VOYAGE OF DISCOVERY

Space probes Voyager 1 and 2 which were launched in 1977 to study the four giant outer planets during a five-year-long mission were not only spectacularly successful in their undertaking but are still functioning perfectly well in what is their 30th continuous year in space. Between them they've studied Jupiter's Great Red Spot and its many moons, returned photographs and information about Saturn's rings and provided the first close-up look at Uranus and Neptune. Subsequently, both probes managed to cross the orbit of the outermost planet Pluto and Voyager 1 has now reached the final frontier of our solar system after having traversed through a region known as termination shock, some 14 billion kilometres from the sun. Outside it lies the vastness of interstellar space. Once the spacecraft crosses this boundary, it will truly have gone where no spacecraft has gone before and its faint signals travelling even at the speed of light will take more than 11 hours to reach earth. Scientists say both Voyagers are capable of returning scientific data from a full range of instruments, with adequate electrical power and attitude control propellant to keep operating until 2020.

After that, of course, Voyager 1, followed by Voyager 2 a little later, will become more of drifter cruising through the emptiness of the space between the stars which is much vaster in scale than that found between the planets of our solar system. For instance, according to some calculations it could be 40,ooo years before either of them comes anywhere near another star's planetary system again. Their drifting, however, will not be altogether purposeless, for wherever they go, each of the Voyagers carries a golden phonograph record bearing messages from earth which include natural sounds of surf, wind, thunder and animals. There are also musical selections, spoken greetings in 55 languages, along with instructions and equipment on how to play the record. Interestingly, the probes also carry a kind of galactic route map describing their point of origin in the Milky Way galaxy. If these ever fall into intelligent alien hands and are deciphered by sentient entities it would mean they would know where to find us. Is that a good thing? Depends entirely on ET's intentions.