October 25, 1925 Emmett W. Chappelle, scientist and researcher, was born in Phoenix, Arizona. Chappelle earned his Bachelor of Science Degree in biochemistry from the University of California in 1950 and his Master of Science degree from the University of Washington in 1954. From 1950 to 1953, he served as a biochemistry instructor at Meharry Medical College and from 1955 to 1959 he was a research associate at Stanford University. In 1958, Chappelle joined the Research Institute for Advanced Studies where he discovered that one-celled plants could convert carbon dioxide to oxygen. This discovery helped to create a safe food supply for astronauts. In 1966, he joined the National Aeronautics and Space Administration where he worked until his retirement in 2001. During that time he discovered a method for instantly detecting bacteria in water which led to improved diagnosis of urinary tract infections and he proved that the number of bacteria in semen could be measured by the amount of light given off by that bacteria. Chappelle has been honored as one of the 100 most distinguished African American scientist of the 20th century and was inducted into the National Inventors Hall of Fame in 2007 for his discovery of the Lyophilized Reaction Mixtures (patent number 3,423,290). He discovered that a specific combination of chemicals caused all living organisms to emit light. He has received 13 additional patents. Throughout his career, Chappelle has mentored talented high school and college students in his laboratories.