Is it humankind's greatest achievement 12 billion miles away a tiny spaceship is leaving our Solar System and entering the void of deep space       It is the first human-made object ever to do so       Slowly dying within its heart is a plutonium generator that will beat for perhaps another decade before the lights on Voyager finally go out       But this little craft will travel on for millions of years, carrying a Golden Record bearing recordings and images of life on Earth       In all likelihood Voyager will outlive humanity and all our creations       It could be the only thing to mark our existence       Perhaps some day an alien will find it and wonder       The story of Voyager is an epic of human achievement, personal drama and almost miraculous success       Launched 16 days apart in Autumn 1977, the twin Voyager space probes have defied all the odds, survived countless near misses and almost 40 years later continue to beam revolutionary information across unimaginable distances       With less computing power than a