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Solar Shed in the South Yard

Smithsonian Archives - History Div
This image is located in the Walter A. Shropshire Oral History Interviews.

Solar shed in the South Yard behind the Smithsonian Institution Building or "Castle." This shed housed solar collectors for Secretary Charles G. Abbot's scientific research.

Smithsonian Solar Observing Station, Table Mountain, CA

Smithsonian Archives - History Div
Original negative number is MAH-33666.

Solar observation instrument stands outside the entrance to the observing tunnel used for the daily measurement of the sun's radiation at the solar observing station at the Smithsonian Astrophysical Observatory, Table Mountain, California.

Tyrone Solar Station, Burro Mountain, NM

Smithsonian Archives - History Div
There are many photos of this area in Smithsonian Insitution Archives, Record Unit 7005, Box 187, Folder: 8.

Outside the instrument tunnel at the Smithsonian Astrophysical Observatory's Tyrone Solar Station (in use from 1938 to 1946), on Burro Mountain at Silver City, New Mexico, are solar observing instruments.

Solar Observation Station at Mt. Montezuma, Chile

Smithsonian Archives - History Div
At the Smithsonian Astrophysical Observatory at Mt. Montezuma, Chile, cave observatory and solar observation instruments are used in the study of the sun. A man using a solar observation instrument stands outside the cave.

Smithsonian Astrophysical Observatory, Table Mountain, CA

Smithsonian Archives - History Div
Solar observation Instruments outside the entrance to the instrument tunnel at the solar observing station of the Smithsonian Astrophysical Observatory at Table Mountain, California.

SAO Mount Whitney Shelter Erected

Smithsonian Archives - History Div
Images of the site are located in the Charles Greeley Abbot Papers, Smithsonian Institution Archives, Record Unit 7006, Box 187, Folder 3.

Abbot, Charles G., "A Shelter for Observers on Mount Whitney," Smithsonian Miscellaneous Collections, No. 1886, Washington, D.C.: Smithsonian Institution, 1910, pp. 499-506, with plates 65 and 66.

Annual Report of the Smithsonian Institution for the year 1909, Washington, D.C.: Government Printing Office, 1910, pp. 12-13, 30-31, 64-66, and plates 3-5.

Annual Report of the Smithsonian Institution for the year 1910, Washington, D.C.: Government Printing Office, 1911, pp. 16-17, 37-38, 73-76, and 99.

In 1909, using a grant from the Thomas George Hodgkins Fund, the Smithsonian Astrophysical Observatory erected a shelter atop Mount Whitney, California, for astrophysical researchers. Smithsonian Secretary Samuel Pierpont Langley (1834-1906) had been at the site in 1881 and deemed it the best location in the country for meteorological and atmospheric observations. SAO Director Charles Greeley Abbot began observations at the site in 1909 and secured the construction of the stone building. Abbot worked with W. W. Campbell, director of the Lick Observatory, in completing the field station.

"Solar Protuberances"

National Museum of American History
Solar power starts with the sun. This color lithograph is one of a set produced by Étienne L. Trouvelot (1827-1895) and published by Charles Scribner's Sons in 1881. “Solar Protuberances” is based on observations of the sun Trouvelot made on 5 May 1873. This particular lithograph was one of several used by traveling science lecturer Charles Came and later by his son-in-law Samuel Corby during public presentations given in the latter nineteenth century.

This Clear Plastic Material Harvests Solar Energy Without You Even Knowing It's There

Smithsonian Magazine

If we stand any chance of reversing or even slowing climate change, we’re going to need all the clean energy we can get. Solar could potentially be a big slice of the power pie. But particularly in large cities, where power consumption is high, there isn’t a lot of open space to set up massive solar farms—for instance, the Ivanpah Solar Electric Generating System takes up 3,500 acres of California’s Mojave Desert.

Energy can be brought in fairly easily from areas outside cities. But solar efficiency has physical limits, so utilizing all available space for energy production is important. And while city rooftops leave some room for solar panels, that space could instead be used to grow local food in temperate climates. 

There are plenty of potentially energy-generating windows in high-rises and skyscrapers, though.

Researchers at Michigan State University have developed clear plastic solar collectors that can be placed on windows without obstructing the view. The same collectors can adhere to the screens of mobile devices as well. According to a recent paper in the journal Advanced Optical Materials, the plastic lets through all visible light. The solar-collecting windows won’t appear tinted or cloudy to the human eye. Instead, the material is embedded with tiny fluorescent organic salt molecules, which have been engineered to absorb only parts of the light spectrum that people can’t see, such as ultraviolet and near-infrared light.

Richard Lunt, an assistant professor at Michigan State and one of the paper’s authors, says the molecules are similar to those found in nature, just slightly tweaked. “We tailor them to suit our needs,” he writes in an email. “That is to harvest particular components on the invisible solar spectrum and glow at another wavelength in the infrared.” That infrared “glow” is then picked up by strips of photovoltaic cells (essentially tiny solar panels) at the edge of the material and turned into electricity. From there, the wired-up windows could shunt the harvested energy to local batteries or back into the electrical grid.

Assistant Professor Richard Lunt and Yimu Zhao, a doctoral student, test the transparent solar material at Michigan State University. (G.L. Kohuth)

The transparent solar collector still needs a fair bit of refining, as its efficiency is relatively low: just 1 percent of the ultraviolet and near-infrared light is converted into electricity. Most commercial solar panels today are between 15 and 20 percent efficient. But Lund thinks the technology should reach 5 percent or higher with further research.

“We are actively exploring routes to improve efficiency by improving the 'glowing' efficiency, expanding the absorption range of the infrared spectrum,” writes Lunt. He also says further tuning the interactions between the light-collecting molecules and transparent material they're embedded in should increase the amount of energy collected.

Lunt says the basic idea of luminescent solar collectors has been around for decades. But, unlike other projects, this work aims to harvest non-visible light. He claims they can be made using standard industrial processing, and they only require a small amount of solar cells at the edge of the material to collect the energy optically. That means they should be fairly inexpensive to produce. The fact that they can be installed on the existing infrastructure of buildings and windows should also reduce the cost versus standalone solar panels.

Lunt thinks it’s likely, though, that the technology will show up in small electronics first, because it already produces enough energy to power things like e-readers and smart windows. The team has founded a company, Ubiquitous Energy, Inc., which is working on commercializing the technology. They expect to see their transparent solar collectors on buildings and mobile electronics within the next five years.

The professor doesn’t think the potential applications stop there, either, noting that the tech can be used on other glass surfaces, such as car windshields.

“You can even think about putting these devices over surfaces where you care about maintaining certain aesthetics or patterns, like siding, textiles or even billboards,” writes Lunt. “They could be all around us without even knowing they are there.”

Observatory at Mt. Montezuma, Chile

Smithsonian Archives - History Div
Solar observation instruments outside the entrance to the instrument tunnel at the Smithsonian Astrophysical Observatory solar station. The solar station operated from 1920 to 1955 at Mt. Montezuma, Chile. A man stands in the entrance holding a cord while another man works on the instruments.

What's Next for Solar Energy? How About Space

Smithsonian Magazine

Think about what you know about clean sources of energy. What’s the greenest?

Hydroelectric, geothermal, wind and solar all probably spring to mind. Environmentally friendly though they may be, they all have significant limits on how much energy they can produce and where they can be used. To wit, despite some really cool advances in solar, solar panels still can only generate energy while the sun shines.

The solution, then, is obvious. Go where the sun never sets: in space.

That’s the vision of scientists, researchers and entrepreneurs both here in the United States as well as in Japan, China and Europe. Though the concept has been batted around at least since the 1970s, it’s been repeatedly revisited and abandoned because getting all the parts up there, and the people to put it all together, was impossibly expensive. Only with the advent of super small, mass-produced satellites and reusable booster rockets are some beginning to take a much harder look at making space solar a reality.

There are dozens upon dozens of ideas for how to build a space-based solar collection system, but the basic gist goes something like this: launch and robotically assemble several hundred or thousand identically sized modules in geosynchronous orbit. One part comprises mirrors to reflect and concentrate sunlight onto solar panels that convert the energy into electricity. Converters turn that electricity into low-intensity microwaves that are beamed to large, circular receivers on the ground. Those antennae re-convert the microwaves back into electricity, which can be fed into the existing grid.

John Mankins, who spent 25 years at NASA and Caltech’s Jet Propulsion Laboratory, received funding from NASA’s Institute of Advanced Concepts in 2011 to refine his space solar power plant concept in greater detail. The technology and engineering required to make space solar a reality already exists, he insists, but as with any expensive new idea, it comes down to greenbacks and gumption.

“It’s not like fusion—there’s no new physics involved,” Mankins says, referencing ITER, the 35-nation collaboration to build a fusion reactor in France. “There’s no secret sauce. It’s a financial hurdle to get funding to develop the elements and demonstrate the new architecture required to do this.”

Mankins and others estimate the total cost for developing, building, launching and assembling all the components of a space-based solar power plant is on the order of $4 to $5 billion—a fraction of the $28 billion price tag on China’s Three Gorges Dam. Mankins estimates a working scale model with full-sized components could be had for $100 million. By comparison, the Tennessee Valley Authority’s recently completed Watts Bar nuclear plant took 43 years to build, from start to stuttering finish, and cost $4.7 billion all told.

Critically, what consumers would pay—the price per kilowatt-hour—needs to be in the same ballpark as conventional sources of energy produced with coal, natural gas and nuclear, which range in price from 3 to 12 cents per kilowatt-hour. Hydroelectric can be staggeringly cheap, at less than one cent per kilowatt-hour—but only if you’re lucky enough to live in a region with abundant high-flow rivers, like in parts of Canada and Wisconsin. Geothermal is very economical too, checking in at 3 cents per kilowatt-hour, but you’ll need to ask the Icelanders how they like their power bills. And wind advocates trumpeted the news last year that costs for that renewable resource had plummeted to 2.5 cents per kilowatt-hour.

Getting the cost into the low double digits or even single digits of cents per kilowatt-hour is absolutely essential to make space solar a competitive utility, says Gary Spirnak, CEO of the California-based energy company Solaren.

Spirnak’s company is approved as a solar energy provider in California, and has had past supply arrangements with Pacific Gas and Electric, but its business model is completely based on generating their power from space-harvested solar. Solaren is in the process of negotiating new agreements with one or more utilities. The company has patents here in the U.S. for its design as well as in Europe, Russia, China, Japan and Canada, and has secured a first round of financing for a lab-based demonstration of its component technologies sometime in the next year. Spirnak hopes to convince investors to support a 250-megawatt pilot plant by the end of the development and testing phase, perhaps within five years.

Two keystone structures are required for space solar to work. First, solid-state power amplifiers that efficiently convert electricity from collected sunlight into radio-frequency waves, and receivers on the ground that re-convert the RF waves back into electricity.

Image by Paul Jaffe. Paul Jaffe holds the Naval Research Laboratory's record-holding, patented space solar "step" conversion module in front of a thermal vacuum test chamber. (original image)

Image by Paul Jaffe. Space Solar Prototype: This sunlight-to-microwave conversion module for space solar was the first to be tested in space-like conditions. Space robotics would be used to assemble thousands to create the transmitter of a space solar satellite. (original image)

Image by Paul Jaffe. NRL's space solar conversion module prototypes were tested in this thermal vacuum and simulated solar illumination test facility. (original image)

Paul Jaffe, an engineer at the Naval Research Laboratory in Washington, D.C., worked on two prototypes of the collection module, which he refers to as a “sandwich” since the solar collector, power converter and RF emitter are all smashed together into a foot-square tile two inches thick. The weight of each individual module ultimately determines the pricing of the distributed electricity on the ground; in terms of watts per launched kilogram, Jaffe says the basic tile design came in at around 6 watts per kilogram.

Taking into account that power output, a 20-year solar power plant lifetime, a launch cost of $2,500 per kilo, and different cost levels of the components themselves, Jaffe calculates that if the mass decreased and wattage increased to 500 watts per kilo, that equates to a cost of 3 cents per kilowatt-hour.

“Doing even really simple things to reduce the mass gets us into the 100 watts per kilogram range, and 1,000 watts per kilogram isn’t crazy,” he says. “You get very good efficiencies with current solar technology that’s already commercially available, and we carry around these very efficient, lightweight RF converters in our pockets every day.”

RF converters are the very reason cell phones work—phones are basically glorified walkie-talkies whose signals are helped along by a network of signal relay stations. The converters in the phone translate radio waves into data that we understand—audio—and vice versa. This technology is central to research into space solar at Caltech, in a collaboration between scientists and engineers there and Northrop Grumman.  

Spirnak says the main thrust of Solaren’s work in recent months has been just that—reducing the weight of their modules. Though reusable rockets would knock the overall production cost down even further, Spirnak isn’t holding his breath in the near term; he’s figuring on using conventional heavy lift vehicles to get Solaren’s components into space.

“We spent a lot of time ruthlessly taking weight out of the system,” Spirnak says. “We can package individual large elements into single launchers, with some interesting feats of origami," though delivering the entire system into space will still require multiple super-heavy launchers.

Jaffe says the single most common question he gets when talking about space solar isn’t whether it can or should be done, but how dangerous that energy beam from space is. Won’t it flash-fry birds and planes in the sky when they pass through the beam?

“If you sit outside on a sunny afternoon for 15 minutes, you don’t get burned,” he explains. “Our radios, TVs and cell phones aren’t cooking us, and those are all at the same frequencies as what’s being proposed. There are already safety limits [on microwave transmissions] set by IEEE [Institute of Electrical and Electronics Engineers], so you design a system to make sure the power is spread over a large area. It won’t accidentally turn into a death ray.”

To get the best cost-to-weight ratios, efficiencies of scale, and have comparable electrical generation capacity of an average nuclear power plant (1 to 2 gigawatts), any solar collection array in space would need to be roughly a kilometer in diameter.

Collection receivers on the ground would need to be accordingly large—for a space-based solar plant to generate around one gigawatt of energy, a one-kilometer (.62 mile) solar collector would beam energy to a 3.5-wide kilometer (2 mile) receiver on the ground. That would require an area of around 900 acres. Compare that with the Solar Star solar panel plant in California, currently the United States’ largest solar utility, which occupies 3,200 acres.

Radio-frequency power transmission does have one significant drawback: the “safe” wavelengths that also won’t get refracted by something as simple as rain are already overcrowded, clogged up through regular radio transmissions, as well as military, industrial and satellite use.

Critics of space solar, prominent among them Tesla’s Elon Musk, say economy-scale efficiencies just can’t be achieved because of all the converting and reconverting of the power that is required.

But Jaffe is hopeful that the old crack on fusion won’t also become true of space solar: “It’s been 10 years away for the last 60 years,” he laughs.

Mankins stresses that with the global population forecast to explode to 11.3 billion by the end of the century, with almost all of that represented in the developing world, space solar deserves serious investment by public entities as well as private partners. He says abundant clean energy is necessary to fulfill basic human needs, as well as address the assured environmental destruction if all of that energy comes from conventional sources.

“If the mix of energy sources does not change radically, there is no way we’ll get to carbon neutral,” Mankins says. “You also can’t tell 800 million people in China that they must stay in abject poverty. There’s a need not just to offset today’s carbon use, but to look forward 70 years and to how we’ll offset three times today’s use. We really need big solutions.”

Why Design Now?: Hope Solar Tower

Cooper Hewitt, Smithsonian Design Museum
Why? Solar towers capture solar energy to heat air under an expansive collector zone. Based on the principle that heat rises, this air flows towards the center of the collector through electricity-generating turbines and up and out of the tower, like a chimney. When built, the tower will be about 750 meters high and could produce enough electricity to power approximately 500 households.

Pendant, Buck Rogers, Solar Scouts, Wilma Deering

National Air and Space Museum
This pendant featuring Wilma Deering, the female lead in the Buck Rogers' comic strips and radio program, was available to fans as a premium sponsored by Cream of Wheat, a hot breakfast cereal. Buck Rogers debuted as a comic strip in 1929. A Sunday strip and a radio program followed. The children's fan group for Buck Rogers was known as the Solar Scouts. This pendant features the message "To my pal in the Solar Scouts" on the reverse.

The existence of a pendant shows that both girls and boys were fans of the early space adventure.

Mail in a cereal box top or a metal strip (like those from tins of Cocomalt, a Buck Rogers radio sponsor) with a little money, and you would receive a token of your special relationship with a space-faring hero. Or you could join a fan club run by a newspaper or radio station. Premiums also included toys, maps, and books.

Collector Michael O'Harro donated this pendant to the Museum in 1993.

Desmodium glabrum (Mill.) DC.

NMNH - Botany Dept.

Solarized Tumbler

NMNH - Anthropology Dept.

Model, Communications Satellite, Intelsat I

National Air and Space Museum
Launched in April 1965, the International Telecommunication Satellite Organization's Intelsat I (also known as "Early Bird") was the first satellite to provide commercial communications services.

Operating in geosynchronous orbit and spin-stabilized, it used a design developed for the earlier Syncom series of satellites, but was augmented with improved electronics and solar collectors. In its first months of operation, the spacecraft primarily performed experimental tests. Beginning in June 1965, though, Intelsat put the satellite into operational use, facilitating voice and video communication between the United States and Europe, It remained in service until August 1969 when it was succeeded by more advanced satellites in the Intelsat series.

The Museum's artifact is a 1/24 scale model of the Intelsat I satellite and was donated by Hughes Aircraft Co. to the Museum in 1975.

The Origami-Like Folds of Ladybug Wings Could Lead to Better Umbrellas

Smithsonian Magazine

Ladybugs are compact little beetles, but their wings are surprisingly large when unfurled from beneath their spotted shells. And as Sarah Knapton at The Telegraph reports, researchers have long puzzled over how ladybugs can fold their wings up so tightly. So scientists in Japan decided to get a better look, replacing the spotted forewing, known as an elytron, with a transparent piece of resin. What they learned could help engineers design foldable solar collectors or even a new type of umbrella.

Kazuya Saito, Assistant Professor at the University of Tokyo’s Institute of Industrial Science, designs foldable structures—so insect wings are a natural interest. "Compared with other beetles, ladybugs are very good at flying and frequently take off," he tells Bryson Masse at Gizmodo. "I thought their wing transformation systems are excellent and have large potential for engineering.” 

He and his team tried several methods to figure out how the ladybug folded its wing. They took high-speed images of the insect opening and closing its wings, but still couldn't see the actual folding process under the opaque spotted forewings. They attempted to 3D print an artificial wing, but they couldn’t make one that was transparent enough to see thorough.

As Masse reports, the researchers' secretary was the one who came up with a solution: clear nail art resin. After crafting the wing out of the resin, the team was able to observe how the insect folded and unfolded its wings.

A ladybug with its see-thru shell (Kazuya Saito )

The creatures use the edge of the elytron and abdominal movements to fold the wing along creased lines. Examination of the wings using a CT scan also revealed that they have springy veins similar to a tape measure that are rigid enough to allow the insects to fly, but elastic enough to fold up.

Saito tells Masse that the wings are unusual because “transformable structures” usually involve moving parts and joints. But the ladybug’s wing lacks those complications, completing a relatively complex task through flexibility and elasticity. The paper appears in The Proceedings of the National Academies of Science.

While the structure of ladybug wings may have applications for things like foldable solar panels for satellites and space ships, Saito seems most excited about its application to something much more domestic. “I believe that beetle wing folding has the potential to change the umbrella design that has been basically unchanged for more than 1000 years,” he tells Knapton. Collapsible umbrellas usually have multiple parts and are easily broken at the joints. But the ladybug umbrella could be made from "seamless flexible frames," he says, making it indestructible in strong wind and quick to deploy using "stored elastic energy.”

Saito admits that he doesn’t have a design for the umbrella yet, but perhaps it will look something like this.

Plesionika trispinus

NMNH - Invertebrate Zoology Dept.

Haliporoides diomedeae

NMNH - Invertebrate Zoology Dept.

Oediplax granulata

NMNH - Invertebrate Zoology Dept.

Odontoplax chacei

NMNH - Invertebrate Zoology Dept.

Pseudupeneus grandisquamis

NMNH - Vertebrate Zoology - Fishes Division
Rec. from: enrique del solar, lima peru. trawl

Scomberomorus sierra

NMNH - Vertebrate Zoology - Fishes Division
Rec. from: enrique del solar, lima, peru. trawl

Scomberomorus sierra

NMNH - Vertebrate Zoology - Fishes Division

Pseudupeneus grandisquamis

NMNH - Vertebrate Zoology - Fishes Division
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