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Solar Power Satellites and the issues going forward after WiSEE 2015.

December 14-16, 2015 was the WiSEE conference on Wireless for Space and Extreme Environments, hosted by University of Central Florida in Orlando and the Institute of Electrical and Electronics Engineers (IEEE). WiSEE included tracks on Space Solar Power, passive wireless sensors and space internetworking. Here is a summary of ideas behind Solar Power Satellites and some of the issues that are holding up progress.

Solar Power Satellites (SPS) are a conceptual form of Space-Based Solar Power (SBSP or SSP) that collect sunlight, transform it into microwaves or lasers and transmit that energy to locations on Earth or in space that need electricity. The receiving equipment is surprisingly simple, building these systems creates jobs and technical skills, and the end product is the greenest form of electricity generation ever invented.

SPS has a dual effect on spaceflight economics that can open up development of the Inner Solar System; it requires many rocket launches driving per-flight costs down while being able to provide kilowatts to gigawatts for in-space receivers for propulsion and industrial use. While eventually providing unlimited green power for Earth, SPS enables our next steps out into the Solar System.

SPS is the only known form of power generation that can provide the entire world with abundant electricity while maintaining the heat balance of Earth’s biosphere. SPS has an extremely low carbon footprint, less than 1/100th of terrestrial solar and around 1/10,000th that of combined cycle natural gas. Most currently proposed systems (by Mankins, Jaffe, Kaya) use gigahertz microwaves at 2.45 Ghz or 5.8 Ghz, 5.8 Ghz being nearly transparent to water, very important for heat balance.

Older SPS concepts typically involved massive metal space-frames covered in solar panels with mile-wide steerable transmitters, assembled by hundreds of astronauts. Modern concepts like Mankins’ SPS-ALPHA use a composite sandwich structure module with amorphous thin-film photovoltaics above a direct current bus leading into a flat phased-array antennae across the bottom. The modules are launched in stacks on conventional rockets and can either self-point at a target or be docked together into a large flotilla of panels, orbiting in geosynchronous orbit (GEO). Together the phased-array antennae beam-form to create pulses that generate current in the receiving antennae or rectenna. Rectenna are typically a large metal mesh suspended above the ground. Higher density signals and smaller receivers are possible under this flexible schema that would provide point-to-point power for in-space transportation along with Earth-based industrial and military applications. Several safety measures are built in, the largest security issue is rectenna and ground transmission lines. Ranching or solar panel fields can utilize the land under the rectenna mesh.

Trained professionals — An issue that is directly related to the IEEE and workforce preparedness is that there are relatively few researchers actively working on what has until recently been an intractable problem. The basic techniques are well-established; the real issues in deploying SPS systems may be a workforce ready to finish developing and build these systems. The number of researchers with current demonstrations can be counted on one hand. People ready to design the circuits, structures, software and enterprises to operate these systems is lacking. Developing what are currently exotic microwave receivers for Earth and space is both a technical and political issue. Integrating these systems with existing rockets is likely the simplest part.

A cohort of engineers trained in this new type of space system, designers and managers able to synthesize the new requirements and policy specialists willing to tackle these issues are needed to make it viable.

Policy — The case for space solar power and SPS systems needs to be made convincingly to both the public and political institutions. This should happen through both grass-roots teaching using devices like Dr. Jaffe’s demonstrator and through coordinated moves to encourage sympathetic policies.

Making young professionals into effective voices for positive change is essential to this effort.

Technology readiness — Many elements of a functional SPS system are at middle Technology Readiness Levels, defined by NASA as TRL 1-9 with 1 being an observed phenomenon and 9 being off-the-shelf hardware. Jaffe has performed vacuum chamber tests at NRL on a complete SPS sandwich module. Marzwell has demonstrated an end-to-end analog system with solar photovoltaic collection providing electricity to a transmitter, received on another mountain in Hawaii. Dr. Kaya has performed multiple lab, public and suborbital rocket demonstrations.

Mankins estimates that it would take around 15 years to go from the current state of the art to flying a power-generating demonstrator (TRL 8) and an equal amount of time to scale up to a 5GW plant in geosynchronous orbit (TRL 9). Currently critical subsystems are stuck between TRL 4 and 6 and some have uncertainty about where to develop further.

New labs and startups with this new cohort of young professionals can drive these subsystems to higher readiness.

Transmission Issues — There is a minimum strength power beam needed to trip the threshold voltage of a typical 20^km rectenna, or any receiving antenna. Ground tests between mountains by Marzwell and separate demos by Kaya and Jaffe show the principle works at smaller scales. Finding the right sizes of rectenna and beam characteristics is important, especially for in-space propulsion and mobile or smaller terrestrial applications such as a military forward operating bases or atop cargo container ships.

For stationary rectenna powering urban cores, much of the technology is fairly simple and can be located nearby on the ocean, desert or farmland. In that case the biggest transmission issues are communication interference from sidelobes and getting over the minimum transmission requirement. Inflatable or deployable rectenna with much higher beam density may be needed for in-space receiving.

Transmission issues are heavily dependent on system implementation and usage details that need to be further characterized as various SPS systems come online. Finding the right scales for in-space, limited/mobile terrestrial and baseline terrestrial beams is an avenue of currently needed research.

Financing & Business Development — The financial hurdle to fund a working SPS is mostly in funding the research & development and proving out the technology subsystems. The operational system can be earning money after the first launch and scales to literally out-of-this world markets.

An operable SPS system might be financed using commercial methods with a payoff time around 10 years after completion for sale of power to high-price markets. The goal is to achieve around $9 per installed kilowatt of capacity (2011 dollars) for a fully operational system. Some have argued that prototype units could be used for in-space propulsion to boost other client payloads but this is currently a small market.

While the payoff to electricity users (both industrial & residential) and to government (in taxes, military lives saved and new space colonies) is potentially quite large, the 15-40 year process of development toward those goals has proven daunting. Financing further technical readiness steps is also daunting as some of them involve spaceflight. NASA, JAXA and the Naval Research Lab have provided much of the previous funding due to the obvious potential but are neither mandated nor properly equipped to finance or run this type of project. Some kind of public-private partnership with loan and purchasing guarantees may be needed.

As SPS systems become viable, a business case must be made to current electricity providers, especially in coastal and desert regions. As with the development of wind and terrestrial solar, new construction sectors will need to evolve to build rectenna, ground transmission equipment and the factories to make thousands of these satellites. Development of one or several new companies will be needed.

Deeper modeling and trade studies are an opportunity to find the minimum viable products of this technology.

Orbits Utilized — The prospect of gigawatts of carbon- and heat- free power for terrestrial applications is compelling but comes at a cost. Most proposals for SPS systems place them in geostationary orbit (GEO), competing for orbital ‘slots’ with the proliferation of world telecommunications satellites. Orbital slots at GEO are precious, limited and nearly full. Multi-kilometer structures with unique control dynamics may not be allowed based on telecommunication needs.

Options include placing telecom transmitters directly on an SPS, beaming power to new, larger telecom satellites or to operate in other orbits. Prototypes, in-space beaming and high-power applications may benefit from flying in a sun-synchronous ‘high noon’ polar orbit. Final system options include Medium Earth Orbit below the GPS constellations or halo orbits around Earth-Moon Lagrange points if GEO slots are unavailable.

Space-based solar power in general and SPS in particular have tremendous potential environmental, technical and industrial benefits, costs to users that could rival terrestrial power sources, provide world energy security and fast in-space propulsion. SPS can be an enabling technology for lowering rocket launch and spaceflight costs. Convincing the US and international community’s citizens, regulators and politicians of this utility will require hard work and dedication among a new cohort of professionals who can practice an integrated approach to engineering these new systems.

 

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VidGrid Interactive Installation

Project VidGrid

VidGrid was a short 10-day project in David Tinapple’s AME598 Media Installations class. This project uses an OptiTrack motion capture suite and projected video to present an introduction of the class. The 40+ students in the class each made two introductory videos each that are laid out in a grid. When the user moves around, the video under them changes to a different video track.

Project VidGrid


 


The Proposal:
Project VidGrid (Joshua, Varsha, Henry, Prashanth & Connor)

The goal is to make a pleasant if somewhat creepy experience of the class staring at you. As one navigates through the space, the students they are directly facing will introduce themselves.

Project VidGrid is an installation using motion-capture and two selections of student video. It will consist of a projected grid of student face videos that align to a person walking through the space. When they stop over a grid space, the eight videos around them switch to the student introduction videos, all oriented to the user.

The positioning will use the B127 Optitrack motion-capture system and ceiling-mounted floor projector combined with a laptop running the video application. The application will be a combination of Processing and any other glue logic needed. Given enough time/CPUs/luck, the tiles of each video will be projected in 3D OpenGL code so that they appear to follow the user. The plan is to provide baseball caps rigged for motion capture to provide 6DOF head tracking of users. An attempt will be made to make the system multiuser but this is unlikely.

This project builds on several team members experience in AME598 Understanding Activity in using the motion capture rig in B127.

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archKit

Title: archKit (Architectural Kit)

Name: Joshua Gigantino

Quote: “Schematics never fully prepare you for the real thing.” – Admiral Patterson, Star Trek: Voyager, Relativity

Description: archKit is a first step in building a life-size rapid prototyping or sketching system for architects. A kit of full-sized, projection-ready wall panels are presented along with a reconfigurable ceiling to provide a first system of rapid prototyping for architecture.

archKit in AME's iStage, 9 December, 2014.
archKit in AME’s iStage, 9 December, 2014.

The system is intended to explore the quality of light in space in the context of defining the negative space needs of the architectural design process organically inside an experiential collaboration framework.

As shown December 9th, 2014, the kit consists of 7 interlocked panels of wood and muslin fabric. Together they form a 28’ (8.5m) wall or a 64^2’ room, a hut, wall or hogan with included fabric doorway. Hogan are 8-sided Dene (Navajo) structures that mean “Sacred enclosure” according to Nabokov & Easton (1989). Similar ritual and functional spaces existed among the Hohokam, Hopi and other Puebla nations. archKit includes a simple adjustable roof that can move between peaked and flat configurations.  A simple re-rigging would enable the roof to also form 2-, 4- and 8- fold peaks to follow these various Puebla people’s architectures along with geodesic domes and yurt structures.

Significance:

Architecture is the construction of thoughtful shelter or the “human-based differentiation” of physical space by the “creation of a BOUNDARY” according to Alexander (2002) . Architecture’s roots are in ancient permanent structures, temporary shelter and the definition of space. Examples of these three states include the Parthenon atop Athen’s Akropolis, ancient North American Tipi tents and palisade walls of wood or cloth.

archKit provides the basics for realizing full-scale prototyping of architectural projects. This is in direct contrast to the standard process of sketching leading to small models to CAD renderings. It allows architects and others to participate in a more hands-on approach.

Alexander makes a point of boundaries, centers and “emerging wholeness”. CAD systems can “just as easily create a monstrosity as something good.” because “There is no such thing as neutrality in such matters.” Instead, Alexander starts by sketching with small bits of material to “find out what harmonious volume would unfold from the site itself.” This process continues on-site with full-size wall segments and materials tests in ever more accurate design spirals that eventually lead to a complete solution.

Current implementation is a ‘Wizard of Oz’ approach of obvious theatrics involving simple projection and artist’s tape combined with narrative components. Further implementations will use AME iStage systems and other digital sensing to present increasing levels of fidelity to these kinds of architectural simulation.

Presenting a scenario in wall configuration.
Presenting a scenario in wall configuration.

Further systems will include wrap-around graphics for environmental/in-situ placement, digital manipulation of window and other elements. Critical digital elements should include accurate projection of horizon, slope, water drainage, sun angles and accessibility features.

Janich (1984) writes that “A topological space is a pair consisting of a set and a set of subsets”. In this project that set is the iStage blackbox theater, the subsets are the defined and undefined spaces generated by the archKit. Typically, the projector system and supporting computers are part of the closed set of the theatrical/studio space and the wall system provides an open set of enclosed space.Topologically the boundary should not exist but with feedback from architects it is clear that the walls need to be significantly thickened. The current panel set is only 7 panels, additional sets would modify but not negate this open set. In wall configuration the panels still define a space.

In creating a performance out of a design practice, elements of Artaud’s Theater of Cruelty organically emerge from the process. The audience are the performers, the only spectators were technicians and students maintaining the iStage’s technical systems, even they became actors inside the closed topological set. Artaud (1934) writes of a goal to make “…theater a believable reality which gives the heart and the senses that kind of of concrete bite which all true sensation requires.” Creating a prototyping system for a specialist field requires that believable reality be as representative and high-fidelity as possible while maintaining flexibility to improvise.

Goals:

Semester Goals:

Highlight Color Explorer – rapid iterations of color for accent walls and other interior exploration.

Mobility – Light, mobile panels that can be quickly reconfigured.

5-8 Panels – Seven panels allows for a simple room to long wall.

Experiment with LEDs for color illumination.

Long-term Development Goals:

Wall Tracking: using RFID or optical tracking for wall positioning.

Interactive wall interfaces for color selection, windows, etc.

Sound Space: changes echo with size and shape of wall using convolution reverb.

DWG output: flat architectural CAD file output.

Wall-thickness units of dense foam.

Produce open-source stack of equipment plus bill of materials for architects and others to build and use as needed.

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Materials:

Wall Panels

1×2” spruce strapping

plywood

108” bleached muslin fabric

screws

eye-screws

paracord

Roof/Ceiling

Plastic sheeting

Mason’s twine

paracord

Video Projector

Methods:

archKit is being developed using action-research and ethnographic approaches. Current methodology is purely qualitative. A more quantitative approach can be achieved when archKit is fully digital with wall sections and people able to be tracked. Construction of the current set of panels consisted of assembling spruce strapping and muslin cloth panels in the AME FabLab. Ethnographic research has consisted of interviews and brainstorming sessions with two Architecture graduate students at the Design School at ASU who both have interests in hybrid digital-physical systems.

Three forms of color projection are being explored. First, using video projection for full color and motion graphics, but also Arduino-powered NeoPixel LEDS and a generic multicolor LED lighting strip.

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LED color tests.
LED color tests.

Construction was with spruce strapping cut to length and mitred together with small braces for stability. 108” white muslin cloth was then stretched and stapled over it. Eye-screws were attached at top and bottom to complete each panel. The panels were then lashed together with paracord into a 7 panel array. The arrangement is mostly self-standing. A simple roof structure was rigged using paracord, mason’s twine and translucent construction plastic. Materials were kept as simple and construction-oriented as possible to provide a familiar environment for architects.

Testing has so far been conducted only in final critique. archKit will continue to be developed as a deployable component or kit for AME to spur collaboration.

Simple roof system can simulate flat and peaked coverings.
Simple roof system can simulate flat and peaked coverings.

Ethnographic notes:

Interviews with two architectural graduate students that are now collaborating on the project:

AF interview notes:

Roof & Foundation are critical to avoid just an interior paneling system. Light angles, drainage and domes need to be considered.

Book: Architectural Graphic Standards

Floor grid-system – IT style lifted floor or elevated floor tiles.

 

JC interview notes:

Interior panel partitions that mimic thickness of real walls. Office partitions crossed with SIPS panels.

Accessibility prototyping will be big – ramps, handholds, etc

System integration with BIM

Ingress/Egress prototyping

Lobby prototyping

Small scale mockups for high-tech buildings like hospitals and urgent care facilities.

Phoenix vs. Chicago: very different building materials. How to take into account?

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Connectors and stowage.

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References:

Alexander, C. (2002) The Process of Creating Life. Berkeley, CA. Center for Environmental Structure.

Artaud, A. (1934) The Theater and It’s Double. Unknown translation or publisher.

Janich, K. (1984) Topology. Silvio Levy, Trans. New York, NY. Springer-Verlag.

Nabokov, P. & Easton, R. (1989). Native American Architecture. New York, NY. Oxford University Press.

 

 

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