In 1924, Earth saw its closest Mars opposition in over a century, and some thought our Martian neighbors might use the event to attempt contact. So for one night, US Naval and Army stations scanned the skies for extraterrestrial transmissions.
On August 22, 1924, the Earth was 55,777,566 km from the Red Planet during the Mars opposition, offering ideal conditions for receiving radio signals from Mars — if anyone happened to be sending them. Amherst College professor David Todd persuaded both the US Army and Navy to listen for messages from Mars. In the telegram above, Edward W. Eberle, the Chief of US Naval Operations, informs Naval stations of the possibility of Martian communications, and instructs them to report any unusual phenomena. For three days, the stations listened for unusual transmissions, but came up empty handed.