It was launched in 1977, the year rock icon Elvis Presley died of a heart attack. Now, scientists are wondering if space probe Voyager 1 has broken the ultimate record of space endurance. They say the latest data from its enfeebled instruments suggests the probe has gone beyond the edge of the solar system into interstellar space.
In 1979, Voyager 1 witnessed at close quarters the violent 'red spot' of Jupiter, a permanent storm on the planet's equator, and sent stunning photographs of its four biggest moons. A year later it flew by Titan, the largest of the 31 known moons of Saturn, and in 1991 its camera took a historic photograph of nearly all of the solar system's nine planets. In February 1998, it overtook the Pioneer 10 probe, launched in 1972, to become the most distant human-made object in space. And now, in a study published in the latest issue of Nature, Stamatios Krimigis of Johns Hopkins University in Laurel, Maryland, usa, and his colleagues argue that Voyager 1, more than 8 billion miles from Earth, is going where no probe has gone before.
The edge of the solar system is the point at which a high-velocity solar wind, essentially a stream of charged particles from the Sun travelling at speeds up to 270.5 kilometres per hour, is replaced by the interstellar winds of deep space. Scientists call this boundary the "termination shock" because there occurs a sudden drop in solar wind velocity, from supersonic to subsonic speeds.