As a college senior in 1966, Forrest Mims III was inspired by the memory of his blind great grandfather to invent a compact infrared device to help the blind get around. This ignited his passion for electronics, and Mims began designing many other devices. He also wrote prolifically on electronics, producing articles for specialist magazines.
An expert in opto-electronics, the genial Texan is also an engineer, inventor, amateur scientist, science teacher, science writer and editor. He has written more than 50 popular, do-it-yourself electronics books for fellow enthusiasts. His achievements are all the more remarkable for the fact that he is largely self-taught.
Focus on Ozone
Mims is intensely curious about nature and its workings, and has his mind’s antenna attuned to the unusual. In 1987, atmosphere researchers made the alarming discovery that ozone concentrations in the stratosphere over Antarctica were declining precipitously in the southern spring. Knowing that stratospheric ozone protects life on the earth’s surface against damaging, high-energy ultraviolet (UV) radiation, Mims was immediately concerned.
Despite the threats of rising UV radiation — rising skin cancer rates and crop damage in temperate latitudes — the U.S. government decided in 1988 to close down its UV-monitoring network. Mims decided to fill the data vacuum by designing his first Total Ozone Portable Spectrometer (TOPS) to monitor ozone, and instruments to measure haze and water vapour. He built his first prototype in the workshop of his century-old farmhouse at Geronimo Creek, near Seguin, in Texas, in 1989.
The TOPS device exploits the fact that ozone and water vapour absorb specific wavelengths of ultraviolet radiation as sunlight travels down through the atmosphere. The amounts absorbed, as measured by UV filters tuned to these wavelengths, reveal how much ozone and water vapour are present in the full vertical depth of the atmosphere.
In 1990, Mims had calibrated two of his TOPS devices to agree with measurements from a multimillion-dollar Total Ozone Mapping Spectrometer (TOMS) aboard a polar-orbiting NASA Nimbus 7 satellite as it flew over Texas. But then the satellite data began to diverge from his TOPS measurements.
Calibrations and Errors
In 1992, Mims checked the TOPS devices against the gold-standard, US$100,000 Dobson spectrometer at Hawaii’s Mauna Loa Observatory — and its readings also differed from the satellite’s. Clearly, the problem lay with the satellite’s TOMS instrument.
Confronted by the possibility that their vital observations of the ozone "hole" over Antarctica were in error, sceptical NASA researchers checked — and found the satellite had drifted in its orbit, so that the satellite could no longer see sunlight scattered from a special calibration panel, and was giving incorrect measurements.
Mims suddenly had the attention, and respect, of professional ozone researchers.
His reputation grew further in 1993 when he won a Rolex Award for his proposal to establish an international ozone-monitoring network called SPAN (Sun Photometer Atmospheric Network), equipping a small number of volunteer observers with his invention so they could gather atmospheric data anywhere in the world, on land or at sea, especially in data-sparse regions.
With the publicity surrounding his Rolex Award, he was soon overwhelmed by requests from hundreds of volunteers in 34 countries who wanted to become SPAN observers.
Before Mims invented his compact TOPS device, atmospheric scientists measured ozone with Dobson or Brewer spectrometers — large, bulky instruments that gaze up through the atmosphere from fixed locations. In 1994, using the funds from his Rolex Award, Mims and friend Scott Hagerup developed an even smaller, hand-held ozonometer, dubbed MicroTOPS. Later, they licensed the Solar Light Company in Philadelphia, Pennsylvania, to make a more advanced version, MicroTOPS II. The basic model sells for between US$6,000 and $9,000.
Battery-powered, and fully automated, MicroTOPS II has three channels tuned to detect UV absorption by ozone, plus two optional channels for measuring water vapour and atmospheric haze. The further away from the Equator, the lower the Sun’s angle in the sky, and the further its rays must travel through the atmosphere, reducing the intensity of its radiation at ground level. When linked to a Global Positioning System receiver, MicroTOPS II compensates for the combined effects of latitude and time of day on UV radiation levels.
The discovery of the Antarctic ozone hole in the mid-1980s had confirmed the worst fears of atmospheric chemists who had predicted from laboratory experiments in 1974 that long-lived chlorofluorocarbon gases (CFCs) and their chemical cousins, halons, might persist long enough to diffuse into the stratosphere. At very high altitude, intense UV radiation destroys the molecules, releasing ozone-destroying chlorine and bromine atoms. CFCs were widely used as refrigerant gases, spray-can propellants and solvents in the electronics industry, while bromine-based halons, which are even more potent ozone-eaters, are used to extinguish electrical fires.
In 1977, under the Clean Air Act in the United States, CFCs were withdrawn as spray-can propellants. A decade later, atmosphere experts from industrialised nations met in Montreal, Canada, and banned the production of CFCs as refrigerants and solvents.
The Montreal Protocol has slowed ozone loss, and the Antarctic ozone hole appears to be slowly recovering.
But Forrest Mims now believes other factors have abetted the erosion of the ozone layer. "My opinion is that methyl chloride and methyl bromide gases released by natural forest fires, and large-scale burning by humans, contribute to ozone loss," he says. "Water vapour is also increasing significantly because the earth is warming. The lower atmosphere is expanding, adding more water vapour that leaks into the stratosphere and destroys ozone.
"The scientific community tends to take a relatively narrow approach to these questions, when ozone loss is a very complex issue."
Taking a Stand
Mims is an iconoclast, and it’s not just his ideas about ozone depletion that run counter to the scientific mainstream. A devout Christian, he accepts the biblical account of creation, and rejects Darwin’s theory of evolution by natural selection. His faith has caused him some problems during his career, but Mims prefers to be judged only on the quality of his science, not his personal beliefs.
When he was controversially sacked — because of his beliefs — from a prized job as a freelance columnist with one of the world’s leading popular science magazines, his keen disappointment was salved when many non-Christian colleagues sprang to his defence. "I cherished their friendship. It was an amazing experience," he explains.
Mims has worked on several NASA projects since the mid-1990s. One of his collaborators, Dr Jay R. Herman, of NASA’s Goddard Space Flight Center, says: "His desire to enable anyone with just a basic capability in science to make a significant contribution to understanding the world and the scientific method remains impressive. I admire Forrest as a colleague, and teacher, and as a researcher with integrity."
In 1996, at NASA’s request, Mims flew to a forest fire in the state of Wyoming to conduct a ground-level check on the accuracy of a new ozone-monitoring satellite, the first capable of measuring smoke at ground level. In 1997, NASA sent him to Brazil to measure the effects on UV levels of smoke from rainforest-clearing operations.
He set up special trays to trap airborne bacteria, and found that the ratio of pigmented to non-pigmented bacteria was strongly correlated with smoke density. Bacteria living on plants protect themselves against UV damage with an orange pigment; non-pigmented bacteria that infect animals, including humans, are killed by UV, so more survive on smoky days.
Mims also found a strong correlation between smoke haze and an influenza outbreak in Brazil. It followed a smoky episode by five days, the average time it takes the virus to incubate and produce the first symptoms of infection.
A Younger Mim's Discovery
The trays also trapped large numbers of fungus spores, but Mims paid them little attention — until his daughter, 16-year-old Sarah, repeated the experiment for a school project in 2002 and found many unusual moulds growing in her trays. Huge fires on Mexico’s Yucatan Peninsula had sent smoke — and fungus spores — billowing across the Gulf of Mexico into southern Texas.
Mims tells the story against himself, with obvious paternal pride. His clever daughter made an original discovery that he had overlooked. "Sarah’s discovery is profoundly important," he says. "Everyone simply assumed forest fires kill fungal spores, yet there’s nothing in the scientific literature to support this notion.
"Fungal spores are very tough, and resistant to UV and temperature extremes. While fires destroy many of the symbiotic fungi that live on plant roots, Sarah’s findings show spores are lofted into the atmosphere, and probably descend later and recolonise regenerating plant communities."
Mims believes wind-borne spores of pathogenic fungi, lofted into the atmosphere by distant fires, may explain mysterious, sudden outbreaks of virulent diseases in crops and forests, such as a recent outbreak of deadly oak wilt in Texas.
Tracking Fires and Fungi
In 1986, he discovered a spectacular star-shaped fungus called the Devil’s Cigar (Chorioactis geaster) on rotting cedar-elm stumps near Geronimo Creek. Known from only a few other locations between Austin and Fort Worth, the fungus is native to the Japanese island of Kyushu. Mims is convinced that an ancient forest fire or windstorm on Kyushu lofted its spores into a jet stream that carried them across the Pacific and deposited them in Texas.
In 1998, fires on the Yucatan Peninsula sent smoke as far as Canada, and caused severe air pollution and high ozone readings across eastern Texas. In the lower atmosphere, ozone becomes a pollutant. As a component of photochemical smog, it causes respiratory problems and headaches, and irritates the eyes, as well as damaging plants and attacking rubber and painted surfaces.
Mims believes spores from non-local species of fungi could identify the origins of smoky, ozone-polluted air from distant fires. Because polluted air masses can travel long distances, improving city air quality will depend as much on improving regional air quality as on cleaning up pollution originating locally, says Mims.
Mims has also been studying the recent climatic record, preserved in annual growth rings in the wood of local stands of bald cypresses, Taxodium distichum. Marked changes in temperature or UV radiation levels can affect the colour or width of tree rings. Mims has found dark rings corresponding to volcanic eruptions by Mexico’s El Chichon — in 1982 — and the Philippines’ Mt Pinatubo — in 1991 — and wide rings corresponding to heavy rain and flooding in recent El Niño years.
While studying the rings, the keen-eyed Texan noted that the cross-sectional structure of the wood from some trees differed from others. He had suspected for some time that two distinct forms of bald cypress grew in his local region. One is lower, wider and more resistant to knockdown during flooding than the more common type, and its cones are also different. Mims believes he may have identified a new sub-species of T. distichum. The citizen scientist revels in his freedom to follow his curiosity wherever it might lead, even into fresh fields.
Published in 2003