A longstanding symbol of summer is the reemergence of fireflies. After months of dreary winter darkness, the prolonged days of summer are a welcome change for many. With these hazy, sunlit evenings comes a phenomenon that people of all ages enjoy: watching fireflies float through the air and dot the sky with twinkling light.
While these gentle winged creatures might appear to be a simple part of nature, their ability to produce light has served as valuable scientific inspiration. Among his many contributions to the field of bioluminescence, National Inventors Hall of Fame® (NIHF) Inductee Emmett Chappelle studied fireflies and used the chemicals they produce to detect signs of cellular life. Chappelle’s discoveries transformed a range of scientific fields including biochemistry, space exploration, medicine and food science, and he is often regarded as one of the most important scientists of the 20th century.
Journey to Becoming a Scientist
Chappelle was born in Phoenix, Arizona, in 1925. At the time, Phoenix was a largely agricultural city, and Chappelle’s family consisted of farmers. He attended a segregated, single-room primary school and then an all-Black public high school, where he graduated at the top of his class in 1942.
Upon graduation, Chappelle was drafted into the U.S. Army and was assigned to the Army Specialized Training Program. During this time, he was able to take a few engineering courses and pursue more advanced training. He also served as part of the 92nd Infantry Division, known as the Buffalo Soldiers — the only Black infantry unit that saw combat in Europe during World War II. Chappelle spent four years in the Army and was wounded twice.
In a letter Chappelle wrote to him in 2014, author of “Black Warriors: The Buffalo Soldiers of World War II” Ivan J. Houston recounted Chapelle saying:
“My work is described on the internet. But so much of who I became — and who I am now — was determined by my years as a Buffalo soldier. Ivan, a great deal of African American experience is unknown, unrecorded and lost. History is, after all, written by the victors. Black Warriors is a contribution of great value to revealing the truth...[it] has brought me more joy than I can say.”
After four years in the Army, Chappelle returned to the U.S. and began his studies. He completed his bachelor’s degree in biology in 1950 at the University of California at Berkeley and taught biochemistry at Meharry Medical College in Nashville until 1953. While teaching, Chappelle conducted his own research in the field, leading him to complete his master’s degree in biochemistry one year later at the University of Washington. In 1958, Chappelle began working at the Research Institute for Advanced Studies in Baltimore, Maryland, followed by Hazelton Laboratories in 1963 and the NASA Goddard Space Flight Center in 1966.
During his time at Hazelton and NASA, Chappelle pioneered a great deal of research in the field of bioluminescence. He discovered that all living cells are capable of bioluminescence (light emission from living organisms) in the presence of the same chemical combination found in fireflies. He developed a process to test for cellular life that involved combining two chemicals produced by fireflies: luciferin and luciferase. When combined, these chemicals will produce light as long as the chemical adenosine triphosphate (ATP) is present. ATP essentially provides chemical energy for cells to function and is therefore found in all living organisms.
Chappelle’s discovery became the building block for many important innovations. He worked alongside fellow biochemist Dr. Grace Picciolo to develop a system for NASA’s Viking lander to discover if life could exist on other planets. Chappelle and Picciolo’s system involved the lander collecting a small amount of planetary soil, grinding it into dust and adding the same bioluminescent chemicals used in his firefly tests. If the soil glowed, a photometer would measure it and the light would be proof that cellular life could exist outside Earth.
His breakthrough had implications beyond just his immediate work, as well. Chappelle used his inventive skills to prove that the number of bacteria in water could be measured by the amount of light emitted from that bacteria, allowing medical tests to detect infections in blood and urine. He also developed a way for satellites to measure luminescence levels to monitor the health of crops and therefore enhance food production. No matter the task, Chappelle found a way to use his skill set to help make improvements in other arenas.
Remembered for Science and Spirit
Chappelle retired from NASA in 2001, after 34 years at Goddard. He had earned 14 U.S. patents and NASA’s Exceptional Scientific Achievement Medal for his work. Throughout his career, he also mentored minority high school and college students in his labs.
In a 1995 edition of U.S. Black Engineer and Information Technology Magazine, Chappelle was described in this way:
“Even with such technical ability, his greatest asset is his personality. His laboratory is always buzzing with students working alongside him. Chappelle wears his prestige like casual clothing, never letting it interfere with how he relates to people. These characteristics may seem unlikely for a great scientist, but for Chappelle’s peers, acquaintances and the students for whom he is a mentor, he simply is the world-renowned Emmett Chappelle.”
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