----- Forwarded message from Keith Lofstrom <[email protected]> -----
Date: Fri, 21 Jun 2013 13:01:22 -0700 From: Keith Lofstrom <[email protected]> To: Eugen Leitl <[email protected]> Cc: [email protected], "Lux, Jim (337C)" <[email protected]> Subject: Re: [Server-sky] [Beowulf] Server Sky - Internet and computation in orbit Reply-To: [email protected] User-Agent: Mutt/1.4.2.2i Most questions are answered on the wiki, http://server-sky.com There's a search function that will help sift through the hundreds of pages. Plenty of unanswered questions, but that is why I am sharing the idea, so others can contribute and claim some of the credit. Forwarded message from "Lux, Jim (337C)" <[email protected]> > 1) orbital debris - fling those thousands of widgets out there. Are they > high enough to stay in orbit for a while? Are they going to damage things > that hit them? 6411km altitude / 12789km radius, about one Re out. Thinsats might damage some objects in crossing orbits if we let collisions happen, but arrays are capable of both continuous maneuvering and high luminance lookdown radar. There aren't many objects in crossing orbits, and all are derelicts, according to the NORAD database. Thinsats are much thinner than the Whipple shields enclosing most critical spacecraft systems. They will remove some paint and some material underneath, but they are unlikely to do anything more than micrometeoroids do. And your next question will be about radiation - we are aiming for the lower van Allen belt. I'm a chip designer. Recent rad-hard developments in semiconductors and integrated circuits are what led me to server-sky. Look at the website for more. > 2) orbital mechanics - the "array" pretty much has to be flat, that is, > they're all at the same orbit height, otherwise they'll drift apart, since > the period is different. All thinsats in an array have identical orbital periods (and the same semimajor axis, to first order), though all have slightly different orbital elements. The arrays rotate, though their shape is skewed by the velocity changes associated with radius variations. Rule of thumb - a 1 meter radial "apogee" turns into a 2 meter retrograde displacement relatve to array center 1/4 orbit later. To see how an array of thinsats evolves over an orbit, look at http://server-sky.com/IEEESustech2013 There are small second order distortions (J₂ and light pressure, for example), factored into array shape and central orbit choice, and third order distortions ( lunar/solar/jupiter tides for example ) that will be dealt with by orbit shape again. The small residual errors ( < 1E-9 of orbit velocity ) can be dealt with by light sail maneuvering. > 3) does it really save anything to put the computation in orbit? Server Sky doesn't save much for developed nations. Google and Amazon will still build 100 megawatt data centers and pump CO₂ into the atmosphere while pretending to be "green". Much of the CO₂ generated while making the concrete and metal and plastic constituting 99.99% by weight of those data centers. Part of the pretense is building solar arrays as if replacing plants with solar panels and destabilizing the electrical grid with intermittent and unpredictable power demand somehow helps the environment. It is quite different for poor nations with large rural populations that haven't deployed much communication infrastructure. India has 400,000 cell towers, connected by microwave and powered by diesel, with the "backbone" being a mix of fiber and microwave that follows their rail network. No way they can afford to deploy much fiber beyond that. Even their microwave grid is way oversubscribed with the rapid uptake of cell phones. Bringing broadband to half a billion rural Indians can create trillions of dollars a year of economic value. The cheapest way to do that is with computation, and large-aperture/millimeter-wave communication in orbit. > I'd like to see more justification of the 100x cost differential > between ground and space 25 years from now. My career as a chip designer has spanned a 1 billion times decrease in the cost of a transistor, and a 1 million times increase in the speed-power capability of transistors. By 2015, we will have deployed a zettatransistor, 1e21 devices. Much of that growth came from invading and transforming seemingly unrelated fields, like biology and publishing and transportation. We point the transistor hose at problems and wash them away. Meanwhile, space development has stagnated - we've built a bunch of plausible-but-wrong systems like shuttle, but our workhorse launchers (Atlas and Proton) are incremental improvements of 1960 designs. The major advances in space technology have been electronic systems like Opportunity, using semiconductors 10 years behind the stuff you can buy at Walmart, and system construction techniques resembling 1950s aircraft. Craig Venter used modern semiconductor technology to sequence the human genome, turning a planned two decade multibillion dollar government effort into a 2 year 300 million dollar transformation of biology. As a direct result of his work, you can get a 1M-SNP genotyping for $99, and can expect a whole genome sequence for less than $1K in a year or two. I've spent my whole life waiting for the "cheap-rocket-first" community to deliver. I'm not waiting any more. I'm not nearly as smart as Craig Venter, but shifting attention from rockets to electronics and market needs doesn't require the same brainpower, just assembling off-the-shelf processes into new systems serving ignored markets, and doing so at Moore's law rates. There's a cornucopia of new technology and new opportunities out there, and those who cling to the old ideas will be left in the dust. 25 years? I've organized chip products in 25 weeks (design/fab/ test/sell). Server sky's long lead times involve team building at the front end, and negotiating with the ITU at the back end. There are plenty of revenue opportunities along the path to deployed arrays, and a team whose combined cleverness far exceeds mine will be rich before we put the first thinsat in space. The job now is to define viable long term goals, discover people who share them, and develop a search process that finds the easiest and most lucrative stepping stones on the shortest path from here to there. There are certainly trillions of plausible-but-wrong ways to do this, and with bad planning my team will pick one of those. But the opportunity is far too large to be ignored, and even a magnificent failure will inspire thousands of others who think they can do better. Some of them will be right. Keith -- Keith Lofstrom [email protected] Voice (503)-520-1993 ----- End forwarded message ----- -- Eugen* Leitl <a href="http://leitl.org";>leitl</a> http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://ativel.com http://postbiota.org AC894EC5: 38A5 5F46 A4FF 59B8 336B 47EE F46E 3489 AC89 4EC5 _______________________________________________ Beowulf mailing list, [email protected] sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
