God of Science and Astronomy
Space Junk – An Overlooked Resource and Business Opportunity
Orbital debris is a growing problem and poses a serious hazard to astronauts, satellites and future space missions. It is estimated that more than 100 million pieces of space junk (6800 tons) are currently in Low Earth Orbit (LEO) traveling at speeds up to 17,500 MPH. and The Department of Defense Space Surveillance Network tracks 15,000 cataloged objects and there are hundreds of collisions every year. With decreasing launch prices and expanding multinational government and private launch capacity, the amount of space debris can be expected to multiply. As current and planned satellites become obsolete, deplete propellant or simply fail, there will be a steady supply of material joining the orbiting canopy of space debris.
Today, it costs $10,000 to put a pound of payload into Earth orbit. It was only by the uncommon exertions of costly rockets, fuel and a complex physical and institutional infrastructure that this orbiting material was released from the pull of Earth’s gravity to become a weightless menace. Proposed space junk disposal systems, such as the NASA ‘Laser Broom’, the Japanese Kounotori ‘Integrated Tether Experiments’ (KITE) and the Surrey Space Center’s ‘Remove DEBRIS’ are all based on deorbiting the junk and having it burn up in the atmosphere. Deorbiting and vaporizing this material disregards the effort and expense previously expended to put the materials into orbit.
Reprocessing scrap metal has always been less energy intensive than refining from natural, raw materials. Consisting mostly of metals, glass, ceramics and plastics, space junk possesses innate value primarily because of its propitious location. Recognizing the inherit value of this orbiting debris as the raw material of a future space manufacturing industry might alone be enough to transform our perception of it from dangerous trash to a useful resource. Implementing such a transformational cognizance might only require an injection of NASA or European Space Agency R&D funding and expertise for proving the feasibility of a Medium Earth Orbit (MEO) or Earth-Moon L4-L5 scrap storage facility. Such a study into space scrap storage technology could initiate a profitable, self-supporting commercial space cleanup, recycling and manufacturing industry. Space Drone tugs, built by London-based Effective Space, may be capable of moving dead satellites to this safe storage point.
Developing the initial design and engineering concepts could spur private and public funding for the construction, launch and implementation of a MEO storage facility. Additional funding for development and maintenance of a central storage facility could be generated with an imposed fee on those who profit from commercializing space or otherwise contribute to LEO space litter. And it is precisely these players who have the most to gain from a cleanup and the most to to lose from ignoring the problem. These include governments, militaries, launch services and satellite companies. Such a fee might also encourage vehicle and satellite designs that would minimize space clutter, incorporate a propellant system to move expended craft to the MEO scrap collection point and make separation, sorting and component recycling easier.
Once a MEO scrap storage facility was operational and the feasibility for scrap recycling realized, the commercial opportunities presented should spur the development of competitive proprietary methods to capture, agglomerate, contain and transport space debris. The next phase would consist of moving space debris to this single collection point in MEO. Transfer of some orbiting materials to the MEO location might be accomplished with NASA Laser Broom technology used to divert or increase orbital velocity.
Once MEO agglomeration of scrap material was initiated, the removal of dangerous debris from LEO would not only make launch and orbiting safer but should generate private sector awareness for the opportunities in related space industries. Eventually the potential value of this growing material resource would become commercially attractive and exploited. The collected availability of unprocessed scrap and other manufactured materials in space would ultimately set the stage for the recycling, production and assembly of finished glass, ceramic, plastic and metal construction products.
Recycling this reservoir of space scrap might then begin by shredding, pulverizing, liquefying or vaporizing the material and sorting the aggregate by magnetism, reflectivity, spectrography and centrifugal mass separation. The resulting metal. plastic, glass and ceramic powders could be directly used in additive manufacturing such as 3d printing, selective laser sintering and fused deposition modeling. Refined powders could then be smelted with solar furnaces for production of wire, sheet and plate products. Sheets and plates can be further fabricated for assembly with digital controlled laser or plasma cutting systems. Finished products created by additive manufacturing, such as sheet, rod, structural beams and tubing, could become the building blocks for a new generation of large-scale space structures. Made In Space’s Archinaut Ulisses proposes robotic, additive manufacturing for large space structures. The availability of sorted and refined materials in space would set the stage for the development of zero g material manufacturing and ultimately the assembly of large-scale structures.
Heat energy for liquefying, smelting, extruding and rolling can be obtained with focused solar energy furnaces. Robotic machinery, powered by solar electric, can be controlled and monitored from an Earth based command center. The scale of the refining operation might be contained in a very modest (possibly tabletop size) area; not nearly the scale of earth based factories. With continuous operation outside of the Earth’s shadow, even a concept demonstration prototype system would steadily accumulate usable ingots, powder and wire. The robotic-operated shredders, smelters and extruders should require infrequent visits for maintenance and upgrades. Working in the vacuum of space would have the additional advantage of minimizing oxidation and other contamination during smelting and shaping of high purity metal and alloys.
The constrained physical capacity imposed on launch vehicle payloads has always made large space structures uncommon. In-space manufacturing and assembly then presents the next best way to create large orbiting constructs. Space ports, interplanetary ships, orbiting hotels and extra-terrestrial habitat could be assembled (at least structurally) from the ever replenished supply of orbiting space junk. With a space manufacturing infrastructure established, the growing demand for raw materials, combined with more efficient collection systems, could make the collection of ever smaller debris economically advantageous. Improved methods of collection combined with the continual resupply of readily processed orbiting material, might forestall the necessity of more costly and energy intensive asteroid mining for raw materials.
Thus a multinational government investment in the development of an MEO space debris storage facility, while immediately mitigating the existing and growing population of space junk, could promote the re-use of available orbiting materials. A collection of orbital scrap could incentivise commercial collection and transport of LEO debris while fostering a profitable recycling system for shredding, pulverizing and reprocessing to provide structural components for the next generation of large-scale, space assembled structures.
Once space manufacturing and the assembly of large-scale structures become a functional reality, a natural demand for resources such as orbital scrap materials would be created at which time the removal, storage and recycling of space debris will become a profit driven, competitive, commercial enterprise.
Relativism of a Straight Line
Consider a simple problem about centrifugal force. Imagine you stood at a pole of the earth, say the North Pole and constructed a wheel whose axis extended from the calculated axis of the earth. (This wheel would spin parallel to the plane of the equator.) Imagine that this wheel contained a precision force gauge whose output you could remotely read as the centrifugal force at the wheel’s rim.
You spin the wheel clockwise (from the top view) and recorded the force at the wheel’s rim. By spinning in the clockwise direction the wheel would be spinning opposite that of the earth’s rotation. Would the rotation of the earth, in effect, be subtracted from the spin of the wheel? Would the centrifugal force readout be higher if the earth did not rotate?
Now you stop the wheel and spin it in the opposite direction, i.e. counter clockwise at precisely the same speed (RPM) relative to you standing on the earth. Again you read the output of the force gauge and record it. In this direction would the earth’s rotation add to the wheel spin? Will the output of the second (counterclockwise) spin have an added centrifugal component that would show up on the force gauge? Or will the wheel produce the same centrifugal force? Does your effort, imparting a force in the wheel, somehow create it’s own frame of reference relative to you (the force) and the wheel? Or could the proximity of the wheel to the earth’s gravity somehow envelop and include the wheel in its rotational motion allowing the two opposite direction spins to produce an identical force output?
The speed of the wheel obviously depends on where you stand when you determine the wheel speed. If you float in space above the pole you will see the wheel spinning at different speeds. The counter clockwise wheel spin being 2 Revolutions per day (RPD) faster than the clockwise direction. And from that point of view you would expect the centrifugal force to be higher in the counterclockwise direction. If you took the remote readout of the force gauge in space above the pole, would the readout be different?
Centrifugal force is derived from the inertia of an object in motion (which prefers to travel in a straight line). Inertial resistance to that ever-changing circular motion produces the force. It is technically called angular momentum. Also, the velocity of that body in motion determines the amplitude of that force. So the question boils down to the immediate straight line moment of velocity of a point on the rim. However, this brings us back to the original problem. If you measured the moment of velocity at a point on the rim standing at the at the earth’s pole (or anywhere on the earth), it would again be the same in both directions. If you measured the moment of velocity from space, it would again be higher in the counter clockwise direction. It seems simple Newtonian motion is relative to the observer’s position and motion.
Our individual motion standing on the earth is far from simple. We are not only moving on a spinning earth but also orbit around the sun, which is moving through the galaxy. This galaxy is spinning around its center and moving relative to the local cluster. And this cluster is moving relative to the more distant background galaxies. So even the task of throwing a ball in space, which would appear to the thrower to go in a straight line, (producing no force of angular momentum) would not be moving in a Newtonian straight line if observed from, for instance, the moon.
So is the straight line motion of the ball solely determined by the force applied, from the point of applied force? If so the wheel would produce the same centrifugal force in both directions as the applied force is equal (though opposite). If the motion of a thrown ball is not a universal straight line but follows the curves and spins of an orbiting earth and moving sun, then the centrifugal force of the wheel will be different between a clockwise spin and a counter clockwise spin.
If the observer’s motion determines weather a line of motion is straight or curved, then consider an observer above the earth, watching a bullet fired from the equator to the north pole. It will naturally take the shortest path, (a straight line for us watching on earth). To eliminate any confusion about following the curvature of the earth I have will make the northern hemisphere a cone with the equator as the base and the north pole the apex and removed the attraction of gravity. From the firing position on the equator the bullet would describe a perfect straight line. From space above the rotating cone the path of the bullet would describe a tightening spiral. So the outside observer would see the bullet traveling a curved path and therefore assume that some outside force was causing the mass to travel a path other than a straight line. They would also assume that there was a side force on the projectile produced by the angular momentum. They would expect anyone traveling inside the bullet to experience this side force as one in a car when turning a corner.
So where lies this frame of reference for determining what is a straight line? The answer could come from the measurement of centrifugal force itself. It could be determined by performing our original experiment of spinning a wheel. If the centrifugal force is identical with both spins, the frame of reference is the wheel itself. If it is additive and subtractive by the earth’s rotation, the frame of reference then occurs in a larger context beyond the earth’s influence.
If the later was true, this experiment on a larger scale could determine the absolute frame of reference for all motion. It would be possible that the reference frame could be the universe and with a large enough wheel we could determine if the universe itself is in relative motion. We could measure this by a series of wheel spins (or tethered weight spins) in space with a precise force sensor. By changing the orientation and speed we could find the condition of zero angular momentum, when the wheel is at rest relative to the universe. The wheel speed and orientation would match the rotation and orientation of the universe. This would also mean that our universe not self contained but part of a larger framework possibly containing other multi-verses.
However, if the reference frame is that of the point of origin of the applied force, then every moving object in the universe determines its own straight line. And producing a universal straight line would be impossible. It would mean that straight line inertial motion is as relativistic as the speed of light. That any straight line motion is determined by the last applied motion changing force. Traveling in space (away from any influencing source of gravity) you would know that you were going in your own straight line but it would be impossible to prove it by observing outside motion.