OK tweeps, a SETI question for you this morning:

Does anyone have primary sources for that time when we had everyone turn off their radios so we could try to hear aliens?

The full story apparently involves Martians, a dirigible, and a cryptographer.

Intrigued? Yea, me too...

This happened in August of 1924, when Mars was making its closest approach in more than a century.

In the early 1900s astronomers already saw radio as a potential way of picking up signals from extraterrestrial intelligence, so ahead of Mars's close pass they hatched a plan...

The project was led by astronomer and previous-steampunk-incarnation-of-Ed-Harris David Peck Todd:

They advertised a "National Radio Silence Day" for a 36-hour stretch on Aug 21-23.

All civilians were asked to be radio silent for five minutes, every hour, ON the hour while naval stations across the country listened for any "electrical phenomenon of unusual character".

SUPPOSEDLY as part of this endeavor some US Naval Observatory guys build a radio receiver to listen for Martian dance music AND THEN SENT IT ALOFT ON A DIRIGIBLE.

They also had a cryptographer on hand for all of this, ready to translate any alien messages that came in.

So:

1) I would absolutely love to find some primary source references for this beyond the couple random links provided by Wikipedia (I mean, my kingdom for a photo of the blimp-telescope, but any citations at all that describe the experiment would be fantastic...)

2) This predates by nearly a decade what we often think of as the "invention" of radio astronomy - when Karl Jansky built an antenna at Bell Labs and wound up picking up radio emission from the center of the Milky Way in 1933.

3) It'd also be one of the earliest instances of airborne astronomy, which didn't really take off (pun absolutely intended) until the 1960s (with THIS business, a LearJet that flew to 50,000 feet with a twelve-inch telescope and a oxygenated astronomer riding in back...)

But in spite of all that everyone was so metal in 1924 that the "EVERYONE BE QUIET FOR A SEC, Mars is swinging by and we've got an airship and a cryptographer and a telescope from the future ready just in case they call" experiment is apparently how we kicked off SETI efforts.

So yes, astronomer tweeps who know this story, please share any references!

For everyone else, I've got a book of wacky astronomy stories out now if you want more ( http://thelaststargazers.com ) and this particular tale will hopefully be making an appearance in a future project