Thirty six years after it was launched from earth, Voyager 1 has become the first spacecraft to leave the solar system, NASA announced on Thursday.
"We got there," said mission chief scientist Ed Stone of the California Institute of Technology, adding that the spacecraft was "setting sail in the cosmic seas between the stars."
Voyager 1 actually made its exit more than a year ago, according to NASA and is now nearly 19 billion kilometers (11.5 billion miles) from Earth. It was not until recently that scientists with the space agency had enough evidence to say that the probe had finally plowed through the hot plasma bubble surrounding the planets and escaped the sun's influence.
But space scientist David McGomas of the Southwest Research Institute in San Antonio, Texas, said he doubted NASA's interpretation.
"It may well have crossed," McGomas said. "But without a magnetic field direction change; I don't know what to make of it."
Lennard Fisk, a space science professor at the University of Michigan said: "Can we wait a little bit longer? Maybe this picture will clear up the farther we go."
First complete photo
Voyager 1, which is about the size of a subcompact car, visited Jupiter and Saturn in 1979 and 1980 and sent back detailed images of their moons.
In 1990, it sent the first complete photo of the solar system.
Its sister craft Voyager 2, which is trailing at 15 billion kilometers from Earth, also sent images of Uranus and Neptune.
Both spacecraft still have signals' contact with Earth.
Eventually, the Voyagers will run out of nuclear fuel and will power down their instruments, perhaps by 2015.
ipj/jm (AP, AFP, dpa)