Alternative spacelaunch methods

Space is the final frontier. The biggest obstacle to human space exploration and colonisation of the solar system are not the distances involved, but rather our hard-to-escape imprisonment - Earth gravity well. Conventional way using only chemical rockets has surely achieved a lot in the past, but it still doesnt allow practical space colonisation. Present-day launch costs are very high — $10,000 to $25,000 per kilogram from Earth to low Earth orbit (LEO). Thats after 100 years of chemical rocket development - clearly we need far more cost-effective ways if we ever want to settle space. So, what are the best options?

en.wikipedia.org...

Launch Loop

A launch loop or Lofstrom loop is a design for a belt-based maglev orbital launch system that would be around 2000 km long and maintained at an altitude of up to 80 km (50 mi). Vehicles weighing 5 metric tons would be electromagnetically accelerated on top of the cable which forms an acceleration track, from which they would be projected into Earth orbit or even beyond.

The published cost estimates for a working launch loop are significantly lower than a space elevator, with a greater launch capacity, lower payload costs and similar or greater payload masses; and unlike the space elevator no new materials need to be developed. The structure would constantly need around 200 MW of power to keep it in place.

The system is designed to be suitable for launching humans for space tourism, space exploration and space colonization with a maximum of 3g acceleration.

Lofstrom estimates that an initial loop costing roughly $10 billion with a 1 year payback could launch 40,000 metric tons per year, and cut launch costs to $300/kg, or for $30 billion, with a larger power generation capacity, the loop would be capable of launching 6 million metric tons per year, and given a 5 year payback period, the costs for accessing space with a launch loop could be as low as $3/kg.[2]

Electromagnetic Mass Driver

In contrast to a space gun, a mass driver can have a length of hundreds of kilometers and therefore achieve acceleration without excessive g forces to the passengers. It can be constructed as a very long and mainly horizontally aligned launch track for spacelaunch, targeted upwards at the end, partly by bending of the track upwards and partly by Earth's curvature in the other direction.

Natural elevations, such as mountains, may facilitate the construction of the distant, upwardly targeted part. The higher up the track terminates, the less resistance from the atmosphere the launched object will receive.[2]

By being mainly located slightly above, on or beneath the ground, a mass driver may be easier to maintain compared with many other structures of non-rocket spacelaunch. If not underground then it still needs to be housed in a pipe that is constantly vacuum pumped in order to reduce drag.

In order to be able to launch humans and delicate instruments, it would need to be several hundreds of kilometres long. For rugged objects, with magnetic assistance, a significantly smaller, circular, track may suffice.[3]

A mass driver on Earth would be a compromise system. A mass driver would accelerate a payload up to some high speed which is not high enough for orbit. It would then release the payload, which completes the launch with rockets. This would drastically reduce the amount of velocity needed to be provided by rockets to reach orbit, since most fuel is needed for the initial phase of conventional rocket launch. On Earth, a mass driver design could possibly use well-tested maglev components.

I have not included presently unrealistic methods which require some technology breakthrough, like antigravity or high tensile strenght materials. Even without them, we are still able to make Earth to LEO trip more practical and cost-effective.

The estimated cost of the Launch Loop concept does not exceed 30 billion dollars, electromagnetic catapults would be far less costly, but offer higher launch costs (still far less than current method). Compare that to estimated Iraq War cost - $100 to $200 billion.
We could already have 5 Launch Loops or many more EM catapults running, driving the launch costs to few dollars per kilogram or even less. How bout that?

[edit on 6-1-2010 by Maslo]

Another promising method could be beam-powered propulsion, when powerful laser is aimed at the craft which can concentrate this energy to combust a propellant or even the air, producing thrust:

reply to post by Maslo


the youtube link didnt work for me, so here is my two cents.

Beam technology would be pretty cool, but the energy beamed to the vehicle would still have to be converted into something useful, that could produce thrust or another force to oppose gravity. Could be used to burn fuel (air) but the higher up you to, the less air (low pressure) and it would get pretty difficult to continue using air as fuel (if you are interested, check out the difference between ram-jet and jet based systems) anyway, would be pretty neat if it could work

As far as the mass driver, there are many problems with the technology. Yes, the energy required to make one operate is attainable. Yes they are more or less simple pieces of technology, which could be built. However, the shear amount of heat generated by accelerating a mass to such a speed that it could break earths orbit without any additional or even minimal additional means of thrust is extreme. Common and good conductive materials cannot withstand that heat (maybe tungsten could, but its hard to machine, and costly). Also, you have both gravity and wind resistance working against you, and only an initial velocity to oppose constant deceleration. I agree that rocket assist would be ideal, but i still dont see this technology being very useful here on earth. A mass-driver that is located on say, a space station, or the moon, or an asteroid or something with little to no atmosphere would be ideal.

[edit on 17-1-2010 by LeeTheDestroyer]

Space Elevator

en.wikipedia.org...

Basically a massive cable connected to the Earth that extends to space with something heavy at the end of it. The giant object would make it stay in space as it rotates with the Earth.

It is a good idea, but if it broke there would be thousands of miles of cable wrapping around the Earth causing much havoc.



[edit on 17-1-2010 by tooo many pills]

reply to post by tooo many pills


I hear you on that one, With current materials, we are looking at pretty much a failure of epic proportions when it comes to the space elevator. Not only would the structure have to have a rediculously high tensil strengty to support the load of something accelerating up and down on its length (controlled acceleration that is) not to mention its own weight... but it would also have to have some incredible elastic properties as well in case the orbiting upper platform shifts in its orbit, any incrament. Simply put, cables dont have that...now spider silk, that would be something making it more useable (however spider silk cant really be made in the amount required for a project of that magnitude (and is still under research for that matter).

But, in the instance that it is ever made, im investing in "falling space cable home insurance" just to be safe

HAHA! Well they did just discover a new species giant spiders. Forget space cable insurance, invest in giant spider silk milking.

OP, I think the Launch Loop and Electromagnetic Mass Driver are the most realistic. I hope another nation gives one of these a chance becuase I think NASA is sticking with rockets for atleast a decade or two.

reply to post by LeeTheDestroyer


Carbon nanotubes are the commonly-proposed substance. Ridiculously strong, but currently fantastically difficult to produce. As for a catastrophic failure, the tether could be rigged to detonate, or be pulled back to the Earth and the orbiting mass, should a snap occur. I'm sure all of that would be thought out before one was built - scientists aren't that dumb

The launch loop is a great idea, though. It does take some time to get to orbit (due to the slow but steady acceleration required), but heck it's cheap and simple (when compared to the alternatives, that is!).

reply to post by tooo many pills


Αs the guy below your post suggested it cannot be donne due to restrctions in material properties ( quite as suggested )

MOREOVER thousands of miles of cable is a false statement

Most manmade sattelites orbit at altitudes of only a few hundred kilometers or even less

I won t suggests exact orbit heights since i am not a specialist but its prety low and certainly not thousands of miles

WIKI it

Originally posted by GEORGETHEGREEK
reply to post by tooo many pills

 

Αs the guy below your post suggested it cannot be donne due to restrctions in material properties ( quite as suggested )

MOREOVER thousands of miles of cable is a false statement

Most manmade sattelites orbit at altitudes of only a few hundred kilometers or even less

I won t suggests exact orbit heights since i am not a specialist but its prety low and certainly not thousands of miles

WIKI it

as much as i agree with you, I feel that I need to point out that the position of a platform, say at the top of one of the cables, is all relative. Although more likely to be located in the hundreds of Km "up," it would be beneficial in some circumstances to have a platform further "up" where the effects of gravity are less, so as to be a more efficient launching platform for lunar and deep space missions. Although, i do agree that it would be excessive to be located at thousands of kilometers.

The cable needs to reach a geosynchronous orbit of 22,236 miles to be geostationary.

If the cable is not geostationary then whatever the cable is attatched to will fly around the Earth like a satelite and the cable would snap and both would fall back to Earth.

[edit on 18-1-2010 by tooo many pills]

reply to post by tooo many pills


Exactly. The body would have to be in a natural geosynchronous orbit at a ridiculous altitude, or be at a lower altitude and be powered. Otherwise it'd be useless. The former is the only feasible solution, at the moment at least.

Originally posted by tooo many pills
The cable needs to reach a geosynchronous orbit of 22,236 miles to be geostationary.

If the cable is not geostationary then whatever the cable is attatched to will fly around the Earth like a satelite and the cable would snap and both would fall back to Earth.

[edit on 18-1-2010 by tooo many pills]

Where is your source on that number? And are you telling me, that something cannot be geostatinary if it is not at that "altitude" because i dont buy that, without source information. I dont know, i may be wrong, but again, you cant just spit out numbers, and leave us hanging. I find it very interesting, is that the distance where an orbital of sufficient mass will require no input forces in order to sustain relative orbit (relative to the surface that is) without haveing to apply some force to "correct" its obital path? Furthermore, with applied force, orbit could be sustained at a much lower altitude anyway.

Just to reiterate, this is not a criticism, just curious how you found that number.

to the above post, Whats not feasable about a powered station, throw a nuke reactore up there, a solare bank, some Thermoelectric material (en.wikipedia.org...), and you have all the power you need, plus the added mass to the platform, and whats to say that the orbital wouldnt need power anyway.

[edit on 18-1-2010 by LeeTheDestroyer]

[edit on 18-1-2010 by LeeTheDestroyer]

It is in the link in my first post.
en.wikipedia.org...

Normal satelites can be at at lower altitudes becuase they are continuously falling around the Earth. But if a satelite wants to stay in the same spot in space directly above the same spot on Earth (geostationary) it must be in a geosynchronous orbit.

en.wikipedia.org...

Geostationary orbits can be achieved only very close to the ring 35,786 km (22,236 mi) high, directly above the equator. This equates to an orbital velocity of 3.07 km/s (1.91 mi/s) or a period of 1436 minutes, which equates to almost exactly one sidereal day or 23.934461223 hours. This makes sense considering that the satellite must be locked to the Earth's rotational period in order to have a stationary footprint on the ground

[edit on 18-1-2010 by tooo many pills]

reply to post by tooo many pills


I respectfully concede, Thankyou for supporting your claim.

however, would it be more realistic, to have say an orbital power plant (nuke, solar, thermal...whatever) generating the needed force to remain in an "artificial" geosynchronous orbit at a lower altitude connected by a "cable" of reletively short length (i.e hundreds of km), or would it be more realistic to have some thing in "natural" geosynchronous orbit, with a "cable" that is twenty six thousand miles long, effectively creating a space elevator?

reply to post by LeeTheDestroyer


Probably, 26,000 miles of cable isn't very realistic. We might as well go all the way to the moon which is a near 10x further. Nano-tech could be the answer. However, I think if the satelite and cable were only a few hundred km/miles the gravity of Earth would pull the cable and satelite back to Earth. Unless, the satelite was powerful enough to keep propelling away from Earth, yet at the same time delicate enough not to snap the cable.

Maybe a fleet of balloons could take our cargo as far as they could. Then a giant magnet in space would be fired up and pull the cargo the rest of the way into space.

I say we try the electromagnetic mass driver first. Only the G-force has to be tremendous on those.

reply to post by tooo many pills


okay, here is an idea, geosyncronous mass at 26,000 kilometers, (tied to earth by a cable) What does that make every point on the cable...

also in geosyncronous orbit. although anchored by a mass at a certain distance.

As, i outlined before, Mass drivers are not practical for a system that exists in atmosphere (or any fluid for that matter) There is too much energy loss due to friction, too much heat build up.

Just think of the system of forces involved. You have only an input velocity from the mass driver, every other force in the system is acting against you, acceleration is only in the negative direction. modern materials science is not up to the task.

reply to post by LeeTheDestroyer


I don't really understand what you said?

A mass driver would be good. Think of it like a magnetic railway starting miles from a mountain, then going at an angle up the mountain pointing at the sky. The object being launched keeps gaining momentum so it could glide into space.

www.youtube.com...

There is no fiction because it isn't actually touching the track. The only resistance would be air and gravity. I don't think people could ride on a mass driver due to g-force, but we could launch all of our heavy space necessities. We could have them remote controlled to dock at a space station for full assembly.

en.wikipedia.org...(transport)


[edit on 21-1-2010 by tooo many pills]

reply to post by tooo many pills


As in accordance to your sources, you are talking about Magnetic levitation (MagLev), Accelerating an object along a manetic track, it is more closely related to to a Gauss rifle than anything else... A true mass driver doesnt operate like this because the transfer of electricity is from one rail, to the accelrated object, back to the other rail. Contact is needed between the mass and the rails for proper transfer or electricity, otherwise spark gaps form, greatly increasing the heat in the system.

Here is the link to some wikipedia mass driver information en.wikipedia.org...

Based on your reply, I am not certain that you fully understand the heat that is involved (purely from wind resistance).

Here is a simple analogy explaining the forces involved in the system.

car is going 70mph, driver slams on the breaks... Same system

in this case, large mass is going 2500m/s at the end of the rail, (number lifted from wikipedia link)

It then decelerates at a rate of 9.81m/s^2, how long does it take for a vehicle for the mass to reach its vertex (zero velocity)

0=2500m/s-(9.81m/s^2)(t)
t=254.84 seconds

now for the position (height reached)(initial height is zero)

x=0+2500(254.84)-1/2(9.81)(254.84)^2

x=318552.5m = 318.55 km

so, with this model, a mass could potentially be launched 318.55km in the vertical direction.

however, this model is very flawed. This is how a mass would behave in a vacuum. It doesnt account for the enourmous amount of force generated by drag (wind resistence) which would massively decrease the height attainable by the accelerated mass, unless it had a drag coefficient of zero, which it wouldnt. Not to mention that this object would be accelerated staight up, which a mass accelerator couldnt exactly do, unless it was hundreds of miles long.

This doesnt even scratch the surface of the major problem with initial velocity methods of launching things into space. The shear heat generated during the acceleration of the mass, causes huge proglems with the rails themselves. Good conductors which are needed in the system generally have a low melting point. (friction=melting rails)

here are the simple dynamic equations used to do the math en.wikipedia.org...

[edit on 21-1-2010 by LeeTheDestroyer]

[edit on 21-1-2010 by LeeTheDestroyer]

Hmm my bad, thought they were the samething.

What if the mass driver was inside a vacuum until it was at a high enough altitude, so that when it is released from the vacuum it is not completely smashed to smithereens by the sudden presence of air?
--Lol never-mind it already says in the mass driver wiki, "If not underground then it still needs to be housed in a pipe that is constantly vacuum pumped in order to reduce drag."

And a launch loop would be half the size of the US and at an altitude of 50miles.

I really thought I was on to something again, I guess there is no reasonable way that I can think of to get to outer space then. We will just have to wait for superman to come or sit on top of an erupting caldera.

So disappointing

reply to post by tooo many pills


Hey man,

mass driver is sweet stuff. Definately interesting and worth developing for use in space. As juicy as the thought of having one lying around is, when you really start getting into it, all the little minute details start jumping up and biting you. I have been on both sides of the argument on this one. As much as i hate to shoot down ideas, i just here to aid the discussion. Been wonderful having this discussion, i hope we all learned something here, i know I did.
Peace,

-Lee