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Unformatted text preview: American Institute of Aeronautics and Astronautics 1 A Passive Microscale Solar Sail Justin A. Atchison 1 Cornell University, Ithaca, NY, 14853 We consider spacecraft length scaling as a means of enabling achieving passive, feasible infinite-impulse orbits. Taking inspiration from the orbital dynamics of dust, this paper discusses the consequences of length scaling on acceleration due to solar radiation pressure and demonstrates its effectiveness on a candidate microscale spacecraft. We propose to fabricate this dime-sized spacecraft on a single ultra-thin substrate of silicon. This choice reduces the total mass to fewer than 7.5 mg and makes the spacecraft bus itself a solar sail, yielding a lightness number β of 0.0175. This architecture can provide passive solar sail formations and various passive methods of changing orbital energy. We also consider augmenting this architecture with traditional CP1 sail material ( β of 0.1095) to reduce transfer times further. The paper surveys and compares passive methods of achieving a marginally stable sun-pointing attitude including the addition of fixed vanes and optical grating of the surface. The microscale infinite impulse (MII) spacecraft design replaces the traditional spacecraft subsystems with a single integrated circuit (IC). Our current fabrication efforts are directed at realizing this spacecraft as a simple sensing and transmitting circuit with standard IC tools. I. Introduction UST in the solar system experiences a surprising lifecycle. Solar pressure and electrostatic forces can compete with gravity to give very small particles highly nontraditional orbits. Some dust finds a stable orbit; some dust gently lands on the surface of planets like our own, and some dust is energetically ejected from the solar system. Dust particles vary in size from a few molecules to 100 μ m and have a mass smaller than a few μ g. At these mass scales, the acceleration due to what would be considered perturbation forces on larger bodies can no longer be neglected. In fact, we propose that they be harnessed and manipulated in order to enable new propulsion techniques and missions. Dust’s unique behavior motivates the present study of the orbital dynamics of extremely small bodies and the development of a spacecraft capable of exploiting on these physical principles. In pursuit of this goal, we are working to create a self-contained “Microscale Infinite-Impulse” (MII) spacecraft capable of demonstrating significant, useful propellantless propulsion by virtue of its small length scale. Inspired by the simple, successful mission of Sputnik in 1957, we focus on a simple, feasible, but genuinely new design. For three weeks, the 23 inch diameter Sputnik I broadcast its internal temperature and pressure as it orbited and demonstrated the feasibility of artificial satellites. A half century later, we expect to duplicate Sputnik’s achievement using less than one ten-millionth of its mass. Our design rethinks the traditional subsystems (power, achievement using less than one ten-millionth of its mass....
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- Spring '11