The Problem

This is a critical time for humans on earth. Specifically:

We are polluting the air and changing the climate.
We are running out of the energy we use the most (oil and gas)
We are running out of jobs for the coming generation.

We are gradually using up our retirement funds (social security, for example), so workers cannot count on being able to retire as planned.

We are running out of fresh water and land to grow food on.

In this paper these five problems will be referred to as the five limits problem. As we have seen before (Aquater Papers ap1-ap5-this site-Jan, Feb), a key to the near term solution of the five limits problem is a source of energy and a new living space. Specifically, vessels are needed to harvest energy on the ocean-a new living space. A vessel, the SEMAN, is currently under development, and it fills that need.

Many experts in the field predict (and hope) that population will peak out at nine to ten billion, and then reduce to about eight billion as a sustainable population. If this is true, we can, and should, design a sustainable (near equilibrium) economic system based on a population of about eight billion. An attempt to design such a system is summarized in the Aquater Papers ap1 through ap5. However, it is not clear that the population will stabilize as hoped. Some experts believe that even eight billion cannot be sustained over the long term. The population may continue to rise even after it initially settles to a quasi equilibrium, albeit at a much lower rate, until starvation or war imposes a limit. In the past, it has been true that the population in a country with natural boundaries increases until natural limits such as starvation, war or disease curb it.

Perhaps more important, it has been suggested that even if the population does stabilize, mankind cannot operate under an equilibrium system. According to this theory, mankind must both grow and expand, or shrink and die out. Prior civilizations (Rome and China, for example) reached peaks and tried to stabilize their borders with natural boundaries and walls. Instead of stabilizing as planned, Rome’s population and power started to contract, and eventually, it’s civilization ended up dying out under pressure from outside “barbarian” civilizations. China expanded and died back, then expanded and died back again as external civilizations (Mongols, etc) pressed in. In at least one case, however the decision to limit China’s growth came from within. Both civilizations entered decadent or contracting phases as soon as they stopped expanding. They could not maintain a constant area and an equilibrium internal population and stable political state for long. It is yet to be seen whether a civilization with a stable area, population level and political system can maintain that state over the long term even if there is no pressure from external civilizations.

So here is the problem. It seems possible that earth’s population may reach its sustainable capacity and then become unstable and begin to decay even if there is no pressure from an external civilization (from another stellar system, for example). Thus, it may be necessary to either work out the principles of a static, sustainable, non-expanding civilization, or to provide a means for man’s expansion beyond this earth, if man’s civilization is to survive. The rules of operation of a static, sustainable economic system have been summarized in the Aquater papers ap1 through ap5, so here, we will look for a new energy source and new living space to accommodate man if and when a static, sustainable civilization is found to be unstable. Even beyond this problem, a new, very large living space and energy source will provide a means of large-scale expansion and a new opportunity for mankind, which may have value in its own right. This begins to address the larger questions, “Can an equilibrium civilization be maintained, or will mankind’s civilization start to decay if equilibrium is reached? In other words, does mankind need to grow and expand all the time? If growth is required, where can mankind expand.”

Is Action Required?

The short answer is “not immediately”. The more critical problem is to achieve near sustainability in the near term, which is described in ap1 through ap5. It is likely, however, that eventually it will be necessary to find a new living space in order to reduce the population pressure on earth, and provide new opportunity elsewhere, if mankind needs to grow and expand. The problem is that there will not be a clear signal that indicates the need for and the correct time to develop the next stage in mankind’s development until a crisis develops. Thus developing such a system now to the extent possible appears to be the correct move.

The Solution

China has attempted to limit population by law. Limiting population by law is very difficult and may be impractical. Women’s desire for children is very strong. Many religions are against birth control and abortion and in favor of large families. The most practical solution to the problem is to find a new energy source and living space, and let the people provide whatever limits they desire without imposing legal limits.

Since the land is filled and the ocean is expected to be filled in the near term future by the vessels harvesting energy, the next available colonization space is satellites in earth orbit. The problem is that space colonization using satellites is extremely expensive using existing methods of getting in orbit. Thus, large-scale colonization of space near earth is impractical without a significant reduction in booster and satellite costs. In order to achieve this goal, the following technologies are needed:

A cheap method of boosting satellites and materials into orbit, and bringing materials and satellites back to the ground.
A cheap energy source for getting into orbit and for operating on orbit..
A cheap means of supplying expendables on orbit, and bringing orbit products to the ground.
A means of making a living on orbit.

Standard boosters cannot accomplish these tasks economically, but a new technology has been proposed and studied that can achieve these goals. Here we will summarize this technology and see how it applies to this problem.

A Cheap Method of Boosting a Satellite to Orbit

The problem with current boosters is that the booster must carry the fuel needed to achieve orbit. Thus the fuel to payload ratio will be very large, and the total weight of the booster and the satellite is also very large, and thus very expensive. The only way to reduce size and expense significantly is to take the fuel and the drive off of the booster. This task can be done by driving a pellet from the ground with an electro-magnetic drive, and exchanging its momentum and part of its energy with the satellite to push the satellite up a step toward orbit. In order to give a steady thrust to the satellite, a sequence of pellets repeatedly striking the satellite is required. This sequence of pellets can be reflected off the satellite back to the ground and then driven again from the ground up to the satellite with the electro-magnetic drive to form a reentrant, but segmented two-way momentum beam. If the beam is used to drive the satellite to synchronous altitude, it will stabilize in a synchronous orbit. In this method, the reentrant beam is tapped of a portion of its momentum and energy to boost the satellite into orbit a step at a time. The beam itself requires little energy to maintain since the energy given to the pellets to put them in orbit can be mostly recovered when they fall down to the ground and then used to put them back into orbit. The energy needed to raise the satellite is taken from the electro-magnetic drive that pushes the pellets from the ground with just a little more energy than is needed to keep the satellite in position. This small step in energy gives a small increase in satellite altitude. If we want to bring the satellite to the ground, it is only necessary to dislodge the satellite from its synchronous orbit, and then bring the satellite back to the ground by supplying a little less energy to the pellets than is required to maintain orbit position. The satellite will settle down on the momentum beam slowly, a step at a time.

Note that with this system, the cost of boosting the satellite into orbit is reduced to:

The electrical energy.
The capital cost of the electro-magnetic pellet drive.
The pellets.
The pellet catching mechanisms (one on the satellite and one on the ground) used for the drive.

The electrical drive, the ground catching mechanism and the pellets can be used again and again, so they can be amortized over many satellites, but the capital cost is significant. A rough estimate of this method’s feasibility and cost will be given here.

Electrical Energy The electrical energy is usually available at about $0.08/KWH (see below). Let us consider cost of the electricity necessary to lift the satellite into orbit. If the satellite weighed 100 KG, and were lifted vertically into orbit with perfect efficiency, energy of 1.8x10exp3 KWH would be necessary. If the cost of the energy is assumed to be $0.08/kwh, and the actual efficiency is roughly 50% (see below), the cost of the energy would be roughly $3000/launch.

Electro-magnetic Pellet Drive The cost of the electrical pellet drive is modest. It is essentially a generator and a set of capacitors. Let us consider the cost of this drive. There are three drives that are possible candidates for a pellet drive. One is a crossed field drive normally used for maglev trains. Another is a parallel bar drive normally used for a rail gun. The third is a capacitor driven solenoid drive well suited for conductive spherical pellets. Although any one of the above could be used, the third appears to be best suited to the pellet drive. The solenoid drive consists of a set of capacitors dumping electricity into the solenoid, which induces an electrical current in a conductive spherical pellet. This current then makes a magnetic field that pushes against the solenoid field and drives the pellet up. Let us assume that the pellet has a mass of 0.5 KG. Further, assume that 1 F capacitors are connected to achieve 4 F that operate at 1000 V to obtain one stage of acceleration. If we then use 31 of these stages in sequence, the resulting pellet velocity is ~11,100 M/S or the velocity needed to achieve synchronous orbit. Initial estimates of the cost of this drive show that it could be constructed for roughly $100,000. Assuming the drive lasts for 20years, capital costs would then be roughly $5000/yr. Assuming one launch per month, cost per launch would be ~$420/launch.

Pellets The most expensive part of the booster system is the pellets because of the large number required. If small mass pellets are used, a large (and thus expensive) number of pellets are required to obtain sufficient thrust to lift the satellite (>1g). If large mass pellets are used, a large, complex and expensive electric drive and catching mechanism is required (see below). Thus minimum cost is obtained by optimizing the mass of the pellet between these two limits. The optimum turned out to be in the range of 0.1% to 1% of satellite mass. When the pellet interacts with the satellite, momentum is exchanged in an impulse reaction and the pellet is reflected toward the ground and the satellite is moved upward. In the act of moving upward, the satellite absorbs energy from the pellet because it is higher, and the pellet moves toward the ground with less velocity (and thus energy) than it started with, so it loses energy. In order to maintain an upward velocity, the satellite must continue to be hit with successive pellets at a rate that achieves slightly more than 1g of force. This succession of pellets is called the momentum beam.

Ideally, a particle would be pushed up to the satellite, reflected from it and then dropped back down to the ground due to reflection and gravity and then be reflected back up from the ground in a closed cycle that loses no energy as long as the satellite does not move. If the satellite moves up, it gains energy and the pellet loses energy, which shows as a loss of velocity on the way down. Thus, ideally all energy put into the momentum beam shows up as an increase in satellite altitude. Of course losses are inevitable, especially in the earth based reflection device, so more energy must be put into the momentum beam than is gained in satellite altitude. These losses will be addressed below. As an example, consider a 100 KG satellite. Assume a 0.5 KG pellet is used in the momentum drive. Then, to achieve a 1g thrust, a new pellet must impact the satellite every 0.3 seconds. In order to fill the momentum beam from ground to satellite (when satellite is in orbit) with pellets 0.3 seconds apart, 24000 pellets are required. Assuming the pellets are injection molded plastic filled with an aluminum structure, and a payload of expendables for the satellite, and a conductive outer layer, it would cost ~$10/KG (including material and manufacture). Thus the cost of the momentum beam is roughly $130,000. The capital cost is then roughly $6,500/yr assuming an interest of 5%. Assume 12 launches per year, the capital cost for pellets is roughly $550 per launch. Assume also that roughly 1% of the pellets will be lost in each launch due to unavoidable changes in the beam direction. This system costs ~$1,300. The total is $1850/launch.

Catching Mechanisms

Two catchers are required, one on the satellite and one on the ground. Each will be described and the cost estimated separately.

1. Satellite Catcher

The satellite catcher must receive a pellet traveling at a high but limited velocity, and turn it around and send it back to the ground without damaging either the pellet or the catcher and with the minimum amount of energy loss, and the maximum amount of energy transfer in the process. The velocity can be chosen to insure minimum damage. In order to accomplish this task:

The receiving aperture must be larger than the pellet area by a factor of 100 to 1000 in order to cover variations in the pellet trajectory due to air turbulence and stray fields on the way up.
The reflector must be able to stretch out the interaction time to reduce the local impact force.

The most straightforward mechanism that accomplishes this task is a funnel feeding a wheel. The funnel directs the pellet to a rotating wheel where the pellet is caught and pulled around the circumference to an exit tube directed toward the ground. The wheel and the pellet are designed to have diameters large enough to keep the force of the impacting pellet on the wheel rim below the stress capability of the pellet and the wheel. Note that the wheel can be coupled to a generator to provide energy to the satellite as it rotates under the pressure of the incoming pellets. It is estimated that this mechanism will cost roughly $10,000. There must be one for each satellite, so its cost will be put into satellite costs.

2. Ground Catcher

The ground catcher has to handle the terminal velocity of the pellet as it falls to earth, which can be as high as 11,100M/S. This is a very difficult task, and is far beyond the capability of the simple funnel and wheel device used on the satellite. Here a series of chambers filled with oil must be positioned above the funnel and wheel to slow and cool the pellet before it reaches the funnel and wheel. Each chamber is designed to push a portion of the oil through an orifice at high (but much reduced) velocity and direct it onto an impact wheel that drives a generator. The pellet passes through each chamber into the next chamber. The energy generated at the impact wheel is stored in capacitors and used to drive the pellet back into orbit after it is recovered. After the pellet is slowed, it reaches the funnel, and is directed onto the wheel where it is slowed more by taking out some more energy with the wheel and then it is turned around and directed back into the electric solenoid drive to be driven back into orbit. Between the wheel and the solenoid drive, a mechanism is provided that can take out old pellets and insert new ordinary or specialty pellets (such as pellets filled with supplies for the satellite, or pebbles for a pebble bed reactor). The cost of this mechanism has been estimated to be roughly $100,000, and so the capital cost will be $5,000/yr at 5% interest. If 12 launches are made per year, the per launch cost is roughly $420. Note that the efficiency of the oil velocity reducer in generating electricity is relatively low (30-50%). A lot of the pellet’s energy will be converted into heat and shock waves in the oil filled chambers. This energy must be replaced by inputting new electricity (see energy efficiency above).

Total booster cost

The total of the operating costs (indicated above) is ~$5500/launch. Overhead and special equipment use (such as tracking radar, etc) is expected to be a little less than three times the operating costs or $16,500/launch. Thus the total cost of the boosting operation is roughly $22,000/launch for a 100KG satellite or $220/KG. Larger satellites (up to 1,000KG) can be obtained by putting up several satellites and connecting them in orbit. This method would not be convenient for satellites larger than 1000KG, so it would be necessary to use a larger base satellite. For example, one could start with a 1000KG base satellite, and then use a sequence of 6KG pellets to push the satellite into orbit.

Difficulties and Risks

The high-risk portions of this system are:

The electro-magnetic pellet drive with a velocity capable of achieving synchronus altitude.
The pellet travel through the atmosphere.
The pellet catchers-especially the ground-based catcher.

The risks involved in each of these portions will be discussed here.

Risk Areas in the Pellet Drive

Drives for small and large payloads (pellets) have been done before with each of the three electro-magnetic drives, but none achieving 11,100M/S. Both high velocity and high accuracy will be required in this system. The high velocity depends on the ability to build high capacitance (>1F) and high reliability condensers, and high-speed switches. The condensers are available, as will as the switches, but until they have been tested for this high velocity application, success is not sure. The high accuracy may require a directing tube as well as magnetic guidance to keep the pellet from intersecting the tube walls. Such a device has been theorized but not constructed and tested. This device appears feasible, but development may be difficult.

Pellet Travel Through the Atmosphere

It is necessary to determine if the pellet will be overheated in the atmosphere. The time spent in the main part of the atmosphere (0 to 100,000FT) is roughly 2.7SEC moving up or moving down. This is not sufficient to heat the pellet significantly due to friction from the atmosphere (<10deg C). Also, we must determine if the atmosphere can deflect the pellet significantly, and cause it to miss the catching area on the satellite. Again, 2.7SEC is very little time to deflect the pellet, and side pressure on a pellet due to atmospheric wind and turbulence is small. Furthermore, if the pellet hits the edge of the funnel catcher, it will exert side pressure on the satellite that will tend to center the satellite on the beam. Finally, sequential pellets are only a few tenths of a second apart, so there is very little time for a pellet to be displaced with respect to the following pellet, so if the beam wanders, it will not wander rapidly, and the satellite will follow it. The only question is if the beam can wander fast enough to move outside of the satellite’s receiving aperture before the satellite follows it. Initial calculations say no. If it can, however, a reaction motor drive and a tracking system can be rigged to keep the beam directed toward the receiving aperture.

The Pellet Catchers

The satellite-based catcher is an easier design than the ground based catcher because the designer controls the velocity it has to handle. The velocity should be as high as it can be without causing damage to the mechanism in order to maximize momentum exchange and minimize the number of pellets required. It should not exceed the velocity of sound (1,100ft/sec) to minimize shock waves. The surface stress of the pellet, the funnel and the wheel determine the pellet and wheel diameter and the funnel angle. The pellet diameter should be in the 0.1 to 0.6 FT range. The wheel diameter should be in the 0.5 to 3.0 FT range. The funnel angle should be in the 20deg to 40deg range.

The ground-based catcher is an especially difficult design because the terminal velocity of the pellets (11,100M/S) rather than a design parameter determines the velocity it must handle, and the velocity is high. A simple funnel and wheel catcher is not possible. Here, it is necessary to have the pellet enter oil in a long funnel shaped tank where part of the energy is absorbed, and then it pushes the rest of the oil into and through the tube to form a high velocity oil stream that is directed to an impact wheel and turns it. The wheel then turns a generator that drives the electro-magnetic pellet drive. New electrical energy is also used to get the proper pellet velocity. The pellet goes on to a wheel that turns the pellet around and directs it to the electro-magnetic drive. The first fluid absorbs energy through friction until the mechanism can handle the pellet’s velocity. Afterward, the generator absorbs the remaining energy. Calculations indicate that the funnel tank should be about 20FT long to insure that the mechanism is not damaged. A radiator must cool the oil.

Cheap Energy Source for Getting Into and Operating on Orbit

Different energy sources are required to get into orbit and to operate on orbit. We will investigate each here.

Energy and Momentum for getting into orbit

The energy needed to push the pellets into orbit can come from SEMAN operating near the launch site (see ap2 Energy Scarcity and New Options). Recall that the launch site must be at the equator, and most of this area is on the ocean. It costs about $0.034/KWH to produce, but is expected to be sold at $0.08/KWH, which is what was used for the cost estimates.

Energy for operating in orbit

The energy used by the satellite in orbit can, and should, come from two sources. The first can be tapped from the momentum beam. The wheel that spins under the pressure of the pellets moving around it can drive a generator. When on orbit, the excess energy that would normally move the satellite higher, can supply the satellite with energy. Also, solar cells can supply energy in earth orbit or closer to the sun. Finally, the pellets that put the satellite on orbit, can contain fission nuclear reactor fuel. These fuel pellets are called pebbles and fuel a pebble bed reactor. This reactor can remain on line for as long as the pebbles are supplied to it, and supply a large amount of energy. In addition, this nuclear power makes the satellite independent of distance from the sun, whereas solar cells begin to fade when the satellite moves much beyond earth orbit. Also, the energy supplied gives the light needed to grow food and recycle water and wastes anywhere in the solar system. Finally, the reactor can supply energy to power a xenon ion drive with a very high specific impulse capable of moving the satellite anywhere in the solar system as long as the pebbles and the xenon fuel is resupplied periodically by the pellets in the momentum beam.

Supplying Expendables

As noted above, the pellets, suitably hollowed out, can be used to supply:

Electricity via the pellet return wheel.
Nuclear reactor fuel pebbles via the pellets in the momentum beam.
Xenon fuel for the ion drive.
Nitrogen and oxygen to replace the normal leakage to space and accidental big leaks.
Water to replace leakage to space, and the water that cannot be recycled.
Seeds, medicines, etc., needed for emergencies.

Making a living on orbit

The people who live on orbit will be expected to provide trade goods that will pay for the capital expense of the satellite, the boost into orbit, and the expendables supplied on orbit. This can be done by:

Diverting sunlight to the ground on the night side of earth to illuminate solar cells that would be unused during the night. Deploying large reflectors in orbit that catch sunlight and divert it to the area on the ground that contains solar cells at night would do this.
Manufacturing machines, drugs and chemicals that require zero gravity conditions. Note that these products can be transported to the ground by use of the momentum beam.
Manufacturing and maintaining nodes that can provide momentum beams for transport of satellites anywhere in the solar system and perhaps beyond. Note that this system requires that the beams transfer the launch point momentum of the nodes to the ground, a task well suited to the synchronous beams on the equatorial ocean.
Manufacturing and maintaining a nuclear fission reactor in orbit for producing nuclear fuel for satellite use from U238. This must be in a synchronous orbit or beyond to insure that the reactor could never impact earth due to orbit decay. Also, the nuclear material used for the reactor must be put on orbit in small amounts, so that an accident in getting it on orbit will only result in a small amount of nuclear material impacting earth. Finally, the booster station should be on the ocean to insure that an accident results in the material going into the deep ocean rather than on land.
Mining the asteroid belt for high value metals and other materials and transporting them to the earth’s surface for sale. Note, this process would require the satellite involved to have a nuclear reactor for electric power because it would operate beyond solar power range. Also, momentum beams would be required for transport of these materials to ground.
Using the momentum transport beams noted above to explore and colonize Mars, the Asteroids, and the moons of Jupiter and Saturn wherever it is profitable to do so.

There are many means of making a profit on orbit as long as the cost of getting there is reasonable. It is expected that many people will take advantage of this style of life.

Summary and Conclusions

It seems possible that earth’s population will eventually become unstable for any of a variety of reasons and need a new space to live. We will then need to find a new energy source and new living space to accommodate man if and when this happens. Even beyond this problem, a new living space will provide a new adventure and a new opportunity for mankind.

The obvious new living space is satellites in orbit around earth. The energy source is two fold, energy from the SEMAN operating near the booster launch zone gives a surface energy source, and energy from pebble bed nuclear fission reactors gives an on orbit energy source.

The satellites can be boosted into orbit by use of pellets fired to the satellite by an electro-magnetic driver where they exchange energy and momentum with the satellite. The pellets are returned to earth where the pellets and some of the energy is recovered. This reentrant set of pellets constitutes a momentum beam that also carries energy. The momentum beam can push the satellite into orbit, and it can also transport energy to the satellite in orbit where it can be converted into electricity. The momentum beam can also carry expendables to orbit in the hollowed out pellets.

The satellite can provide trade goods to earth to pay for its capital and maintenance cost by:

Diverting sunlight to the night side of earth to illuminate solar cells that would otherwise be useless at night.
Manufacturing machines, drugs and chemicals that require zero gravity, and transport them to ground.on the momentum beam.
Mining the asteroid belt for high value metals and transporting them to ground on a sequence of momentum beams.

Note

The preliminary design work is done. The physical prototype has not yet been started.
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