In 1924, the US turned off its radios to search for life on Mars

Thanks to our orbits, Earth and Mars make relatively short passes every 26 months. Every now and then there is a very close approach. For example, in 2003 we passed at a distance of 55.7 million kilometers (34.6 million miles), the closest the two planets have been to each other in 60,000 years.

In 1924 the two planets came almost as close. During this time, astronomers and the US government took advantage of the situation and attempted to search for life on Mars.

This was not in the form of turning our visual telescopes towards the planet to get a better view of it, but a search for potential radio signals emitted by alien civilizations living on the Red Planet.

The idea may seem strange from a modern perspective. Thanks to better telescopes, visiting space probes, analyzes of the Martian environment and rovers we have allowed to roam the planet, we now know that the planet has no such civilizations. However, in the decades leading up to the narrow approach, scientists were not too clear.

For a time, astronomers suggested that there might be oceans on the planet. Then came the suggestion, supported by maps made by astronomer Giovanni Schiaparelli, that Mars had a series of canals running across the planet. In 1894, the public also became enthusiastic about the idea, after astronomer Percival Lowell suggested that Schiaparelli’s observations showed canals built by an alien civilization.

Lowell eventually used a significant amount of his own money to take photographs of these “canals” in 1907, proving that the features had been created by an alien species.

“After the melting of the southern polar ice cap got underway, channels began to appear,” Lowell said at the time, as reported by the New York Times.

“It is a direct result of this that the planet is currently the abode of intelligent constructive life,” he added. ‘I may say in this connection that the theory of such life on Mars was in no way an a priori hypothesis on my part, but was deduced from the outcome of observation, and that my observations have since fully confirmed it. No other assumption is consistent with all the facts here.”

Others, however, were less convinced, and the photographs he took ultimately helped discredit the idea.

After this, most astronomers were convinced that the channels were an optical illusion, which was confirmed in 1964 when NASA’s Mariner IV probe showed that such features do not exist on the planet. Nevertheless, there were still people who believed that there could be life on the planet and that they could potentially communicate with it via radio.

Although the idea was not widespread and there were indications that the planet was not habitable, when the two planets came close to each other in 1924, humanity began its first real search for extraterrestrial radio signals.

A telegram was sent requesting cooperation in the search for extraterrestrial life.

A telegram sent to all US naval stations.

Image credit: US National Archives

The US government asked the public to maintain radio silence for the first five minutes of each hour for “National Radio Silence Day” as Mars and Earth made close approaches. During this time, astronomers kept an ear (and eyes) on the planet, while the US government requested all Navy outposts to silence their own radios to listen for possible communications from Martians.

It was certainly optimistic, and the outcome was predictable. No radio signals were picked up from Mars because there was no one to transmit them. It now seems likely that analog radio signals are an unlikely way for aliens to communicate, while other signals are more likely. However, it was an interesting and exciting early attempt to find advanced alien species, efforts that have continued to this day and may one day find advanced alien life. That is, if they can be found at all.

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