NASA's Voyager 1 has journeyed farther from Earth than any other man-made object, but there's a debate about exactly how far it's traveled and whether it's actually left our solar system.
In June, NASA reported that the 36-year-old Voyager, which launched on Sep. 5, 1977 to study the outer Solar System and interstellar space, had traveled more than 11 billion miles from the sun and was nearing the edge of the solar system and interstellar space.
However, a team of researchers from the University of Maryland yesterday reported that the spacecraft has already left the solar system and entered interstellar space - or the space between star systems in a galaxy. "It's a somewhat controversial view, but we think Voyager has finally left the Solar System, and is truly beginning its travels through the Milky Way," said Marc Swisdak, a research scientist at the University of Maryland.
Voyager 1, according to university researchers, has begun the first exploration of our galaxy beyond the Sun's influence.
The scientists have created a model of the outer edge of our solar system and say the data coming back from Voyager fits what they would expect to see in that model.
NASA officials could not be reached for comment.
However, less than two months ago, NASA said Voyager 1 was believed to be near the edge of the heliosphere, which basically is a bubble around the sun. The spacecraft is so close to the edge of the solar system that it now is sending back more information about charged particles from outside the solar system and less from those inside it, according to the space agency.
"This strange, last region before interstellar space is coming into focus, thanks to Voyager 1, humankind's most distant scout," Ed Stone, Voyager's project scientist at the California Institute of Technology, said in an earlier statement. "If you looked at the cosmic ray and energetic particle data in isolation, you might think Voyager had reached interstellar space, but the team feels Voyager 1 has not yet gotten there because we are still within the domain of the sun's magnetic field."
NASA noted that its scientists don't know exactly how far Voyager 1 needs to travel to enter interstellar space. It could take a few months or even years.
Researchers from the University of Maryland, however, say they believe Voyager left our solar system a little more than a year ago.
The issue revolves around how scientists detect the edge of our solar system. The university noted the conventional view is that that scientists will know it's passed through this mysterious boundary when Voyager stops seeing solar particles and starts seeing galactic particles, along with a change in the prevailing direction of the local magnetic field.
Researchers say that NASA isn't taking into consideration that the border of the heliosphere is very uneven and magnetic field lines become confusing and variable when the magnetic fields of the sun and of interstellar space connect.
Part of Voyager 1's mission is to measure the size of the heliosphere.
Scientists are eager to see what the spacecraft will find in interstellar space, which is believed to be filled with star particles.
Voyager 1 launched with its twin spacecraft, Voyager 2. Both have flown past Jupiter, Saturn, Uranus and Neptune. In 1990, they embarked on a mission to enter the interstellar region. Voyager 2 is currently just 9 billion miles away from the sun, according to NASA.
Scientists are debating whether Voyager 1 has entered interstellar space or is still in our solar system. (Image: NASA)
Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin, on Google+ or subscribe to Sharon's RSS feed. Her email address is firstname.lastname@example.org.
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