There’s a star system near our sun; it’s distance from us is only 4 light years and change. This Alpha Centauri system (AC) has long fascinated science fiction visionaries, since its close distance makes interstellar travel a little easier to imagine.
But consider this: while we are not even close to being able to send a probe to AC at even a fraction of the speed of light, we can, today, send radio messages to this nearby system, with a chance of it being detected within a human lifetime.
Let’s review what kind of system that might be over there. The AC system consists of two stars, both are approximate analogs to our sun. Assuming that it’s possible for planets to have formed around these stars (this would require both stars to have formed at a greater distance apart, then moved closer together), there would then be two habitable zones.
Imagine a habitable planet around each star, or better yet, TWO habitable (and inhabited) planets around Alpha Centauri A, with another around Alpha Centauri B.
Suppose our Venus was not only habitable, but also possibly inhabited. Wouldn’t our space exploration experiences be a little different today? Would our civilization be different? And our attitude toward space exploration?
Inhabitants of one of the planets around Alpha Centauri A would, after exploring and perhaps colonizing, and certainly learning from their Venus, would be prepared to explore Alpha Centauri B’s planet, and possibly then Proxima Centauri.
What I am saying is, that it’s very possible that our nearest star system could be an ideal place to search. The civilization there would not have to be much more advanced than our own, but due to their environment and experiences, they could have a rich set of data for us.
Unfortunately, AC cannot be seen by those of us north of the equator, at about -60 degrees of declination. And more to the point, many scientists are wary about deliberately sending out a message into space, imagining that ET would look like Darth Vader and seek our solar system for reasons that would not benefit humanity.
Keep in mind, however, that faster-than-light travel may be completely impossible, that even a practical sub-light trip to AC would take more resources than any responsible civilization would commit (involving cannibalization of their home star). Further, we may safely presume that any interstellar civilization capable of coming to our star system and wreaking havoc, probably knows about us already.
That said, there is a new radio-telesope array being prepared, south of the equator, that will be capable of detecting radio signals from the AC system. This is the Square-Kilometre Array or SKA (http://www.skatelescope.org/).
The SKA will be capable of detecting extremely weak extraterrestrial signals if existing, and may even detect planets capable of supporting life. Astrobiologists will use the SKA to search for amino acids by identifying spectral lines at specific frequencies. SKA will be able to detect an airport radar within 50 light years.
One of the candidate radiotelescopes in this array is located in Murchison, Australia, close to where the legendary Murchison meteorite was found. Perhaps that is a harbinger for this project’s future success.