Author Topic: Promise to reliable and economic space access: candidates of future propulsion tech  (Read 30593 times)

Offline 8900

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Let's discuss some advanced transportation concepts and their feasibility in this century
they may one day bring RELIABLE and ECONOMIC MANNED/UNMANNED space access
I've found this question quite interesting
the shuttle was supposed to accomplish this job, but it failed
There are some candidate technology
[1] Scramjet technology
[2] Superconducting Mass Driver
[3] Space elevator
[4] a combination of [1] and [2]
[5] fully reusable rocket
[6] or you may think of other alternatives
but some may think reliable and economic space access will never come true
no matter which idea you support, let's discuss the different possibilities

Offline neviden

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Offline MTKeshe

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Gravitational systems in collaboration with propulsion systems

Offline khallow

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[8] Expendable rocket

Probably the best choice in today's economic climate. I just don't see a more reliable solution replacing expendables until launch volume goes up substantially.
Karl Hallowell

Offline 8900

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khallow - 21/12/2007  6:21 PM

[8] Expendable rocket

Probably the best choice in today's economic climate. I just don't see a more reliable solution replacing expendables until launch volume goes up substantially.
please note that it's a prediction by 2100, not current situation ;)
It seems unlikely that the launch demand will be the same 100 years later

And what is MagBeam and Gravitational......
I haven't heard them before, can u explain a little bit? :cool:

Offline neviden

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MagBeam is quite an interesting concept (if we could make it work of course). You create focused beam of plasma and shoot it at payload. Payload then uses its own magnetic field, so that it can use that energy and momentum.

What that practically means is that you would have something like heavy high-powered SEP/NEP system in LEO. You launch your rocket straight up to get sufficiently high (above atmosphere) and then beam your power to achieve orbital velocity. Because we don’t have to carry the power source and propellant with us SSTO becomes quite practical and doable. 3 km/s reduction in needed delta-v to achieve LEO would be revolutionary.  

But it doesn’t end there. Once in LEO you can shoot to your payload again to change it to HEO, TLI, TMI or anywhere else. And since you leave your power source at home this means you get everything you would want: high acceleration, high delta-v, high isp. This means that you could get to mars in days or weeks instead of months. In sci-fi terms we are talking about something that would function like “Jump gate”, with the exception that it could actually work.

http://www.ess.washington.edu/Space/magbeam/WingleePhaseI_final.pdf

Offline MTKeshe

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Gravitational system is the one  which creates natural gravitational field force within  a rector, very much like earth gravitational field forces , which causes the craft which the system is attached to, for the craft to posses gravitational field force like earth, and by reducing the strength of this field or increasing it strength of the filed , one allows attraction and repulsion of the craft in respect to the central gravitational field of the given planet.

The initial systems for this has been tested and confirms this is achievable.

This system has an advantage , that due to its magnetic gravitational field force inherent principle, the system will create its own magnetospherice protection around the craft, very much like our atmosphere around our earth.

NASA has done a number of development in this respect, and as far as we know from Chinese space agency,  according to internal sources, Chinese are already developing and testing very similar principles.

With this technology , the propulsion engines and rocket technology for taking off becomes out of date, but using propulsion system once air born, will allow manoeuvrability in atmospheric and space motion for change of direction or correction in the direction of motion.

A Prototype of this system is about the size of a football and weight about less than 10 KG, and in full operation should be able to lift a few tons and coverage of 50-80 meter diameter magnetosphere area .

The participant on this forum from Marshall Space Flight Centre can enlighten us more regarding this technology.

Offline meiza

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[1] Scramjet technology

Not useful for spaceflight. It is an atmospheric cruise technology. High mass, high drag, low thrust, expensive, hot. Space launch is an acceleration mission, not cruise. Rocket engines have very high T/W.

[2] Superconducting Mass Driver

Not useful. The earth has an atmosphere which prevents all such launches. The stress of the launch is immense too.
On the moon, a sling is much much simpler and cheaper.

[3] Space elevator

Perhaps. The material and energy demands are extremely hard technical problems. The capital cost is huge. If the materials are developed, remember that the competing alternatives can use the materials too.

[5] fully reusable rocket

Getting closer here...

[6] or you may think of other alternatives

A partially reusable rocket would be the first step. It requires no radical new fundamental technologies, but patient development and testing. STS is just one example that doesn't work very well, but it doesn't mean the concept sucks.
Initial markets would help to increase launch rates and thus make reusable launch vehicles profitable and spaceflight cheaper.

Offline mikes

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[3] Space elevator
The material and energy demands are extremely hard technical problems.
Material, yes. Why energy? I understood it to be "just" precision-pointing a fairly high-power laser at the climber. Is the pointing regarded as well beyond current SOTA, or are there other problems?

thanks

Mike

Offline A_M_Swallow

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mikes - 21/12/2007  12:02 AM

Material, yes. Why energy? I understood it to be "just" precision-pointing a fairly high-power laser at the climber. Is the pointing regarded as well beyond current SOTA, or are there other problems?


c/fairly/very/

The climber's motors need several mega-watts of power.  So the laser needs to send something like 6 MW 24 hours a day, 365 days a year.  Designing that laser will cost a $1bn is its own right.

The space elevator people claim super laser is not a weapon whilst requesting the FAA make the beam path restricted airspace so no one flies through it.

All that energy gets converted into heat so the ribbon will glow yellow hot, the climbers will have enormous photo-voltaic panels and large radiators.  Due to the effects of the wind the panels and radiators cannot be deployed until the climbers are above the atmosphere.

Offline MKremer

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A_M_Swallow - 21/12/2007  7:01 PM
The space elevator people claim super laser is not a weapon whilst requesting the FAA make the beam path restricted airspace so no one flies through it.
The beam will be in the same plane as the ribbon and close enough that both ribbon and beam would fall under the same airspace restrictions.

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All that energy gets converted into heat so the ribbon will glow yellow hot, the climbers will have enormous photo-voltaic panels and large radiators.  Due to the effects of the wind the panels and radiators cannot be deployed until the climbers are above the atmosphere.
Huh? If the laser has a focus on the climber's reciever, why would the ribbon be involved in any heating? In the case of a full-sized ribbon and climber, the recieving area(s) would be extended away from the climber/ribbon itself, and unless the plan is to use the ribbon itself as a heat sink, a power beam shouldn't contact the ribbon at all (unless the beam has a really crappy focus).

Offline A_M_Swallow

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The first laser may be next to the ribbon but subsequent ones will probably be on land in South America and possibly on mountains in the USA.  The extra lasers will allow more than one climber to be on the ribbon.

The ribbon heating is coming from the motors and friction.  Unlike cars on roads the wheels are not air cooled.  To grip the wheels deform, see rolling resistance for details.
http://en.wikipedia.org/wiki/Rolling_resistance

Offline MTKeshe

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Can you please explain how scientists and engineers are going to physically  construct such a cable needed  as per the link given.

May be the electric charge down load to earth has not been considered, and if nano materials are to be used  as a cable?

Can you explain how due to their superconductivity properties, one can handle these geomagnetic planetary charge interferences which cause massive currents within the cable.

I think we need all the substation transformers on earth  to be connected to each other to be able to handle such power and be able to consume all of it too at the same time.

Offline sticksux

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MTKeshe - 21/12/2007  12:36 PM
Gravitational system is the one  which creates natural gravitational field force within  a rector, very much like earth gravitational field forces , which causes the craft which the system is attached to, for the craft to posses gravitational field force like earth, and by reducing the strength of this field or increasing it strength of the filed , one allows attraction and repulsion of the craft in respect to the central gravitational field of the given planet.

What? This does not sound like coherent English, let alone understandable technical description.

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The initial systems for this has been tested and confirms this is achievable.

Never heard anything about it from credible sources.

Offline sticksux

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khallow - 21/12/2007  11:21 AM
[8] Expendable rocket
Probably the best choice in today's economic climate. I just don't see a more reliable solution replacing expendables until launch volume goes up substantially.

My favorite too. With gradual drift towards reusability of some parts.

Offline A_M_Swallow

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MTKeshe - 22/12/2007  9:12 AM
May be the electric charge down load to earth has not been considered, and if nano materials are to be used  as a cable?

Can you explain how due to their superconductivity properties, one can handle these geomagnetic planetary charge interferences which cause massive currents within the cable.

The current space elevator designs assume that high tensile strength carbon nanotubes have a electrical resistivity of 10^-4 ohm-metres.  This makes them only a medium conductor of electricity.

Offline MTKeshe

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This we know as it has been measured by us some two years back (Please see the  link on the site , where we show 10^4 ohms resistance between two wires  measurement ), but in reality radio frequencies in atmosphere make the nano tube cables conductive,  thus they  are conductive all the time  in space .

We have tested this and using  welding arc machine some 5 meters away from the nano cable , the cable losses its resistance totally and become superconductor once the arc is produced ( This test was done in September 2006) .

Picture of test in the lab to show this property of the nano tubes can be posted.

Thus this assumption of 10^ 4 ohms resistance of nano cable will not be applicable in the atmospheric conditions , with all the lightening which are taking place around the earth atmosphere( about 1000 at any time).

Offline mboeller

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Maybe something like this from Phaser Telepropulsion could solve the problem:

http://www.patentstorm.us/patents/6193194-description.html

I read about it first in the JBIS Vol50 April 1997

Offline MTKeshe

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Talking about the gravitational systems for space energy and their use in space travel, one can further conclude.

All celestial bodies simultaneously,  while are generating energy in their inner cores,  they maintain gravitational field forces for attracting elements from their surrounding, and concurrently by the presence of  magnetic field (atmospheric protection) they  protect themselves from floating materials in space  too .

Now that world of science have understood the physical structure and the mechanism by which  celestial bodies can created and maintain all three factors,  a) internal production of energy , which lead’s to creation of b) gravitational field and c) magnetic field.

One can replicate the operation of these planetary mechanism in a simple system , and utilising  them to human advantage, for example for production of clean energy, without any waste, or for motion in space.

The gravitational  systems not only can provide the space industry with unlimited amount of energy. When , used in a given  environment,  they can assist with production or extraction of specific element in any given point in the universe.

For example, in reality, gravitational systems can help to extract CO2 from atmosphere, while the system is used for transportation, and/or for energy production  on other planets for extraction of oxygen and so on allowing development of  human colonies  in space.

In gravitational systems, one can control the strength of field, thus one can generate a gravitational field which can match  gravitational field of any matter, this  being single nitrogen atom or molecules of  CO2.

Gravitational system can be developed that can match gravitational strength of any element or composites of elements.

The development of a gravitational systems that only attracts to itself CO2 for cleaning atmosphere , will solve the dilemma with global warming.

The gravitational strength  can be used to clean- up specific toxic matters from rivers , or for extracting oxygen  from environment of other planets for the survival of space travels of the future.

This is  the principle by which the universal mechanism of existence has worked through from the time of creation.

Where in the cosmos, variation in the gravitational field force of different position in the galaxies , allows different planets to have the ability to hold on to specific element , like helium as in case of Saturn  or a mixture of elements , allowing the creation of planet like earth and so on.

The power to be able to attract any specific matter, is purely being due to interaction and attraction between the internal gravitational field forces, which celestial bodies generate within their sanctum and the gravitation field strength of an atom of a given matter.

If this was not so,  then all planets in solar system would have been made of  mixture of the same elements in their inner construction as earth, which this is not so as we observe.

Where at the same time, as gravitational systems like earth , by their nature, are current generators within their own system ( as we know from the inner cores of the earth operation),  and the instigator for their rotation and  motion in their environment.

Using this knowledge to produce clean energy to one’s advantage, the gravitational systems can be developed  to separate the constituent of matter like the CO2, to release the O2, and be left with carbon as a solid residual.

Where, this carbon as solid matter can be reused for nano matters , construction materials ,or returned into earth as solid carbon.



We Know this is possible and CO2 absorption and Carbon separation through this method of CO2 capture has been confirmed by governmental  independent  test report as of early 2007.

Thus the gravitational systems are /or would be most logical and the possible salvation for control and even reversal of  the global warming due to CO2.

Where,  in space technology , these systems can produce energy, gravitational lift and the illusive shielding for the protection of the same object in any environment.

Not forgetting that to produce such a system does not  cost that much.  

Scientists, have  been told for decades, that,  1000 000 stars are created every day in the galaxies in the universe possessing all these three , of energy, gravitational field force and magnetic field all at the same time.

Now through advancement in technological arena, the principle of working of the planets and stars has been understood and systems to replicate them has been developed and tested.

Where this newly gained knowledge in how to produce planetary  gravitation fields can be used to man’s advantage, in not only creating clean energy without any waste ( in the universe stars and planets travel for billions of years, without leaving any waste in their environment) and maitaing motion in space.

Where Simultaneous  use of  this principle allows the clean-up of the mess which the planet has reached with global warming.

Clean-up or extraction of matter,  while one is travelling in space or even while one is generating energy for immediate consumption is the only option for the travellers of future if space technology is to  achieve long hull space flight of future.

The ability to travel within earth atmosphere was achieved by man copying and replicating bird’s mechanism of flight.

Now the knowledge to replicate the working of universal order of energy and motion has been understood and replicated in simple systems in the recent past , is it not the time that scientists collectively strive to concur the cosmos and free man from the peril of what to come due to progresses of the past?

Offline sticksux

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MTKeshe - 25/12/2007  6:10 PM
Now that world of science have understood the physical structure and the mechanism by which  celestial bodies can created and maintain all three factors,  a) internal production of energy, which lead’s to creation of b) gravitational field and c) magnetic field.

(b) does not follow from (a). 100 km diameter chunk of pure lead will have gravitation field but sure as hell does not generate energy.

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One can replicate the operation of these planetary mechanism in a simple system

We can build gravity generators???! This is big news to me.

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For example, in reality, gravitational systems can help to extract CO2 from atmosphere

Obviously, you live in different reality than I. In my reality, there are no known "gravitational systems". Sorry, coke bottles with electrodes don't count.

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The development of a gravitational systems that only attracts to itself CO2 for cleaning atmosphere, will solve the dilemma with global warming.

Wow, can you build a grav system which attracts only Santa Claus to my house? :)

Offline MTKeshe

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The prototype system producing  gravitational field force is shown in this link

http://www.keshetechnologies.com/keshe_gravity.html

The system is exactly half sphere.

Through tests with full sphere prototypes. http://www.keshetechnologies.com/dynamic_reactors.html ,

it was noted , that to achieve a more effective anti-gravitational field system  semi-spheres are more efficient, and allow use of Hydrogen , where there are no needs for additional systems for ionisation of hydrogen.

The Link for PCT  and European patent  application publication for gravitational system

http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=EP1770717&QPN=EP1770717

There are two further substantial patent applications still to be released.

NASA, USA military labs in England , Marshal space lab,  other space agencies, aircraft and defence organisations and military  organisations in USA have been going through our patents and site like professionals for past years.

Testing these new findings for past two years, and have been running test from these patents.

Do not forget M2P2 project of NASA advance concept program

http://www.space.com/scienceastronomy/solarsystem/m2p2_propulsion_817.html

NASA has  achieved  the use of Argon gas , with use of arc, to produce magnetosphere, without gravitational field forces.

NASA hope to achieve  the use  of  helium in their prototype  in the next few years, if NASA can find the money for advance concept projects, which has been cancelled this year.

Then , may be , then NASA can found development of Hydrogen system , about 10 years after that.

So, Production of magnetospheres  for propulsions are not a dream , but reality, which   NASA has been founding and clearly chasing, but their scientists never understood the concept fully.

We have developed and successfully tested the Hydrogen system, and this has been hard to accept by NASA, and they have made every endeavour to block this technology.

May be  , this is a good point and time to put out the hand  of cooperation , and let personal animosities of the past  to be put a side for the advancement of science to prevail and let lawyers to get back on the table and finish the negotiations.

As the top NASA patent attorney told me , we will run parallels. (But the reality is that one drinks coca cola every day , but no one knows the combination except the firm).

May be  some one in NASA management  to get on the line and bring this feud for past two years to an end, then people will not ask for Santa, but we can get on with real development.

We can release all the regular visits of all above organisations , even with their computer terminals numbers, duration of reading and coping, and pages they have downloaded,  in the past years from  our site.

Finally: Cola bottle is for production of graphene.

In reality one day I might even release the importance of nano matters and graphene in production and control of  gravitational system.

We have released more information on our site than one needs to know.

Is for the wise man to make the connections.

May be Santa has already delivered his X-M gift, but as they say, how can a man in the outback’s whom has always used  candle to light his home, ever going to  appreciate the beauty of a light  generated through complex nuclear power.

Offline meiza

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"The realization of eradication of cancer through non-intrusive treatment without any radiation or medication, by just resetting the energy levels of the defected cells."

Sounds like a good thing.

Offline khallow

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8900 - 21/12/2007  3:34 AM

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khallow - 21/12/2007  6:21 PM

[8] Expendable rocket

Probably the best choice in today's economic climate. I just don't see a more reliable solution replacing expendables until launch volume goes up substantially.
please note that it's a prediction by 2100, not current situation ;)
It seems unlikely that the launch demand will be the same 100 years later

Just remember that you need to get there from here. Seems likely that we'll need to build up demand using cheaper than current expendables and eventually switch to reusables when there's enough demand to support them. It's not clear to me whether any of these other technologies will become feasible economically much less technologically.
Karl Hallowell

Offline MTKeshe

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The gravitational systems are “feasible or economically viable” or “they sound good“.

In the universe the working of an atom ,  a solar system or  galaxies are all based on the same principles.

They all in their physical scale, possess their own internal energy source, their own gravitational field system and  their own magnetosphere cocoon to protect the inner power production centre.

According to US federal government report over  120 000 individuals in USA die of COPD (Chronic obstructive pulmonary disease) a year
http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=35020

The illness causes reduction in lung capacity. In most cases takes an individual to go through the process of living a normal life to gradual , limited movement( 50% lung capacity), home bond (30-40% lung capacity), wheelchair bond, then bed bond and then the use of oxygen cylinders, before the death.

Which this can take up to 20 years of ones life.

To look after these people cost tens of thousands of dollars a year for the nation per person.

Understanding the working of universal gravitational system ,  replicating the same principle and developing simple drinking cups, where by just 1.5 litter of  drinking water a day  from the tap and breathing air which goes through these cups, the gravitational principle has been put to the test.

Where volunteer , with 32% lung capacity,  whom has been home bond with community nurse home help to wash her and cleaning her for 6 years. Where after walking 10 meters, she needed  5 minutes to recover before she could talk in September 30th of 2007.

In less than 6 weeks use of the system, today , she goes shopping for two hours on her own,  doing her own X-M dinner on her own, walking for hundreds of meters a day and cycles for over 4 km in one go.

All this without any medication or any other interference.

In other instances using the variation of gravitational system allows volunteer with fibromyalgia,  starts to live a normal life after 30years of suffering.

http://www.google.be/search?hl=en&sa=X&oi=spell&resnum=0&ct=result&cd=1&q=fibromyalgia&spell=1


Where through gravitational system developed to isolate the damage area in the nerve system, the cause and the area  damage of  multiple sclerosis MS can be identified  http://en.wikipedia.org/wiki/Multiple_sclerosis .

Where further it has become clear that MS is just response to an allergy, which attacks the spinal never protection cover.

Through the use  of gravitational systems, it has become apparent that in our nuclear power systems , we have experience of the same effect by the same element, with the same phenomenon, with similar devastating effect as on  human nerves system with MS.

Read about some study cases in this link http://www.keshetechnologies.com/medical.html  

In space when man will  travel, there will be  no chemist shops round the corner and there are no pharmaceuticals firms to develop new medicine, and we can not carry all medication with space crafts of future.

Illness are created out of unbalances in the plasmatic energy of proteins in human body and change in their  internal gravitational field force.

New germs and bacterias which man will come across in space all will have to have their own plasmatic magnetic field and their own gravitational field force, otherwise they  do not and can notexist.

Thus  the future of deep space exploration depends on being able to support , the life of the crew and passengers and the working of their craft all through one universal order of existence and no more.

The understanding of gravitational systems from sub nuclear to cosmos levels , is the key to successful and sustainable programs.

Where at the same time  development of other  technologies have to be considered and perused, as through accumulated integration with gravitational systems, they will be the solid corner stones of human success in man's jury through space.

Therefore it is right to say  that gravitational systems are “feasible or economically viable” or “they sound good”, depending on their scale of applications.

Offline sticksux

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MTKeshe - 26/12/2007  11:19 PM
The prototype system producing  gravitational field force is shown in this link
http://www.keshetechnologies.com/keshe_gravity.html
The system is exactly half sphere.
Through tests with full sphere prototypes. http://www.keshetechnologies.com/dynamic_reactors.html

I read these web pages and linked pdf. None of them contain even one equation, only scientific sounding nonsense. It does not matter how often you insert words "plasma", "gravitational", "fields" - it does not become more credible in my eyes. No real content there.

Offline MTKeshe

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May be this a valid point, May be there are no equations in any of developments which we have explained.

In most original discoveries of the past, there were no equations, has the human race not benefited by them.

If one needs to have equations for the others to understand the  technologies which is working. Where the working of  the systems have been described and  physically demonstrated.

Then we have achieved in what we set out  to do.

That being the collaboration of other scientists is needed, in trying to explain the working of the system which has physical results and produces physical products, which they can not be denied.

You  are welcome to write the formulas for the working of systems.

If this was a point of criticism, then as I said in a presentation to some scientists ,  I keep the formula of the systems exactly in the same safe as the universe when it created the earth and the solar system.

Then the working of the earth and the existence of the earth is not real as we do not have the formula and equations for its creation.

In any case there are equations and pre-set loading formulas for everything we have explained.

We are engineers and we understand the working of the system, equations are for those  whom need to explain the working.

Offline Nathan

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go to www.emdrive.com

this is the most promising tech i've seen in years. It obeys all laws of physics, is funded by the US government and there is a video of a demonstrator that is shown to work.
Given finite cash, if we want to go to Mars then we should go to Mars.

Offline Frediiiie

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"go to www.emdrive.com

this is the most promising tech i've seen in years. It obeys all laws of physics, is funded by the US government and there is a video of a demonstrator that is shown to work."

The wikipedia article explains the basic problem
http://en.wikipedia.org/wiki/EmDrive
physics as currently understood does not allow violation of mass conservation or energy conservation.
If someone wants to claim that (like emdrive) then there is a whopping great burden of proof on them.

back to the topic.
I think the problem of getting cheaper space access is more one of economics rather than this or that new technology.
What is needed is to move from a situation where every mission has to stand alone to a more generalised systems approach to space.
We need a Bigelow space station where Sats can be serviced.
We need a spacetug on orbit that can bring used sats to this station for refueling & refurbishment This brings down costs by extending satellite life
A Bigelow like inflatable workshop where sats can be brought inside to be worked on in a shirtsleeve environment.
A fuel depot in space.
An ion drive type tug to cart larger loads to the moon or mars
These and other bits of infrastructure when put together make a system where things can be done more easily at lower costs.
After all launch costs are only part of the problem and not even the biggest part.
It also takes pressure off mission designers where everything has to be done in a single package

Offline Nathan

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Frediiiie - 29/12/2007  10:37 AM

"go to www.emdrive.com

this is the most promising tech i've seen in years. It obeys all laws of physics, is funded by the US government and there is a video of a demonstrator that is shown to work."

The wikipedia article explains the basic problem
http://en.wikipedia.org/wiki/EmDrive
physics as currently understood does not allow violation of mass conservation or energy conservation.
If someone wants to claim that (like emdrive) then there is a whopping great burden of proof on them.
There is no violation of momentum or energy. Rather the theory behind the operation uses the theory of relativity very wisely. The wiki article is heavily biased against the proposal - however -if you went to the website you will see a demonstrator in operation! The US govt is funding thruster development. I agree that they have the burden of proof but i can see that they are collecting that proof. Also the theory is valid and well explained. This is not one of the nonsensical ideas that have been throw around in the past. This one has some promise and should not be dismissed lightly. Go see the working demonstrator.

(The nonsense peddelled by one of the other posters on this board should be dismissed as there is no physical theory to back - not one simple equation - not even a working demonstrator).
Given finite cash, if we want to go to Mars then we should go to Mars.

Offline tnphysics

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The EmDrive is nonsense. It violates momentum conservation. Hence it is impossible.

My favorite future propulsion technology is NTR, either the nuclear lightbulb type or a fusion type if that is possible. It is the only high-thrust, high-Isp propulsion candidate out there.

Also, a nuclear lightbulb for a GCNTR has been demonstrated.

Offline khallow

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I agree with tnphysics. The key problem with the EM drive is that there's no mechanism for transfering momentum out of the system. Someone needs to do a proper accounting here. If the system isn't closed, as proponents claim, then they need to close the system and explain where the missing momentum went.
Karl Hallowell

Offline cpcjr

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tnphysics - 29/12/2007  6:52 AM

The EmDrive is nonsense. It violates momentum conservation. Hence it is impossible.

If I understand the concept, it uses the entire rest of the universe as a reaction mass. In other words accelerates but pushing the rest of the universe in the opposite direction. That would not violate conservation of momentum.  

Quote
My favorite future propulsion technology is NTR, either the nuclear lightbulb type or a fusion type if that is possible. It is the only high-thrust, high-Isp propulsion candidate out there.

That said, I agree that the nuclear lightbulb type or fusion  probably the best possibility out there.




Offline GreenGlow

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[6]
   Tethers show that it is possible to generate thrust with the geomagnetic field.   This doesn't require any adjustment to the laws of physics.  Of course tethers are difficult to deploy so may be impractical.  A tether is the only well-known method of generating a force by acting against a magnetic field.  A current loop generates a torque.  By using the geomagnetic or solarmagnetic field to accelerate a spacecraft continuous acceleration is possible.   The force may be small, but is always there. 
« Last Edit: 05/02/2010 03:10 AM by GreenGlow »

Offline tnphysics

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Not enough to reach LEO. Once in space-yes, but VERY slow. Same uses as ion drive, but limited to ionosphere.

Offline GreenGlow

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Not enough to reach LEO. Once in space-yes, but VERY slow. Same uses as ion drive, but limited to ionosphere.

It's a given that rockets will be needed to reach LEO in the foreseeable future.   No one can predict the usefulness of a propulsion system that  to them is only theoretical.   While electrodynamic propulsion is theoretically possible, there is no generally accepted method of achieving it.  A tether that is several km. long and that conducts tens or hundreds of Amps. could produce a very large force by acting against the Earth's magnetic field.  A different method may similarly produce large forces outside of the ionosphere.  It is not impossible.
« Last Edit: 05/02/2010 08:35 PM by GreenGlow »

Offline mlorrey

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Well, I'm looking at the Air Launched Sortie Vehicle concept that the USAF had been considering in the early 1980's. It uses an FDL-7 type spaceplane with the rocket engines on it and some fuel supply, with an underbelly drop tank, all mounted to the dorsal side of a large transport plane like a 747 that would have its engines modified to have afterburners on them.

Once I get a concept modelled in 3d I'll post some pics.
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Offline Solman

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Not enough to reach LEO. Once in space-yes, but VERY slow. Same uses as ion drive, but limited to ionosphere.

It's a given that rockets will be needed to reach LEO in the foreseeable future.   No one can predict the usefulness of a propulsion system that  to them is only theoretical.   While electrodynamic propulsion is theoretically possible, there is no generally accepted method of achieving it.  A tether that is several km. long and that conducts tens or hundreds of Amps. could produce a very large force by acting against the Earth's magnetic field.  A different method may similarly produce large forces outside of the ionosphere.  It is not impossible.

 Electrodynamic tethers can actually be used for getting to LEO.

The hanging type ED tether can start with a tether only a few km long and grow to one thousands of miles long as more tether modules are added. The lower end of the tether will be moving at the orbital velocity of the center of mass of the tether. A payload attached to the low end will cause the tether to lose altitude to gain kinetic energy to accelerate the payload. Provided the mass is not too high relative to that of the tether, the payload will remain high enough that the tether's small force is greater than drag at the payload's new altitude. The tether can then either raise the payload such that it will remain in orbit on its own once released or climbers could be used to raise the payload as the tether climbs back to its original altitude.
 The tether modules provide a reduced velocity to LEO that only gets lower as more sections are added. This stands in stark contrast to the beanstalk type tether which must be complete before it is at all useful. The hanging ED tether can be made of materials we have now since its purpose is to reduce required delta V to LEO not eliminate it and so its length can be less than a beanstalk type and still be useful. Also every tether section or module added after the first one will require less delta V to LEO - quite an advantage.
 As tether length increases, rockets will not need their second stages and more massive payloads can be handled. Eventually scramjets or even airliners could rendevous with the lower end as it gets so slow that it can be extended into the stratosphere because the now enormous tether would have the thrust to overcome considerable atmospheric drag. Regardless of whether it is practical to extend the tether to this extreme, just reducing delta V to practical SSTO level would be quite effective at reducing cost of LEO access.

Sol

Offline Solman

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tnphysics - 29/12/2007  6:52 AM

The EmDrive is nonsense. It violates momentum conservation. Hence it is impossible.

If I understand the concept, it uses the entire rest of the universe as a reaction mass. In other words accelerates but pushing the rest of the universe in the opposite direction. That would not violate conservation of momentum. 

Quote
My favorite future propulsion technology is NTR, either the nuclear lightbulb type or a fusion type if that is possible. It is the only high-thrust, high-Isp propulsion candidate out there.

That said, I agree that the nuclear lightbulb type or fusion  probably the best possibility out there.

 That's like saying unobtanium is needed given today's economy isn't it?

Now while it may be technically true that NTR is the only high thrust high Isp propulsion; Solar thermal has higher Isp than solid core NTR and can acheive as much as .1 gee. By using a series of thrusts at perigee, an STR can still take advantage of the Oberth effect especially if lower Isp used for final thrust by increasing H2 mass flow rate. Overall the efficiency can come very close to NTR for something like Mars with only a week or two more time getting away from Earth.

 I was once told that the problem with STR tech was that it was too inexpensive.

 The use of advanced concentrators can greatly increase STR performance. By using a tech I call inflation insitu-form with deradable elements, I believe concentrators with specific power in excess of 100KW/kg could be formed. These concentrators would inflate to shape once on orbit and UV would degrade some parts and harden others to form a mirror with holes smaller than visible light wavelengths. Such concentrators would be able to exceed the thrust of solid core NTR at higher Isp and much lower cost.

 The concentrator can also be used for concentrator type PV which has efficiencies approaching 40% at around 1 KW/kg. It can also be used for high baud communications, radio telescope, ISRU solar furnace and other applications.

Sol 





Offline Jim

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Well, I'm looking at the Air Launched Sortie Vehicle concept that the USAF had been considering in the early 1980's. It uses an FDL-7 type spaceplane with the rocket engines on it and some fuel supply, with an underbelly drop tank, all mounted to the dorsal side of a large transport plane like a 747 that would have its engines modified to have afterburners on them.

Once I get a concept modelled in 3d I'll post some pics.

look here

http://forum.nasaspaceflight.com/index.php?topic=18949.0

Offline GreenGlow

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Not enough to reach LEO. Once in space-yes, but VERY slow. Same uses as ion drive, but limited to ionosphere.

It's a given that rockets will be needed to reach LEO in the foreseeable future.   ...

 Electrodynamic tethers can actually be used for getting to LEO.

The hanging type ED tether can start with a tether only a few km long and grow to one thousands of miles long as more tether modules are added.  ...

Sol

NASA should do more tether experiments; or maybe I should say should have done more when they had LEO capability.  An up-coming mission will test a solar sail.  The Echo 1 balloon, almost 50 years ago, demonstrated this.   Its a big jump to go from a theory that can't be tested on the ground to a working model deployed in orbit.   While tethers prove the possibility of propellantless electrodynamic propulsion, even a simple tether has been very difficult to deploy.  I think electrodynamic tethers will be surpassed by another method.

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Offline mlorrey

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tnphysics - 29/12/2007  6:52 AM

The EmDrive is nonsense. It violates momentum conservation. Hence it is impossible.

If I understand the concept, it uses the entire rest of the universe as a reaction mass. In other words accelerates but pushing the rest of the universe in the opposite direction. That would not violate conservation of momentum.


Actually, you are thinking of the Mach Effect Thruster. An EmDrive doesnt use the same theory, and based on the way it claims to work, I'm not sure it could do so.
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Offline Epis

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I think that future is in hybrid chemical/nuclear rocket engine designs, that will offer high T/W (>70:1) + higher isp ~600-700s
Skylone designed SSTO plane also have some future but once again if they could integrate additional NT fuel heater (1000-1500C) then payload could double.

also Launch assist systems like space cannons in ocean, mountain Top launch, etc launchers were rocket is pushed by gas pressure in the tube are good, but they need daily launches.
 SO my proposal is to build One time usable S-glass fabric 2.8-5km tube Quickly inflatable with hydrogen gas and then send rocket through it, I quickly calculated that sending second stage rocket through tube, that will replace first stage rocket boosters will require ~10x less fuel than using SRB First stage boosters, so its >10X efficient way to gain speed, and would be much cheaper+ environmentally friendlier if recycling S-glass tube. but it requires Near Perfect Weather conditions, + low wind speed. otherwise that won't work.
for more info see topic http://forum.nasaspaceflight.com/index.php?topic=24115.60

Offline SimonDM

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As mentioned in the other thread on advanced concepts your interested in:

1. Third fluid rocket engine to increase thrust to weight ratio of hydrogen engines, by Balepin. For a good second stage of a TSTO design.

2. Also some other precooled airbreathing design by Balepin, as well as the SABRE engine (Skylon), ATREX engine (Japan) and some other designs (like patent http://www.wikipatents.com/US-Patent-4224790/jet-engine) allowing the use of a single flowpath instead of weight adding two flowpaths (over/under or wraparound turboramjet) for a good first stage of a TSTO design.

There's also nothing wrong with existing SSTO concepts like SASSTO, Beta, Chrysler SERV designs or existing TSTO concepts like Boeing's in patent 4,802,639.

Offline sarjil

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the technologies that i am interested in and i think that might make launch cost go down is:

1. hydrogen gun like the one quicklaunch is researching on
2. beamed power launch that peter diamandis of x-prize is thinking of
3. skylon air-breathing technology
4. neptune rockets like interorbital systems it has been influenced by OTRAG
5. reusable rockets
6. space elevator if/when its possible of course. :)

i list these because these are the only things i see that gets talked about, i do not care what technology we use though whatever gets us up there and whatever makes it cheap i am all for it. :)

Offline colbourne

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I still think the best solution is the rotating tether (bolo) launch method where a fast jet or rocket plane docks with a rotating tether in LEO.

The tether and  a large mass (asteroid ) can be made to keep up to speed by solar electro- magnetic means. 

The space craft releases at the top of  rotating tethers cycle and then can head off at twice orbital velocity.

Offline mlorrey

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I still think the best solution is the rotating tether (bolo) launch method where a fast jet or rocket plane docks with a rotating tether in LEO.

The tether and  a large mass (asteroid ) can be made to keep up to speed by solar electro- magnetic means. 

The space craft releases at the top of  rotating tethers cycle and then can head off at twice orbital velocity.

There is no free lunch, you still need to add the energy in somewhere.
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Offline indaco1

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He said "solar electro- magnetic means". 

In any case to reboost rotovator you can use low thrust high isp means.

I'm aware these concepts are well known, but links are useful so I post some:

http://forum.nasaspaceflight.com/index.php?topic=21101.0
http://www.niac.usra.edu/files/library/meetings/annual/jun01/391Grant.pdf

I don't know if this, even if workable, will be cheaper than other approches for a reasonable launch demand.
« Last Edit: 04/02/2011 09:57 AM by indaco1 »
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Offline JohnFornaro

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5A:  Mostly reusable rocket.  Possibly with wings.
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Btw, does anyone have a good estimate of the per-seat cost of a sensible TSTO reusable, if for some reason launches rivaled that of airplane flights?

If you are discussing Space elevators, I have always thought an orbital loop seems much more plausible. Think of it as an overhead monorail just above the atmosphere. In some schemes it drops a stationary tether down to the surface but I prefer the idea that it merely catches suborbital flights.

Unlike a space elevator,
* there is no need for any particular material strength. Every part of it is in freefall.
* it can survive if any portion is wiped out. The rest will stay in orbit.
* It is accessible from anywhere near the equator.
* It can accelerate a craft smoothly up to twice its own velocity, much faster than an elevator but with much lower g-forces than a rotating tether.

We are a long way from the scale where this would pay for itself right now, but if we had a civilisation spanning the earth and the moon and were smelting and launching components from the moon using mass drivers..

Offline colbourne

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Btw, does anyone have a good estimate of the per-seat cost of a sensible TSTO reusable, if for some reason launches rivaled that of airplane flights?

If you are discussing Space elevators, I have always thought an orbital loop seems much more plausible. Think of it as an overhead monorail just above the atmosphere. In some schemes it drops a stationary tether down to the surface but I prefer the idea that it merely catches suborbital flights.

Unlike a space elevator,
* there is no need for any particular material strength. Every part of it is in freefall.
* it can survive if any portion is wiped out. The rest will stay in orbit.
* It is accessible from anywhere near the equator.
* It can accelerate a craft smoothly up to twice its own velocity, much faster than an elevator but with much lower g-forces than a rotating tether.

We are a long way from the scale where this would pay for itself right now, but if we had a civilisation spanning the earth and the moon and were smelting and launching components from the moon using mass drivers..


If this is in LEO , how is it going to accelerate an object up to orbital velocity from a sub-orbital state.
I see little advantage over a rotating tether but it would be almost impossible to build and is only equivalent to a high mountain (if I understand the idea correctly).

Offline mlorrey

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Btw, does anyone have a good estimate of the per-seat cost of a sensible TSTO reusable, if for some reason launches rivaled that of airplane flights?

If you are discussing Space elevators, I have always thought an orbital loop seems much more plausible. Think of it as an overhead monorail just above the atmosphere. In some schemes it drops a stationary tether down to the surface but I prefer the idea that it merely catches suborbital flights.

Unlike a space elevator,
* there is no need for any particular material strength. Every part of it is in freefall.
* it can survive if any portion is wiped out. The rest will stay in orbit.
* It is accessible from anywhere near the equator.
* It can accelerate a craft smoothly up to twice its own velocity, much faster than an elevator but with much lower g-forces than a rotating tether.

We are a long way from the scale where this would pay for itself right now, but if we had a civilisation spanning the earth and the moon and were smelting and launching components from the moon using mass drivers..


If this is in LEO , how is it going to accelerate an object up to orbital velocity from a sub-orbital state.
I see little advantage over a rotating tether but it would be almost impossible to build and is only equivalent to a high mountain (if I understand the idea correctly).

Space elevators have to have their centers of gravity at GEO, and stretching far enough to reach earth means an insanely large amount of mass to put in orbit, which makes it impossible for at least the next century.

A TSTO RLV is essentially what SpaceX plans to make the Falcon 9 become. It is two stages, and they hope to be able to recover both of them eventually, without destroying the useful payload capacity by using it up with TPS mass. So, essentially, look at what it cost them to develop Falcon 9, and you have your budget answer for a TSTO. What is ideal about doing it the way they are, of making it first capable of making orbit, then trying to make it recoverable, is that treating achieving reusability at a secondary goal behind that of being profitable until you do achieve it, is intelligent. Now, they may need to make the upper stage hydrolox fueled to preserve profitable payload capacity, unless they start experimenting with injecting some nanopowder fuel additives into the combustion chamber to boost Isp some more, or come up with some other performance enhancing features.

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Offline Proponent

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Space elevators have to have their centers of gravity at GEO, and stretching far enough to reach earth means an insanely large amount of mass to put in orbit, which makes it impossible for at least the next century.

I certainly agree with the larger point here:  elevators require a large amount of mass beyond GEO.  One nitpick, though: it's not the case that an elevator's center of gravity is at GEO.  I just mention it because people often analyze tethers (of which the elevator is a special case) as though their centers of gravity were "in orbit" and consequently draw incorrect conclusions.

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Space elevators have to have their centers of gravity at GEO, and stretching far enough to reach earth means an insanely large amount of mass to put in orbit, which makes it impossible for at least the next century.

I certainly agree with the larger point here:  elevators require a large amount of mass beyond GEO.  One nitpick, though: it's not the case that an elevator's center of gravity is at GEO.  I just mention it because people often analyze tethers (of which the elevator is a special case) as though their centers of gravity were "in orbit" and consequently draw incorrect conclusions.

Um, yeah, an elevators center of gravity *is* GEO if it is to remain over one location on Earth. What, you thought it was standing on Earth like a building?
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Offline Hop_David

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Um, yeah, an elevators center of gravity *is* GEO if it is to remain over one location on Earth. What, you thought it was standing on Earth like a building?

The outward pull from GEO must balance the inward pull.

Gravity falls with r^-2. So-called centrifugal force climbs with r.

A kilogram 36000 km below geosynch pulls down 9.8 newtons. At geosynch (about 36000 kilometer altitude) centrifugal force and gravity cancel out and the pull is zero newtons. At 36000 kilometers above geosynch, a kilogram pulls up about .35 newtons. This leads me to believe that if mass were distributed symmetrically about geosynch, the stalk would fall to earth.
« Last Edit: 04/05/2011 05:00 AM by Hop_David »

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If this is in LEO , how is it going to accelerate an object up to orbital velocity from a sub-orbital state.
I see little advantage over a rotating tether but it would be almost impossible to build and is only equivalent to a high mountain (if I understand the idea correctly).

Hi colbourne,

Wikipedia calls it an 'orbital ring':
http://en.wikipedia.org/wiki/Orbital_ring
Though I generally imagine it without the elevator portion. It is effectively a magnetic rail, which both gives the ability to prevent a vehicle from falling down once it has latched on, and to accelerate/decelerate it at any rate you find comfortable. Momentum is recovered during the deceleration of returning craft.

A rotating tether is either short (but still hundreds of km) with very high g-forces, or very long with all the problems I mentioned for a space elevator. Unlike an elevator you need exquisite timing to catch it. Imagine catching a tennis ball at the very top of its 100km trajectory under 10 gravities.

An orbital ring is just a string of satellites in LEO so it is easier in almost every respect to construct than say a space elevator. The scale is probably beyond anything we would want to launch from the earth but since we are not talking about one-piece carbon nanotube miracle materials we would probably build it segment by segment from common lunar materials launched by mass driver.

Im not proposing this as any near-future thing, just as several times more reasonable than a space elevator.

Offline SimonDM

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I still think the best solution is the rotating tether (bolo) launch method where a fast jet or rocket plane docks with a rotating tether in LEO.
While I find it a very elegant solution as it reduces the deltav required and works already theoretically current day materials instead of ultrahighstrength carbon nanotubes, I think practically it may not be easy and would require significant simulation effort. I am doing among other things computer simulations of yarns on weaving looms and fibres on cards for a living, so believe me when I tell you that realistic simulations of dynamic tether behaviour are not going to be a cakewalk.
« Last Edit: 04/05/2011 12:17 PM by SimonDM »

Offline Proponent

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Um, yeah, an elevators center of gravity *is* GEO if it is to remain over one location on Earth. What, you thought it was standing on Earth like a building?

No, I view the elevator as being supported from the ground.  It is in orbit; I merely point out that it cannot be analyzed as though it were a point mass.

The outward pull from GEO must balance the inward pull.

Gravity falls with r^-2. So-called centrifugal force climbs with r.

A kilogram 36000 km below geosynch pulls down 9.8 newtons. At geosynch (about 36000 kilometer altitude) centrifugal force and gravity cancel out and the pull is zero newtons. At 36000 kilometers above geosynch, a kilogram pulls up about .35 newtons. This leads me to believe that if mass were distributed symmetrically about geosynch, the stalk would fall to earth.

That's a nice, simple illustration that the elevator cannot be viewed as a point mass located at the elevator's center of mass.  Similarly it cannot be viewed as a point mass at its center of gravity (which is very different from its center of mass) either.
« Last Edit: 04/05/2011 01:33 PM by Proponent »

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I thought I understood that a space elevator was to be anchored to the ground with a large mass (small asteroid) at the top, (beyond GEO orbital radius). The large mass is to be accelerated to a velocity faster than orbital velocity to keep it synchronized above the anchor. The elevator cable keeps the large mass in place which keeps the cable taunt. Mass changes caused by rising and lowering payload don't significantly change the location of the COM.
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Offline aceshigh

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Space elevators have to have their centers of gravity at GEO, and stretching far enough to reach earth means an insanely large amount of mass to put in orbit, which makes it impossible for at least the next century.


not really. A single space shuttle can launch a space elevator to its orbit.

well, not the entirety of it. Just a single strand. The proposal is to build the space elevator just like cable bridges are built. One strand, and then you use a machine that goes up and down that cable and with each pass, it adds other strand and the cable gets thicker and thicker.

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An orbital ring is just a string of satellites in LEO so it is easier in almost every respect to construct than say a space elevator.

My favorite concept starts off a little like this, except:

1) The satellites are single use.  Each satellite is a small ~1 gram solar sail about 30cm x 30cm.  They transfer momentum to the spacecraft almost by direct impact.  (Rather than directly hitting the spacecraft, they are vaporized by collision with the exhaust of a small cold gas thruster.  This converts the sail itself into a puff of gas, which can then be diverted by a bowl shaped pusher plate rather than causing an impact crater.)

2) The satellites are in solar orbit rather than Earth orbit.  They fly in a retrograde solar orbit, resulting in an impact velocity of 50+km/s.  The way the pusher plate works, this translates to a specific impulse of 100+km/s.

3) The satellites are solar sails, so they take a few years to spiral in/out from the sun and crank orbit inclination.  See, for example, Solar Sail Trajectory Optimization for Intercepting,
Impacting, and Deflecting Near-Earth Asteroids
for an explanation of how a solar sail would fly itself into a solar retrograde orbit.

The nice thing about this technology, which I call "solarkinetic pulse propulsion", is that the mass investment of the propellant is an order of magnitude less than the payload.  In order to boost a 10 ton suborbital spacecraft to Earth escape velocity, you only need 1 ton of sailbots.

This is why you don't need the sailbots to be reusable.  You get a lot of bang for your buck just from a single use!  For every ten missions, you can devote one or two to launching more batches of sailbots.

In contrast, space elevators and orbital rings and tethers require large infrastructure mass compared to the payload mass.  In order to be worth doing, they need to be heavily reusable and/or built using matter from somewhere other than Earth.  Neither of these will offer economic space access in the near future!  Either way, we're talking about a huge infrastructure investment.  You don't get cheap access to space if you need to spend oodles of gigabucks to start it up!

Solarkinetic pulse propulsion only requires an infrastructure investment of a tenth of the payload mass.  A one ton demonstrator mission would require only a hundred kilograms of sailbots (at 1 gram each, that's still an impressive batch of 100,000 sailbots).  A ten ton mission would require only 1 ton of sailbots.

(About the name--"solarkinetic pulse propulsion" is based on "nuclear pulse propulsion".  Nuclear pulse propulsion involves using high velocity pulses of plasma from nuclear bombs to push a pusher plate.  Solarkinetic pulse propulsion is much the same, except the pulses of plasma come from sailbots.  The individual pulses are puny compared to nuclear bombs, though, so it doesn't need extreme shock absorbers.)

Offline mlorrey

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Space elevators have to have their centers of gravity at GEO, and stretching far enough to reach earth means an insanely large amount of mass to put in orbit, which makes it impossible for at least the next century.


not really. A single space shuttle can launch a space elevator to its orbit.

well, not the entirety of it. Just a single strand. The proposal is to build the space elevator just like cable bridges are built. One strand, and then you use a machine that goes up and down that cable and with each pass, it adds other strand and the cable gets thicker and thicker.

This implies that a single strand can handle a load twice its own mass. Firstly, the single strand method wont cut it, because the tensile load at GEO is going to be MASSIVE. The cable has to be rather thick at GEO and taper as it goes out in either direction.
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Offline RobLynn

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I still think the best solution is the rotating tether (bolo) launch method where a fast jet or rocket plane docks with a rotating tether in LEO.

The tether and  a large mass (asteroid ) can be made to keep up to speed by solar electro- magnetic means. 

The space craft releases at the top of  rotating tethers cycle and then can head off at twice orbital velocity.

I think this would make a great X-Prize

Entrants fly a trajectory that rendezvous with a non-existant simulated rotovator.  Prize based on minimum approach distance at precise time achieved on two consecutive launches by same launcher to eliminate flukes.  Measure using a suitable gps/inertial guidance system (or perhaps use earth based radar).

This is largely a control and thrust modulation problem, but set the delta V to a relevant 3-5km/s level to make it more challenging - and give some delta V growth from past and current prizes.
I'm a "glass is twice as big as it needs to be" kinda guy

Offline MikeAtkinson

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If the NOFBX fuel is as good as is claimed, then it would make 1st stages much simpler and cheaper. A stage would need only a single tank, no helium pressurant, simplified plumbing, no insulation and a simple engine (a reduction in parts count by a factor of 2 or more). A single, safe, non-toxic, non-cryogenic propellant would make pad operations easier.

My guess is that it would allow a reasonable SSTO (but making a cheap reusable SSTO would still be a big challenge) payload.

The most cost effective would probably be a TSTO with flyback 1st stage.

As a propellant it probably needs a few years yet of experience before it is ready for main propulsion applications.

thread:
http://forum.nasaspaceflight.com/index.php?topic=24352.0

AIAA presentation:
http://www.aiaa.org/pdf/industry/presentations/Greg_Mungas.pdf

Offline aceshigh

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Space elevators have to have their centers of gravity at GEO, and stretching far enough to reach earth means an insanely large amount of mass to put in orbit, which makes it impossible for at least the next century.


not really. A single space shuttle can launch a space elevator to its orbit.

well, not the entirety of it. Just a single strand. The proposal is to build the space elevator just like cable bridges are built. One strand, and then you use a machine that goes up and down that cable and with each pass, it adds other strand and the cable gets thicker and thicker.

This implies that a single strand can handle a load twice its own mass. Firstly, the single strand method wont cut it, because the tensile load at GEO is going to be MASSIVE. The cable has to be rather thick at GEO and taper as it goes out in either direction.

can a single strand of steel cable handle a load twice its own mass, when you build a cable bridge by the same method??

http://www.spaceward.org/elevator-feasibility

Offline mlorrey

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Space elevators have to have their centers of gravity at GEO, and stretching far enough to reach earth means an insanely large amount of mass to put in orbit, which makes it impossible for at least the next century.


not really. A single space shuttle can launch a space elevator to its orbit.

well, not the entirety of it. Just a single strand. The proposal is to build the space elevator just like cable bridges are built. One strand, and then you use a machine that goes up and down that cable and with each pass, it adds other strand and the cable gets thicker and thicker.

This implies that a single strand can handle a load twice its own mass. Firstly, the single strand method wont cut it, because the tensile load at GEO is going to be MASSIVE. The cable has to be rather thick at GEO and taper as it goes out in either direction.

can a single strand of steel cable handle a load twice its own mass, when you build a cable bridge by the same method??

http://www.spaceward.org/elevator-feasibility

We are talking a thread 46,000 miles long vs bridge cables that are a few miles long at most. The tensile strength of CNT's may be high, but not high enough for that sort of load. All Space elevator estimates of any seriousness to date have expected the cable to be tapered in thickness.

Another problem with elevator feasibility is that climber cars will travel so slowly that a single trip to GEO will take a couple weeks, so the space elevator will have the same lift capacity as a normal chemical rocket. You can't get enough power from solar panels to make a climber car go more than a few dozen miles per hour.
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Founder, Lorrey Aerospace, B&T Holdings, ACE Exchange, and Hypersonic Systems. Currently I am a venture recruiter for Family Office Venture Capital.

Offline ANTIcarrot

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Another problem with elevator feasibility is that climber cars will travel so slowly that a single trip to GEO will take a couple weeks, so the space elevator will have the same lift capacity as a normal chemical rocket. You can't get enough power from solar panels to make a climber car go more than a few dozen miles per hour.

Then give it a reactor. If polywell works (if) then a small unshielded 'power car' could push/pull the cargo up and down. All you'd then need is a 'shunting engine' to get the polywell up to a few hundred meters high so it can turn on safely - and that can be done in any number of conventional ways.

Offline mlorrey

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Another problem with elevator feasibility is that climber cars will travel so slowly that a single trip to GEO will take a couple weeks, so the space elevator will have the same lift capacity as a normal chemical rocket. You can't get enough power from solar panels to make a climber car go more than a few dozen miles per hour.

Then give it a reactor. If polywell works (if) then a small unshielded 'power car' could push/pull the cargo up and down. All you'd then need is a 'shunting engine' to get the polywell up to a few hundred meters high so it can turn on safely - and that can be done in any number of conventional ways.

Doesn't matter. If you get beyond 100-200 mph, your climber gripper is going to be heating the carbon nanotube so much that it will cause the CNT to dissociate (in vacuum thats at about 2200F, in atmosphere thats only 750F). And imagine the snarl you will get when a bearing blows out...

Minimum trip time to GEO on an elevator is going to be 4 or more days, one way, unless you can figure out a way for the cable to carry a TON of electric current for the car to climb inductively with no physical contact.
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Founder, Lorrey Aerospace, B&T Holdings, ACE Exchange, and Hypersonic Systems. Currently I am a venture recruiter for Family Office Venture Capital.

Offline jiffylube84

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My canidate would be a blast from the past, Orion or Prometheus. To my knowledge nuclear explosions are the most powerful things man has created and we know a lot about how to build them. The biggest problem is fear, I have a big problem with people that would hamstring humanity because of the fear that we will blow ourselves up. Nuclear explosions have a place, just could we all stop building them to kill one another and maybe use them for some good like exploring our solar system. From this point on many new discoveries and powersources could be used to create very powerful weapons so should we not develope those power sources?

Offline pummuf

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First of all, whatever the solution it will require massive reductions in infrastructure, maintenance, servicing and personnel. You can't have economic space flight that relies on standing armies of thousands to run just the launch side of it. That will have to be one of the things this new propulsion technology gives.

Next, I think 'economic' can also be reliable. Some space agencies spend huge premiums for small gains in performance ... so go the other way with slightly lower performance when there is a large economic benefit. Shoot for reliability through simplicity when possible. Sacrifice a few points of performance when needed.

Reusable designs ... This is doable, just hasn't been done in a way that saves money and labor, yet.

An obvious first idea is flyback boosters. Look at glide back, power back, power ahead, and so on ... Can simple ramjets be incorporated into the wings for powered return, and to add some boost during favorable parts of the ascent? Can the flyback booster have a common core with latter stages of the launch system?  Sea recovery probably wouldn't save any money.

Idea two. The X-33 was to demonstrate concepts for SSTO, and the design got close but at massive expense. Can it be simplified and cost reduced, accepting a performance hit? And then can it be paired, belly to belly w/crossfeed, to make a TSTO - fully reusable? The two stages would be identical. On launch, the booster would have some extra fuel tanks and the final stage would carry the payload.

Idea three. Similar to the Pegasus system but with an autonomous, purpose built first stage. The carrier would go faster and higher, and it might attract additional funding as a test bed for airbreathing/hypersonic research. The mothercraft would be designed for minimal servicing between launches, as well as being autonomous. This fits nicely with solid stages that require minimal attention.

The space industry could take better advantage of new technology that's becoming commonplace and less costly - autonomous flight has been mentioned above, another is robotic manufacturing;

Robotic manufacturing used to be really expensive, and it's used for the filament winding of some solid boosters. But the price has come way down - many people build cnc equipment in their garages as a hobby, using discarded printers. I think there is an opportunity for a new space company to make solid stages less expensively than the current big US manufacturers. Some additional ideas; thermoplastic binders instead of thermosets (pvc has equitable performance to HTPB). This allows less manufacturing infrastructure because you can manufacture the propellant as ingots, a little at a time. Less capitol equipment needed. The ingots are easier to store and move. Then the grain can be injection molded as needed from those ingots. There's an opportunity here for smaller companies with less overhead using lower cost equipment. 

To improve space launch economics, the expensive things have to become much simpler, while cheap things should be relied on more; infrastructure, manpower, launch complexity and expensive designs for small performance gains have to be re-thought. Conversely, electronics, automated flight and automated manufacturing is becoming less expensive and should be used more. These can be mutually reinforcing.
« Last Edit: 04/12/2011 06:00 PM by pummuf »

Offline DLR

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I think that on the long run, if there's a desire to industrialize space (perhaps through the construction of space solar power satellites), very large, expendable, sea-launched boosters (Sea Dragon) would provide reasonable prices for the launch of large masses, if the launch rate is sufficiently high. I could see them working together with smaller reusable boosters (K1, Skylon, etc. ...) for high-value cargo and people.

Now this requires solving the chicken and egg problem of cheap access to space. Without payloads you're not going to get large expendable rockets mass produced and without cheap, mass-produced expendable rockets you won't get payloads. Also the cost of payloads has to come down. No wonder a launch is expensive when you're launching a unique multi-million or multi-billion dollar satellite or space probe. In that case, a launch failure is not an option. If you launch a constellation of identical satellites which are produced on some form of assembly line, a certain risk of launch failure may be tolerable.

Reducing the cost of space access is not an engineering issue, but a political and economic question.
« Last Edit: 04/14/2011 12:13 PM by DLR »

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