IEEE 2013 SusTech Abstract
Server Sky – Computation and Power in Orbit
- Keith Lofstrom
- Version 0.2 2013-03-21
- “Space Solar Power is a great dream, achievement of which is a great necessity for the 21st century world.”
- - Dr. APJ Abdul Kalam
The problem: Data centers consume almost 3% of US electrical power, a fraction doubling every 5 years, growing faster than efficiency improvements. Power generation grows too slowly to meet this demand. Energy production scales with mechanical structure and land/habitat diversion, which suffer from dis-economies of scale.
Neither the rural developing world nor the natural environment can afford to replicate this American path to connectivity. Rural India and western China are cut off from global knowledge and markets, as well as reliable water, electricity, medicine, and schooling. Coastal megacities cannot hold all of them, and are plagued with infrastructure crises as well. These rural regions cannot afford capital-intensive, logistically sophisticated data centers and vast fiber optic networks requiring high-tech maintenance skills and distributed, high-reliability, 24x7 electrical power.
With high bandwidth connections to the global internet, the people in these areas can offer the most valuable commodity on the internet - trained, diligent attention - and rapidly improve their education and economic condition. How can this happen without massive regional infrastructure deployment?
New possibilities: The sun produces 384 trillion terawatts which nature cannot use, streaming past the planets into interstellar space. Space is expensive to get to, but zero-gee structures can be incredibly thin and ultra-light-weight, permitting solar photovoltaic systems that are cheaper to deploy in orbit than on the ground. Space offers 20 hours a day of unattenuated, cloud-free sunshine in a stable, clean, zero-maintenance environment. Sunlight captured in space is does not steal land and sunlight from agriculture and wilderness on the ground.
Previously, space enthusiasts have contemplated vast structures that capture gigawatts of solar power and beam it to huge receivers on earth, 40,000 kilometers away. What if we made very small systems instead, using the power and dissipating the heat on the spot? Computation and communication are two great uses for space power.
Currently, satellites are built with aircraft technology, resulting in high costs, low reliability, and multi-decade lags in the deployment of advanced technologies. What if we gave space a solid state make-over? Recent advances in solar cell materials and VLSI radiation hardness permit unshielded gram-scale satellites. Mesh networks can connect millions of devices in an obstruction-free environment. There are no barriers to scaling function-to-weight ratios by more than one million over terrestrial solar, and one hundred thousand over traditional satellites.
Server Sky converts space solar power into computation with arrays of thousands of tiny solid-state satellites. Each server sky thinsat is 20 cm across, 50 microns thick, and weighs 3 grams. The aluminum substrates are covered with integrated circuits, radios, solar cells and slot antennas, propelled and steered by light pressure, networked and located by microwaves, and cooled by black body radiation.
Thinsats are stacked by the thousands in solid cylinders, and launched into 6400 kilometer altitude equatorial orbits. They are deployed into precisely located and actively stabilized three dimensional geodesic arrays with 1 meter spacings. A typical array may contain 8,400 thinsats, producing 34 kilowatts of power for computation and radios. Phased array transmitters are synchronized to produce narrow beams to hundreds of kilometer-sized receiver footprints simultaneously. Thousands of arrays communicate with ground receivers and each other.
Thinsat arrays are not geostationary, instead passing through the sky five times a day, visible for an hour per pass from 35 degrees latitude north to south. One launch can put three million thinsats into orbit, 100 arrays, with 10 to 20 arrays visible at any time. Data and programs are replicated across many arrays, providing redundancy and global 24 hour availability. New capabilities: The first server sky deployments will be used for satellite and space debris tracking, with potential billion dollar per year revenues. The tanks of derelict rocket bodies may be captured and cut into gram-weight ballasts for next generation ultralight thinsats, increasing launch rates 10x. When thinsats become obsolete, they can also be cut into ballast. This will clean and tame the space environment, permitting vastly expanded future deployment.
Like the ground data centers they replace, thinsats can be rapidly reprogrammed to serve customers on the ground. Unlike multi-ton single-function satellites, thinsats can be redeployed and migrate autonomously between arrays, rapidly adapting to new applications and market opportunities.
Server sky ground antennas can be attached to existing cell towers, with sophisticated speech recognition and assisted-intelligence functions provided by orbiting software and human assistants on the ground. This can greatly expand the capabilities of existing towers, while reducing the cost of new deployment in very remote areas.
Special purpose "medical phones" and "agriculture phones" can be equipped with sensors for telemedicine, soil measurement, pest, microbe, and hazardous waste identification, allowing hospitals and agricultural institutes anywhere to gather data and provide instant advice, aided and implemented by quickly-trained local assistants.
Imagine a crop blight caused by a local parasite. Rather than bomb it with chemicals, we can send entirely different crops to grow in those infected fields, naturally immune to the pest, and train the farmers to work the new crop and negotiate global markets for the produce. Diversity is better than fragility.
Imagine a life-threatening neonatal emergency evaluated in minutes by world experts, with efficiently-scheduled air medivac system transferring the threatened mother and child to world-class facilities halfway around the globe while maintaining their connection to their family at home. The new global "arms race" may be a fierce competition for the love and respect of rural villages, whose votes will change the direction of global geopolitics.
Small arrays will grow into vast numbers, replacing ground data centers and relieving the global grid of their huge energy appetites. In time, we may revisit the old dreams, and use gigantic arrays to generate terawatts to feed the planetary electrical grid, eliminating the need for most terrestrial generation. We probably won't use microwaves - with billions of educated minds working on the problem, we will certainly find something much better.
The important task is to grow our solutions beyond fighting nature and other nations for energy and resources, and begin expanding life beyond the bounds of earth. With the exponential tools of Moore's Law and photolithographic production, and limitless space energy, we can shrink vast global problems down to human scale. With the internet connecting the entire planet, we can connect any problem to the best minds on the planet to solve it. Together, we can expand life and intelligence to fill the solar system and beyond, while restoring and protecting our home, the earth.
For more details: http://server-sky.com/SusTech2013 (improving daily)