Many future space mining applications involve capturing a small asteroid and putting it in orbit around earth and mining the asteroid for the various compounds it contains. One of the main compounds that will be mined is water. Water (in the form of ice) is one of the main constituents of most asteroids. From that water, it can easily be broken down into Hydrogen and Oxygen for both fuels and breathing, and water for drinking. Usually, heat is used to initially melt the ice and process the resultant liquid water into the required products. The sun is an abundant source of heat, but collecting that heat into a focused beam to efficiently heat the asteroid material to extract the water requires a significant amount of ‘collection area’ from the solar collector. Most present engineering models use large (20 to 30 meter diameter) reflective surfaces or large fresnel lenses to perform that collection process. These models are massive, expensive and highly complex to control. They also require multiple reflections, which introduce losses at each reflection surface.
This ‘collection” process could be accomplished using a simple fluid lens made up of two space qualified, clear, reinforced meshed/net materials held together by an outer clamped ring structure. In between these two thin, reinforced sheets, is introduced water at a small enough pressure to stretch the films into the natural shape it would form. This “natural” form can be modified with appropriate variation of the mesh material within the two films, to produce the desired, bi-concave ‘spherical lens’ shape. Small changes in applied pressure can ‘focus’ the lens to the proper working distance. The lens system consists of three main subsystems: 1) The outer mechanical (circular) structure which holds the edges of the two film layers and applies both the clamping forces and the stretching force (both minimal in magnitude) to adhere the edges together and to focus the lens, along with the water pumps for filling/deflating the lens. 2) The two layers of film form the outer boundaries of the lens. This set of films will be designed (using the reinforcing mesh) to form a specific shape, with the proper axial loads applied and require pressure of water on the inside of the lens. 3) The third part of this system (the most massive of the system) is the water that will be mined locally from the asteroid.
If the lens material becomes damaged (micrometeorites, fatigue, etc.), the water can be pumped to a reserve tank, the film can be detached and released from the holding mechanism, another identical film can be easily put into place and the ‘lens’ can be refilled with the water. Dozens of replacement lens films could be included in the original construction of this structure.
A 10 meter diameter fluid lens can collect up to 125 KW of solar power continuously. Depending on the focal length of the lens, which can be designed to various diameters, the focus spot can vary from 2 meters in diameter
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