator/Archive 2

plea for politeness
My yesterday's change to the economics section has been reverted by Rei. Please explain why or I will revert back .... Refrain from ad hominem attack, please. Paul Beardsell 17:18, 5 May 2004 (UTC)

Some people seem to be straining to reach the conclusion that something must somehow make space elevators impossible to operate. Before you do that, consider reading Edward's report: .

Is there something crucial in Edward's report that the Wikipedia article leaves out ?

discussion trimming

 * /Archive 1 - Prior to May 8 2004

Okay, I trimmed it down to only 62 k. I don't think I cut any live discussions, but you can check the page history, and copy & paste it back if necessary. --wwoods 08:00, 8 May 2004 (UTC)

I wonder if it would be better to split this article into 2 or more parts somehow ? Perhaps a detailed economic exploration of a "simple" "basic version" (up-only, unmanned, etc.), and another page listing all kinds of variations and additions ("advanced version") and history. DavidCary 17:23, 11 May 2004 (UTC)

I agree with Paul Beardsell that we need to compare apples-to-apples; do we need 3 seperate economic analyses to compare * satellite to LEO: rocket vs. elevator * satellite to GEO: rocket vs. elevator * human payload to LEO: rocket vs. elevator ? -- DavidCary 17:23, 11 May 2004 (UTC)


 * The elevator doesn't really go to LEO -- it goes to GEO, and beyond. --wwoods 00:24, 12 May 2004 (UTC)

advanced versions

 * Regeneration is hampered by transmission losses. Elsewhere these are said to be very high.  If the 0.5% efficiency figure is used again then it is almost not worth bothering.  Or is there another flaw in my thinking?  Paul Beardsell 14:43, 6 May 2004 (UTC)


 * Will we build the advanced version after we have built the basic version? To solve other problems we have people suggesting here we detach the cars at the top to send them back.  Is that a feature of the the basic version?  And the energy you have to recover is not only the up/down potential energy but the sideways kinetic energy.  Any plan for that?  Paul Beardsell 06:23, 2 May 2004 (UTC)


 * OK, I've reworded the section. I believe it now incorporates both views without making a stronger case for either. Comments are welcome. Fredrik 16:19, 1 May 2004 (UTC)

Yes, much better balanced. Thanks. What remains unclear is


 * whether the now sub-$2/kg figure includes both the energy required for lifting 38000km and the energy required to accelerate it laterally.


 * whether the capital cost is included

Paul Beardsell 18:43, 4 May 2004 (UTC)

vertical potential energy and sideways kinetic energy
"vertical and tangential energy"

I put some numeric calculations dealing with


 * up/down potential energy
 * sideways kinetic energy.

at http://c2.com/cgi/wiki?SpaceElevator .

Want me to move them here to wikipedia ? -- DavidCary


 * First off, people need to stop trying to distinguish between vertical and tangential energy.

Why ? -- DavidCary 17:23, 11 May 2004 (UTC)

energy conversion efficiency of the wireless power beam
I agree with Paul Beardsell that "100% conversion efficiency" of the wireless power beam is unrealistic.

Perhaps it would be less controversial / more realistic to
 * use the conversion number in the Edwards report (1% if I remember correctly)
 * use the $100/lb figure published at http://isr.us/SEHome.asp?m=1

at least until we get a better estimate of a "realistic" number.

Would it be crazy to stick with the Edwards report of up-only elevators in the economic analysis of a "basic elevator", then add these other nifty ideas and improvements in a later section (perhaps fore-shadowing with "Even neglecting other suggested improvements, this economic analysis shows ...") ?

Can we say the climbers use Beam-powered propulsion ?

operational costs compared to rockets
It is unavoidable that it takes 57e6 N*m = 16 KWh of energy, per kilogram, to move any mass from the ground to geosynchronous orbit (allow me to call this "orbit energy"), no matter how you do it.

The overwhelming reason space elevators are (in theory) far less expensive than rockets is because
 * rockets have to accelerate their propellant with them.

That's it.

Other reasons (such as


 * propulsion is more efficient with a larger reaction mass. Rockets use tons of reaction mass to get pretty good efficiencies. The "reaction mass" of the space elevator is planet Earth.


 * The "reaction mass" of rockets burns up. The "reaction mass" of the space elevator (planet Earth) can be used over and over again.


 * rockets have to travel at high speeds -- some kinetic energy is lost to air resistance loss


 * because SE can spread out orbit energy over a longer period of time (days instead of minutes) means don't need to pay (at $10,000 per pound) for padding you otherwise would need to protect fragile cargo from launch vibration.

) are much less significant.

variations: "run electricity up cable" seems reasonable until ...

 * As to whether you can just run energy up the cable, that seems pretty unreasonable unless you have a superconducting cable. I've done the math on how much energy will be lost; there's no way it can be done if there is any resistance at all, even if you use silver wire.  To power the elevator, you're going to need a lot of power going through it, so even with superconductors, weight is a definite issue.  For a quick calculation, if your wire weighs only 10 grams per meter, that's about 358 metric tons worth of cable that you have to support.  It would take a truly incredible space elevator to be able to support that kind of weight.

Edward's design has the "initial cable" has a mass of 19 800 kg, slightly less than a Russian geosynchronous communication satellite. At geosync, it's is strong enough to hold up the rest of the cable hanging "down" with a safety factor of 2.

(Should we discuss "running electricity up the cable" in an article -- rather than this talk page ?)


 * No ... using carbon nanotubes ... a 20,000kg cable of Edwards' design has a maximum cross section area of 2cm, and with the low density of CNTs, is incredibly light. You do the math of what happens if you try and make it hold a couple hundred tons worth of superconducting cable.  That's why you need power beaming.  Rei 17:09, 6 May 2004 (UTC)


 * The lossless conversion number is what should be included; of course there will be loss, but people need to know the lower bound.


 * There are all sorts of ways to regain energy. If you had lossless energy being spent on the way up, equal up/down traffic, and lossless regeneration/transfer, the elevator's total energy usage would be zero.  Noone proposes anything close to this  ;)  However, since most proposals on how to get energy up to the elevators are incredibly lossy, any energy that you can gain on the way (such as from down-travelling elevators, magnetospheric braking, etc) are a huge advantage.  Also, down-travelling elevators need to get rid of energy.


 * Well, the lower bound is NOT the lossless transmission of energy. Here is an example where you do not have to be a rocket scientist (heck, I've always wanted to use that appropriately) or a space elevator expert to know that the theoretical best efficiency is never 100%.  This is what you are implying.  The base cost is NOT theoretically lossless.  With the best will in the world microwave and laser even in a vacuum is very lossFULL.  So it is misleading to suggest figures of $1.74 unadjusted.  It is misleading to suggest that the regenned energy is going to make any difference if only a very small percentage of that is recoverable.  What I had presumed was that you would not want a misleading article.  Paul Beardsell 17:58, 6 May 2004 (UTC)


 * Lastly, I have to back up the removal of the rockets paragraph. For one, it is incorrect.  Energy-lossless rockets don't come even close to the space elevator's economics, because you have to accelerate your propellant with you, you have to travel at very high speeds that suffer severe wind resistance problems, etc.  Chemical rockets aren't incredibly lossy when it comes to the amount of energy contained within them to how much thrust you get out of them; they're just an inefficient propulsion method.  There's a big difference.  For a space elevator, you'd need to have energy wasted at 6,000:1 ratio (or have other major expenses) to be as inefficient as using the most efficient chemical rockets.


 * This does not include capital costs. This is a baseline.  The inefficiencies of the system are discussed elsewhere, such as the fact that our best energy beaming systems get less than 1% efficiency.


 * Ok, I think I've covered my take on the subject. --Rei


 * But the capital cost is so huge that it is a travesty to not take them into account when pretending to discuss the economics!  How many KG do we have to elevate before we break even against inefficient chemical rockets?  Paul Beardsell 20:44, 4 May 2004 (UTC)


 * The baseline capital cost is mentioned elsewhere in the article as 5by$, which I believe is based on Dr. Bradley Edwards' work. If you want more detail, I suggest you read through Edwards' calculations.  The key element is the tensile strength of the cable.  While I have some problems with some of Edwards' assumptions, it is a fully calculated and quite detailed work.  If a cable with a tensile strength of over 100GPa can be produced, the system will only cost a few billion dollars.  The cost of the system rises exponentially if you have to reduce the tensile strength, however; this is also discussed.


 * So, if we transport 2.5billion kg we will only have doubled the cost per KG to $4/kg. Or if we transport 2.5million kg the cost will be $2002/kg.  But if we use the efficiency figure of 0.5% then its $2000(capital cost)+$400(marginal).  Or $2400/kg.  Paul Beardsell 22:52, 4 May 2004 (UTC)


 * It seems that as a consequence of me asking questions a number of important clarifications have been made. Possibly I missed a thing or two but some of it was not clear.  Paul Beardsell 22:52, 4 May 2004 (UTC)

Cost per kilogram
We must compare like with like. Rei's recent edit changing Bryan's figure of $100 to $1.74 is not valid because it is being compared with the actual rocket launch cost. As 0.5% is considered optmistic the correct figure must be at least 1.74*200 = $350/kg. Despite that this does not include capital costs and so is still understated in comparison to the rocket figure which includes at least some capital cost. I will change the figure accordingly. Paul Beardsell 02:33, 5 May 2004 (UTC)


 * Um, in a discussion of baselines of a per-lift cost, No You Won't. When one mentions that it takes 10,000$ to lift a pound of mass to LEO on the space shuttle, that 10,000$/lb doesn't include capital costs for the shuttle.  Consequently, it is completely irresponsible and completely inaccurate to compare the two.  If you want to get into the economics and costs of the entire system, read Edwards' work.  Quit acting like an authoritative source when you haven't read a d**n think about the subject.  You're getting annoying.  It's like having a six year old in a discussion of particle accelerators talking about how they have problems with the concept due to their experience playing marbles.   Rei 16:21, 5 May 2004 (UTC)

Shuttle? Araine is $13000/kg (1993 figures) to LEO. To geostationary is $25000/kg (1999), the kid with the marbles reckons. (But if I am the kid with the marbles you are the one attempting to leave the boot marks in his face.) There are plans dating from 1993 which are a lot more feasible than the space elevator to reduce rocket LEO costs to $1300/kg. If the same factor applies then $2500/kg for geostationary. Capital cost inclusive and no major invention required. Compare that to the $2400/kg for 2.5million kg I have calculated for the basic $5bn elevator (and on which I invite criticism). Put that in your economics section. Paul Beardsell 16:44, 5 May 2004 (UTC)


 * ... LEO (Low Earth Orbit). ...  Ariane is a lot cheaper than the shuttle.  For one, the Ariane series is generally unmanned, although they have been used to launch tests of the Hermes mini-shuttle (which itself notably increases the launch costs, but still cheaper than the shuttle).  ...

(we're talking about, right ?)


 * The article you linked is complete and utter extrapolation. It is worthless.  I certainly hope this wasn't published anywhere other than his website.  This person has no clue what makes rocket launches expensive, and thinks that it is just a "quantity of production" issue.  It's not.  The propellants are already mass produced.  Much of the skin and some of the internal components are simple mass-produced material, and won't gain much from automation.  The shuttle costs $500-600m *per turnaround* to launch.  This isn't "repaying capital costs" - this is what is needed for the inspections, replacing the parts that are designed not to survive, paying for all of the fuel, etc.  Even if you go to disposable vehicles, you're not saving yourself a ton.  The orbiter only costs 1.3-2b$, but is designed for over 100 missions.  The construction capital cost is already low.   And with its capacity for 25,000 kg to LEO, even with the most pessimistic numbers, the capital cost is only 800$.  It's the per-launch cost that costs a fortune.  It costs almost a million dollars just to carry the shuttle across the country.


 * Let's put it this way: each of the external boosters carry 453,592 kg of propellant. The main tanks contain 500,000 gallons of liquid oxygen and hydrogen.  Lets guestimate that it is 3 kg per gal; that's then 2 million kg of propellant that you have to pay for on each mission.  Are you going to try and claim that this isn't "mass production"?  The solid boosters have the following fuel breakdown: 16% atomized aluminum; 70% ammonium perchlorate; 2% fine iron oxide powder; 12% polybutadiene acrylic acid acrylonite binder; and 2% epoxy curing agent.  Go ahead - find a way to reduce the production cost.  Tell me what it is - and while you're at it, tell NASA - I'm sure they'll be interested.  The hydrogen/oxygen burning is more efficient, but as Ariane has made clear, cryogenic tanks are very dangerous.


 * BTW - when people say that it costs 10,000$ to lift a pound of mass to orbit on the shuttle, that is *NOT* counting capital costs (do the math - I've provided the numbers).

Paul Beardsell 23:40, 5 May 2004 (UTC) supplies some excellent links:
 * http://www.eere.energy.gov/vehiclesandfuels/facts/favorites/fcvt_fotw205.shtml which says "hydrogen costs ... $1.00-$1.40/lb for delivered liquid hydrogen."
 * http://www.astronautix.com/props/loxlh2.htm which says "By the 1980's NASA was paying $ 0.08 per kg [of liquid oxygen]" and "In the 1980's NASA was actually paying $ 3.60 per kg [of liquid hydrogen]" and also mentions "LOX/LH2. Optimum Oxidiser to Fuel Ratio: 4.00. ... Density: 0.28 g/cc. ... Oxidiser: LOX. Oxidiser Density: 1.14 g/cc. ... Fuel: LH2. Fuel Density: 0.071 g/cc."

That gives us
 * LH2 at 0.071 g/cc =~= 270 g/usgallon
 * LH2 at $3.60/kg =~= $1.63/lb (apparently NASA pays a little more than the average industrial user at the other site)
 * LH2 at ($3.60/kg) * (270 g/usgallon) = $0.97/usgallon


 * LO2 at 1.14 g/cc =~= 4 kg/usgallon
 * LO2 at $0.08/kg =~= $0.036/lb
 * LO2 at ($0.08/kg) * (4 kg/usgallon) = $0.32/gallon

The appropriate propellant mix (4 g LO2 + 1 g LH2, which eventually produce 5 g H2O) gives an average of
 * LO2+LH2: (4/5)*($0.08/kg) + (1/5)*($3.60/kg) = $0.78/kg
 * LO2+LH2 (4/5)*(usgallon / 4 kg) + (1/5)*(usgallon / 0.3 kg) = 0.87 usgallon/kg =~= 1.15 kg/usgallon
 * LO2+LH2 (calculated another way) at 0.28 g/cc =~= 1.06 kg/usgallon
 * LO2+LH2 at ($0.78/kg) * (1.06 kg/usgallon) = $0.83/usgallon

I think that's close enough for back-of-the envelope calculation; remind me to do more accurate calculations later. -- DavidCary


 * Ariane 5 fuel payload = 645000kg. Volume is 430000usgallons.  Cost is $94600.  Ariane 5 payload is 6000kg.  Fuel cost per kg to geostationary orbit is $16.  Or $7.20/lb.


 * Will you tell NASA or must I?


 * Paul Beardsell 00:04, 6 May 2004 (UTC)


 * ... Third, you've got the Ariane 5 completely wrong. There is the main cryogenic stage, and there are the two solid booster stages, in addition to the upper stage.  The cryogenic stage contains 132.7 metric tons of liquid oxygen, and 25.84 metric tons of liquid hydrogen.

So that's 25 840 kg of LH2 * $3.60/kg =~= $ 93 000 worth of LH2, plus a bit more for the oxidizer, comes out to about what we calculated above.


 * The solid rocket boosters' fuel (aluminum, polybutadine, ammonium, etc) is notably more expensive thant the LOX and LH.

Ooopsies, I forgot all about that. Anyone have dollar figures for that ?


 * And even with all of this, you're still completely out of whack. Ariane-5 alone does not take human payloads up (and with the cancellation of Hermes, probably never will) (I wouldn't want to ride one, anyway... ).  Its payload is notably reduced and costs drasticly increased if you include the ARD (if you want reentry, you need that).  Etc.  Lastly, you're looking at payload to LEO.  You're comparing apples and oranges, and you're looking at the oranges under a microscope and the apples through a fisheye lens.  Even with all of that, the Ariane series cost between 10 and 20 thousand dollars per kg to LEO, with the Ariane-5 at 11.8. The Titan series gets better; I'm not a big fan of the Ariane series.  The propellant is only a small part of the issue.   Rei 17:49, 6 May 2004 (UTC)


 * Even this boy with marbles, the one who cannot read, knows that LH2 is 280g/usgallon. A lot less than a pound weight per gallon.  So get your facts straight!  Your vivid imagery does not compensate for being careless!  In the article I doubled the cost to $30 fuel cost per kg transported to be safe.  I tell you what, let's double it again:  It does not destroy the argument.  You tell me how much the fuel costs and we'll plug that figure in.  Paul Beardsell 18:08, 6 May 2004 (UTC)

Would you mind if I moved this discussion to [Ariane] ... or is there a page about the economics of rocket propellant in general ? Atlas launch costs, shuttle launch costs, [Space Shuttle program], Ariane launche costs, etc.)


 * Once again, I will ask you: Go read a paper on the subject of space elevators. I would suggest Edwards, but there are a number of good studies out there, so take your pick.  Rei 17:30, 5 May 2004 (UTC)

alternative ways to space

 * By the way: there ARE cheaper ways to get things to space than standard chemical rockets being worked on.


 * Excellent. Do any wikipedia pages exist for these other ways ?

Yes:


 * the HARP project, which uses ballistically launched sabot-fired projectiles to get a chemical rocket into the upper atmosphere; it was cheap per launch, the development costs were proportionally tiny, and they were almost to orbit (they had reached the altitude, and had demonstrated that a rocket can survive the launch and fire at altitude; they just needed to apply the proper thrust to make it orbit).


 * Other methods are things like the high powered coil guns, railguns, and ram accelerators (also with a second-stage rocket); as well as combining any of these methods and/or conventional ballistics with a scramjet engine (and second stage rocket).

However, the space elevator is the "maximum cost efficiency per launch" method physically possible - and it *is* feasable if materials tech advances. Rei 17:40, 5 May 2004 (UTC)

sway
Do you think that the sway will only be 200m? I just guessed a figure. But if the cable is 2m or 20m wide this is a tiny proportion of the length. The cable needs to be light and tension will have to be limited to limit the necessary strngth of the cable. How stiff will the cable be? If the sway is 2km and we want a 1km safety margin either side then it is a 4km swathe being cut through the sky. Space traffic control is going to be very difficult! And the sway could be 20km or more! A 22km swathe would surely be impossible to manage. Every low earth satellite would have to have its orbit adjusted every several hundred revolutions. Every second week!


 * I answered this one already, but it looks like my answer's been deleted without the question also being removed. Paul's way overblowing the scale of the sway and the magnitude of the space traffic control problem the elevator would present. Next time someone archives this page, please be more careful about how you cut things; this whole talk page has become a colossal mess. Bryan 04:27, 12 May 2004 (UTC)

weather
And then, just as we have it all worked out, the weather forecasters force us to move the base 50km to avoid a storm. So we decide to build an untethered elevator instead but this destroys the economics: All the fuel wasted in rockets overcoming air resistance to get to the base station.

But once we are above the atmosphere rockets are no longer as inefficient and ion drives work: We can take the cable cars off their rails!

I know I'm going to be told I have added nothing knew - that all this is known. But what I am trying to illustrate is that each solution seems to make another problem worse.

Paul Beardsell 01:52, 5 May 2004 (UTC)




 * The sway is smaller the lower you go. If the cable's anchored on Earth's surface, and LEO is only a few hundred kilometers up, you're not going to get more than a few hundred meters sway at most at those altitudes at the absolute maximum - we're talking about extremely small angles here, not something you'd be able to see with the naked eye. At higher altitudes there's huge amounts of space for satellites to maneuver in. You don't seem to appreciate just how big a volume of space is being dealt with, and how tiny satellites and the elevator will be in comparison to that vastness.

...


 * Bryan 07:31, 5 May 2004 (UTC)


 * Just a couple comments, Bryan.


 * I agree completely with your comments about sway in the atmosphere. Sway outside the atmosphere is relatively easy to deal with, assuming that NASA's current work on magnetospheric braking/acceleration pans out (the physics are good; it's currently a materials problem, in that the last time they tried, they had gas leak from the insulation which created a plasma that severed the tether).  Not only does braking against the magnetosphere resist momentum of the tether, but it also generates electricity.  Even without magnetospheric braking, harmonics can be avoided by proper timing of the climbing craft.


 * Dr. Edwards did a number of calculations on the effect of weather, and found that such an elevator *is* succeptable to wind even with the tiny cross section that you get using his >100GPa fiber calculations (although his design uses a flat epoxied ribbon, which I find unreasonable; a more realistic design would be a partial hoytether mesh, which would also suffer from wind less and be less succeptable to damage). Nonetheless, the cumulative effect of winds across the entire troposphere can start to have problems when they get close to hurricane force.  His solution was not only a moving platform, but locating the elevator in the waters west of the Galapagos, where storms, high winds, and lightning, are incredibly rare and would be relatively easy to avoid.


 * Interesting, I would have thought most of the equator would be relatively "safe" since tropical cyclones don't form there. In any event, I presume the movement of the platform wouldn't be fast enough to present extra space traffic control difficulties? Bryan 01:52, 6 May 2004 (UTC)


 * If the platform is moved maybe the satellites don't need to be nudged. Dodgems for the space age.  Paul Beardsell 02:02, 6 May 2004 (UTC)


 * You have to deal with gusts and high-altitude winds, not just sustained surface winds. Also, all storms may be dangerous because of lighting (one interesting suggestion on the HighLift Systems message board, if the conductivity/water buildup on the cable was too high, is to "maypole" the cable near the ground so that there are multiple paths, and the severing of one wouldn't be a showstopper).  Rei 18:01, 6 May 2004 (UTC)

above the weather

 * I agree with your comment about ion drives. The biggest problem with that, furthermore, is the sheer cost of getting them to LEO to begin with, due to the inherent inefficiencies in chemical rocket propulsion. Rei 16:15, 5 May 2004 (UTC)

Review please
I am trying to moderate the Economics section of the article. Rei keeps on reverting my proposed change. I propose the following text. Essentially my changes are (i) a modification to the first paragraph to repair the misleading comparison of the full cost of rocket launches to the marginal cost assuming lossless transmission of energy of elevator lifting and (ii) a new paragraph which essentially points out that unless a helluva lot of mateial is transported the elevator cannot be justified on cost grounds. The proposed text

Economics

With space elevators like this, assuming a 0.5% energy conversion efficiency, materials can be sent into orbit at a fraction of the current costs. Total marginal cost is between $10,000 and $40,000 per rocket payload kg today and this compares to a marginal cost of $350 ($1.74 adjusted by the 0.5% efficiency factor) per space elevator transported kg. The marginal cost of a trip would consist solely of the electricity required to lift the elevator payload, some of which could be recovered by using descending elevators to generate electricity as they brake (suggested in some proposals), or generated by masses braking as they travel outward from geosynchronous orbit (a suggestion by Freeman Dyson in a private communication to Russell Johnston in the 1980s.) This means that hospitals, mining facilities, international trade, and travel could all be done in space with the help of these space elevators.

The efficiency of power transfer is a limiting issue. The most efficient power beaming in the present-day is a laser beaming system with photovoltaic panels on the climber optimized to the wavelength of the laser. With the best (and most expensive) current technology, between atmospheric losses, losses in generation of laser power, and losses in absorption on the panels, the efficiency is around 0.5%, the multiplier used above. And if climbers are to be disposable, the most expensive photovoltaic panels may not be an option.

Losses due to atmospheric spreading could be reduced by the use of adaptive optics, and losses due to absorption could be reduced by a properly chosen laser wavelength. But although laser and photovoltaic technologies have been rapidly advancing, it is unknown whether the losses can be reduced to an acceptable level. Barring significant development, costs will remain far higher than in the speculative optimal figures, and space elevator transports will be more expensive than current rocketry.

The cost of the power provided to the laser is also a limiting issue. While a land-based anchor point in most places can use power at the grid rate, this is not an option for a mobile oceangoing platform.

Up-only climber designs must replace each climber in its entirety or carry up enough fuel to get it out of orbit - a potentially costly venture.

When comparing the costs of the space elevator with conventional rockets it is important to take capital costs into account. Whereas the cost per kilogram to place 1kg in geostationary orbit using Ariane 5 is about $25,000 this does include much of the capital cost: The cost of fuel being but a tiny percentage of that, less than $30/kg. The energy cost of the space elevator is perhaps $350/kg, if a 0.5% transmission efficiency is taken into account. With the lowest estimate of capital cost of around $5bn for the simplest space elevator, the elevator requires a substantial payload to be transported before it would become cheaper than rockets. The next generation of Ariane rocket can lift twice the payload, requiring perhaps twice the fuel, but other costs are unlikely to double. It is speculated by some, possibly naively, that future technological and efficiency advances, coupled with a demand to shift into geostationary orbit the amount of material which would justify a space elevator, could reduce rocket costs substantially, making the task of justifying the elevator on cost grounds somewhat more onerous.

OK, what's wrong with that? Rei says the fuel cost is out but if so it is not out enough to ruin the argument. Paul Beardsell 22:42, 6 May 2004 (UTC)


 * Let's try something constructive: Here's a proposal. Lets try and agree on a general plan, then make the edits.


 * The problem with including specifics on economics beyond a baseline is that you have to pick a particular space elevator design plan. There are many out there, with varying levels of research behind them.  If I had to pick, I would support the HighLift (Bradley Edwards) proposal, partly because it is one of the most thorough I've come across, and partly because I'm most familiar with it because I spent a while debating details on the message board for it (and, just so you know, I was one of the pessimists there).  However, I would like other people's stances first as to what design plan to cover.


 * The 0.5% is just an approximate number, and Edwards thinks he can get notably higher (although I disagree on some specifics). We can get more exact numbers if you would like; again, however, it really varies depending on what specifics you use.  With adaptive optics, there are really only three issues: absorption by the air (which varies based on the wavelength); efficiency of power to light conversion by the laser (unfortunately, different lasers have different wavelengths, so it is a balancing act with the above mentioned issue); and the efficiency of the solar panels (used to be pretty bad, but high-end panels are getting pretty good - however, with Edwards' proposed one-way climbers (which I disagree with for a variety of reasons, this being one), the best may not be affordable.  The biggest loss is the energy conversion from wall to light power by the laser.  Diode lasers are the only really efficient ones currently, but diode lasers have poor coherence.  There's more work to be done if we want to improve the laser efficiency figure.


 * Whatever base stats are chosen, it needs to be explained that this is one possibility, and may be more or less efficient than other methods. ... you may want to look at how quickly launch costs have been advancing since the 50s - the old Titan series is actually more cost efficient than new series' like Ariane, and is close to the new Atlas series.  This page has a nice graph made from Astronautix stats  which puts it into perspective.


 * So, trying to portray chemical rockets as having the potential to advance anywhere close to that of a space elevator seems kinda silly (you'll find most people at NASA will agree on this); however, I do agree that an example or two of the overall economics of the system (instead of just the baseline) would be a nice addition. Rei 23:14, 6 May 2004 (UTC)

OK, anything which isn't a whitewash of the costs is fine with me. The problem with the costs of space transport is that the costs are often at least partly hidden in defence budgets - the accounts are not transparent. Another problem (from an economics perspective) is that some people so much want to do the space exploration that the huge cost is played down by them. Similarly, the science/exploration/adventure/survival "right stuff" aspect almost makes cost a non-issue, from time to time. And, of course, the benefits of space travel, even if they are substantial, are often intangible and difficult to measure. However, there is an economics section in the article and that section must be seen to deal honestly with the costs.

I think my use of the term capital cost was unhelpful or it was misunderstood here. I do not know how transparent the Ariane accounting is, but the charge per kg lifted is $25,000. My estimate of the fuel cost per kilogram lifted, (for LH2+LO2, admittedly, and even if it was out by a factor of 10, which it wasn't) at $15 per lifted kg (doubled in my proposed edit of the economics section, above) certainly shows that Ariane customers are paying for a lot more than just fuel: They are paying extra presumably to contribute to or to cover the manufacturing cost of the essentially disposable rocket, staffing costs, the cost of preparing the launch, cost of maintaining the launch site etc. This $25,000/kg figure rocket figure is used in the first paragraph of the economics section in comparison to the $1.74/kg figure for the idealised electricity usage of the elevator. As I have tiresomely demonstrated, this is a misleading comparison. There is the cost of building the elevator which is not factored into the 1.74 figure whereas the cost of the rocket is factored into the $25,000 figure. Essentially the issue is one of marginal cost vs total cost. For the rocket it is the same total cost per kg, more or less, no matter how much we lift. For the elevator we need to lift a lot before the total costs fall below the rocket. Why this obvious point is resisted I do not know. The economics section, as it stands, reeks of bias.

Before a reply, if any, is crafted, please take a second to read what I have written. Responses have put words in my mouth. Please note that yet again I have not mentioned the word "shuttle".

Paul Beardsell 11:45, 7 May 2004 (UTC)

( Beardsell correctly calculates the density of LH2, someone claims his LH2 calculations are "way off", Beardsell gets upset. I think I would too. Focus on getting the correct numbers in the article, people. I don't care who was "right" and who was "wrong". -- DavidCary 17:23, 11 May 2004 (UTC) )


 * We need to discuss both a reusable space launch mechanism (like the shuttle) and a disposable one (like most versions of the Ariane series). Also, note that you are being unfair by comparing a rocket which cannot compare a human payload to a space launch system like a space elevator which *can*.  Additionally, you are comparing a system with no reentry capability (without an additional module that you're not factoring in) to one that has reentry capability like a space elevator.  That would be like me comparing Project HARP to the Space Shuttle (yeah, you could launch people, but they'd be liquified on arrival).  This is consequently an unfair comparison, and I would like you to acknowledge that.  Furthermore, you're comparing costs to LEO; a space elevator can go to GEO and even directly fling craft as far as Saturn.  I will discuss both systems below anyway, and only cover the far lower LEO costs.  But, again, I want you to acknowledge that you're making an unfair comparison.


 * You have this upside down. I am not the one who is comparing rocket costs to elevator costs.  It's right there in the article NOW.  I did not introduce the comparison.  Someone else did.  And you reinforce it with your placing of your 1.74 figure in the same sentence as the 25,000 figure.  Both expressed in US$ per lifted kg.  It is not my comparison.  I would be happy to remove the comparison but happier to compare them more fairly.  And it is an unfair comparison for the reasons I give AND for the reasons you give.  I AM NOT MAKING THE COMPARISON.  The comparison is made already.  UNFAIRLY.


 * As I demonstrated with the shuttle, the turnaround cost per launch of the shuttle of inspections, refuelling, replacement parts, etc *ALONE* costs the 10,000$/lb. *AND*, as I demonstrated (which you keep ignoring), given the 100-flight expected lifetime of the shuttle, the manufacturing cost per kilogram is almost nothing..


 * I never mentioned the shuttle.


 * If instead of making components of the Ariane 5 reusable (as ESA is trying to do), your goal is mass production to try and lower costs - GOOD LUCK. This is a 278 metric ton craft.  You will NEVER get a 278 metric ton high-tech spacecraft for cheap, *regardless* of "mass manufacturing"; furthermore, much of the craft *already is mass manufactured*, from the fuel to the casing to most of the electronic components.  I don't know why this is a difficult concept for you.  Rockets have not been getting measurably cheaper, and there is no sign that they are going to by any significant amount, no matter what we do.  Also, I'm wondering why you keep focusing on the Ariane; the Ariane program, by many standards, has been one failure after another.  If I were to send a payload up on an Ariane, I'd want to have a pretty darn good insurance policy   ;)


 * Once again, you put words in my mouth: I cited one paper which suggests cost savings in rocketry are possible.  I said it was "speculative" and "possibly naive".  Your attack on the study some time back may or may not have had substance but it was masked by the vitriol.  As to the Ariane:  The issue isn't the Ariane specifically.  By contrast, I am not an Ariane-bigot.  And if any one rocket fails the consequence is?  Insurance for the elevator?  Before you reply remember I did not raise the issue of insurance - you did.  Paul Beardsell 18:03, 7 May 2004 (UTC)


 * In short, the cost of a disposable rocket MUST be factored into its launch cost, while the cost of building a reusable rocket becomes relatively insignificant to the turnaround costs.


 * ... Fine.  Let's factor it in.  Paul Beardsell 18:03, 7 May 2004 (UTC)

(...discussion about incompetence and insanity snipped...)


 * ... Here is Edwards' report ... . He's not the most optimistic, nor the least optimistic, of analysts out there, so it would only be proper to mention that other proposals have higher and lower costs for construction; also, it would be proper to mention that this is the cost for an elevator on Earth; elevators elsewhere (such as Mars, and especially on smaller bodies) are far cheaper.  As you'll notice referenced near the end, once you get a single space elevator up, the cost of all future space elevator construction drasticly drops, and continues to drop.  So, while your first elevator will be the most expensive to repay capital costs (but still far, far ahead of anything chemical rockets could conceivably achieve), future elevators' capital costs drop drastically.  In fact, one of Edwards' suggestions is to use the elevator to build other elevators and sell them to industry, paying off the initial investment in short order.  And, furthermore, one must not forget that this doesn't just bring payloads to LEO, it brings them to GEO and [does all kinds of other cool and wonderful things].  It is completely unfair to compare to a single stage, no-reentry, human-incapable disposable LEO rocket, and I'm sure you know that.   Rei 16:48, 7 May 2004 (UTC)


 * The hidden issue is this: What is the project?  For you, it seems, the project is the elevator!  NO!  The elevator is not pretty enough to be justifiable on its own.  What is the project that requires us to lift (and return?) many millions of tons to GTO?  Because when we know the tonnage, whether passengers will be making frequent trips, when we know how much material must be returned, etc etc, then the rocket vs elevator comparison can be more fairly made.  In the interim THERE IS NOW AN UNFAIR COMPARISON IN THE ECONOMICS SECTION.  I will have yet another attempt to make this better.  Not perfect (because you are the prickly judge) but better.  And I ask you to leave the better version in place.  Paul Beardsell 18:03, 7 May 2004 (UTC)


 * Rei: Additionally, you must think that groups like NASA and the ESA are incompetent. They've spent phenominal quantities of money on rocket systems, and they haven't gotten anywhere remotely close to what you think rockets should cost, so clearly they're incompetent, right?
 * I wouldn't lean too hard on this point. There's ample reason to believe the cost of getting to LEO via rockets could be cut by ~an order of magnitude. --wwoods 18:14, 7 May 2004 (UTC)


 * Could you document this, please? From someone who actually has any sort of authority in the field?  They haven't been really cut for 50 years - what's your evidence?  Psb has an article by someone who has no apparent experience in rockets (the founder of Autodesk, Inc and co-author of AutoCad - a programmer.  At least his programming had *something* to do with design).  On the other hand, lets see what NASA has to say.   "Current systems have essentially pushed chemical rockets to their performance limits." .  I mean, there are improvements in the works: better materials tech to enable reuse without so much maintinance; aerospike engines for more efficiency at different altitudes in the atmosphere, reducing the need for more stages; more compact propellants (such as solid hydrogen, or forms of benzene instead of kerosine) to reduce the needed size of propellant tanks, reducing mass and air resistance; etc.  But these things can only go so far.


 * Your quote says "performance" not "cost". You continue to resort to ad hominem attacks.  You should play the ball, not the person.  What is wrong with the paper?  Paul Beardsell 19:55, 7 May 2004 (UTC)

I found this but would be interested to see any other reference. Paul Beardsell 18:25, 7 May 2004 (UTC)

meta wikipedia: intersperse vs. quote

 * Ok, again, I'll ask you not to intersperse comments. It makes it hard to follow.


 * I would rather intersperse my comments. I find it easier to follow.  And it avoids the illusion you create of answering my points by quoting selectively from my post.  Which needlessly increases the length of the post and makes it hard to follow.


 * I would rather intersperse my comments. Well, it's your choice if you want to be a pain to the person you're debating with.

This is something that applies to every talk page, not just the space elevator talk page. Could we take this to


 * http://CommunityWiki/TurnBasedVsInterruptedThreadMode
 * http://en.wikipedia.org/wiki/Wikipedia:Tutorial_(Talk_pages)

? -- DavidCary 17:23, 11 May 2004 (UTC)

cost comparison

 *  I am not the one who is comparing rocket costs to elevator costs. . But you're not getting what the numbers are.  The rocket launch cost is not repaying capital costs.  It just isn't.  These are per-launch costs.  So, that means that reusable rockets are repaying their maintinence and refueling, while disposable rockets are paying for their construction.  A reusable elevator is paying only for its power.  If the rocket numbers are not repaying initial costs, then the elevator costs shouldn't either.  They are cost per launch.  So is the elevator.  End of story.


 * That does not follow. The 25000 is all inclusive.  The 1.74 is marginal idealised (not theoretical minimum but idealised - there is a difference - but this is not the main point here).  It is THAT COMPARISON WHICH IS WRONG.  Mine might be wrong but they are BETTER.  Paul Beardsell 19:42, 7 May 2004 (UTC)

...


 * ... if you want an accurate comparison with a space elevator, you need to compare to one that is at the very least man-rated and reentry capable. Do you accept this?


 * Depends upon the project. If we use the safer, more expensive rocket for people and cheaper, less reliable ones for [unmanned satellites], that allows for cost savings.  Do you accept that?  Paul Beardsell 19:42, 7 May 2004 (UTC)


 * You speak as if NASA had a choice. The technology of the day is the rocket.  NASA are not foolish to use that, nor are they foolish to look at alternatives, howevr outlandish.  I assume you mean "foolish enough not to look at alternatives".  Yes - and almost all of the methods to get cheaper access to space do *not* involve rockets.  Because rockets have *not* been getting cheaper, despite all of our advancements, and there is no way forseen to do so.  They are investigating scramjets (so that the lower stage can be air breathing).  They are investigating ballistic and electrical launch mechanisms (HARP, ram accelerators, rail guns, etc).  They are investigating magnetospheric acceleration.  And, more distantly, they are investigating space elevators.  And the results *have* been good.  Here, let me quote:


 * "The massive size and complexity of the space elevator concept is often cited as making such a system impossible to ceonceive except in the realm of science fiction. More detailed analysis of the system indicates that it is indeed very complex, but is comparable to other Earth-based infrastructures that have been built."  It then goes on to compare to other Earth-based systems which are deemed to be of comparable difficulty, such building the Panama canal.  Their pros and cons section has, number one: "The space elevator is one of the very few concepts that may allow Earth to orbit launch costs less than 10$/kg."  They cover the many pros and cons, although I strongly disagree with some (such as "a catastrophic failure of a space elevator could produce ... ecological disasters with massive loss of human life" - yeah, maybe if you build it out of kevlar or some other comparatively low-strength material .... although you'll notice from several other cons and in the solutions section, they're considering such materials (as low as 20GPa!!!!!), which, honestly, an elevator will never be built with - the economics just don't work out).  They recommend significant further study, with it flagged as a realistic possible candidate for the latter part of the 21st century.  Rei 19:11, 7 May 2004 (UTC)


 * Less than $10/kg marginal or inclusive of capital cost? You must be making the SAME mistake again.  At $5bn typical estimate for capital cost that would be 500,000,000 kgs before we start paying for the electricity.  I.e. that figure was the marginal cost and is 7 times your $1.74 figure.  Paul Beardsell 19:42, 7 May 2004 (UTC)


 * IN FIFTY YEARS - where in the article does it say that it will be built tomorrow? Of course there is a significant time frame - we need to get the tensile strength of nanotubes exhibited on the microscale on the macroscale.  Few doubt that this is possible - the question is when it will be achieved.  Certainly it's going to be more than 10 years from now.  Probably more like 20 or more before it is achieved and cost effective.  But such materials will exist in the future.  And when such materials exist, a space elevator *does* become a very realistic, cost-effective structure.  Even if such materials also improve "conventional" rocketry by a sigificant amount, it still doesn't stand a chance of being cost-comparable.


 * That does not follow. The 25000 is all inclusive.  (Assuming you mean the shuttle's 25000):  No, it isn't.  It doesn't include a dime to recoup research costs; and, because it is used so much, the original construction cost is insignificant compared to the turnaround cost.  I've mentioned this several times.

'''Shuttle? How many times must I say that is what it costs on Ariane V all in! That is what it costs to put your pet science project on the rocket. Paul Beardsell'''


 * Cutting costs, according to you, is impossible. Now that it seems it is possible you don't want to do it..  Oh please, you know very well what I meant.  You can always sacrifice safety by cutting costs.  We could try to send the shuttle up right after landing.  It'll blow up, but hey, we can do it.  I was mentioning that with as poor of a track record as the Ariane-5 has, cutting costs (and sacrificing safety) would be a Bad Thing(tm).


 * Depends upon the project. Then you need two sets of numbers.  You are currently comparing the best case.  The "worst case" with rockets - where you need to fling something as far out as, say, Saturn - has a *huge* amount of difference.  Should we list the savings for transfer orbits?


 * Less than $10/kg marginal or inclusive of capital cost? You must be making the SAME mistake again.  *I* must be?  All I did was quote.


 * At $5bn typical estimate for capital cost that would be 500,000,000 kgs before we start paying for the electricity. Psb, you're driving me crazy.  You know very well that this is the *BASELINE*, and that I welcome the concept of including full economics figures.  However, since NASA isn't recouping the R&D with the shuttle launch costs, the ESA isn't with its R&D for Ariane-5, etc, it is *wrong* to include it in the section of rocket comparison.


 * So you say but you are seemingly struggling with total vs marginal cost.  I would turn that statement around, since you seem to think that, with a 500-600m$ turnaround on the shuttle, that the development cost is being repaid.  Do the math.  The money to develop the shuttle is not being paid in there.  The shuttle (excluding the time after the replacement of the external tank in 1998, which is not included in the launch cost) is 24,400.  Divide, say, 550,000,000 by 24,400... and you get... ?  22541$/kg.  Now, some of this money is administrative and refinement, component testing, etc - SSC gets 10m$, Goddard gets 483k$, HQ gets 3m$, etc, etc; but you get the picture.


 * I did it to draw attention to it. If bold had not been available I suppose I could have added "(ha ha ha)" afterwards.  It's not a joke.  That is the baseline.  The baseline not only has the fact that it is a baseline mentioned, but has it emphasized with the fact that no proposal gets near the baseline.  I did that, and I find it insulting that you are acting like I'm trying to hide some sort of secret to make a space elevator look better.  If there were a single, *But There Isn't*.  We can only fairly address this by putting in an economics section that covers one set of calculations for one particular design.


 * To remedy this, do you want to sum up the calculations in the Edwards report, do you want me to, or do you want to sum up the calculations in a different report? Rei 21:20, 7 May 2004 (UTC)

Economics Case Study 1 - Satellite launch
It's 2054 and the Namibian Telecommunications Agency senior civil servants have been reading Wikipedia. They persuade the Minister of Telecommunications that the NTA now needs to launch its own 1000kg satellite. For arcane budgeting reasons they would like the quote in 2004 US$. They first approach the ESA who explain that cost savings have unfortunately not been possible since 2004 so the price is the same in 2054, expressed in 2004 US$, as it was back in 2004. The NTA says stop mucking about, how much? $25million. The NTA gulped and hurried away.

How much to use the Space Elevator, they ask NASA? The answer was confidentional but was significantly above the $1,740 budget. But how much more?

Paul Beardsell 20:44, 7 May 2004 (UTC)


 * I'm not getting what you're trying to say, apart from "I think the space elevator will be more expensive without backing it up". Go read some Edwards or something.  Hasn't that bothered you?  The fact that you're debating something that you haven't even read a paper on?  No?  Rei 21:20, 7 May 2004 (UTC)


 * You've read it, you tell us. Why not?  Paul Beardsell 21:41, 7 May 2004 (UTC)


 * I'm trying to get you to read it. You're insistant on debating about this subject.  Why do you refuse to educate yourself on the subject?  Engineering projects aren't simple.  Read about it before debating.  In case you lost it, here's the link again.  Rei 21:56, 7 May 2004 (UTC)


 * I have read it. But I want you to tell us the figure because every figure I quote is wrong. Paul Beardsell 22:03, 7 May 2004 (UTC)


 * ...  The design is to build a cable whose climbers carry a 13t payload.  Now, this system's primary use would be to build a much larger cable for mass-scale colonization and exploration, but lets just pretend that we're going to stop building and start launching satellites at this point.  And, while all future elevators will be far cheaper, lets just pretend that we only have the original, most expensive one.  Lets say we want to pay back our investment in 10 years.  40 billion dollars - cheaper than the cost of developing the space shuttle, in modern dollars.  13 metric tons every ~four days = ~90 launches = ~1.1 million kg per year = ~11 million kg in 10 years.  ~3,400$ per kg - about the rate which is often cited as where many different economic possibilities begin to open up, and about 1/8th the cost of a shuttle ride, and far better than anything on the drawing board.


 * Now, lets stop with the ridiculous handicapping assumptions. Lets start by taking one off: we'll 10x the size of our cable (we'll be nice and make all of the subsequent size all be at the "second cable" price, even though it keeps plummetting from there).  That's a little over 1,000$ per kilogram, and you're completely paid off in 10 years.  What if we do our accounting like a real space program?  Since launch costs on the shuttle, on Ariane, etc, don't include the development cost, it is unfair to do the same here.  What happens if we do the same?  Well, using Edwards's design, operating costs for 10 years is 1.56 billion dollars for a single 13t cable.  That's 142$/kg.  I have some disagreements with Edwards's design, such as not using up-only climbers; while it lowers throughput some, it saves both on energy costs and climber costs, dramatically reducing maintinence; on the other hand, I'm less optimistic about the power transfer efficiency.  But, anyway, we won't get into this stuff; you get the idea of a general range.  Rei 23:17, 7 May 2004 (UTC)


 * $142/kg? At 2% efficiency the electricy costs are 1.74*50 or $87.  I think the operating costs do not include the electricity.  What do you think?  Paul Beardsell 00:59, 8 May 2004 (UTC)


 * The link to the Edwards study is just a few paragraphs above, and also right here: . I think you can read it and find out quite easily whether the operating consts include electricity, if you want to know. Bryan 01:06, 8 May 2004 (UTC)


 * I can't work it out from the reference given. I can't see an estimate for the oil /gas for the generating station.  Paul Beardsell 18:15, 10 May 2004 (UTC)


 * They provide the 10 year operating costs. FYI, electricity at the grid rate goes for about 10 cents per kilowatt hour. Rei 18:58, 10 May 2004 (UTC)


 * It was not obvious (to me) from the Edwards paper that the operating costs include the electricity costs. We know that much of the operating costs will be incurred if the number of elevator trips was halved or doubled.  Paul Beardsell 19:18, 10 May 2004 (UTC)

AutoCAD Rocketry (very) Limited got its dubious tender under the door just before midnight: $2.5million. Paul Beardsell 20:55, 7 May 2004 (UTC)


 * What is that supposed to mean? Rei 21:20, 7 May 2004 (UTC)


 * It was meant as humour to lighten things up a bit. These are the guys you think are cowboys but (miraculously?) they have done what they said and reduced costs by an order of magnitude.  Actually they've reduced costs to $1300/kg (as claimed in their paper) and are making a helluva profit because, although the elevator is cheap, Otis can't keep the doors from sticking.  Paul Beardsell 21:41, 7 May 2004 (UTC)


 * But they didn't build a darn thing. They talk about building things, and put absolutely no detail into it.  They assume that you can make a V2 reach orbit by spending 10 times more money (with no specifics).  You can't.  If it were that simple, every country and a few large cities would have their own space program.  It's not remotely, even the tiniest bit, that simple.  It is all completely uneducated speculation not worthy of the few kilobytes of disk space it's written on.    The V2 was cheap not because it was "mass produced" more than conventional rockets.  The V2 was cheap because it was a mere SRBM, built with slave labor.  ...  Rei 21:54, 7 May 2004 (UTC)


 * Y'know, that is what they were saying in 2004. But by the time the elevator opened in 2054 (amazingly they were on time but the budget had been blown!) the elevator had significant competition from AutoCAD Rocketry.  And AutoCAD weren't the only players:  Wwoods Inc was nearly as cheap.  Paul Beardsell 22:00, 7 May 2004 (UTC)


 * Oh, I get your joke now. Ha.  ...

Y'know, I will try very hard (but I will fail) not to say "I told you so" when someone comes up with some more authoritative source for reducing rocketing costs. Paul Beardsell 23:55, 7 May 2004 (UTC)

Justification of the Space Elevator
As I suspected (and as you all knew) it seems that the economic justification of the space elevator depends on lifting a whole lot more stuff into orbit than we currently do. If all we want to do is to have GPS (and the new Euro equivalent) and telecoms and weather forecasting and infra red astronomy and the occasional probe to the rings of Saturn then the financial justification of the elevator is difficult.

So, what is the elevator for?

Can we not remind ourselves that the solar system has no other planet which is habitable on economic grounds. That no nearby star has a habitable planet. That we could do a lot with US$40bn other than build an elevator.

Paul Beardsell 23:55, 7 May 2004 (UTC)


 * Holy potatoes, I spend a day away from Wikipedia and this talk: page doubles in size to 100 kilobytes. Sorry I left you to do all the heavy lifting, Rei. Anyway, Paul, the purpose of a space elevator would be to lift a whole lot more stuff into orbit than we currently do. Do you think the only things that can be done in space are the things that we've already been doing for the past few decades, launching handfuls of small robotic satellites and probes? There's tons of other stuff that could be done - colonization of the Moon, Mars, and other bodies (just because you can't walk around in shirt sleeves doesn't mean they aren't habitable, it simply requires more work to live there), the construction of solar power satellites, etc. If all you want to do is what we're already doing then of course a space elevator would be pointless; the whole point of having a space elevator (or other cheap "mass transit" system for getting stuff to and from orbit) is to expand the scope of the things that people can do there. Bryan 00:13, 8 May 2004 (UTC)

And I thought I (or we) had annoyed you into staying away. Recently I have wanted to reflect in the article that in order to justify the elevator that we must want lift a whole lot more mass than we do. I have been frustrated in that. Paul Beardsell 00:23, 8 May 2004 (UTC)


 * How much mass *did* we lift into orbit last year ? -- DavidCary 17:23, 11 May 2004 (UTC)


 * You want a justification for cheaper access to space? Here's one: Gold, silver, platinum, rhenium, and other rare metals.  There are several hundred near earth metallic asteroids with an average 1.4 *trillion* dollars worth of rare metals in a form far purer than is typically ever found on earth (due to the way that they're formed).  Even better, asteroids are often relatively poorly held together, and if they have any significant rotational momentum, mini-elevators (made out of materials as mundane as steel, and only a few miles long) can toss the mined material back to earth with no energy required, and power can be generated by tossing junk out into space.   Even with conventional lift costs, this is being seriously considered.  With low lift costs, it would be a *huge* industry. Rei 00:35, 8 May 2004 (UTC)

Economics NPOV
I dispute that any reading of the current version of the Economics section allows it NPOV status. My issues are Paul Beardsell 18:11, 10 May 2004 (UTC)
 * It reads as if no capital or turnaround costs are recovered from the currently charged launch costs.
 * If any figures have been given in support of this assertion they are shuttle-only figures - rocket figures are not given.
 * Ariane 5 fuel costs are in the same ballpark as (or better than) the elevator electricity costs once the Edwards inefficiency figures of 2% or worse are factored in. The cost of fabricating the rocket does not account for the remainder of the $25,000 cost.  So (at least some) turnaround/launch/capital costs are in there somewhere.


 * ... 1) The shuttle and Ariane DO NOT include their capital costs in their launch cost, so it is completely unfair to do so here.  I've already demonstrated this to you concerning the shuttle - lookup their turnaround cost (I already quoted it), look up their payload (also quoted), and do the math.  2)  If you want me to do the math for the Ariane as well, I will, but I can guarantee you they use the exact same scheme.  3) It's not just fuel costs.  There are tons of cost associated with the turnaround.  ... there is a reason that rocket launches cost so much?  The implication of your argument is that all of the collective brain trust of the USA, USSR, ESA, Chinese, etc, are just fools for not seing this.  That is not the case.


 * In short, we have a development cost around what the shuttle's development cost was (in modern dollars). We have the same accounting system as the shuttle.  The Ariane works similarly.  What is the problem? Rei 18:58, 10 May 2004 (UTC)

Once again you put words in my mouth: I did not say it's just fuel costs. I acknowledged, if you read what I wrote with the slightest care, there are other costs. But you make unsupported assertions. Feel free to do the maths for the Ariane. Surely it is the intellectual duty of they who assert the elevator is cheaper to properly back up their assertions. I did not introduce the Economics section here. But if it is here it must be NPOV. Oh, and as I have to say every time: I have not said anything about the Shuttle costs. Paul Beardsell 19:29, 10 May 2004 (UTC)