spacetoday.net: Voyager on cusp of entering interstellar space

Posted: Sat, Jun 16, 2012, 8:52 AM ET (1252 GMT)
Voyager illustration (NASA/JPL)

Data returned from NASA's Voyager 1 spacecraft suggest it is on the verge of crossing the heliopause into interstellar space. Project scientists said this week that they have seen in recent weeks a "very rapid escalation" in the number of galactic cosmic rays detected by the spacecraft, something they said they would expect to see once the spacecraft crossed the heliopause, the boundary between the area of space under the influence of the Sun's magnetic field and interstellar space. However, scientists add they have not yet seen a corresponding sharp decline in the intensity of energetic particles generated within the heliosphere, and they are analyzing data on the direction of magnetic field lines in the vicinity of the spacecraft, which will provide conclusive evidence of when the spacecraft passes into interstellar space.