= ISDC 2013 = I will present two papers: * Server Sky Technology, Thursday at 11 - 1150 * Server Sky Applications, Saturday 10 - 1030 === New ideas since 2010: Thinsat design === * 5 gram Version 4 thinsats, 5 m^2^/kg for light pressure stability. * Version 3 thinsats assumed 3 grams and 8 m^2^/kg Thinsat orbits are modified by light pressure, and drift over the course of a year. The drift is too high for Version 3, bringing the thinsats closer to the [[Lageos]] orbits without enough safety margin. * More conservative non-transparent reflective electrochromic thrusters. * Based on inorganic amorphous nickle hydroxide and tungsten oxide with a solid state electrolyte. * These should be highly radiation resistant and leak-proof compared to organic/liquid thrusters. * Aluminum substrate. * This provides the reflector for the thrusters, and provides an electrical ground plane. * Can be roll fed, and embossed with slots, through-holes, and cavities for chips. * Less fragile than V3 glass substrates. * Slot antennas * Rather than wire antennas surrounded by insulator, slot antennas are cut into the ground plane and offer much higher drive impedance. * Slots can be dual-fed, providing low SWR at both 60GHz and 70GHz for intra-array and ground-link communication. * Most of the ground plane remains intact for solar cells, chips, and wiring. Signal strengths are small enough that there will be little RF coupling to differential signalling wires. * Slot antennas can have E-W or N-S orientation in different arrays. * This permits two different families of thinsats, [[OpenManaged|"open"]] and [[OpenManaged|"managed"]], allowing some countries to manage internet access for their citizens, while others allow unrestricted access to the internet. * Geodesic arrays * An icosahedron (12 vertices, 20 faces, 30 edges) derived geodesic sphere, squashed in the radial direction. * A V=31 sphere contains 9612 thinsats, weighs 48 kg, is about 100 meters across, and produces 37 kilowatts peak. * Preliminary research shows 300 meter diameter half-power ground spots with uniformly dispersed scatter * No high power grating lobes * No more tinkering with a three dimensional cartesian grid * Dish-shaped thinsats with two different curvatures, not flat * Alternating curvature thinsats will be stacked and squashed together for launch * In orbit, the stack will be released, and the squashed thinsats will deploy like a giant Belleville spring * Curved thinsats always have some edge-on exposure. If a thinsat somehow becomes stably aligned edge-on to both the equator and the sun (this can happen at the spring and fall equinoxes), there is enough solar exposure to provide a trickle of power and turning thrust, so the thinsat can reorient face-forwards to the sun. * This also stiffens the thinsat, increasing the frequency of the vibration modes and dampening faster * This makes reflective dishes possible, pairing thinsats as dish and focus. === New ideas since 2010: Applications === * Thinsat arrays are > 500x more weight efficient compared to space solar power feeding ground data centers * Developed world data centers will remain leaders in their markets * Developing world areas lacking infrastructure and reliable power can access arrays for low startup costs and rapid growth * ''' I will cover data center applications on thursday, not enough time on saturday ''' * Internet via cell phones for the rural developing world * India can build and launch * India and its disconnected half billion are of particular interest * Western China has similar opportunities * Intel Hillsboro will make the high-tech chips, but both these countries can make everything else, and launch the results * Space debris radar tracking * Multiple look-down arrays can focus megawatts of power on a small region of space. * Interference patterns create high power standing waves. * Space objects passing through the standing waves will create sub-kilohertz-modulated returns * Thinsat receivers and computers can correlate the returns for precise object location, velocity, shape, and rotation * Space debris ballast * Ultralight thinsats, too light for long term stability, can be launched from earth at far lower cost * With precision tracking, and EDDE or VASIMR space tugs, derelict space debris can be captured and returned to M288 orbit * At M288, laser cutters can chop the debris into gram-weight ballast, which is attached to the ultralight thinsats * This reduces launch costs, while eliminating large debris objects, turning garbage into gold * Obsolete and damaged thinsats can also be cut up and turned into ballast * When the space debris is gone, material gathered on the moon can be used as ballast * This is a very simple first step to space manufacturing === I will not cover these at applications ISDC with only half an hour === * Space substrates * With more sophistication, obsolete chipsats can be refurbished with new chips from earth * The chips are 99% of the technological capacity and 1% of thinsat weight * Substrates can be formed from lunar materials, rolled, embossed, wired, and cut in orbit * The aluminum substrates for thinsats need not be high quality aluminum * However, metal refining, forming, and wire patterning are far more complicated than making ballast * Using antenna polarization to deliver both "open" and "managed" internet service * No chip manufacturing in space. * Terrestrial fabs are huge, expensive, and delicate. It will be decades before we can orbit them, along with the huge staffs and supply chains necessary to run them. * A fab never turns out more than a tiny fraction of its weight in silicon, so it makes sense to leave them on the ground until ground and buildings and residences are cheaper in orbit. * A fab uses 12 kilograms of water to make a square centimeter of silicon wafer. Making ultrapure silicon wafers, and thinning the wafer, uses even more.