Army and Navy radio stations around the world had something extra to listen for 100 years ago this week: Mars. The Red Planet was passing closer to Earth than it had in centuries. A retired astronomer thought that Martians might take advantage of the encounter to beam greetings to the neighbors. So he organized an effort to hear the transmissions.

David Todd had led the astronomy program at Amherst College in Massachusetts. Most scientists of the day said there was no chance of a Martian civilization, but Todd disagreed.

Radio pioneers Nicola Tesla and Guglielmo Marconi had reported hearing odd signals from space several years earlier. Some interpreted the signals as broadcasts from Mars. And Percival Lowell had created maps of Martian “canals” – built to bring water from the polar ice caps to a dying civilization. All of that convinced Todd that it was worth listening for Martian broadcasts.

Todd asked radio stations to go silent for five minutes of every hour for several nights. Only one complied – station WRC, in Washington, D.C. But technicians at other stations listened for odd signals. The military instructed its radio operators to listen as well, but only if it didn’t interfere with normal operations. And it made its leading cryptographer available to decode any Martian messages.

Todd also enlisted the help of a television pioneer, and we’ll have more about that tomorrow.

Script by Damond Benningfield