Washington D.C.: Mars Opposition Radio Detection Attempt

Background On August 22-23, 1924, Mars reached opposition closer to Earth than any time in the preceding century. This astronomical alignment prompted an unprecedented attempt to detect extraterrestrial communications.

Operation Details Retired astronomer David Peck Todd led the initiative with support from Admiral Edward Walter Eberle, Chief of Naval Operations. A specially equipped dirigible was lifted 1.9 miles above the U.S. Naval Observatory in Washington, D.C., carrying an SE-950 radio receiver tuned to wavelengths between 8-9 kilometers. The device employed a "radio photo message continuous transmission machine" developed by Charles Francis Jenkins of Amherst College, recording signals on chemically treated film.

Signal Reception A coordinated "National Radio Silence Day" was implemented across the United States during August 21-23, with all radios silent for five minutes each hour. William F. Friedman, U.S. Army chief cryptographer, was assigned to analyze any received messages. The equipment recorded one signal displaying "fairly regular arrangement of dots and dashes" on one side and "curiously jumped groups" resembling crudely drawn human faces on the other.

Scientific Interpretation Todd stated: "It may not be a message from Mars, but if it isn't from Mars, where is it from?" However, Frederick E. Fowle of the Smithsonian attributed the patterns to "disturbances introduced by solar or terrestrial causes." Other scientists proposed alternative explanations including static from passing trolley cars, equipment malfunction, or natural radio waves from Jupiter.