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A laser pilot beam guide the

microwave power transmission to a

rectenna.

NASA Suntower concept.

Space-based solar powerFrom Wikipedia, the free encyclopedia

See also: Solar panels on spacecraft

Space-based solar power (SBSP) is the concept of collecting solar power in space (using an "SPS", that is, a"solar-power satellite" or a "satellite power system") for use on Earth. It has been in research since the early 1970s.

SBSP would differ from current solar collection methods in that the means used to collect energy would reside onan orbiting satellite instead of on Earth's surface. Some projected benefits of such a system are a higher collectionrate and a longer collection period due to the lack of a diffusing atmosphere and nighttime in space.

Part of the solar energy is lost on its way through the atmosphere by the effects of reflection and absorption. Space-based solar power systems convert sunlight to microwaves outside the atmosphere, avoiding these losses, and thedowntime (and cosine losses, for fixed flat-plate collectors) due to the Earth's rotation.

Besides the cost of implementing such a system, SBSP also introduces several new hurdles, primarily the problemof transmitting energy from orbit to Earth's surface for use. Since wires extending from Earth's surface to an orbitingsatellite are neither practical nor feasible with current technology, SBSP designs generally include the use of somemanner of wireless power transmission. The collecting satellite would convert solar energy into electrical energy onboard, powering a microwave transmitter or laser emitter, and focus its beam toward a collector (rectenna) onEarth's surface. Radiation and micrometeoroid damage could also become concerns for SBSP.

Contents

1 History

1.1 SERT

2 Advantages

3 Disadvantages4 Design

4.1 Solar concentrator

4.2 Microwave power transmission4.3 Laser power beaming

4.4 Orbital location

4.5 Earth-based receiver

4.6 In space applications

5 Dealing with launch costs

5.1 Non-conventional launch methods

6 Building from space

6.1 From lunar materials launched in orbit

6.2 On the Moon

6.3 From an asteroid6.4 Gallery

7 Counter arguments

7.1 Safety

8 Timeline

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8 Timeline

9 In fiction

10 See also

11 References

12 External links

13 Videos

History

In 1941, science fiction writer Isaac Asimov published the science fiction short story "Reason", in which a spacestation transmits energy collected from the Sun to various planets using microwave beams.

The SBSP concept, originally known as satellite solar-power system (SSPS), was first described in November

1968.[1] In 1973 Peter Glaser was granted U.S. patent number 3,781,647 for his method of transmitting powerover long distances (e.g. from an SPS to Earth's surface) using microwaves from a very large antenna (up to one

square kilometer) on the satellite to a much larger one, now known as a rectenna, on the ground.[2]

Glaser then was a vice president at Arthur D. Little, Inc. NASA signed a contract with ADL to lead four othercompanies in a broader study in 1974. They found that, while the concept had several major problems – chiefly theexpense of putting the required materials in orbit and the lack of experience on projects of this scale in space – it

showed enough promise to merit further investigation and research.[3]

Between 1978 and 1981, the Congress authorized the Department of Energy (DoE) and NASA to jointlyinvestigate the concept. They organized the Satellite Power System Concept Development and Evaluation

Program.[4][5] The study remains the most extensive performed to date (budget $50 million).[6] Several reportswere published investigating the engineering feasibility of such an engineering project. They include:

Resource Requirements (Critical Materials, Energy, and Land)[7]

Financial/Management Scenarios[8][9]

Public Acceptance[10]

State and Local Regulations as Applied to Satellite Power System Microwave Receiving Antenna

Facilities[11]

Student Participation[12]

Potential of Laser for SBSP Power Transmission[13]

International Agreements[14][15]

Centralization/Decentralization[16]

Mapping of Exclusion Areas For Rectenna Sites[17]

Economic and Demographic Issues Related to Deployment[18]

Some Questions and Answers[19]

Meteorological Effects on Laser Beam Propagation and Direct Solar Pumped Lasers[20]

Public Outreach Experiment[21]

Power Transmission and Reception Technical Summary and Assessment[22]

Space Transportation[23]

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Artist's concept of Solar Power

Satellite in place. Shown is the

assembly of a microwave

transmission antenna. The solar

power satellite was to be located in a

geosynchronous orbit, 36,000 miles

above the Earth's surface. NASA

1976

SERT sandwich concept.NASA

The project was not continued with the change in administrations after the1980 US Federal elections.

The Office of Technology Assessment[24] concluded

Too little is currently known about the technical, economic, andenvironmental aspects of SPS to make a sound decision whetherto proceed with its development and deployment. In addition,without further research an SPS demonstration or systems-engineering verification program would be a high-risk venture.

In 1997 NASA conducted its "Fresh Look" study to examine the

modern state of SBSP feasibility.[25] In assessing "What has changed"since the DOE study, NASA asserted that:

US National Space Policy now calls for NASA to makesignificant investments in technology (not a particular vehicle) todrive the costs of ETO [Earth to Orbit] transportation downdramatically. This is, of course, an absolute requirement of spacesolar power.

Conversely, Dr. Pete Worden claimed that space-based solar is about five orders of magnitude more expensivethan solar power from the Arizona desert, with a major cost being the transportation of materials to orbit. Dr.

Worden referred to possible solutions as speculative, and that would not be available for decades at the earliest.[26]

On Nov 2, 2012, China proposed space collaboration with India thatmentioned SBSP, " . . . may be Space-based Solar Power initiative sothat both India and China can work for long term association with properfunding along with other willing space faring nations to bring space solar

power to earth."[27]

SERT

In 1999, NASA's Space Solar Power Exploratory Research andTechnology program (SERT) was initiated for the following purposes:

Perform design studies of selected flight demonstration concepts.Evaluate studies of the general feasibility, design, and requirements.Create conceptual designs of subsystems that make use of advanced SSP technologies to benefit future

space or terrestrial applications.

Formulate a preliminary plan of action for the U.S. (working with international partners) to undertake an

aggressive technology initiative.Construct technology development and demonstration roadmaps for critical Space Solar Power (SSP)

elements.

SERT went about developing a solar power satellite (SPS) concept for a future gigawatt space power system, toprovide electrical power by converting the Sun’s energy and beaming it to Earth's surface, and provided aconceptual development path that would utilize current technologies. SERT proposed an inflatable photovoltaic

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gossamer structure with concentrator lenses or solar heat engines to convert sunlight into electricity. The programlooked both at systems in sun-synchronous orbit and geosynchronous orbit.

Some of SERT's conclusions:

The increasing global energy demand is likely to continue for many decades resulting in new power plants of

all sizes being built.

The environmental impact of those plants and their impact on world energy supplies and geopolitical

relationships can be problematic.Renewable energy is a compelling approach, both philosophically and in engineering terms.

Many renewable energy sources are limited in their ability to affordably provide the base load power

required for global industrial development and prosperity, because of inherent land and water requirements.

Based on their Concept Definition Study, space solar power concepts may be ready to reenter thediscussion.

Solar power satellites should no longer be envisioned as requiring unimaginably large initial investments in

fixed infrastructure before the emplacement of productive power plants can begin.Space solar power systems appear to possess many significant environmental advantages when compared to

alternative approaches.

The economic viability of space solar power systems depends on many factors and the successful

development of various new technologies (not least of which is the availability of much lower cost access tospace than has been available), however, the same can be said of many other advanced power technologies

options.

Space solar power may well emerge as a serious candidate among the options for meeting the energy

demands of the 21st century. Space Solar Power Satellite Technology Development at the Glenn ResearchCenter—An Overview] James E. Dudenhoefer and Patrick J. George, NASA Glenn Research Center,

Cleveland, Ohio.

Launch costs in the range of $100–$200 per kilogram of payload to low Earth orbit are needed if SPS are

to be economically viable.[6]

Advantages

The SBSP concept is attractive because space has several major advantages over the Earth's surface for thecollection of solar power.

There is no air in space, so the collecting surfaces could receive much more intense sunlight, unobstructed by

the filtering effects of atmospheric gasses, cloud cover, and other weather events. Consequently, collection in

orbit is approximately 144% of the maximum attainable on Earth's surface.[citation needed]

A satellite could be illuminated over 99% of the time, and be in Earth's shadow on only 75 minutes per night

at the spring and fall equinoxes.[28] Orbiting satellites can be exposed to a consistently high degree of solar

radiation, generally for 24 hours per day, whereas surface panels can collect for 12 hours per day at

most.[29]

Relatively quick redirecting of power directly to areas that need it most. A collecting satellite could possibly

direct power on demand to different surface locations based on geographical baseload or peak load powerneeds.

Elimination of plant and wildlife interference.

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Artist's concept of a solar disk on top

of a LEO to GEO electrically powered

space tug.

Disadvantages

The SBSP concept also has a number of problems.

The large cost of launching a satellite into space

Inaccessibility: Maintenance of an earth-based solar panel is relatively simple, but performing maintenance ona solar panel in space incurs the extra cost of transporting a team of astronauts into space.

The space environment is hostile; panels suffer about 8 times the degradation they would on Earth.[30]

Space debris is a major hazard to large objects in space, and all large structures such as SBSP systems have

been mentioned as potential sources of orbital debris.[31]

The broadcast frequency of the microwave downlink (if used) would require isolating the SBSP systems

away from other satellites. GEO space is already well used and it is considered unlikely the ITU would allow

an SPS to be launched.[32]

The large size and corresponding cost of the receiving station on the ground.

Design

Space-based solar power essentially consists of three elements:

a means of collecting solar power in space, for example via solar

concentrators, solar cells or a heat enginea means of transmitting power to earth, for example via microwave

or laser

a means of receiving power on earth, for example via a microwaveantenna (rectenna)

The space-based portion will not need to support itself against gravity(other than relatively weak tidal stresses). It needs no protection fromterrestrial wind or weather, but will have to cope with space hazards suchas micrometeors and solar flares.

Two basic methods of conversion have been studied: photovoltaic (PV) and solar dynamic (SD). Photovoltaicconversion uses semiconductor cells to directly convert photons into electrical power. Solar dynamic uses mirrorsto concentrate light on a boiler. The use of solar dynamic could reduce mass per watt. Most analyses of SBSP havefocused on photovoltaic conversion (commonly known as “solar cells”).

Wireless power transmission was proposed early on as a means to transfer energy from collection to the Earth'ssurface, using either microwave or laser radiation at a variety of frequencies.

Solar concentrator

Microwave power transmission

William C. Brown demonstrated in 1964, during Walter Cronkite's CBS News program, a microwave-poweredmodel helicopter that received all the power it needed for flight from a microwave beam. Between 1969 and 1975,Bill Brown was technical director of a JPL Raytheon program that beamed 30 kW of power over a distance of 1-

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Comparison of laser and microwave

power transmission. NASA diagram

mile (1.6 km) at 84% efficiency.[33]

Microwave power transmission of tens of kilowatts has been well proven by existing tests at Goldstone in California

(1975)[33][34][35] and Grand Bassin on Reunion Island (1997).[36]

More recently, microwave power transmission has been demonstrated, inconjunction with solar energy capture, between a mountain top in Mauiand the main island of Hawaii (92 miles away), by a team under John C.

Mankins.[37][38] Technological challenges in terms of array layout, singleradiation element design, and overall efficiency, as well as the associatedtheoretical limits are presently a subject of research, as it is demonstratedby the Special Session on "Analysis of Electromagnetic Wireless Systemsfor Solar Power Transmission" to be held in the 2010 IEEE Symposium

on Antennas and Propagation.[39]

In 2013, a useful overview was published, covering technologies andissues associated with microwave power transmission from space toground. It includes an introduction to SPS, current research and future

prospects.[40]

Laser power beaming

Laser power beaming was envisioned by some at NASA as a steppingstone to further industrialization of space. In the 1980s, researchers at NASA worked on the potential use of lasersfor space-to-space power beaming, focusing primarily on the development of a solar-powered laser. In 1989 itwas suggested that power could also be usefully beamed by laser from Earth to space. In 1991 the SELENEproject (SpacE Laser ENErgy) had begun, which included the study of laser power beaming for supplying powerto a lunar base. The SELENE program was a two-year research effort, but the cost of taking the concept tooperational status was too high, and the official project ended in 1993 before reaching a space-based

demonstration.[41]

In 1988 the use of an Earth-based laser to power an electric thruster for space propulsion was proposed by GrantLogan, with technical details worked out in 1989. He proposed using diamond solar cells operating at 600 degreesto convert ultraviolet laser light.

Orbital location

The main advantage of locating a space power station in geostationary orbit is that the antenna geometry staysconstant, and so keeping the antennas lined up is simpler. Another advantage is that nearly continuous powertransmission is immediately available as soon as the first space power station is placed in orbit; other space-basedpower stations have much longer start-up times before they are producing nearly continuous power.

A collection of LEO (Low Earth Orbit) space power stations has been proposed as a precursor to GEO

(Geostationary Orbit) space-based solar power.[42]

Earth-based receiver

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The Earth-based rectenna would likely consist of many short dipole antennas connected via diodes. Microwave

broadcasts from the satellite would be received in the dipoles with about 85% efficiency.[43] With a conventionalmicrowave antenna, the reception efficiency is better, but its cost and complexity are also considerably greater.Rectennas would likely be several kilometers across.

In space applications

A laser SBSP could also power a base or vehicles on the surface of the Moon or Mars, saving on mass costs to

land the power source. A spacecraft or another satellite could also be powered by the same means.[44][45]

Dealing with launch costs

One problem for the SBSP concept is the cost of space launches and the amount of material that would need to belaunched.

Reusable launch systems are predicted to provide lower launch costs to low Earth orbit (LEO).[46][47] As ofNovember 2013, one company, SpaceX, is two years along on a privately funded multi-year development programfor a reusable rocket launching system with the stated intention to commercialize "fully and rapidly reusable" launch

technology.[48][49][50] SpaceX has completed eight test flights of their low-altitude booster return prototype,

Grasshopper,[51] and one test flight of a high-altitude/high-velocity booster return test vehicle, with a second

booster return test flight planned for early 2014.[52][53]

Much of the material launched need not be delivered to its eventual orbit immediately, which raises the possibilitythat high efficiency (but slower) engines could move SPS material from LEO to GEO at an acceptable cost.Examples include ion thrusters or nuclear propulsion.

Power beaming from geostationary orbit by microwaves carries the difficulty that the required 'optical aperture'sizes are very large. For example, the 1978 NASA SPS study required a 1-km diameter transmitting antenna, anda 10 km diameter receiving rectenna, for a microwave beam at 2.45 GHz. These sizes can be somewhat decreasedby using shorter wavelengths, although they have increased atmospheric absorption and even potential beamblockage by rain or water droplets. Because of the thinned array curse, it is not possible to make a narrower beamby combining the beams of several smaller satellites. The large size of the transmitting and receiving antennas meansthat the minimum practical power level for an SPS will necessarily be high; small SPS systems will be possible, butuneconomic.

To give an idea of the scale of the problem, assuming a solar panel mass of 20 kg per kilowatt (without consideringthe mass of the supporting structure, antenna, or any significant mass reduction of any focusing mirrors) a 4 GWpower station would weigh about 80,000 metric tons, all of which would, in current circumstances, be launched

from the Earth. Very lightweight designs could likely achieve 1 kg/kW,[54] meaning 4,000 metric tons for the solarpanels for the same 4 GW capacity station. This would be the equivalent of between 40 and 150 heavy-lift launchvehicle (HLLV) launches to send the material to low earth orbit, where it would likely be converted intosubassembly solar arrays, which then could use high-efficiency ion-engine style rockets to (slowly) reach GEO(Geostationary orbit). With an estimated serial launch cost for shuttle-based HLLVs of $500 million to $800million, and launch costs for alternative HLLVs at $78 million, total launch costs would range between $11 billion

(low cost HLLV, low weight panels) and $320 billion ('expensive' HLLV, heavier panels).[citation needed] To thesecosts must be added the environmental impact of heavy space launch emissions, if such costs are to be used in

comparison to earth-based energy production. For comparison, the direct cost of a new coal[55] or nuclear power

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plant ranges from $3 billion to $6 billion per GW (not including the full cost to the environment from CO2 emissionsor storage of spent nuclear fuel, respectively); another example is the Apollo missions to the Moon cost a grandtotal of $24 billion (1970s' dollars), taking inflation into account, would cost $140 billion today, more expensivethan the construction of the International Space Station.

However in 2013 based on Recent innovations, Electric Space: Space-Based Solar Power Technologies &

Applications [56] suggested a new way to reduce costs by replacing smaller satellites and in lower Orbits.

Non-conventional launch methods

Main articles: Non-rocket spacelaunch and Skyhook (structure)

SBSP costs could be significantly reduced if a means of putting the necessary materials into orbit were developedthat did not rely on expendable rockets. One idea for this is the non-rotating Skyhook, a type of space elevator thatcan be affordable built with existing materials and technology. Some more speculative possibilities include groundlaunch systems such as Star Tram, mass drivers or launch loops, or the Earth surface to geostationary orbit SpaceElevator. However, these ideas require technologies that have yet to be developed.

Building from space

From lunar materials launched in orbit

Gerard O'Neill, noting the problem of high launch costs in the early 1970s, proposed building the SPS's in orbit

with materials from the Moon.[57] Launch costs from the Moon are potentially much lower than from Earth, due tothe lower gravity. This 1970s proposal assumed the then-advertised future launch costing of NASA's space shuttle.

This approach would require substantial up front capital investment to establish mass drivers on the Moon.[58]

Nevertheless, on 30 April 1979, the Final Report ("Lunar Resources Utilization for Space Construction") byGeneral Dynamics' Convair Division, under NASA contract NAS9-15560, concluded that use of lunar resourceswould be cheaper than Earth-based materials for a system of as few as thirty Solar Power Satellites of 10GW

capacity each.[59]

In 1980, when it became obvious NASA's launch cost estimates for the space shuttle were grossly optimistic,

O'Neill et al. published another route to manufacturing using lunar materials with much lower startup costs.[60] This1980s SPS concept relied less on human presence in space and more on partially self-replicating systems on thelunar surface under remote control of workers stationed on Earth. The high net energy gain of this proposal derivesfrom the Moon's much shallower gravitational well.

Having a relatively cheap per pound source of raw materials from space would lessen the concern for low massdesigns and result in a different sort of SPS being built. The low cost per pound of lunar materials in O'Neill's visionwould be supported by using lunar material to manufacture more facilities in orbit than just solar power satellites.

Advanced techniques for launching from the Moon may reduce the cost of building a solar power satellite fromlunar materials. Some proposed techniques include the lunar mass driver and the lunar space elevator, first

described by Jerome Pearson.[61] It would require establishing silicon mining and solar cell manufacturing facilities

on the Moon.[citation needed]

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On the Moon

David Criswell suggests the Moon is the optimum location for solar power stations, and promotes lunar solar

power.[62][63] The main advantage he envisions is construction largely from locally available lunar materials, usingin-situ resource utilization, with a teleoperated mobile factory and crane to assemble the microwave reflectors, and

rovers to assemble and pave solar cells,[64] which would significantly reduce launch costs compared to SBSPdesigns. Power relay satellites orbiting around earth and the Moon reflecting the microwave beam are also part of

the project. A demo project of 1 GW starts at $50 billion.[65] The Shimizu Corporation use combination of lasers

and microwave for the lunar ring concept, along with power relay satellites.[66][67]

From an asteroid

Asteroid mining has also been seriously considered. A NASA design study[68] evaluated a 10,000 ton miningvehicle (to be assembled in orbit) that would return a 500,000 ton asteroid fragment to geostationary orbit. Onlyabout 3,000 tons of the mining ship would be traditional aerospace-grade payload. The rest would be reactionmass for the mass-driver engine, which could be arranged to be the spent rocket stages used to launch the payload.Assuming that 100% of the returned asteroid was useful, and that the asteroid miner itself couldn't be reused, thatrepresents nearly a 95% reduction in launch costs. However, the true merits of such a method would depend on a

thorough mineral survey of the candidate asteroids; thus far, we have only estimates of their composition.[69] Oneproposal is to capture the asteroid Apophis into earth orbit and convert it into 150 solar power satellites of 5 GW

each.[70]

Gallery

A Lunar base with amass driver (the longstructure that goestoward the horizon).NASA conceptualillustration

An artist's conception ofa "self-growing" roboticlunar factory.

Microwave reflectors onthe moon andteleoperated roboticpaving rover and crane.

“Crawler” traversesLunar surface,smoothing, melting a toplayer of regolith, thendepositing elements ofsilicon PV cells directlyon surface

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Sketch of the LunarCrawler to be used forfabrication of lunar solarcells on the surface ofthe Moon.

Shown here is an arrayof solar collectors thatconvert power intomicrowave beamsdirected toward Earth.

A solar power satellitebuilt from a minedasteroid.

Counter arguments

Safety

The use of microwave transmission of power has been the most controversial issue in considering any SPS design.

At the Earth's surface, a suggested microwave beam would have a maximum intensity at its center, of 23 mW/cm2

(less than 1/4 the solar irradiation constant), and an intensity of less than 1 mW/cm2 outside of the rectenna

fenceline (the receiver's perimeter).[71] These compare with current United States Occupational Safety and Health

Act (OSHA) workplace exposure limits for microwaves, which are 10 mW/cm2,[72] - the limit itself being

expressed in voluntary terms and ruled unenforceable for Federal OSHA enforcement purposes.[citation needed] Abeam of this intensity is therefore at its center, of a similar magnitude to current safe workplace levels, even for long

term or indefinite exposure. Outside the receiver, it is far less than the OSHA long-term levels[73] Over 95% of thebeam energy will fall on the rectenna. The remaining microwave energy will be absorbed and dispersed well within

standards currently imposed upon microwave emissions around the world.[74] It is important for system efficiencythat as much of the microwave radiation as possible be focused on the rectenna. Outside of the rectenna,microwave intensities rapidly decrease, so nearby towns or other human activity should be completely

unaffected.[75]

Exposure to the beam is able to be minimized in other ways. On the ground, physical access is controllable (e.g.,via fencing), and typical aircraft flying through the beam provide passengers with a protective metal shell (i.e., aFaraday Cage), which will intercept the microwaves. Other aircraft (balloons, ultralight, etc.) can avoid exposure byobserving airflight control spaces, as is currently done for military and other controlled airspace.

The microwave beam intensity at ground level in the center of the beam would be designed and physically built intothe system; simply, the transmitter would be too far away and too small to be able to increase the intensity to unsafelevels, even in principle.

In addition, a design constraint is that the microwave beam must not be so intense as to injure wildlife, particularlybirds. Experiments with deliberate microwave irradiation at reasonable levels have failed to show negative effects

even over multiple generations.[76]

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Some have suggested locating rectennas offshore,[77][78] but this presents serious problems, including corrosion,mechanical stresses, and biological contamination.

A commonly proposed approach to ensuring fail-safe beam targeting is to use a retrodirective phased arrayantenna/rectenna. A "pilot" microwave beam emitted from the center of the rectenna on the ground establishes aphase front at the transmitting antenna. There, circuits in each of the antenna's subarrays compare the pilot beam'sphase front with an internal clock phase to control the phase of the outgoing signal. This forces the transmitted beamto be centered precisely on the rectenna and to have a high degree of phase uniformity; if the pilot beam is lost forany reason (if the transmitting antenna is turned away from the rectenna, for example) the phase control value fails

and the microwave power beam is automatically defocused.[75] Such a system would be physically incapable offocusing its power beam anywhere that did not have a pilot beam transmitter.

The long-term effects of beaming power through the ionosphere in the form of microwaves has yet to be studied,but nothing has been suggested which might lead to any significant effect.

Timeline

1941: Isaac Asimov published the science fiction short story "Reason," in which a space station transmits

energy collected from the sun to various planets using microwave beams.

1968: Dr. Peter Glaser introduces the concept of a "solar power satellite" system with square miles of solar

collectors in high geosynchronous orbit for collection and conversion of sun's energy into a microwave beam

to transmit usable energy to large receiving antennas (rectennas) on Earth for distribution.

1973: Dr. Peter Glaser is granted United States patent number 3,781,647 for his method of transmitting

power over long distances using microwaves from a large (one square kilometer) antenna on the satellite to a

much larger one on the ground, now known as a rectenna.[2]

1978–81: The United States Department of Energy and NASA examine the solar power satellite (SPS)

concept extensively, publishing design and feasibility studies.

1982: Boeing proposal[79]

1987: Stationary High Altitude Relay Platform a Canadian experiment

1994: The United States Air Force conducts the Advanced Photovoltaic Experiment using a satellite

launched into low Earth orbit by a Pegasus rocket.

1995–97: NASA conducts a “Fresh Look” study of space solar power (SSP) concepts and technologies.

1998: The Space Solar Power Concept Definition Study (CDS) identifies credible, commercially viable SSP

concepts, while pointing out technical and programmatic risks.

1998: Japan's space agency begins developing a Space Solar Power System (SSPS), a program thatcontinues to the present day.

1999: NASA's Space Solar Power Exploratory Research and Technology program (SERT, see below)

begins.

2000: John Mankins of NASA testifies in the U.S. House of Representatives, saying "Large-scale SSP is a

very complex integrated system of systems that requires numerous significant advances in current technology

and capabilities. A technology roadmap has been developed that lays out potential paths for achieving all

needed advances — albeit over several decades.[6]

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2001: Dr. Neville Marzwell of NASA states, "We now have the technology to convert the sun's energy at

the rate of 42 to 56 percent... We have made tremendous progress. ...If you can concentrate the sun's rays

through the use of large mirrors or lenses you get more for your money because most of the cost is in the PV

arrays... There is a risk element but you can reduce it... You can put these small receivers in the desert or in

the mountains away from populated areas. ...We believe that in 15 to 25 years we can lower that cost to 7

to 10 cents per kilowatt hour. ...We offer an advantage. You don't need cables, pipes, gas or copper wires.

We can send it to you like a cell phone call—where you want it and when you want it, in real time."[80]

2001: NASDA (One of Japan's national space agencies before it became part of JAXA) announces plans to

perform additional research and prototyping by launching an experimental satellite with 10 kilowatts and 1

megawatt of power.[81][82]

2003: ESA studies[83]

2007: The US Pentagon's National Security Space Office (NSSO) issues a report[84] on October 10, 2007stating they intend to collect solar energy from space for use on Earth to help the United States' ongoing

relationship with the Middle East and the battle for oil. A demo plant could cost $ 10 billion, produce 10

megawatts, and become operational in 10 years.[85] The International Space Station may be the first test

ground for this new idea, even though it is in a low-earth orbit.

2007: In May 2007 a workshop is held at the US Massachusetts Institute of Technology (MIT) to review

the current state of the SBSP market and technology.[86]

2009: Several companies announce future SBSP partnerships and commitments, including Pacific Gas and

Electric (PG&E) & Solaren,[87][88][89] Mitsubishi Electric Corp. & IHI Corporation,[90][91] Space Energy,

Inc.,[92] and Japan Aerospace Exploration Agency.[93]

2010: Europe's EADS Astrium announces SBSP plans.[94][95][96][97]

2010: Professors Andrea Massa and Giorgio Franceschetti announce a special session on the "Analysis ofElectromagnetic Wireless Systems for Solar Power Transmission" at the 2010 Institute of Electrical and

Electronics Engineers International Symposium on Antennas and Propagation.[98]

2010: The Indian Space Research Organisation and US' National Space Society launched a joint forum toenhance partnership in harnessing solar energy through space-based solar collectors. Called the Kalam-NSS

Initiative after the former Indian President Dr APJ Abdul Kalam, the forum will lay the groundwork for the

space-based solar power program which could see other countries joining in as well.[99]

2010: The National Forensics League announces the resolution for the 2011–2012 debate season to besubstantial space exploration and/or development. Space Based Solar Power becomes one of the most

popular affirmative arguments.

2012: China proposed joint development between India and China towards developing a solar power

satellite, during a visit by former Indian President Dr APJ Abdul Kalam.[100]

In fiction

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Space stations transmitting solar power have appeared in science-fiction works like Isaac Asimov's Reason(1941), that centers around the troubles caused by the robots operating the station. Asimov's short story "The LastQuestion" also features the use of SBSP to provide limitless energy for use on Earth.

In the novel "Skyfall" (1976) by Harry Harrison an attempt to launch the core of powersat from Cape Canaveralends in disaster when the launch vehicle fails trapping the payload in a decaying orbit.

Several Simcity games have featured space-microwave power plants as buildable options for municipal energy,along with disaster scenarios where the beam strays off the collector.

In the manga and anime Mobile Suit Gundam 00, an orbital ring containing multiple solar collectors andmicrowave transmitters, along with power stations and space elevators for carrying power back down to Earth'ssurface, are the primary source of electricity for the Earth in the 22nd century.

See also

Attitude controlFuture energy development

Orbital station-keeping in GEOPhotovoltaics

Project EarthSatelliteSolar power

Solar panels on spacecraftSpace Fountain

Friis transmission equation equation for beamed wireless power efficiency

References

1. ^ Glaser, Peter E. (22 November 1968). "Power from the Sun: Its Future"

(http://www.sciencemag.org/cgi/reprint/162/3856/857.pdf) (PDF). Science Magazine 162 (3856): 857–861.

2. ̂a b Glaser, Peter E. (December 25, 1973). "Method And Apparatus For Converting Solar Radiation To ElectricalPower" (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=3,781,647.PN.&OS=PN/3,781,647&RS=PN/3,781,647). United States Patent 3,781,647.

3. ^ Glaser, P. E., Maynard, O. E., Mackovciak, J., and Ralph, E. L, Arthur D. Little, Inc., "Feasibility study of asatellite solar power station", NASA CR-2357, NTIS N74-17784, February 1974

4. ^ Satellite Power System Concept Development and Evaluation Program July 1977 - August 1980. DOE/ET-0034,February 1978. 62 pages (http://www.nss.org/settlement/ssp/library/1978DOESPS-ProgramPlanJuly1977-August1980.pdf)

5. ^ Satellite Power System Concept Development and Evaluation Program Reference System Report. DOE/ER-0023,October 1978. 322 (http://www.nss.org/settlement/ssp/library/1978DOESPS-ReferenceSystemReport.pdf)

6. ̂a b c Statement of John C. Mankins (http://www.nss.org/settlement/ssp/library/2000-testimony-JohnMankins.htm) U.S. House Subcommittee on Space and Aeronautics Committee on Science, Sep 7, 2000

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8. ^ Satellite Power System (SPS) Financial/Management Scenarios. Prepared by J. Peter Vajk. HCP/R-4024-03,October 1978. 69 pages (http://www.nss.org/settlement/ssp/library/1978DOESPS-FinancialManagementScenarios(Vajk).pdf)

9. ^ Satellite Power System (SPS) Financial/Management Scenarios. Prepared by Herbert E. Kierulff. HCP/R-4024-13, October 1978. 66 pages. (http://www.nss.org/settlement/ssp/library/1978DOESPS-FinancialManagementScenarios(Kierolff).pdf)

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29. ^ Collection at Earth's poles can take place for 24 hours per day, but not consistently, and only for 6 months of theyear.

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Techniques 32 (Volume: 32, Issue: 9 On page(s): 1230- 1242 + ISSN: 0018-9480): 1230.Bibcode:1984ITMTT..32.1230B (http://adsabs.harvard.edu/abs/1984ITMTT..32.1230B).doi:10.1109/TMTT.1984.1132833 (http://dx.doi.org/10.1109%2FTMTT.1984.1132833).

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36. ^ POINT-TO-POINT WIRELESS POWER TRANSPORTATION IN REUNION ISLAND (http://www2.univ-reunion.fr/~lcks/Old_Version/PubIAF97.htm) 48th International Astronautical Congress, Turin, Italy, 6–10October 1997 – IAF-97-R.4.08 J. D. Lan Sun Luk, A. Celeste, P. Romanacce, L. Chane Kuang Sang, J. C.Gatina – University of La Réunion – Faculty of Science and Technology.

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46. ^ Dr. Lee Valentine in conversation on The Space Show aired on the 6th of October 2010 said there is a potentialfor a hundred times cost reduction in the cost of Earth to orbit transportation by using reusable vehicles. TheSpace Show (http://www.thespaceshow.com./detail.asp?q=1438)

47. ^ http://www.reactionengines.co.uk/downloads/ssp_skylon_ver2.pdf

48. ^ Simberg, Rand (2012-02-08). "Elon Musk on SpaceX’s Reusable Rocket Plans"(http://www.popularmechanics.com/science/space/rockets/elon-musk-on-spacexs-reusable-rocket-plans-6653023). Popular Mechanics. Retrieved 2012-02-07.

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72. ^ Radiofrequency and Microwave Radiation Standards(http://www.osha.gov/SLTC/radiofrequencyradiation/standards.html) interpretation of General Industry (29 CFR1910) 1910 Subpart G, Occupational Health and Environmental Control 1910.97, Non-ionizing radiation.

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73. ^ 2081 A Hopeful View of the Human Future, by Gerard K. O'Neill, ISBN 0-671-24257-1, P. 182-183

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External links

William Maness on why alternative energy and power grids aren’t good playmates and his plans for beamingsolar power from space. (http://seedmagazine.com/content/article/getting_solar_off_the_ground/) in Seed

(magazine)The World Needs Energy from Space

(http://www.space.com/opinionscolumns/opinions/glaser_000223.html) Space-based solar technology is thekey to the world's energy and environmental future, writes Peter E. Glaser, a pioneer of the technology.Reinventing the Solar Power Satellite" (http://gltrs.grc.nasa.gov/cgi-bin/GLTRS/browse.pl?2004/TM-2004-

212743.html), NASA 2004-212743, report by Geoffrey A. Landis of NASA Glenn Research CenterJapan's plans for a Solar Power Station in Space (http://www.spacedaily.com/news/ssp-01a.html) - the

Japanese government hopes to assemble a space-based solar array by 2040.Space Energy, Inc. (http://www.spaceenergy.com/) - Space Energy, Inc.

Whatever happened to solar power satellites? (http://www.thespacereview.com/article/214/1) An article thatcovers the hurdles in the way of deploying a solar power satellite.Solar Power Satellite from Lunar and Asteroidal Materials (http://permanent.com/p-sps.htm) Provides an

overview of the technological and political developments needed to construct and utilize a multi-gigawattpower satellite. Also provides some perspective on the cost savings achieved by using extraterrestrial

materials in the construction of the satellite.A renaissance for space solar power? by Jeff Foust, Monday, August 13, 2007

(http://www.thespacereview.com/article/931/1) Reports on renewed institutional interest in SSP, and a lackof such interest in past decades.

PowerSat Corporation / PowerSat Limited website (http://www.powersat.com/) Commercial space basedsolar power companies in Europe and the United States."Conceptual Study of A Solar Power Satellite, SPS 2000"

(http://www.spacefuture.com/archive/conceptual_study_of_a_solar_power_satellite_sps_2000.shtml)Makoto Nagatomo, Susumu Sasaki and Yoshihiro Naruo

Researchers Beam 'Space' Solar Power in Hawaii (http://blog.wired.com/wiredscience/2008/09/visionary-beams.html) (Wired Science)

http://www.nss.org/settlement/ssp/library/index.htm — The National Space Society's Space Solar PowerLibrarySpecial Session on "Analysis of Electromagnetic Wireless Systems for Solar Power Transmission"

(http://www.apsursi2010.org/?m=page&id=47) 2010 IEEE International Symposium on Antennas andPropagation

The future of Energy is on demand? (http://www.festivaldellecittaimpresa.it/index.php?option=com_events&Itemid=28&lang=en) Special Session at the 2010 Festival delle Città Impresa

featuring John Mankins (Artemis Innovation Management Solutions LLC, USA), Nobuyuki Kaya (KobeUniversity, Japan), Sergio Garribba (Italian Ministry of Economic Development, Italy), Lorenzo Fiori(Finmeccanica Group, Italy), Andrea Massa (University of Trento, Italy) and Vincenzo Gervasio (Consiglio

Nazionale dell'Economia ed del Lavoro, Italy). White Paper(http://www.ursi.org/en/publications_whitepapers.asp)- History of SPS Developpements International Union

of Radio Science 2007

Videos

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Powering the Planet (http://www.thefutureschannel.com/dockets/realworld/space_based_solar_power/) 20-minute streaming video from The Futures Channel that provides a "101" on space-based solar power

Space Solar Power (http://www.youtube.com/watch?v=eTdJw30Pg4Q) NewSpace 2010 Panel, 72minutesSpace Solar Power and Space Energy Systems (http://www.youtube.com/watch?v=kMW64hqipGI) SSI –

Space Manufacturing 14 Panel – 2010 – 27 minNASA DVD in 16 Parts (http://www.youtube.com/watch?v=og9UvxrHA9E) Exploring New Frontiers for

Tomorrow's Energy NeedsSpace Solar Power (http://www.youtube.com/watch?v=2E_z6L9Hn0Q) Press Conference September 12,

2008 (71 minutes) National Space Society

Retrieved from "http://en.wikipedia.org/w/index.php?title=Space-based_solar_power&oldid=598060822"Categories: Photovoltaics Space technology Thermodynamics Energy conversion Satellites

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