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18          \copyright  IEEE, 2015.  A doi and link to IEEE Xplore will go here after electronic publication.
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29 \hyphenation{op-tical net-works semi-conduc-tor}
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31 \begin{document}
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41 \title{Server Sky - Information Farming in Space}
42
43 \author{Keith~Lofstrom, \IEEEmembership{Member,~IEEE,}
44  	Ulises~Qui\~{n}\'{o}nez,
45 	and~Gary~Barnhard
46 \thanks{K. Lofstrom is with Server Sky, Beaverton, OR 97075 USA e-mail: keithl@server-sky.com}
47 \thanks{Ulises Qui\~{n}\'{o}nez is with the Facultad de Ingenier\'{i}a, Universidad de San Carlos de Guatemala, Guatemala City, GT}%
48 \thanks{Gary Barnhard is with ISP Inc., Cabin John, MD 20818 USA}}
49
50 \maketitle
51 \begin{abstract}
52 Server sky is a proposal for vast constellations of tiny space satellites,
53 computing and exchanging information directly with cell towers serving
54 customers, students, researchers, and entrepreneurs in the developing world.
55 Paper-thin 5 gram thinsats'' will power processors, memory, and 60/70 GHz
56 radios with 4 watts of space solar power.  7842 thinsat arrays produce
57 sub-kilometer ground spots.  Highly redundant, cryptographically secure,
58 radiation-resistant thinsats will be recycled at end-of-life.
59 \end{abstract}
60
61 \begin{IEEEkeywords}
62 Space Technology; Integrated Circuits; Solar Energy; Internet; Globalization
63 \end{IEEEkeywords}
64 \IEEEpeerreviewmaketitle
65
66 \section{Introduction}
67
68 \begin{quote}
69 \emph{A telephone in every village ... I believe it is a realistic and
70 desirable goal by the year 2000.  It can be achieved now that millions
71 of kilometers of increasingly scarce copper wire can be replaced by a
72 handful of satellites in stationary orbit.''}
73 --- Sir Arthur C. Clarke, 1983 \cite{clarke}
74 \end{quote}
75
76 Billions of valuable minds are trapped in poverty and isolation in
77 the developing world, performing manual labor in want and squalor,
78 rather than participating in the design and deployment of an abundant
79 and efficient global civilization.
80
81 The developed world is enabled by the consumption of massive quantities
82 of energy and minerals, much gathered in the developing world.
83 Fortunately, increased efficiency enabled by technological innovation
84 has reduced resource consumption per unit of economic output;  for
85 example, steel production in the United States consumed 67 MJ/kg of
86 energy in 1950, reduced to 15 MJ/kg in 2005.
87 The annual power consumption of refrigerators made with that steel dropped
88 from 1900 kWh to 500 kWh between 1972 and 2009.
89 Knowledge can reduce physical consumption \cite{naam}.
90
91 The changing product mix reduces energy and resource consumption as well.
92 Production and use of a 112 gram iPhone 5 creates 75 kg of CO$_2$ over a
93 three year lifetime \cite{apple} and connects to the planet, while an
94 875 kg, 4.9 liter/ 100 km Smart Car produces 75 kg of CO$_2$ traveling
95 only 650 kilometers \cite{smart}.
96 Telework, online shopping, and online social networking can save
97 thousands of kilometers and hundreds of hours of driving per year in a
98 society already centered on the automobile.
99
100 New information-centric societies optimized for personal electronics
101 and global networking can develop faster, cheaper, and greener without
102 replicating the developed world's consumption of materials, energy,
103 and distance.  Innovation is inspired, or hindered, by everyday experience.
104 Information-centric cultures can invent new systems for living
105 unimaginable in cultures chained to steel and carbon.
106 Info-cultures will have the key to the future,
107 which will open the door to the solar system.
108
109 Information can be expensive.  Data centers consume more
110 than 10 GW in the United States, almost 3\% of US electrical power
111 \cite{epa}.  Most of this power is spent on voltage transformation
112 and cooling; less than 40\% of the incoming grid power reaches
114
115 400 000 diesel-generator-powered cell towers provide rural India
116 with basic telephone service, connected by microwave links \cite{indiasciam}.
117 Basic communication bypasses middlemen and increases rural income,
118 while bringing education, rule of law, and political power to
119 remote and vulnerable communities \cite{roshan}.
120 Broadband internet offers more, but requires more power and bandwidth.
121
122 Google manufactures information from energy, producing \$20 of revenue 123 per kilowatt-hour of wholesale electricity. Google's green" slogan 124 is renewable energy is better than carbon" ( RE$>$C ) but they are 125 enormously wealthy because information is better than energy ( I$>$E ). 126 Google sells their products worldwide, at the speed of light, because 127 information is easier to move than energy. 128 Much of Google's workforce was born in the developing world \cite{diverse}, 129 and many more could work near their birthplaces with inexpensive 130 and reliable high bandwidth infrastructure. 131 132 While computation efficiency is increasing at Moore's Law rates, 133 computation demand is increasing faster. The global power demand 134 for computing and data distribution may someday exceed a terawatt. 135 Power consumption limits the continued exponential expansion of 136 new information technologies, 137 restricting the growth of the semiconductor industry 138 139 \section{Power From Space} 140 141 The earth intercepts 174 thousand terawatts from the sun. 142 120 thousand terawatts passes through clouds to reach the surface, 143 warming the earth to a black-body temperature$T_{bb} $of 255 K, 144 -18 {\textdegree}C. 145 Most of that power lands on ocean, and the power reaching land is 146 mostly gathered by plants drawing CO$_2$out of the atmosphere. 147 Land covered with solar photovoltaics can displace carbon emission 148 by power plants, but it also displaces natural carbon removal by 149 soil microbes, trees, deep-rooted grasses, and other perennial plants. 150 Destruction of natural ecosystems by agriculture \cite{reick} \cite{plows} 151 has already brought significant climatic change. 152 The pumped storage reservoirs needed to timeshift solar power, 153 and the inefficiencies of storage and power transmission that 154 increase their extent, will disrupt nature further. 155 156 The sun emits 380 trillion terawatts into empty space. 157 600 million terawatts of 24x7 sunlight streams through the region of 158 space closer than the Moon's orbit. 159 Diverting 100 terawatts of that power to the Earth's surface could 160 power the entire world at US levels of energy consumption, 161 while increasing the Earth's surface temperature by only 162 \mbox{0.05 {\textdegree}C .} 163 100 TW can also convert up to 60 ppm of atmospheric CO$_2$into 164 elemental carbon and oxygen per year. Space energy can provide 165 massive benefits to earth. 166 167 In 1968, Peter Glaser proposed capturing terawatts of space power 168 in geosynchronous orbit, converting the power to 2.45 GHz microwaves 169 with vast space solar power satellites (SSPS), 170 and beaming it to equally vast rectifying antennas (rectennas") on the earth, 171 which would convert it to grid power \cite{Glaser}. 172 Transmitting and receiving antennas are scaled by diffraction 173 limit over 39 000 kilometer distances - 12 centimeter waves 174 result in antennas 5 kilometers across, assuming 25{\textdegree} 175 above-horizon elevation and 9\% sidelobe loss. 176 177 %% 25° elevation: 57.13° radial angle, which can be an SSPS 178 %% deflected 5 degrees south by tidal perturbations, talking to a 179 %% site at 46.2° north and 30° east or west (plus or minus 2 hours) 180 %% from SSPS meridian. 181 %% Geometry calculator and Fraunhofer integrator is file fra0.c 182 183 2.45 GHz SSPS may interfere with terrestrial communications 184 and radar. Sidelobe power from a single 5 GW SSPS satellite is 185 predicted to be 1mW/m{\tw} 300 km from the rectenna \cite{arndt}, 186 more than 70 dB higher than the Earth's thermal background. 187 188 Alternatively, space power may be beamed as 183 GHz millimeter 189 waves \cite{ssps183} to 20 km altitude aerostat \cite{stratosolar} 190 rectenna platforms in the stratosphere, 191 above the winds and shielded from the surface by tropospheric water vapor. 192 Transmit and receive antennas could be 75 times smaller than 2.45 GHz 193 SSPS proposals, and run at higher power densities than sunlight. 194 Even scaled down, this is a huge first step, 195 and we do not currently have the technology to efficiently transmit 196 and receive 183 GHz power. 197 198 Instead of beaming low value energy at enormous power levels to 199 vastly expensive rectennas on earth, with incredibly high initial 200 costs, what if we turn space power into high value, scalable, 201 easy-to-transmit products - like information? 202 203 \section{Global Data Transmission} 204 205 Radio broadcasting works because vast amounts of information can 206 be encoded in tiny amounts of energy. Shannon teaches that 207 information can be represented with an energy of$ln(2)kT$per bit, 208 2.9e-21 joules at 300K, or 26e-24 joules (26 yoctojoules) at the 209 2.7K cosmic blackbody temperature. Information transmission 210 requires enough power to overcome ambient thermal and artificial 211 noise. For example, across the 2.45$\pm$0.05 GHz ISM band, 212 the earth emits 20 pW/m{\tw} and receives 20 fW/m{\tw} from the sun. 213 This means that a small antenna on an IEEE 802.11g USB stick can 214 receive 54 Mbps data from a 20 mW transmitter tens of meters away. 215 Point-to-point information transmission can use much less power and 216 tolerate far higher losses than bulk power transmission. 217 218 %% k=1.3806503e-23J, kln2 = 9.57e-24 Tbb=2.735K -> 2.617e-23 219 %% Skolnik p 2.29 effective noise temperature 100K at 0° elevation 220 221 Cisco estimates that global IP traffic will exceed 1.1 zettabytes 222 per year in 2016 \cite{cisco}, averaging 280 terabits per second. 223 224 Even with 1\% power-to-microwave conversion efficiency, and 90 dB 225 path loss, all global internet traffic can be received with 20 dB 226 signal-to-noise ratio with only 200 MW of transmitter feed power, 227 and 1 MW total broadcast power divided among millions of individual 228 receivers on earth. This is 40 dB less than a single space solar 229 power satellite delivering 5 GW to the grid, and it will occur at 230 frequencies much higher than existing services, creating no interference. 231 232 Existing geosynchronous (GEO) satellite internet services are bent pipe" 233 up-and-back paths relaying traffic to and from the wired internet. 234 A request-and-response transaction makes four 38 000 km journeys 235 through space, adding 510 ms of delay to an internet transaction, 236 as well as significant queueing time for the bitrate-limited link. 237 Latency (round trip ping time) is at least 550 ms, typically 700 ms, 238 and can exceed 1500 ms when the link is saturated \cite{vsat}. 239 240 Can we do better? What if servers orbit closer than GEO? 241 242 \section{Space Power's Solid State Makeover} 243 244 Satellites are essentially energy-processing surfaces, 245 converting sunlight into information broadcast to earth. 246 Ivan Bekey teaches us to replace structures with information, 247 build gossamer structures in distributed systems, and transport 248 energy and information, not mass \cite{Bekey08}. Middle Earth 249 Orbit (MEO,$>$2000 km altitude) is subject to extremes of radiation 250 and temperature, but is free of friction, contamination, and 251 mechanical stress. Satellites have line-of-sight access to vast 252 areas of the earth. Low drag orbits are precisely predictable. 253 254 Mesh networks can connect thousands of small satellites in a 255 three-dimensional obstruction-free environment \cite{techsat}. 256 Thin satellite array function-to-weight ratios can be orders of magnitude 257 better than terrestrial infrastructure or aircraft-style satellites. 258 259 220 nm thick direct-bandgap indium phosphide photovoltaic cells 260 collect sunlight with 15\% efficiency, 200 W/m{\tw}\cite{li03}, 261 weighing 1 g/m{\tw}. More efficient multilayer cells are 262 possible, but are far more expensive and vulnerable to radiation. 263 264 Integrated circuit silicon is lightweight. The lifetime power 265 cost of a typical microprocessor is higher than the production cost. 266 Thinned to 20 {\textmu}m, a 10 mm{\tw} die weighs 500 {\textmu}g. 267 It is far cheaper to move silicon to a power source in space than 268 to move space power to terrestrial silicon. 269 270 Integrated circuit chips for RFID tags are as small as 271 50 {\textmu}m x 50 {\textmu}m x 5 {\textmu}m, 272 draw milliwatts of power, weigh 30 ng, cost a fraction 273 of a cent, yet contain thousands of 90 nm transistors \cite{50muA} 274 \cite{50muB}. Cost and size will plummet exponentially with time. 275 276 \section{Server Sky} 277 278 Server sky \cite{onlinecomm} \cite{sustech} proposes migrating 279 gigawatts of data center computation into a ring of satellite 280 arrays orbiting the earth, 281 directly servicing users between 40{\textdegree} north to south latitudes. 282 Individuals can communicate directly to arrays in the sky, 283 through their own satellite antennas, or antennas on cell towers, 284 without landline infrastructure. 285 Arrays will originate or proxy content and services without an 286 additional round trip to earth. 287 288 Server sky communication is point to point, using 70 GHz, 4.3 mm, 289 phase-array-steered beams to paint sub-kilometer ground spots. 290 Cross-orbit and intra-array communications in vacuum can happen at 60 GHz. 291 That frequency is strongly absorbed by atmospheric oxygen resonance and 292 does not reach the ground. 293 294 The primary task of server sky arrays will be data center computation; 295 retrieving and formatting data from solid state memory, data analysis, 296 simulation and modeling, video and sound, synthesis and recognition. 297 298 Server sky \textbf{thinsats} will be rounded triangles 20 cm across, 299 240 cm{\tw} in area, and weigh 5 g. 300 Thinsat front sides will be covered with indium phosphide solar cells 301 that directly power silicon chips millimeters away. 302 303 \begin{figure}[!t] 304 \centering 305 \includegraphics[width=3.3in]{V5thinsat.png} 306 \caption{Thinsat back side chip array, 20 cm wide, 70 {\textmu}m thick, 307 5 g, not to scale, real thinsats will have 1400 2.1 mm slots and 308 350 chips. The black vertical bars represent slot antennas, the 309 corners are electrochromic light pressure thrusters. 310 Antenna slots pass through the aluminum foil substrate to the front, 311 covered with InP photovoltaic cells and corner thrusters} 312 \label{thinsat} 313 \end{figure} 314 315 Thinsat back sides, illustrated in Fig. \ref{thinsat}, will be covered 316 with 1400 2.1 mm slot antennas in a hexagonal grid at full-wave spacing, 317 cut through a 70 {\textmu}m thick aluminum substrate \cite{fjelstad}. 318 Groups of 4 slots are fed by one of 350 3.6 mm x 3.6 mm x 20 {\textmu}m thick 319 customized integrated circuits, all with built-in RF power modulators 320 fed by the nearest of 12 intermediate frequency synthesizers. 321 The rest of the chips are a mix of simple microprocessors, ROM, and RAM, 322 and connected by a redundant mesh of low voltage high speed wiring. 323 Security will not be a software afterthought - encryption and decryption 324 will be performed by dedicated hardware invisible to software. 325 Advanced semiconductor chip design is complex and expensive; the high 326 non-recurring engineering expenses will be spread over billions of production die. 327 328 The larger-than-halfwave spacing will create grating lobes spaced 60 329 degrees from the main downlink lobe; Fortunately, the earth occupies 330 less than 60 degrees of the sky visible from the server sky orbit, 331 so waste downlink power will disperse harmlessly into empty space. 332 The sidelobe waste power is defocused by thinsat curvature, 333 frequency spread, and the nonuniform array. 334 There will not be enough concentrated power to interfere with other services, 335 though sidelobe waste from hundreds of millions of arrays may someday 336 raise the noise floor. 337 338 Thinsats will deploy into actively stabilized three 339 dimensional geodesic arrays. Array sizes can vary from hundreds 340 to millions. This paper considers arrays of 7842 thinsats, 341 producing an average of 24 kW for computation and radio. 342 343 Server sky orbits will not be geostationary. 344 Thinsats will be launched in 40 kg solid-cylinder stacks into 6411 345 km altitude equatorial orbits, about twice the radius of the earth. 346 This is in the inner van Allen belt, 347 a high radiation zone with few other active satellites. 348 Compared to GEO, the MEO orbit reduces round trip ping time, 349 path-length attenuation, and the size of the ground footprint 350 for point-to-point communications. 351 352 \begin{figure}[!t] 353 \centering 354 \includegraphics[width=2.6in]{Morbits20.png} 355 \caption{Server sky M288 equatorial orbit radius, round-trip ping time, 356 and northern visibility with 20 degrees elevation, compared to other orbits. 357 Relay satellites such as O3B and traditional comsats do not originate data, 358 so round trip pings will make two passes through these satellites, 359 doubling ping time.} 360 \label{orbit} 361 \end{figure} 362 363 Arrays will pass through the sky five times a day, every 288 minutes, 364 so this orbit is called \textbf{M288}, as shown in Fig. \ref{orbit}. 365 In the northern hemisphere, 366 the M288 orbit appears close to the southern horizon, 367 below 20{\textdegree} elevation from latitudes above 42{\textdegree} N. 368 369 \begin{figure}[!t] 370 \centering 371 \includegraphics[width=3.4in]{PopLatitude20.png} 372 \caption{ Population and array visibility for 20{\textdegree} minimum 373 antenna elevation. The vertical axis is latitude south to north, 374 and the horizontal axis represents M288 array midnight and daytime 375 visibility vs latitude, and world population vs latitude. 376 Array visibility is lower at midnight because arrays are eclipsed by the earth. } 377 \label{population} 378 \end{figure} 379 380 Most of the developing world's population is below 42 degrees north 381 as shown in fig. \ref{population} \cite{rankin}. Farther north, 382 and near midnight, server sky arrays can relay through existing 383 constellations such as O3B, Iridium, and ViaSat to polar and 384 insomniac customers. 385 386 Arrays will eclipse 17\% of 387 every orbit in spring and fall, 11\% in summer and winter. 388 Arrays will go into cold shutdown when eclipsed, 389 while other visible arrays in full sunlight continue serving customers. 390 Extra arrays are cheaper than batteries. 391 392 393 Server sky data centers do not need chip packaging, power conversion, 394 air conditioning, land, structure, or fiber data links. 395 Thin film space systems assembled with photolithography and automation 396 may cost less less than traditional earthbound systems, 397 with more versatility and fewer environmental costs. 398 399 A booster such as India's PSLV \cite{PSLV} can put 24 40kg arrays 400 (with spares) into equatorial M288 orbits (5 overhead passes per day, 401 288 minutes apart). Any launch system capable of 402 10 km/s delta V can dispense dozens to hundreds of server sky arrays. 403 404 \section{Space Power Transformed} 405 406 \begin{figure}[twopaths] 407 \centering 408 \includegraphics[width=3.4in]{twopaths6.png} 409 \caption{(a) One minimum size 10 GW Space solar power satellite 410 feeding terrestrial data centers. 411 (b) Constellations of server sky arrays 412 broadcasting directly to customer cell towers. 413 Server sky can start profitably with an 600 kW constellation of 25 arrays, and grow exponentially.} 414 \label{twopaths} 415 \end{figure} 416 417 Fig. \ref{twopaths} shows two different ways space power can be 418 used to power the internet. 419 The first column represents a 10 GW SSPS satellite and one terrestrial 420 rectenna feeding the electrical grid and powering data centers. 421 The second column represents the power used directly in space to 422 feed as few as 25 arrays of thinsats, 423 scaling up to 80 000 arrays, 630 million thinsats, 424 matching current global data center productivity. 425 Optimization reduces launched mass at these high production levels. 426 427 Due to diffraction limits, everything about space power transmission 428 must be large; 35 000 tonnes of material launched into orbit for a 429 single SSPS satellite. The complex path power takes from photovoltaic 430 cells in space to a user such as a terrestrial data center has many 431 energy conversion steps. Radiating end-user waste heat into a 300K 432 ambient environment requires more power to extract and dissipate it. 433 PV-to-compute-load efficiencies may be lower than the 20\% shown. 434 435 The second column represents Server Sky, moving electrical power directly 436 from PV to the compute load centimeters away. 32 kW of full illumination 437 computes and narrowcasts data over a microwave link that can tolerate high 438 ( 90 dB! ) inefficiencies. 20 sunlit arrays out of 25 can provide complete 439 24 hour coverage near the equator. 440 There is room in the M288 orbit for millions of arrays. 441 As the constellation grows exponentially, many more launch 442 rockets will be mass produced, and the aerospace experience curve" 443 will reduce launch costs significantly. 444 445 Server sky does not eliminate the need to make terawatts for other 446 purposes - it merely increases the efficiency of a few of those 447 terawatts, producing scalable revenue from a much smaller beginning. 448 The greatest obstacle to space solar power is inadequate and expensive 449 launch capacity. 450 Server sky, growing at Moore's law and internet rates, 451 can pay for and rapidly develop that launch capacity. 452 453 Server sky can be the kindling for a flame that has proven too 454 difficult and expensive to ignite for half a century. 455 456 \section{Light Pressure Maneuvering} 457 458 Thinsats will have area-to-mass (sail'') ratios of 5 m{\tw}/kg, 459 maneuvering as light sails such as the 460 Japanese Space Agency's IKAROS \cite{ikaros}. 461 Heavier than true solar sails, 462 thinsats will have enough thrust to travel in formation, 463 avoid colliders, and migrate from underutilized arrays to larger ones. 464 465 1360 W/m{\tw} sunlight makes a tiny 4.54 {\textmu}Pa pressure if absorbed, 466 and double that if reflected. 467 The three corners of a triangular thinsat 468 will be 5 cm diameter (19.6 cm{\tw}) electrochromic mirrors, 469 which electrically switch from dark to reflective, changing 470 acceleration by 3.5 {\textmu}m/s{\tw}, or turning in 15 minutes. 471 472 Accelerations will be small, but accumulate to large displacements over 473 hours and months. A thinsat can move in nanometer increments, or 474 move 40 000 km, halfway around the M288 orbit, in half a year. 475 476 \section{Radiation} 477 478 Radiation will be the number one problem for server sky thinsats. 479 Recent advances in solar cell materials and VLSI radiation hardness, 480 a fortuitous result of transistor scaling, 481 permit unshielded gram-scale satellites. 482 483 The Intel hafnium oxide gate stack, designed to reduce gate 484 leakage, produces transistor gates highly resistant to 485 charging by ionizing radiation \cite{dixit08}. 486 Modern digital processes operate at supply voltages too low to sustain latch-up. 487 New microprocessor designs that recover from noise errors \cite{razor08} 488 can evolve into designs that recover from radiation-induced single event upsets. 489 Thin indium phosphide solar cells can survive radiation doses of 490 10$^{18}$electrons/cm{\tw} (1 MeV) \cite{li03}. 491 492 \section{Geodesic Arrays, Radio, and Ground Patterns} 493 494 The 1.1 million antenna slots on 7842 thinsat subarrays combine into a 495 giant 100 meter aperture antenna. The array of thinsats is shaped 496 like a distorted geodesic sphere, which can beam packets 497 to sub-kilometer-sized receiver footprints on the ground. 498 Server sky internet cannot compete with optical fiber in a dense urban 499 environment, but works well for suburban, rural, and mobile customers, 500 in emergencies, and in war zones. 501 502 An intriguing ground antenna design from Kymeta \cite{kymeta1} \cite{kymeta2} 503 uses liquid crystals in a metamaterial configuration as a Ka band antenna. 504 These antennas steer slowly (30{\textdegree}/s) and are not suitable 505 for time-sharing many users to many server sky arrays at once. 506 Presumably, these antennas can evolve to faster LCD materials and shorter 507 wavelengths, so they can timeshare between multiple arrays in orbit. 508 509 Uplink from small antennas will be slower than downlink. This 510 matches typical asymmetrical internet usage. There will be few customers 511 in the mid-Pacific, so bulk content can be uploaded from large 512 high-bandwidth surface antennas sited near trans-oceanic data cables. 513 514 \section {Light Pressure, Ballast, and Space Resources} 515 516 Light pressure distorts orbits, shifting apogee and perigee eastward 517 (viewed sunwards). The minimum eccentricity of a precessing orbit 518 increases with sail ratio (area over mass) and orbit radius. 519 The elliptical orbit must not precess into the paths of other 520 satellites, limiting the maximum sail ratio and the minimum mass. 521 522 The minimum mass can be reduced by half if light pressure from the 523 sun on the front is balanced by infrared emissions out the back. 524 A frontside conductive grid with a mesh size of 2 micrometers can 525 pass and focus optical photons on the photovoltaics, while 526 reflecting (and not emitting) longer infrared wavelengths. 527 A high emissivity black coating on the thinsat backside will 528 radiate the heat isotropically, and half of the infrared light 529 pressure will be directed forwards, 530 opposing the light pressure of incoming sunlight. 531 532 Launch mass can be reduced further by attaching ballast mass in orbit. 533 Recycled obsolete thinsats will be one source of ballast, 534 gram-weight pellets cut from captured space debris will be another. 535 This makes space debris into a valuable resource; hopefully we will 536 capture and re-use all of it before plummeting rocket costs reduce 537 the relative profitability of space debris recycling. 538 539 \section{ Environmental Effects } 540 541 If space computation power grew to a terawatt, 250 billion thinsats 542 facing the sun at M288 could reflect 25\% as much light into the night 543 sky as the full moon, disrupting nature and optical astronomy. So, 544 thinsats will turn edge-on to the terminator in the night-side half of 545 the orbit (see Fig. \ref{nightsky}) to eliminate night sky light pollution, 546 reducing average power by 17\%. 547 548 \begin{figure}[nightsky] 549 \centering 550 \includegraphics[width=3.4in]{ir-reflect3a.png} 551 \caption{ Filtering infrared to emit away from the sun permits 552 thinsat mass reductions. Turning thinsats edge-on to the terminator 553 (the day-night boundary) prevents sunside reflections from making 554 light pollution in the night sky. 555 Turning the infrared emissive backside towards the earth keeps the 556 thinsat warmer during eclipse, reducing thermal stress and increasing 557 reliability.} 558 \label{nightsky} 559 \end{figure} 560 561 Thinsats cool rapidly in eclipse, Turning the high thermal emissivity 562 backside coating towards the nearby warm earth (see Fig. \ref{nightsky}) 563 minimizes thermal shock. 564 This protective measure encourages light pollution minimization turns. 565 566 High latency computation tasks should deploy further out. 567 At lunar-distance Lagrange points, arrays are in continuous sunlight 568 and have better access to lunar materials, while worst-case light 569 pollution is reduced by a factor of 3000. 570 It is difficult to imagine how humanity will use more than 1 MW of 571 computation per capita, but as recently as 1896, Arrhenius could not 572 imagine reaching CO$_2$levels of 400 ppm in less than a millennium. 573 574 When forecasting the consequences of our engineering designs, we should 575 think about millenia and exponentials, not mere decades and S curves. 576 Learn from nature, and choose designs that make environmental protection 577 and material recycling the most profitable way to operate, 578 without relying on good intentions. 579 580 \section{Ownership and Security} 581 582 Server sky thinsats will be owned and used by people with few 583 security skills, and will sometimes run insecure, poorly-designed software. 584 The thinsats connect to an entire planet of spies, criminals, and cyber vandals. 585 Defending thinsats will be difficult but not impossible. 586 587 Thinsats will contain large arrays of inexpensive one-time pad 588 using ICID technologies \cite{icid}. Bits may be extracted at 589 at the wafer level during manufacturing, but are otherwise impossible 590 to predict or intercept. 591 592 Thinsats will use custom chips designed for survival and reliable 593 computation in a high radiation environment. 594 The same hardware that corrects radiation single-event upsets can 595 be applied to security tasks. Thinsats will have built-in 596 cryptographic hardware primitives to perform kilobit integer 597 arithmetic and other useful primitives found in most secure encryption 598 algorithms. Large integer results can be tested 599 with a verification modulus \cite{bos} ( a woop" \cite{ferguson} ) 600 computed with a small, randomly generated prime number. 601 602 Thinsats have many processors, and the user portions of each processor 603 can be temporarily rented by others. These proplets" \cite{proplets} 604 will communicate to a restricted set of ground users, identified by 605 affiliation, geography, and time. Thinsats work at the speed of light. 606 Physical attacks require slow satellite rendezvous, allowing hours for 607 countermeasures or self-destruction. 608 609 Thinsats can be transferred as property, or used as collateral for 610 loans. Hardware implementation of smart contracts" \cite{contracts} 611 permits automatic transfers to lien-holders if payments are not made 612 or terms are violated. This lowers transaction costs and interest 613 rates, permitting new borrowers without trustworthy credit histories 614 to establish them. 615 616 These capabilities are fragile if the owners and users are inept, 617 gullible, and isolated. Server sky will support protocols for users 618 to team with friends, family, and trusted professionals to 619 authenticate important transactions. 620 621 All security protocols fail over time; they may be compromised, or merely 622 obsolete and inefficient compared to newer protocols. Accumulating 623 radiation damage, and new generations of higher performance thinsats 624 competing for the same orbits, will eventually force the retirement 625 and recycling of obsolete thinsats. 626 627 \section{Serving Clients} 628 629 The developed world needs help extracting itself from the material 630 consumption trap. Unleashing the creative power of billions of 631 people can bring new ideas, new inventions, and economic growth 632 rates undreamed of in national capitals and corporate boardrooms. 633 634 C. K. Prahalad teaches us that typical S" curve economic growth 635 is compacted in time into an I" curve (double-digit percentage 636 growth rates per month) for products that satisfy important needs 637 in the developing world\cite{prahalad}. Our goal is not merely to 638 provide new clients for developed world corporations, but to connect 639 the world to technical, entrepreneurial, educational and cultural 640 products and services invented by billions of newly empowered people. 641 642 We offer an alternative to the developing world: replace material 643 resources with information, just as a smart phone embeds vast 644 intellectual resources and value in a few pennies of raw materials. 645 Information manufactured with space solar power can be expanded to 646 vast scale, without extracting resources or dissipating heat in the 647 biosphere. This eliminates the tradeoff between economics and the 648 environment that characterizes the resource consuming technologies 649 of the developed world. 650 651 A cruise ship arriving in port emits a flood of passengers flocking 652 to the shops and sights on shore, followed by a flood of crewmembers 653 seeking internet cafes to communicate with their families back home 654 \cite{schwartz}. High bandwidth server sky internet to cruise ships 655 underway will not only provide sporting events and other realtime video 656 to the passengers, but family connection for the crew during the voyage. 657 That increases the value of the cruise to everyone on board. 658 659 In 2015, almost 3\% of the world's population lives and works outside 660 of their birth country, making the painful choice to leave loved ones 661 and familiar landscapes behind. Many of the passengers cruising on 662 spaceship earth would find their lonely journey eased with video 663 connections, news, and information gifts exchanged with those at home. 664 665 Moving remittances (job wages sent home) between countries is difficult 666 and costly with traditional services like Western Union and Moneygram, 667 with fees taking as much as a 10\% bite of the transfer \cite{cryptocurrency}. 668 Some guest workers use Bitcoin to transfer 669 money to ebanking services such as Kenya's M-Pesa, avoiding fees 670 and risks. The developing world, with its high percentage of 671 un-banked" individuals, and high levels of corruption, may develop 672 cashless economies long before complacent and wealthy countries do. 673 674 All of this will cause massive cultural change. We must not lose 675 the values and wisdom of the past in our headlong rush to the future. 676 In particular, young and educated people are ignoring their poor and 677 illiterate elders, especially damaging to traditional elder-dominated 678 societies \cite{crisis}. An elder can verbally dictate her memories 679 and values over voice uplink to server-sky storage, 680 producing thousands of hours of transcriptions, available forever to 681 her descendants, ethnologists, and historians. When her callow children 682 grow old and wise, they will treasure this storehouse of cultural 683 knowledge, as will their distant descendants. One poor village elder 684 can leave a more permanent legacy than the kings of the ancient past. 685 686 Some elders claim I am too old to learn to read". 687 Many Guatemalans are enthusiastic f\'{u}tbol (soccer) fans, like many 688 in India love cricket. 689 Adults watching sports on smart phones or tablets can choose 690 education enhanced-sports", 691 providing game information enhancements involving letters, 692 then simple text, growing towards more complex text. 693 An adult version of Sesame Street, with an important difference: 694 each personal channel can individually adapt to the progress 695 of the learning reader, 696 and connect their lessons to those of their friends and neighbors, 697 strengthening friendships and community while building literacy. 698 Machines are patient - if a new reader needs ten years to 699 learn, they will be guided at a comfortable rate. 700 701 Education designers can observe individual progress, and evolve 702 better teaching software. The 21st century will progress beyond 703 universal literacy to continuous learning. As new inventions 704 emerge ever faster from a world full of new inventors, 705 new teaching methods developed for adult literacy will help 706 train everyone to master those new inventions and take control 707 of their technological environment. 708 709 \section{Creating Entreprenuers} 710 711 Creative, newly educated server sky clients will become active 712 providers of local and global content and services. A farmer could 713 tend her crops during the day, and sell her harvest on the Chicago 714 Mercantile Exchange at night. Her brother could drive a robot 715 tractor for a farmer in Iowa. Her sister could teach Kenyan 716 schoolchildren. And next year, they can run businesses employing 717 hundreds of people around the world to do the same. 718 Work globally, live locally. 719 720 It is an accident of history that computers are programmed with text; 721 Inca quipu, Mayan and old world weaving, and Jacquard machine-woven 722 brocades were designed and coded visually and tactually. Programs 723 may be created, compiled, and evaluated with other sensibilities; 724 weaving a \emph{huipul} garment or hoeing a weed in a \emph{milpa} 725 cornfield requires preception and skill, which may be transferrable 726 to the creation of software and the visual presentation of information. 727 With the right interfaces, the corn farmers of the past may become the 728 information farmers of the future. 729 730 New income can be invested in thinsat hardware. A thinsat might 731 cost \$100 to build and launch, affordable by families or village
732 cooperatives.  Thinsats can be collateral for loans.  When a strong,
733 protected international market develops, this may be the first
734 opportunity many people have to become investors and property owners.
735
736 Peruvian economist Hernando De Soto \cite{desoto} offers evidence
737 that property rights in land and houses foster economic development,
738 providing collateral for loans that purchase materials and tools
740 Individual server sky thinsats are depreciating capital goods, but
741 are highly fungible and reusable during their functional lifetime.
742 When thinsat cost drops below \\$100, even the poorest families can
743 afford a piece of the action".  With proper community safeguards,
744 and development environments usable by the uneducated but persistent,
745 those families can develop their information farms" into valuable
746 properties in the server sky information economy.
747
748 Thinsat arrays can be international cooperatives.  Since different
749 regions desire different content, regional" thinsats will source
750 content to the rest of the array, which will synchronize the packets
751 and send them to an owner's customers below as the array passes
752 overhead.  If the rules and operation of a coop are not to an owner's
753 liking, she can migrate her thinsat to a nearby array - or simply
754 swap content and ownership with another owner in that other array.
755
756 \section{Three Billion New Researchers}
757
758 Today, ecotourists travel the world searching for nature,
759 while professional scientists travel to gather data.
760 Instead of travelers burning megatons of jet fuel and trampling
761 wildlife underfoot,
762 local people can place thousands of cameras and sensors in the
763 wild places near their villages, observing nature without disturbing it.
764 Villagers selling data from an acre of forest can produce more annual
765 revenue than one-time lumbering, or turning jungle into desert to get
766 at the minerals underneath.
767
768 But people can do more than maintain sensors.  We will need more minds
769 than ever to interpret this flood of data, choosing what to gather next,
770 finding and understanding patterns, and explaining those patterns
771 to others.  Beyond literacy, we should develop a universal ethos of
772 observational science, so that everyone learns what to look for, and why.
773
774 In the near term, we can use Server Sky to enhance the scientific
775 and educational potential of existing tropical universities.
776 Remote education programs can be delivered nationwide and worldwide,
777 with computer-assisted speech translation to regional and global
778 languages.  We can connect resource-and-equipment-poor researchers
779 in these universities to world-class labs elsewhere, stretching
780 limited budgets and fostering international collaboration.
781
782 Remote submersibles in the tropical ocean and satellites in space can be
783 controlled via server sky arrays overhead.  One very exciting possibility
784 is controlling small experiments directly on the International Space
785 Station (ISS), collecting vast amounts of experimental data for analysis
786 in Server Sky arrays.  ISS is continuously visible from a large swath
787 of the Server Sky constellation, far more visibility due to its altitude
788 and the lack of atmospheric attenuation.  Someday, thousands of server
789 sky arrays can provide petabit-per-second bandwidth to ISS and its
790 successors, using frequencies near 60 GHz, and precisely focused beams
791 that do not penetrate the atmosphere.
792 This bandwidth, the automation it supports,
793 and the torrent of data it can return,
794 can enable many researchers to run millions
795 of small experiments simultaneously, 24 hours a day.
796
797 Developing world research institutions will have the resources to
798 join their wealthy peers, releasing a flood of new space science
799 accomplishments and discoveries.  Every country will become a space
800 power, and the International Space Station will become truly
801 international, the world's largest and most inclusive research center.
802
803 \section{Serving the Future}
804
805 Human prosperity will no longer be a zero sum game, played at the
806 expense of nature.  Indeed, as good stewards and creative inventors,
807 with doomsday pushed beyond the foreseeable future, we can help
808 nature grow richer and more diverse than it has ever been during
809 the long history of life.  Information is power,  and exawatts of
810 off-Earth power can become information products that serve all of
811 nature.  Humankind can become wealthy and smart enough to become
812 nature's collaborators, not merely her cruel and ignorant destroyers.
813
814 Server sky arrays will, like foraging ants serving their queen,
815 serve and protect the human societies on Earth that gave birth to them.
816 Myrmecologist (ant expert) Edward O. Wilson writes:
817 \emph{Laid before us are new options scarcely dreamed of in earlier ages.
818 They empower us to address the greatest goal of all time,
819 the unity of the human race.''} \cite{Wilson2}.
820
821 Server sky can be a first step towards opening the
822 rest of the solar system, and beyond.
823 Intelligence, mind and machine, can build gardens of life in space,
824 and someday connect earth life to the stars.
825
826 Wilson again: \emph{Someday, perhaps in this century, we, or much
827 more likely our robots, will visit these places in search of life.
828 We must go and we will go, I believe, because the collective human
829 mind shrivels without frontiers.  The longing for odysseys and far
830 away adventure is in our genes.''}
831
832 The authors of this paper are still discovering new opportunities
833 for server sky, and for information resources provided from space,
834 by developing world creators, for the world.  We hope
835 GHTC2015 will connect us with innovators from around
836 the world, who will suggest more improvements and opportunities.
837
838 \begin{thebibliography}{1}
839
840 \bibitem{clarke}
841 A. Clarke, \emph{Beyond the Global Village}, address to the United Nations
842 on World Communications Day, May 17, 1983.  Reprinted in \emph{Analog Science Fiction Science Fact}, December 1983, pp. 6-14.
843
844 \bibitem{naam}
845 R. Namm, \emph{The Infinite Resource : the power of ideas on a finite planet},
846 Lebanon, NH, University Press of New England, 2013.
847
848 \bibitem{apple}
849 Apple Inc., \emph{iPhone 5 Environmental Report}, 2012. [Online]. Available: \url{
850 http://images.apple.com/environment/reports/docs/iPhone5_product_environmental_report_sept2012.pdf}
851
852 \bibitem{smart}
853 \emph{Smart Fortwo Passion}, 2015. [Online].
854 Available: \url{https://www.smart.com/id/en/index/smart-fortwo/passion.html#engine1}
855
856 %% \emph{Car Emissions, SMART Fortwo Cabrio, turbo with 15" rear wheels 2014}, 2015. [Online].
857 %% Available: \url{http://www.car-emissions.com/cars/view/53303}
858
859 \bibitem{epa}
860 U.S. Environmental Protection Agency, \emph{Report to Congress on Server and Data Center Energy Efficiency Public Law 109-431}. [Online]. Available: \url{http://www.energystar.gov/ia/partners/prod_development/downloads/EPA_Datacenter_Report_Congress_Final1.pdf?8889-6004}
861
862 \bibitem{intelDC}
863 T. Aldridge, A. Pratt, P. Kumar, D. Dupy, G. AlLee, \emph{Evaluating 400V Direct-Current for Data Centers}. [Online]. Available: \url{http://blogs.intel.com/wp-content/mt-content/com/research/Direct 400Vdc White Paper.pdf}
864
865 \bibitem{indiasciam}
866 K. Tweed, \emph{Why Cellular Towers in Developing Nations Are Making the Move to Solar Power}, Scientific American, January, 2013. [Online]. Available: \url{http://www.scientificamerican.com/article.cfm?id=cellular-towers-moving-to-solar-power}
867
868 \bibitem{roshan}
870 an.aspx}
871
872 \bibitem{diverse}
873 J. Elder, \emph{What Silicon Valley’s Diversity Reports Say About the Tech Workforce}, Wall Street Journal, 2014. [Online]. Available: \url{http://blogs.wsj.com/digits/2014/06/19/what-silicon-valleys-diversity-reports-say-about-the-tech-workforce/tab/print/}
874
875 \bibitem{reick}
876 C. Reick, T. Raddatz, J. Pongratz, and M. Claussen, \emph{Contribution of anthropogenic land cover change emissions to pre-industrial atmospheric CO2}, Tellus (2010), 62B, pp. 329–336. [Online]. Available: \url{http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0889.2010.00479.x/pdf}
877
878 \bibitem{plows}
879 W. Ruddiman, \emph{Plows, Plagues, and Petroleum : How Humans Took Control of the Climate}, Princeton, NJ, Princeton University Press, 2005.
880
881 \bibitem{Glaser}
882 P. Glaser, \emph{Power from the sun: Its future}, Science 162.3856 (1968): 857-861.
883
884 \bibitem{arndt}
885 G. Arndt and L. Leopold.  \emph{Environmental considerations for the microwave beam from a solar power satellite}, 13th Intersociety Energy Conversion Engineering Conference, vol. 1, 1978, pp. 195-200.
886
887 \bibitem{ssps183}
888 K. Lofstrom, \emph{Aerostat 183 GHz Rectenna for SSPS}, 2015. [Online]. Available: \url{http://server-sky.com/SSPS183}
889
890 \bibitem{stratosolar}
891 Stratosolar Inc, \emph{PV Generation Platforms}, 2015. [Online]. Available: \url{http://www.stratosolar.com/pv-generation-platforms.html}
892
893 \bibitem{cisco}
894 Cisco Systems, \emph{Cisco Visual Networking Index: Forecast and Methodology, 2013-2018}, (2014). [Online].
895 Available: \url{http://www.cisco.com/c/en/us/solutions/collateral/service-provider/ip-ngn-ip-next-generation-network/white_paper_c11-481360.pdf}
896
897 \bibitem{vsat}
898 VSAT Systems, \emph{Latency - why is it a big deal for Satellite Internet?}, (2013). [Online].
899 Available: \url{http://www.vsat-systems.com/satellite-internet-explained/latency.html}
900
901 \bibitem{Bekey08}
902 I. Bekey, \emph{Advanced space system concepts and technologies, 2010-2030+},
903 El Segundo, CA, Aerospace Press, 2003, p. 10.
904
905 \bibitem{techsat}
906 R.  Burns, C. McLaughlin, J. Leitner, and M. Martin, \emph{TechSat 21: formation design, control, and simulation}, IEEE Aerospace Conference Proceedings, 2000, vol. 7, pp. 19-25.  [Online].  Available \url{http://formation-control.googlecode.com/svn/papers/00879271[1].pdf}
907
908 \bibitem{li03}
909 G. Li, Q. Yang, Z. Yan, W. Li, S. Zhang, J. Freeouf, J. M. Woodall, \emph{Extreme radiation hardness and light-weighted thin-film indium phosphide solar cell and its computer simulation}, Solar Energy Materials and Solar Cells, v75 n1 (2003): 307-312
910
911 \bibitem{50muA}
912 M. Usami, \emph{Powder RFID chip technology}, APCCAS 2008-2008 IEEE Asia Pacific Conference on Circuits and Systems (2008): 1220-1223
913
914 \bibitem{50muB}
915 Hitachi Central Research Laboratory, \emph{Operation verified on world's smallest 0.05mm x 0.05mm contactless powder IC chip"}, 2007. [Online]. Available: \url{http://www.hitachi.com/rd/portal/pdf/news/crl070213nrde_RFID.pdf}
916
917 \bibitem{onlinecomm}
918 K. Lofstrom, \emph{Server Sky - Data Centers in Orbit}, Online Journal of Space Communication, 16: Solar Power Satellites Winter 2010. [Online]. Available: \url{http://spacejournal.ohio.edu/issue16/lofstrom.html}
919
920 \bibitem{sustech}
921 K. Lofstrom, \emph{Server sky - Computation and power in orbit}, 1st IEEE Conference on Technologies for Sustainability (2013). [Online]. Available: \url{http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=6617309}
922
923 \bibitem{website}
924 \emph{Server sky website}, 2009-2015. [Online]. Available: \url{http://server-sky.com}
925
926 %% \bibitem{o3b}
927 %% \emph{O3B Networks Corporate Brochure}, 2013. [Online]. Available: \url{http://www.o3bnetworks.com/media/6434/o3b corporate brochure.pdf}
928
930 J. Fjelstad, \emph{Aluminum: A Sustainable Substrate Alternative to FR4 in PCB Assemblies}. [Online]. Available: \url{http://sites.ieee.org/sustech/files/2013/12/EM_Fjelstad-Aluminum-Substrates.pdf}
931
932 \bibitem{rankin}
933 B. Rankin, \emph{Population Histograms}, 2008. [Online]. Available:\url{http://www.radicalcartography.net/histpop.png}
934
935 \bibitem{PSLV}
936 Indian Space Research Organisation, \emph{Polar Space Launch Vehicle}. [Online]. Available: \url{http://www.isro.org/launchvehicles/PSLV/pslv.aspx}
937
938 \bibitem{ikaros}
939 Japanese Aerospace Exploration Agency (JAXA), \emph{Solar Power Sail Demonstrator IKAROS''}, launched 2010. [Online]. Available: \url{http://www.jspec.jaxa.jp/e/activity/ikaros.html}
940
941 \bibitem{dixit08}
942 S.K. Dixit, \emph{Radiation-induced charge trapping studies of advanced Si and SiC based MOS devices}, Ph.D.  dissertation, Interdisciplinary Materials Science, Vanderbilt Univ., Nashville, TN, 2008. [Online]. Available: \url{ http://etd.library.vanderbilt.edu/available/etd-03312008-170923/unrestricted/Sriram\_Dixit\_Dissertation\_final.pdf}
943
944 \bibitem{razor08}
945 D. Blaauw, S. Kalaiselvan, K. La1, W. Ma1, S. Pant, C. Tokunaga1, S. Das, D. Bull, \emph{Razor II: In Situ Error Detection and Correction for PVT and SER Tolerance}, ISSCC Dig. Tech. Papers, Feb. 2008.
946
947 \bibitem{kymeta1}
948 K. Palmer, \emph{Metamaterials make a broadband breakthrough}, IEEE Spectrum, v49 n1 (2012): pp. 13-14. [Online]. Available \url{http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6117818}
949
950 \bibitem{kymeta2}
951 N. Kundtz, \emph{Next Generation Communications for Next Generation Satellites}, Microwave Journal, v57 n8 (2014), pp. 56-61.[Online]. Available: \url{http://www.microwavejournal.com/articles/print/22760-next-generation-communications-for-next-generation-satellites}
952
953 %% N. Kundtz, \emph{Next Generation Communications for Next Generation Satellites}, Microwave Journal, v57 n8 (2014), pp. 56-61. [Online]. Available: \url{http://www.kymetacorp.com/assets/Next-Generation-Communications-for-Next-Generation-Satellites-Microwave-Journal.pdf}
954
955 \bibitem{icid}
956 K. Lofstrom, R. Daasch, and D. Taylor, \emph{IC identification circuit using device mismatch}, Digest of Technical Papers, ISSCC 2000, IEEE Solid State Circuits Conference, IEEE, 2000, pp. 372-373.  [Online]. Available: \url{http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=839821}
957
958 \bibitem{bos}
959 J. Bos, \emph{Practical Privacy}, PhD thesis, Technical University of Eindhoven, 1992.  Chapter 6, Verification of RSA Computations on a Small Computer". [Online]. Available \url{http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.37.5801&rep=rep1&type=pdf}
960
961 \bibitem{ferguson}
962 N. Ferguson, B. Schneier, and T. Kohno,  \emph{Cryptography Engineering: Design Principles and Practical Applications: Design Principles and Practical Applications}, Hoboken, NJ, John Wiley \& Sons, 2011, Chapter 15, Implementation Issues (II)".
963
964 \bibitem{proplets}
965 N. Szabo, \emph{Proplets: Devices for Controlling Property}, 2001. [Online]. Available: \url{http://szabo.best.vwh.net/proplets.html}
966
967 \bibitem{contracts}
968 N. Szabo, \emph{Smart Contracts}, 1994. [Online]. Available: \url{http://szabo.best.vwh.net/smart.contracts.html}
969
971 C. K. Prahalad,  \emph{The Fortune at the Bottom of the Pyramid},
972 Upper Saddle River, NJ, Wharton School Publishing, Pearson, 2005.
973
974 \bibitem{schwartz}
975 Randal L. Schwartz, personal conversation.
976
977 \bibitem{cryptocurrency}
978 P. Vigna and M. Casey, \emph{The Age of Cryptocurrency},
979 New York, NY, St. Martins Press, 2015.
980
981 \bibitem{crisis}
982 J. Hawkins, J. McDonald, and W. Adams,
983 \emph{Crisis of Governance in Maya Guatemala},
984 Norman, OK, University of Oklahoma Press, 2013.
985
986 %% \bibitem{IRA}
987 %% A. Witteveen, \emph{Boston College Oral History Project Faces Ongoing Legal Issues}, Library Journal, March 12, 2015. [Online].  Available: \url{http://lj.libraryjournal.com/2015/03/litigation/boston-college-oral-history-project-faces-ongoing-legal-issues/#_}
988
989 %% \bibitem{1493}
990 %% C. Mann, \emph{1493: Uncovering the New World Columbus Created}, New York, Alfred A. Knopf, 2011, p. 370.
991
992 \bibitem{desoto}
993 H. De Soto, \emph{The Mystery of Capitalism: Why capitalism triumphs in the West and fails everywhere else}, New York, NY, Basic Books, 2000.
994
995 \bibitem{Wilson2}
996 E. O. Wilson, \emph{The Meaning of Human Existence}, New York, W. W. Norton, 2014, pp. 173-174 and p. 106.
997
998 % other Wilson quote here, p. 106, ... Someday, perhaps this century ...
999
1000 \end{thebibliography}
1001
1002 \vspace{2mm}
1003 ghtc2015.tex / KHL / 2015 June 3 / 2340 PDT.  \emph{Note to reviewers:}
1004 During the draft review and editing of this paper, the pdf and the LaTeX
1005 file will be available and updated at http://server-sky.com/ghtc2015
1006
1007 \end{document}


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