Talk:Space elevator/Archive 4

Anonymous Economic Evaluation

 * ''This anonymous IP (4.232.144.53(talk)) economic evaluation was moved from the main article page. It likely has some valid points, but it is too long for the main article.  Also, it is written in first person, and talks directly to the reader in second person, both violations of Wikipedia style.  Any valid points need to be summarized and put into the Economics section.  If it is rewrittend and scanned for validity, it might be suitable for inclusion in the Space elevator economics article.

WERTMULLER'S EVALUATION This article - "Space Elevator Economics" - as presented before December 26 2005, was severely flawed.

First there was no consideration of dramatic improvements in alternative space technologies. For example, Bert Rutan's Space Ship One completed two flights to an altitude of 100 km and a speed of Mach 3 carrying a payload equal to three men at phenomenal low cost in just the past year. Space Ship One weighs less than 10 000 pounds. See Wikipedia "Scaled Composites SpaceShipOne". It is carried from the ground to a launch altitude of about forty thousand feet by a special mothership. Such "lift-launch" spacecraft are more efficient than simple rockets. Yet this technology was not compared at all to the space elevator. And "lift-launch orbiters" will surely be improved. Consider what Burt Rutan could launch if he leased and used the new Airbus A380 for his ground launch mothership. See Wikipedia "Airbus A380".

So the economics of other technologies has probably been mistated towards the high side. Meanwhile, the economics of the space elevator have undoubtedly been mistated on the low side due to mistakes regarding the basic physics of tethered space elevators. I will present the corrected physics here in this section. I recommend leaving the current mistakes in the "Physics" section unchanged so that new readers can comprehend what has transpired. The best way to understand everything is to perform "Gedanken" experiments......

You are floating in space in your space suit in absolutely perfect geosynchronous Earth orbit. You gently unholster your favorite weapon - a grenade launcher - and fire one off in precisely the opposite direction from Earth.

Conservation of momentum and energy together with Newton's Third Law means you move initially with a small constant linear velocity towards Earth. See Wikipedia "Newton's Laws of Motion". But you are in orbit! This means you have both linear and angular velocity relative to Earth. Your angular velocity is your number of orbits around Earth per unit of time - exactly one revolution per 24 hours at first. Your linear velocity in geosynchronous orbit is roughly 7 000 miles per hour - straight "east". You would fly off straight into space but gravity pulls you around in a circle. Newtonian physics dictates that this linear velocity remains unchanged unless some force changes it.

But you are moving closer to Earth because of the grenade so you are traveling around in a smaller and smaller circle around Earth. Smaller circle; Same linear speed. You circle the Earth in slightly less time. You are no longer in geosynchronous orbit.


 * Not correct. Due conservation of angular momentum around the Earth, you're still in geosynchronous orbit, but you've changed your eccentricity. (You're now in an elliptical orbit, but still with a period of 1 day).WolfKeeper 15:53, 27 December 2005 (UTC)


 * Good point but I am attempting to speak to non-physicists. Elliptic orbit still means "disturbance:.

You also are no longer "stabile". Since you travel around Earth in slightly less time, you have higher angular velocity hence higher centrifugal force. This higher centrifugal force throws you away from Earth counteracting the inward speed you got from your grenade. The grenade launch is actually a brief linear impulse which does not remain directed at the Earth's center as you fly around curving thru space, but we can ignore this non-Earth-centricity for a short time for simpler exposition with little error. In due time you stop moving in or out from Earth and stabilize in a lower, faster, non-geosynchronous orbit.


 * Sorry, not quite.WolfKeeper 15:53, 27 December 2005 (UTC)

The exact same forces occur in reverse if you push yourself away from Earth, that is, if you fire a grenade towards Earth. You would keep the same linear velocity in a larger orbit; lose angular velocity; lose some slight centrifugal actually centripetal force;  and stabilize at a higher, slower, non-geosynchronous orbit. Changes in angular velocity with changing orbital altitude is directly related to the Coriolis Effect. See Wikipedia "Coriolis Effect".

DEPLOYMENT The forces described above greatly complicate the deployment of a tethered space elevator. Again we assume you are in perfect geosynchronous orbit. An alien from another galaxy drops off a complete space elevator kit without making the slightest gravitational wave or other distrubance. Following the included easily comprehended directions, you begin unwinding the thousands of miles of graphite ribbon. But the ribbon does not drop down to Earth.

No object changes its state of motion unless it is forced to do so. Newton's Laws. If you spin a reel of tether in space centripetal force will pull all the ribbon en masse off the reel in a tangled mess. It will not "unwind" like an elevator cable on Earth which is subject to constant gravitational acceleration - constant force. Hence some method of careful folding might be best when transporting space tether tape.

But then you must unfold it. It will not unfold itself. It will just "hang" there in orbit wherever some rocket unloaded it. Most likely you will use some kind of little rocket propelled tractor to pull the tape towards Earth. And you pull the other end away from Earth. And for every inch of movement, you encounter the exact same forces described above. Higher angular velocity in lower orbits destroying geosynchronicity. Rocket-propelled correction required. Continuously. During all unfolding and movement. Likewise lower angular velocity in higher orbit. Rocket firing will be required at both ends of the tape during all deployment movements. Thousands of miles. Hundreds of hours. Weeks. Months. A year?

The cost of this deployment operation was not even mentioned in the "Space Elevator" Wikipedia entry as it existed before December 26, 2005. And there is another cost underestimate which may be even more problematic. The December 25 2005 Wikipedia article contained these words:

"Launching Into Outer Space As a payload is lifted up a space elevator, it gains not only altitude but angular momentum as well. This angular momentum is taken from Earth's own rotation......"

The climber does not gain angular momentum solely from the Earth. Any object sitting on the surface of the earth at the equator is moving with angular velocity of exactly one revolution per 24 hours and a linear velocity of roughly 1 000 miles per hour. A satellite in perfect geosynchronous orbit also has an angular velocity of exactly one revolution per 24 hours but a linear velocity of roughly 7 000 miles per hour. Climbers do not obtain their velocity increase strictly from Earth. Every climber will distort the tape slightly and will pull on BOTH the elevator structure - including any counterweight - as well as the Earth. The climbers "want" to go "slower" slower angularlly as they go higher at every point. As climbers climb higher, more and more of this backward pull is levied upon the elevator and counterweight.


 * Yes.WolfKeeper 15:53, 27 December 2005 (UTC)

The backward pull slows the velocity of the entire elevator structure. The entire system - climber plus elevator - wants to rotate and "lie down" upon the Earth. The size of the backword force depends on how fast the climber climbs. If it goes up fast, it gains linear horizontal velocity faster which which requires greater horizontal force to create the acceleration. You cannot defeat Newton's Laws. A greater horizontal accelerating force on the climber means a greater horizontal retarding force on the Earth-Elevator system. The climber is accelerated to 7 000 mph and the elevator is correspondingly slowed, albeit less because of greater mass. Conservation of energy cannot be denied. The climber gains momentum and the elevator loses momentum. The elevator will have to be pulled back to proper velocity and position by a rocket motor firing at the far space end of the elevator during all climbing.


 * Actually, no. The elevator cable below the elevator car takes on a lean- about 1 degree at 200km/h. This lean means the Earth is pulling on the Space Elevator sideways, accelerating it. So the Earth is slowing minutely, as the car climbs. But the overall energy and angular momentum is conserved. So no rockets are needed. If the car was to go a lot faster it would be very different thing though; the elevator would indeed fall over if the center of mass went below GEO. Part of the design is to make sure that the center of mass is far enough above GEO that any likely lean on the cable will prevent it from 'falling over'.WolfKeeper 15:53, 27 December 2005 (UTC)


 * Actually yes. Anything other than a truly perfect geosynchronous orbit will be intolerable. It  will degrade worse and worse.  Truly perfect means circular and alinged with the equator.  A perfectly circular orbit tilted with respecty to Earth's axis making figure eights in the sky will be intolerable.  An elliptic orbit will be intolerable.  And as the climber approaches the goestation, it DOES affect the station, not just the Earth.  a geostation with a 100 000 km extended counter weight will never "fall" but in the most extreme case it will wrap the tether around the Earth a short ways while oscillating wildly.  Not acceptable.

Thus both construction and operation of a tethered space elevator will be more costly than implied by the previous Wikipedia article.

There is an alternative. Attach a tether to the Moon instead of Earth. Allow a low orbit space station to "hang" close to Earth while dragged around from the Moon. The low altitude space station would be motionless relative to the Moon but would fly "backwards" relative to other Earth satellites. The Earth would be spinning around at a thousand miles per hour underneath the effectively motionless "satellite". Such a near-earth station would actually "hang" - it would not be held in place by centripetal force. The Earth would spin around every 24 hours below while the hanging station stayed motionless with the Moon. Low cost orbiters like Burt Rutan's Space Ship One could rendevzous with this slow moving space station just like fighter aircraft rendevzous with aerial tankers. There is still abundant uncertainty of cost and feasibility.


 * end of anonymous economic evaluation moved from the article page. Hu 09:37, 26 December 2005 (UTC)

Anonymous Economic Evaluation
I posted the "anonymous economic evaluation" and herewith present an improved entry. Dudes: Somebody gotta post this in the main article. The Institute for Scientific Research is very nearly committing criminal fraud. IF NOT SEVERE ERROR, THEN con artistry. Capiche?

ECONOMICS RECONSIDERED

The Wikipedia Space Elevator article as presented before Christmas 2005 underestimates the cost of a tethered elevator due to a severe error in the basic physical design. The previous economic analysis also underestimates progress made with other technologies. See Wikipedia "Scaled Composites SpaceShipOne" and consider the added implications of the Wikipedia article "Airbus A380".

"Space Elevator" Section 2.5 contains the sentence "The angular momentum is taken from the Earth's own rotation." This is the same as saying that a bridge with two uneven supports - one larger than the other - is supported only by the larger support, which is absurd. Increased angular momentum is transferred to a climber via the Coriolis Effect. See Wikipedia "Coriolis Effect". Any climber on a space tether will gain angular momentum from both the Earth and the tether structure. The effect on the space end of the tether will be to pull it down and backward. The tether / counterweight structure will be pulled out of geosynchronous orbit. To pull it back will require a rocket motor firing nearly continuously at the space end of the tether. This implies enormous costs for fuel and refueling.

Installation of a tether involves similar problems. A reel of carbon tape unloaded from the Space Shuttle in geosynchronous orbit will not unwind itself. One end must be pulled into space with some kind of rocket tractor and the other end must be pulled to Earth. At all points of this unwinding operation the rocket tractors must compensate for the very same Coriolis effects. Installation thus means many many hours of very precise rocket firing with attendent costs. You cannot defeat conservation of energy. The Space Elevator disguises the energy of space acceleration as Coriolis Effect. One possible alternative is to deploy a tether all the way from the Moon to somewhere near the Earth. A space station then might literally hang near Earth. It would not be held up by centrifugal force. It would actually hang from the Moon. It would be motionless relative to the Moon. The daily rotation of the Earth would make it appear as if this station was flying towards the west at 1 000 miles per hour. Low cost orbitors such as SpaceShipOne could then rendevzous with this station and from there pull cargo all the way to the Moon. The Moon would sacrifice an unmeasureable amount of momentum.


 * May I suggest that a Wikipedia article's discussion forum may not be the optimal place for allegations of fraud or incompetence? You surely won't get many eyeballs on the problem.  A better place would be the Yahoo SE mail list at http://groups.yahoo.com/group/space-elevator/ or Liftport's Forum at http://www.liftport.com/forums/


 * Note that ISR has been quiet WRT space elevator's since Brad Edwards departure. I am not sure what this means, or what import - if any - it has. brian dunbar


 * Thank you for your comment. I am sure you are right.  The space elevator has garnered such enthusiasm; such attention; is a featured article; that pointing out catastrophic high-school level errors will likely be unwelcome.  But needs to be said sometime.  I doubt that fraud is the problem.  Rather some kind of mania.  That is why I try to offer some kind of alternate fantasy trip.  Call them "Moonbelts".  Maybe?  -- HRW


 * Thank you again Brian for the news that Edwards left ISR. I do not know where to read news of this sort.  Having just read wikipedia regarding 'Nanotubes' I suspect Edwards heard rumors inre nanotube strength and decided to quietly exit the wild, whacky, manic, traveling space elevator show. Therealhrw 04:03, 29 December 2005 (UTC)


 * Your post contains a number of errors. For one, keeping the space station in orbit would not require 'a rocket motor firing nearly continuously at the space end of the tether', as the space station is continually pulling the cable tout through centripetal force, as it is in orbit beyond the geosynchronous orbit you imagine. In light of such, rather obvious and glaring errors, it's hard to take your post seriously. Something isn't 'con artistry' simply because you do not understand it. -- Ec5618 10:15, 27 December 2005 (UTC)


 * No, no glaring error by HRW. Glaring error in Section 2.5.  Thinkabout it.  Coriolis force sideways at point of climber.  'Taut' tether like giant spring.  SOME slight displacement - movement - in tether / counterweight system even tho 'taut'.  NO displacement tolerable - not if there will be thousands of climber trips.  You think space elevator disposable?.


 * Any displacement of the cable or the entire system is temporary, because the system will 'spring back', powered by the centripetal force on the space station. I'm sorry, but why do you so steadfastly believe that you have found a glaring error, when dozens of qualified scientists see no impassable hurdle outside of the required tensile strength in the cable? -- Ec5618 13:59, 27 December 2005 (UTC)


 * No, tether / weight system does not just spring back. As soon as you change position of stuff in orbit it starts to rotate - different angular velocities at different altitudes.  I have wondered about the 'conspiracy of silence".  Maybe publishers like Discover magazine want circulation and don't care about disinformation?  Ever hear about Borna virus and mental illness? What happened there?

Climber Design
I offer another revision proposal for the Space Elevator article......


 * Wertmuller's Climber Design

Climbers could be equipped with sideways firing rocket motors to combat the Coriolis Effect. Some have argued that uncompensated Coriolis Effects would ruin the entire Space Elevator system, causing a loss of geosynchronicity thereby forcing prohibitevly costly rocket-powered realigmnment of the tether and counterweight. To avoid disturbing the tether / counterweight system, each climber could have a small sideways-firing rocket capable of exactly countering any Coriolis effects generated by the climber.


 * The most desireable propellants from an environmental view would be the components of the atmosphere - nitrogen, oxygen, or carbon dioxide. The quantities of carbon dioxide involved would be near nothing compared to ground vehicle emissions.  One of these propellants could be stored in frozen liquid or solid form and then heated and expelled using electric power - from whatever power supply system is invented for climbers.  If the carbon nanottube tether could be made conductive, alternating electric current could be fed into the tether at ground level and extracted by climbers thru capacitor banks at virtually any location.


 * A 5000 pound climber might have 4000 pounds of propellant and a 1000 pound payload. To completely avoid Coriolis disturbances, the rocket motor would be fired both when climbing and descending.

Dudes, you gotta face the fact that as it now stands, the Space Elevator article / design is outrageously wrong. As pointed out in my previous posts, the Earth alone does not drag the climbers to higher angular momentum. That is the same as saying only one of two supports carries all the load on a bridge. The climbers exert Coriolois force on both the Earth and the counterweight ((or vice versa)) thereby gaining momentum. And the slightest distuturbance of counterweight geosynchronicity will need to be corrected at some point.

Brian Dunbar I greatly appreciate your replies. I want to repeat that I am complaining about such a primitive, pivotal error that it ALMOST looks like fraud. But I lean strongly toward believing in outrageous error. It has happened before. Constantly. Seems to be something human...... Therealhrw 08:55, 27 December 2005 (UTC)


 * Please stop calling everyone 'dude'. -- Ec5618 14:03, 27 December 2005 (UTC)


 * Okee Doke. Call you Something Else Sir. --therealhrw.


 * OMG I just finished reading this brilliant indictment of the SE concept. And to think I just put my Liftport stock certificate in safety deposit! Not only is the space elevator a fraud, but so is basic physics! I call upon the participants of this talk page to join with me and Therealhrw to create our own physics and then create our own space elevator based on this new theory. Who's with me?!!! Plowboylifestyle 16:19, 27 December 2005 (UTC)

Climber Design II
A revision of my previous proposed main article revision:


 * Wertmuller's Rockets
 * Climbers could be equipped with sideways firing rocket motors to combat Coriolis effects. Some have argued that uncompensated Coriolis effects would ruin the entire Space Elevator system, causing a loss of geosynchronicity thereby forcing prohibitevly costly rocket-powered realigmnment of the tether and counterweight.  To avoid disturbing the tether / counterweight system, each climber could have a small sideways-firing rocket capable of exactly countering any Coriolis effects generated by the climber.  The required compensation is small.  If a climber takes 100 hours to climb from Earth to geostationary platform,  the necessary sideways acceleration is roughly  1/50  ft/sec/sec  for the entire 100 hour (360 000 second) climb.  To completely avoid systemic Coriolis disturbances, the rocket motor would be fired both climbing and descending.


 * The most desireable propellants from an environmental view would be the components of the atmosphere - nitrogen, oxygen, or carbon dioxide. The quantities of carbon dioxide involved would be near nothing compared to ground vehicle emissions.  One of these propellants could be stored in frozen liquid or solid form and then heated and expelled using electric power - from whatever power supply system is invented for climbers.  If the carbon nanotube tether could be made conductive, alternating electric current could be fed into the tether at ground level and extracted thru capacitor banks on board climbers.  Such a climber might have 4000 pounds of propellant and a 1000 pound payload.  An ion rocket engine with extremely high propellant exhaust velocity could reduce the amount of propellant required thereby achieveing higher overall efficiency.


 * If reels of carbon tape are delivered to geosynchronous orbit by some means such as the Space Shuttle when first building a Space Elevator, the ends of the tape would need to be pulled into position by similar high-efficiency, high-precision, long-burn rocket engines. The tape will not fly into position by itself.  Supplying power to the the deployment tractor engines is much more problematic.

Construction And Decay
Wolfkeeper's replies regarding orbital decay and elliptic orbits are well made "Econonmic Evaluation". But it is a fact that climbers *will* affect the motion of the space end of a space elevator. A climber nearing the geostation will exert a negative acceleration (negative with respective to orbital motion) on the station / counterweight due to Coriolis effects. This negative impulse will add a slight negative velocity to the far end of the structure. The entire structure will "try" to wrap itself around the Earth, albeit imperceptibly at first. The connection of the tether to the ground will prevent continued westward motion leading to complex counter forces. These counter forces and continued westward impulses from climbers will lead to a complex decay of the position and motion of the elevator.


 * Nope. The car moves the geostation about 1 degree to the west of the attachment point; but the centrifugal (remember we're in a rotating reference frame, so centrifugal is 'real') acts directly away from the Earths axis. So there is a restoring force pushing the cable/station/car back above the attachment point on the Earth due to the non vertical component of the tension in the cable. It's also critical to remember that the geostation ISN'T in orbit. It's moving too fast to be in orbit, it's above GEO, and hanging on the cable, but rotating around the Earth axis once a day, so it goes further than an object in GEO per day- it's faster. By way of contrast, orbital velocity goes *down* the higher you are, since the gravity is lower there.WolfKeeper 01:58, 28 December 2005 (UTC)

If you say you are going to store so much energy in the station / counterweight system that all perturbations will be acceptably small even for so many - millions? - of tons of payload, you are saying you are going to fire rocket tractors for hours; days;  weeks;  months;  hauling everything into place during construction and then use the stored energy later to climb into space without rockets.


 * Nope. Space Elevators are passive (except for the cars, and possibly moving the base around.)WolfKeeper 01:58, 28 December 2005 (UTC)

Why? Why not just fire a rocket when you want to go into space? Like Burt Rutan?


 * Burt Rutan's is suborbital. Space Elevators allow access to *GEO*.WolfKeeper 01:58, 28 December 2005 (UTC)

There remains the possibility of building uniquely efficient rockets either for construction or Coriolis compensation. This is the subject of my "Wertmuller's Rockets" proposed revision. Please read it. --THEREALHRW


 * Actually, as long as the elevator's center of mass is out beyond geosynchronous (as it is in all serious design proposals) you don't need to fire any rockets to keep the elevator up. The angular momentum imparted to the rising climber comes directly out of Earth's rotation, not out of "stored energy" put into the system during the elevator's construction. The tug of the tether's connection with the ground as the elevator "tries" to move west adds back the momentum that was given to the climber, restoring the elevator's orbit and preventing decay. Bryan 01:05, 28 December 2005 (UTC)


 * Please come off of your high horse, Therealhrw; you did not just find a major flaw in the concept of space elevators. 'Wertmuller's Rockets', indeed. Incidently, even if you had found such a flaw, it would constitute original research, and could not be included. Now please stop spamming this page with nonsensical 'theories'. -- Ec5618 21:21, 28 December 2005 (UTC)


 * Finally understand it. Thank you all for your patient responses.  I dare not get off my high horse because if I do, intestinal gas esccapes. Therealhrw 03:18, 29 December 2005 (UTC)

Archive Anyone?
If no objection posted here in next couple days, I will attempt to create archive within this page; titled 'Newbie's Arguements";  and move all my spam-grade entrys and related replies thereto.  This would be entries 29, 30, 31, 32  and 33. Therealhrw 09:30, 30 December 2005 (UTC)


 * I have no objection, though I would suggest an different description. Therealhrw's arguments, perhaps, or Therealhrw's newbie arguments. Just 'newbie' makes it sound like a repository for newbies, and something all newbies should refer to. 'One newbie's regretable arguments' might work, if you agree with the sentiment. -- Ec5618 00:30, 31 December 2005 (UTC)


 * I would prefer "Arguement With HRWertmuller" Therealhrw 00:54, 31 December 2005 (UTC)

An Explanation
A little explanation here regarding my arrogant irrational persistence. A long time ago I told Frank Thornburg about the space elevator from my si fi reading. He said it wouldn't work. Frank was a really heavy duty aerospace engineer who worked on the kind of stuff you cannot talk about. I effectively relayed his criticisms to you after only the barest skimming of the article. With what I knew and that "asteroid" top front on the article, it really looked like a bunch of cold fusion con artists dragging around some dumb wikipedians. You might remove the asteroid.

The section on "Launching Into Space" might be improved. You might write: ''The spaced elevator transmits forces in and out of the Earth as long as there is tension on the tether. A rough analogy would be a monorail with a sail hanging loosely underneath. If a wind blows the loose sail, it just flaps. But if the sail is weighted, any wind will push the monorail. The Earth is the monorail. The sail is the space elevator. The wind is the force added or subtracted to Earth's rotation by climbers going up and down. ''

Thank you all. I have learned about both space propulsion and wikipedians. Therealhrw 00:50, 31 December 2005 (UTC)


 * The 'Launching to Space' section does not need replacing with your proposed text. What you're suggesting is to replace a reasonable explanation using appropriate concepts with analogy, which in my experience rarely works.  A better analogy that you provided might work for a 'FAQ' or an elementary tutorial but not a wikipedia entry. Bdunbar 12:40, 2 January 2006 (UTC)