Over the years we've sent a lot of stuff into space. Most of that has been spacecraft sent out to explore the solar system -- the moon and sun, planets and asteroids. With Voyager poised on the edge of the sun's influence, we'll eventually be able to add a tiny pocket of interstellar space to that list.

But those are all lumps of metal (love you really, Voyager). Sending out a message is something we've been a little more hesitant about.

For one, we're pretty sure there's nobody close-by to listen. The vast distances any message would have to travel makes the whole effort seem rather fanciful. The point of sending a probe to Saturn is obvious. Justifying sending a message to someone (something?) we can't even confirm the existence of is a bit trickier.

But, whether we like it or not, we've kind of already been doing it. Thanks to television broadcasts, mobile phone conversations, satellite transmissions and military, civil, and astronomical radars we've been making a lot of electromagnetic noise for the past 100 years or so.

Extraterrestrial civilisations with sufficiently sensitive telescopes could, potentially, pick up this radiation leaking out from Earth over interstellar distances.

And, we have been sending out some messages deliberately. We've made a few attempts at METI (messaging to extraterrestrial intelligence, the active counterpart to SETI, the search for extraterrestrial intelligence) including the three minute Arecibo message sent in 1974 at a ceremony to mark the remodeling of the Arecibo radio telescope.

Not everyone is comfortable with humans deliberately sending these kinds of messages out into the cosmos. Broadcasting our existence is not necessarily a good idea if we don't know who we're broadcasting to. Some people have gone so far as to suggest there should be a moratorium on all METI until an international agreement is reached.

Those people are really not going to be happy about a project that's launching tomorrow.

Sending out radio signals to communicate with extraterrestrial civilisations is exactly what Lone Signal plans to do.

As reported in Universe Today:

"Lone Signal will be using the recommissioned radio dish at the Jamesburg Earth Station in Carmel, California, one of the dishes used to carry the Apollo Moon landings live to the world.

Lone Signal will be sending two signals: one is a continuous wave (CW) signal, a hailing message that sends a slow binary broadcast to provide basic information about Earth and our Solar System using an encoding system created by astrophysicist and planetary scientist Michael W. Busch. The binary code is based on mathematical “first principles” which reflect established laws that, theoretically, are relatively constant throughout the universe; things like gravity and the structure of the hydrogen atom, etc."

And the second signal? As of tomorrow, Lone Signal will be accepting tweet-sized messages from the people of Earth to send out to the stars. (You can pay to send additional messages, including images -- full details at Universe Today.)

The messages will be headed for Gliese 526, a red dwarf star 17.6 light years away. We don't yet know whether the star has any planets. But judging by the number of alien worlds the planet-hunting Kepler telescope has found around other stars in our galaxy, it's a fair bet that it'll have at least one. Odds of there being someone to listen go down when you start to factor in habitability and the communication window based on the lifetime of a sufficiently advanced civilisation.

If the signal does reach another civilisation, and they decide to reply, it's hardly going to be a snappy conversation. As Dr Jacob Haqq-Misra, a member of the Lone Signal team, admits in a recent paper (available on the arXiv, and critiqued in a recent io9 article):

"...the vast distances between stars renders any conversation a multigenerational project."

So we're unlikely to have any back and forth on this. Better make your message good.

But perhaps it doesn't matter. Maybe the messages are just a token, meant more for the people sending them than any future, as yet hypothetical receivers.

In the same paper, Haqq-Misra suggests this was the case with previous METI projects:

"[Past] efforts can be considered as symbolic or demonstrations of human technology rather than serious efforts to converse with extraterrestrial civilisations."

The Arecibo message, for instance, has no hope of ever reaching the star system it was supposedly aimed at, 25,000 light years away, because the system will have moved in the intervening time.

So is this project any different? For one, it will be a continuous broadcast -- a lot longer than Arecibo's three minutes. And the Lone Signal team say they have taken into account the movement of Gliese 526 in the time between us sending the message and the star receiving it. This signal, at least, should reach its destination.

But, on the other hand, Lone Signal seem to accept that messages in comments made at a press event on June 11, Lone Signal co-founder Pierre Fabre said:

“Our scientific goals are to discover sentient beings outside of our solar system. But an important part of this project is to get people to look beyond themselves and their differences by thinking about what they would say to a different civilization. Lone Signal will allow people to do that.”

And maybe that's enough. In deciding what to shout into the void, we will have to think about how we would want other civilisations to see us. In the process, we might just learn a little about ourselves too.

Besides, if these messages don't really have a chance of reaching another sentient being, that might not be such a bad thing.

Image: LoneSignal.com screenshot, 17 June 2013