NASA's Voyager 1 spacecraft may be getting its first taste of interstellar waters beyond our sun's familiar shores and, like the pioneers that first took to the oceans to explore seas unknown, the 34-year-old robotic spacecraft is about to make history as the first man-made object to venture beyond the known horizon.
This historic announcement was made on Thursday by the team keeping a careful eye on Voyager 1′s particle detectors who noticed an uptick in interstellar cosmic ray counts in recent years. That can mean only one thing: the mission is beginning to leave the outermost regions of the heliosphere - the farthest extent of the sun's influence.
"The latest data indicate that we are clearly in a new region where things are changing more quickly. It is very exciting. We are approaching the solar system's frontier," said Ed Stone, Voyager project scientist at Caltech in Pasadena, Calif.
"From January 2009 to January 2012, there had been a gradual increase of about 25 percent in the amount of galactic cosmic rays Voyager was encountering," he continued. "More recently, we have seen very rapid escalation in that part of the energy spectrum. Beginning on May 7, the cosmic ray hits have increased five percent in a week and nine percent in a month."
Complementing the detection of the uptick of interstellar cosmic rays, another detector has watched a marked decline in the quantity of energetic particles emanating from within the heliosphere. When the spacecraft completely exits the sun's sphere of influence, this particle count will disappear.
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To emphasize the rapid changes in the high energy environment surrounding Voyager 1, the Voyager 2 Twitter feed on Wednesday reported about the well-being of its sister craft:
Interesting. Compare my data 4 high-energy nucleons
The final measure will ultimately be the detection of a shift in magnetic field orientation. Currently, Voyager 1 is still "feeling" the magnetic influence of the sun, but once the probe flies beyond the boundary - called the heliopause - a radical change in magnetic field orientation is expected.