On Thursday NASA confirmed that after a 36 year voyage the Voyager 1 spacecraft, which is about 12 billion miles from the sun, has left our solar system and in fact has been on its journey travelling between the stars in interstellar space for a little over one year.
Using vibrating plasma oscillations on the spacecraft in April 2013 which were a product of a solar coronal mass ejection 13 months earlier and the interstellar plasma, the Voyager scientific team preliminarily found evidence that the determined the craft is now in interstellar space. The team reviewed previous recorded data as well and found similar though weaker oscillations in October 2012 and November 2012.
Extrapolating from these findings, the scientists estimate that Voyager 1 had crossed the boundary between the Solar System and interstellar space sometime around August 2012.
The Voyager 1 plasma sensor, which normally would have been used to more directly detect the plasma, or ionized gas, is inoperative.
University of Iowa physics professor Don Gurnett, a member of the plasma wave science team remarked, “We literally jumped out of our seats when we saw these oscillations in our data; they showed us the spacecraft was in an entirely new region, comparable to what was expected in interstellar space, and totally different than in the solar bubble."
He added, “Clearly we had passed through the heliopause, which is the long-hypothesized boundary between the solar plasma and the interstellar plasma.”
A full report was published Thursday in the journal Science.
Launched in September, 1977, Voyager 1 had two highly successful planetary flyby missions to Jupiter in 1979 and to Saturn in 1980.
Its sister craft, Voyager 2, was launched in the month prior to Voyager 1 and successfully flew by not only Jupiter in 1979 and Saturn in 1981, but also flew by Uranus in 1986 and Neptune 1989, the only craft to visit these two distant worlds. Voyager 2 is presently 9.5 billion miles from the Sun.
New Horizons, a spacecraft launched by NASA in 2006 is scheduled to fly by the dwarf planet Pluto and its moons in July 2015.