We hams pride ourselves on our ability to make contacts, across town, across the country, across the ocean. However, if intercontinental contacts get to be old hat, what about…interplanetary ones? if one wanted to get a message to another world, how would one do it?
An author at Gizmodo asked that question and came up with some possible ways to go about it:
A golden plaque or record has a kind of aesthetic appeal to it, and letting there be light can make one feel nice and biblical, but the best way to transmit messages is using radio waves. Visible light is energetic, but it has a very short wavelength. That short wavelength can get scrambled as it goes out through space. Though the universe is most famous for being a horrible, soul-shattering void, it’s also pretty dusty. Dust in space, or on the planet you’re trying to reach, scatters short wavelengths. Longer wavelengths move through dust clouds without getting splattered all over the place and made unnoticeable.
If you want to try transmitting messages at higher ends of the spectrum, try broadcasting at the frequency 1420 megahertz. This is the frequency at which hydrogen vibrates. Not every society is going to have a base ten number system. Not every civilization is going to use certain frequencies for cell phones, and not every song will sound the same through a different atmosphere. But it’s unlikely that whatever corner of the universe the signal ends up in will have a more basic atom than hydrogen. This is the way to get a civilization to notice you.
Unfortunately, 1420 MHz is not in the amateur bands, at least not in IARU Region 2. The closest you can get is the upper end of the 23 cm band (1240-1300 MHz).
Of course, hams can contact each other via moonbounce, and the article does mention one of the earliest attempts at EME transmission, Project Diana (3 kW at 111.5 MHz with a 24 dB gain antenna). It’s an interesting read nonetheless.
One thing I found interesting is that we may be transmitting less radio waves out into space:
Some astronomers have speculated that, as we move from radio waves to fiber optics and internet connections, we might be currently ‘going quiet’ to alien astronomers. What’s more, the radio waves we do send out are less powerful, because receivers are more accurate. As a planet, we’re shutting up. But at least this means you’ll have little competition.
So could a legal limit signal beamed up to the sky reach a faraway planet? Hey, who knows?