Carl Sagan (1934-1996) Astronomer, science writer. Sagan’s best known scientific contribution is research on extraterrestrial life, including experimental demonstration of the production of amino acids from basic chemicals by radiation. He argued the now-accepted hypothesis that the high surface temperatures of Venus can be attributed to and calculated using the greenhouse effect. 8 ½” x 11” typed letter signed, Cornell University, May 24, 1978, to William Hartel. “…no one has yet found life on other planets and therefore the subject is necessarily a speculative one.At the same time there are certain areas of the subject, such as the design of instrumentation for detecting life elsewhere or the investrigation of organic matter on the moon or meteorites or interstellar space…a person might be interested in the detection of possible radio signals from civilizations on planets of other stars…Another might be interested in the design of experiments to search for microorganisms by automatic landings on a planet such as Mars….”