First Man-made object to leave solar system
A space probe launched 35 years ago has become the first
man-made object to leave the solar system, scientists said today.
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.
But American space agency NASA has
disputed the claim and called it premature. It denies that the probe is now
outside the solar system. 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, dropping to less than 1% of their previous level.
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 in Las Cruces, 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. And everything we’re
measuring is different and exciting.” Voyager 1 and sister probe Voyager 2 were
launched in 1977 to explore the outer planets. Both are now on an extended trip
to the stars.
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 life forms, a
range of scientific information, spoken greetings, Earthly sounds such as a
baby crying, and music including works by Mozart and gospel blues singer Blind
Willie Johnson.
In 15 years’ time,
Voyager 1’s plutonium power source will run out, cutting off all communication
as the probe coasts on through the vast emptiness of space. Dr Edward Stone,
Voyager project scientist at the California Institute of Technology in
Pasadena, said: “The Voyager team is aware of reports today that Nasa’s Voyager
1 has left the solar system. “It is the consensus of the Voyager science team
that Voyager 1 has not yet left the solar system or reached interstellar
space.”
Source: irishtimes.com