Space Launcher for under $100.00/lb.
CIRCULAR ELECTROMAGNETIC MASS DRIVER:
SPACE LAUNCHER FOR UNDER $100.00/LB.
The current cost to insert payloads into low earth orbit is a prohibitive $10,000.00 per pound. The new NASA initiative envisions technologies costing $1,000.00 per pound. Both of these figures are cost prohibitive to make space affordable for private enterprise users.
Chief among these users will probably be the entertainment industry and the retirement industry. Billions are spent by the casino industry and the cruise ship industry to build facilities for entertaining, one of the largest economic activities on Earth, and one that will inevitably expand into space. While there is a pent-up demand to just simply experience a space ride, at some point there will be a much larger demand to go into space and spend time there being entertained in the very luxurious style we have become accustomed to on cruise ships and in places like Las Vegas.
Another major user of space will probably be the retirement industry. Space holds one characteristic that no planetary body large or small does, that of being able to offer various degrees of gravity within a single facility. This will be a major draw to millions of well-off retirees that would otherwise be living in exclusive gated communities. As one ages, most people experience an increase in joint pain and stiffness. A large rotating space retirement community would be able to offer accommodations ranging from full Earth gravity on the outside levels, to various sub-g spaces as one moved in toward the middle, culminating in a 0-g play space in the center. Spending time in sub-g spaces during the day, and sleeping at night in the full-g outer ring to prevent bone loss would be a welcome relief from otherwise painful conditions in old age. Of course, these facilities would have all the comforts and entertainments of some of the most exclusive gated communities, along with relative safety and freedom from most infectious diseases. One could envision condo prices being less than twice that of the most exclusive terrestrial equivalents, with time-sharing being used extensively.
These large-scale profitable facilities will probably be orbiting in space rather than located on the surface of the Moon or Mars. Descending and re-ascending the gravity -well of other space bodies is needlessly costly and risky. Most space tourists would baulk at the 2-year interval between opportunities to make the transit to Mars. The variable gravity mentioned above would be a great plus in space, as would the easier access to real-time connection to the internet and satellite programming. Visits to and from loved ones on Earth would be much easier from an orbiting facility than on distant objects.
While there will eventually be research facilities on the surface of the Moon and Mars, they will probably never be large-scale population centers. However, provisioning research facilities on the surface of the Moon and Mars will be much more efficient with low cost Earth-based sources of $1.00-per-lb. metals and essentially free water rather than complex and complicated schemes of extracting these common Earth-based resources with remote off-planetary factories. Re-supply from Earth becomes the most feasible alternative with very low cost orbital technologies.
The ability to place many blocks of Las Vegas or many cruise ships in space will depend on the ability to place millions of tons of infrastructure in orbit reliably and cheaply. Large amounts of energy must be expended to accelerate mass to orbital velocity. One can carry all this energy in the form of chemical energy with the payload as in the case of rockets. Of course this means that most of the energy will be expended on carrying the energy itself, and is theoretically incapable of truly cheap space access.
The other strategy is to use Earth based energy to insert mass into orbit. There are three theoretical ways to do this. One can lift mass, one can push mass, or one can throw mass. Lifting mass more or less equates to the space elevator concept. This has major problems with technical considerations and cost. Pushing mass, currently conceptualized as lifting mass with light or other beamed energies, would have major technical problems, especially considering that the major acceleration for orbital insertion would be horizontal and over the horizon.
The third option, throwing mass, or imparting momentum to just the payload using earth-based energy resources, currently is the most technically well developed and is probably the strategy that will result in the lowest cost-per-pound of payload in the long run.
Below is a novel method using this strategy for inserting freight into low earth orbit for approximately $100.00 per pound.
Circular Maglev Track Launcher
What is proposed is to build a circular maglev track launcher of 10 to 20 miles in diameter. This would use a technology similar to particle accelerators or maglev trains. It would be used to gradually accelerate containers up to approximately 25,000 miles per hour. These would then be switched off the track, and up an adjustable launcher and shot into orbit.
Maglev, short for magnetic levitation, is a propulsion system used for trains in which a series of electromagnets of alternating polarity in the track and train form a system of linear acceleration and lift. This technology has been developed for several decades, with Japan and Germany having well-developed test lines. A commercial system has been in place since 2003 in Shanghai. Test speeds in some systems have exceeded 300 mph.(1)
This same technology has been proposed since the 70's for launching mass into orbit under the names mass-drivers, rail guns or electromagnetic accelerators.(2-15) After a period of research and publishing on these concepts during the 70's and 80's, the technology was largely ignored due to two overwhelming problems. The early concepts all depended on a linear launch track. This imposed limitations on the length of the acceleration track, and thus required a very high amount of power to be delivered in a very short period of time to accelerate payloads to escape velocities. This in turn made it necessary to envision huge multi-ton energy devices to store and discharge this energy along the launch track very rapidly. In addition, the fixed linear tracks from 10-20 Km. long made it impossible to vary the aim, and thus impractical.
The circular maglev concept overcomes these two disadvantages. By building up the acceleration in a circle, one can apply the acceleration gradually, and for as long as one likes. For instance, using a 1g acceleration, one can achieve escape velocity of 25,000 mph (at ground level) in 19.1 minutes.
If Acceleration x time = Velocity, then
32ft/s^2 * t = 25,000 mph;
32ft/s^2 * t = 36,667 ft/s
t = 1,146 sec.
t = 19.1 min.
The other advantage to the circular maglev concept is the ease of varying the trajectory. Due to the large centrifugal forces generated at high launch speeds, the maglev tracks would probably be located on the outside vertical wall of a sunken circular trackway. This would be buried in the Earth and circled with thick reinforced concrete for safety and to resist the tremendous centrifugal forces generated. At the appropriate moment after achieving launch speed, a switch would open and divert the payload onto a tangential trackway. This would gradually transition up an incline and be ejected into the atmosphere at an appropriate incline to achieve orbit. The point of diversion would determine the type of orbit.
At 25,000mph, a container would make one revolution around a 10 mile diameter track in 4.5 sec. or in 9 seconds for a 20 mile diameter track. High speed switching should be able to be accomplished within these time frames.
Current hi-speed maglev trains run in the 250-300 mph range. Thus we are talking about increasing the current capacity by approximately a factor of 100. This will be an engineering challenge to be sure, but given recent advances in material technology, this should not be an insurmountable obstacle.
One of the current frontier areas of railgun technology is research by the military on using railguns as actual guns. The new DD(X) class of Navy destroyers propose to use electromagnetic railguns to launch kinetic projectiles at over 5,000 mph. Tests conducted at the University of Canberra were able to accelerate a 16 gram projectile down a 5 m. barrel at 13,000mph. (16)
However probably the most interesting current work is being conducted by Sandia Labs at the D.O.E. research site located at Kirtland Air Force Base near Albuquerque, NM. In 2001, using the facility's Z-Machine, a 20 million amp magnetic field generator, a research team headed by Marcus Knudson was able to accelerate pellets used for materials testing to a speed of 20 km./sec. (44,739 mph.). (17) This is well over the speed necessary to launch payloads into orbit.
In 2005, this same team achieved accelerations of 34 km./sec. Upgrades planed for 2006 are expected to achieve velocities of 45 to 50 km/sec. (18) Technical papers referring to these developments are available from Sandia (19), and the International Journal of Impact Engineering (20).
One early problem identified was the very high speed switching required for the maglev magnet segments at the higher speeds. A number of the papers listed in the bibliography deal with this, and innovations involving single coil switching and pull-only designs were developed that addressed this problem. Bearings for resisting the very high centrifugal loads on the side walls has been identified as a key problem. This may be able to be overcome by superconducting maglev coils.
The track would probably need to be run in a vacuum to allow the very high speeds to be attained. This could be attained in part by using the container itself to push the air out of the covered track like a piston.
The equation for drag does vary as the square of velocity. Drag = Cd * r * (V^2/2) * A where Cd = coefficient of drag, A= cross section area of the Payload, V=velocity, and r= density of the air through which one is accelerating. As the air density "r" approaches 0, the whole drag equation approaches 0. One of course could never achieve this. Another factor in the drag equation which must be considered is that the payload would accelerate in the close-fitting tube, and push the very reduced atmosphere around the track in front of it, not go through it as in the open atmosphere producing turbulence.
However, the largest potential problem is dealing with the entrance into the atmosphere upon launch. Ejecting the escaping air along the launch trajectory may help ease the transition into the atmosphere, but this will need much engineering to find a solution. Of course, if this facility were in an airless location such as the moon or in space, this would not be a problem.
There will be a heat buildup in the electronics. If 10% of the power used in the system turns into heat, then the 109,525 Kw of power required to accelerate 1000 Kg. would generate 10,952 Kw of heat.
Let us assume two very large tracks with a cross section area of .1 m^2 each. A facility with a diameter of 20 mi.(42.2 Km) would have a circumference of 132.6 Km. The volume of the track would be 26,520 cubic m. of steel track. At a density of 7.85 g./ cm^3 this equates to a mass of 208 X 10^6 Kg. of steel.
At a specific heat of steel of .434 joules /g.-C, this would absorb 90 X 10^9 joules of heat to have its temperature raise 1 degree C. This in contrast to the 10.9 X 10^6 watts of heat generated by the 1000 Kg payload generating 10 % heat. ( 1 Joule = 1 watt/ sec.) This paper contemplates payloads of 70,000 Lb. This would generate 337 X 10^6 watts of heat.
Others have proposed similar impulse accelerators in the form of large cannons powered by huge tanks of compressed gas as propellant (21) These do not provide all of the energy necessary to achieve orbit, and include an upper stage rocket as part of the payload. Payloads are much smaller due to limitations in barrel diameter, and they are fixed in position. However, they would be a improvement over very expensive rockets in that the majority of the energy needed to exit the Earth's gravity-well would be Earth-based.
One advantage of this system is that the containers can be standardized, with a number of advantages. The most obvious is that of cost. One suggestion is to make the containers the same dimensions as a standard 40 ft. ocean freight container. There is a tremendous infrastructure in place to handle these units, from ocean shipping, to train transportation, to over-the-road trucking capabilities.
A further advantage of standardized containers is that the containers themselves could be part of the payload, thus they could be developed to be used as modular construction units. Standard steel shipping containers have an interlocking system of corner connects that could be adapted to clamping together to form modular space or planetary habitation units or space vehicles. Standard 40 ft. steel shipping containers are commonly rated at 70,000 lb. or 35 tons. The containers would have small remote-controlled gas jets for final maneuvering, and would be almost all payload except for the track-engaging mechanism. Each container would be custom designed to take the high g loads of launch, and built for a particular function such as liquid or bulk cargo, living quarters, labs, engines, and so forth.
One would want to site this launch facility with several parameters in mind. First would be to have available a large flat area of land that would also be isolated enough that launches would not pose a problem for airports or civilian populations. The US government owns many millions of acres of land that would meet this requirement.
The second requirement would be convenient access to rail and interstate highway transportation. Access to a major seaport would also be a plus. The third factor would be access to large amounts of available electrical power. These requirements would seem to be most easily met in the southwestern area of the United States. However, there are also advantages to locating such a facility near the equator.
This technology would be for materials only, as the centrifugal forces generated at the top speed of 25,000 mph would be on the order of 800-1600 g's, depending on the diameter of the track. However, for potential space stations and resorts, materials would be by far the most abundant and costly items to lift into orbit. Materials could be lifted to orbit and assembled, and people could be ferried to the completed structures by conventional space vehicles.
The energy used to accelerate the payload on this maglev track would be grid electricity. If the amounts of power required would overload local resources, a natural gas fired electrical generating facility could be constructed for the peak loads required, as they are easily powered up for peak power utilization.
The direct cost of launch would be the cost of the electricity.
One lb. going 25,000 mph is going 132,000,000 feet per hour or 36,667 feet per second. Thus each lb. requires an input of 36,667 foot-pounds/sec of energy. One Kilowatt of electrical energy = 737.56 foot-pounds/sec of energy.
Thus each lb. requires approx. 50 Kw of energy to accelerate it to 25,000 mph, disregarding friction and efficiency losses. 70,000 lb.(35 tons) requires 3.5 million Kw of energy. At a wholesale cost of 5 cents per Kw, this requires $175,000.00 worth of electricity. So by dividing this by the 70,000 lb. payload, each lb. costs $2.50/ lb. to launch for direct energy costs.
If we double this to take account of friction and efficiency losses, we still get only a direct energy cost to launch of $5.00 per lb. As the technical and personnel costs would be extraordinarily low under this system compared to those of heavy-lift rockets, one could realistically propose launch costs of under $100.00 per. lb.
A preliminary estimate of drag resulted in a figure of approximately 115.6 G’s of drag at sea level, 32.5 G‘s at 37,335 feet, and 15.4 G‘s at 52,800 feet.
In the first 20 miles of vertical distance traveled, figuring a 45 degree launch, it will take roughly 6 seconds to achieve 20 miles vertical height, at which point drag becomes somewhat negligible.
Using the above G’s of drag for two seconds each, (and adding 1 G for gravity’s deceleration itself) we get a reduction in speed of 7,462 ft./sec in the first two seconds, 2,144 ft./sec in the second two seconds, and 1,050 ft./sec in the third two seconds. Together these cause a reduction in speed of 10,656 ft./second, or 29% reduction in the original launch speed of 36,666 ft./sec (25,000 mph) This leaves 71% of our original speed, or 17,750 mph, about what we want.
Let us look at the heat buildup on the payload. If 30% of the total kinetic energy turns into heat due to atmospheric drag, then 1.05 million Kw of energy will be turned into heat.
If we make the simplifying assumption that all the kinetic energy will be turned into heat in one second rather than the 5 or 6 seconds necessary to transit the atmosphere, then 1.05 * 10^9 joules of heat will be generated.
If this heat would be able to be evenly distributed throughout the 35 Ton container, then the 31.75 *10^6 grams of the container would absorb 13.78 * 10^6 joules of heat to be heated by one degree C. Thus the 1.05 * 10^9 joules of heat would heat the whole container by 76.2 degrees C. if evenly distributed throughout.
However, we know that during the limited time of heat buildup, the heat would be concentrated in a very shallow area of the surface of the container. We will assume that the 8ft. by 8ft end of our container payload will encounter all the friction heat. At a heat penetration of 5 cm. on this surface, this 2.33 * 10^6 g. of steel would absorb 1 * 10^6 joules of heat per C. degree temperature rise. Thus the 1.05 * 10^9 joules of heat produced would raise the temperature of the top 5 cm. by 1,050 degrees C.
This compares to the melting point of steel of 1,363 degrees C., and the boiling point of steel of 2500 degrees C. Thus, significant ablation of the containers due to atmospheric drag heating should not occur if the end of the container be sufficiently thick.
As payloads launch at some given angle and speed, they will start to experience a change of both speed and trajectory due to the forces of drag and gravity. Their trajectory will start to curve back down from its initial straight launch angle. What is required is that the correct solution of speed and angle be found that would result in the trajectory at low Earth orbit being tangential to Earth, and the speed being in the area of 17,500 mph required for stable orbit.
Of course we do have one data point of confirmation that some 20 or so meteorites on Earth have been blasted off Mars, so we do know that things can achieve orbital velocity and more by initial velocity alone, albeit from Mars' lower gravity and atmospheric drag.
A key factor in achieving very low overall costs would be high utilization. Once the basic launch facility is constructed, costs will be for the most part depend on paying off the amortization cost of the facility. Thus, the main cost factor is how often the facility is utilized.
Because space launches will be somewhat limited during the early life of the facility, efficiency will depend on utilizing it for other tasks. One such task could be disposing of nuclear waste by launching it into escape velocity on an orbit into the Sun. This could develop into a very lucrative business as fossil fuel reserves continue to be depleted.
There are about 7,000 tons of high-level nuclear waste generated every year in the world's 443 nuclear power generating facilities, with 30 to 50 more reactors in the pipeline. The U. S. is spending approximately 60 billion dollars to outfit a permanent disposal facility at Yucca Mountain, but the total capacity is only 77,000 tons, it is projected to be at capacity in under 25 years from U. S. production alone, and it may not even go on-line because of concern about discoveries of earthquake faults under the facility. Projected costs to permanently dispose of high-level nuclear waste currently are in the range of $200.00 to $400.00 per pound.
Thus one could charge $100.00 per pound to launch half of the high-level waste currently produced, and generate $700,000,000.00 per year in gross revenue. With a rough estimate of the cost of building the facility at approximately 2billion dollars, this would result in a reasonable payback period. Thus this facility would be a good candidate for development by private for-profit enterprise.
We may be starting to see the first evidence of a malinvestment bubble forming in the private sector segment of the space industry. It was inevitable that malinvestment occur in the public sector of space in the form of over-investment in rocket technology, because there are of course no incentives for rational investment decisions in the public sphere with its almost unlimited funding and no necessity to respond to market demands.
However, we may now be finding the same phenomenon occurring in the private sector. We have at least four companies backed by private fortunes which are developing small space vehicles based on rocket technology, with the apparent aim of giving rides to people to the edge of space and back. While there is a demand for this, and we need reliable and cheap people movers, having all the available private development capital focused on this one area seems redundant. Perhaps we need a new X-Prize focused on price-per-ton placed in orbit to attract some attention into this area.
A new generation of investment capital needs to rationally look at potential markets and rates of return in the space industry and make investment decisions that reflect real-world market demands by investing in infrastructure that commands pricing power and significantly advances our ability to take the next step to a spacefaring civilization.
1. "Final Report on the National Maglev Initiative", US Dept. of Transportation, NMI Office, FRA. Available at the National Transportation Library, http://ntl.bts.gov/DOCS/TNM.html
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21. Eder, K. "A Low Cost Earth Based Launch System and its Effects on Space Industrialization" Space Manufacturing 4, Proceedings of the Fifth Princeton/AIAA Conference, May 18-21, 1981, Grey, J. and Hamden, L. A., ed. 1981, AIAA, New York, p. 221.