Voyager space probe ‘has left solar system’

By JOHN VON RADOWITZ
Published on 22/03/2013 00:00

A SPACE probe launched 35 years ago has become the first man-made object to leave the solar system, scientists said yesterday.

Voyager 1 is on a lonely journey away from the sun and its planets, but still communicating with Earth. According to a new report, the probe has travelled beyond the heliosphere, the region of space dominated by the sun. At a distance of more than 11 billion miles from the sun, it was said to have left the solar system and entered a twilight zone on the frontier of inter-stellar space.

But American space agency Nasa has disputed the claim and called it premature.

A paper for the journal Geophysical Research Letters points to evidence in the form of a dramatic change in the radiation surrounding the craft.

“Anomalous” cosmic rays trapped in the outer heliosphere have all but vanished. At the same time, the intensity of galactic cosmic rays originating from outside the solar system appears to have doubled.

Lead author US astronomer Professor Bill Webber, from New Mexico State University, said: “Within just a few days, the heliospheric intensity of trapped radiation decreased, and the cosmic ray intensity went up, as you would expect if it exited the heliosphere. It’s outside the normal heliosphere, I would say that. We’re in a new region.”

Voyager 1 and sister probe Voyager 2 were launched in 1977 to explore the outer planets.

Each craft carries a gold-plated audio-visual disc for the benefit of any intelligent aliens that might pick them up.

The discs carry photos of the Earth and its lifeforms, a range of scientific information, spoken greetings, Earthly sounds such as a baby crying, and music including works by Mozart and blues singer Blind Willie Johnson.

In 15 years, Voyager 1’s plutonium power source will run out, cutting off all communication as the probe coasts through space.