It's no secret that searching for life beyond Earth, whether it is within our own Solar System or beyond, is very challenging work. For decades, scientists have sent robotic and crewed missions to other celestial bodies to search for signs of past or present life.
In fact, with the Voyager probes, the Cassini-Huygens mission and the New Horizons' spacecraft, all of the major bodies of our Solar System beyond Earth have effectively been explored. That's Mercury, Venus, the Moon, Mars, Ceres and Vesta, and Jupiter, Saturn, Uranus, Neptune, and Pluto (as well as their largest moons).
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And yet, all our best efforts have managed to turn up nothing - or at least, nothing conclusive. Now, why is that? Could it be that intelligent life is rare, hard to find, or not looking to be found? Or could it be humanity is alone in the Universe, staring out into a great black abyss with no one looking back?
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