There is no doubt now - evidence presented a year ago that the Voyager 2 spacecraft had joined its twin in interstellar space, has been confirmed as the first data from the probe as it crossed the barrier is released to the wider astronomical community.
Scientists expected that the edge of the heliosphere, called the heliopause, can move as the Sun's activity changes, sort of like a lung expanding and contracting with breath. In December past year, NASA announced the spacecraft had left the solar system, saying data returned suggested there had been a major change in the environment, with a marked increase in galactic cosmic rays and decrease in heliospheric particles from the Sun. But a plasma-measuring instrument on Voyager 1 had been damaged, so that probe could not gather crucial data about the transition from our solar system into interstellar space.
Though NASA continues to monitor, communicate with, and collect data from both Voyager probes, the conversion of this data into useful scientific insights is largely on the back of scientists based at different institutions throughout the US.
The two Voyager spacecraft have now confirmed that the plasma in local interstellar space is significantly denser than the plasma inside the heliosphere, as scientists expected. Voyager 1 taught scientists that the heliosphere protects the planets in this solar system from more than 70 percent of the radiation from the space in between the stars. The fact that both spacecraft left the solar system at pretty much the same distance, at two very different locations, is a source of confusion at the moment.
"We were outside", said Dr Stone, "but we were seeing particles from the inside". "Here we find a very hot plasma mass coming outward from the sun that encounters the cold plasma in the interstellar medium". An accompanying standpoint implies that Voyager 2 is going to be the last spacecraft to cross this boundary for at least 25 many years. These influences are limited by the influence of our galaxy, which has its own magnetic field and an interstellar medium full of its own charged particles.
Before the Voyager missions, scientists predicted the solar bubble just sort of dissolved into interstellar space as you ventured farther and farther from the sun. Measurements also confirmed that the density of the plasma is higher outside, compared to inside, the heliosphere. They had different trajectories through space. "It's just astonishing how fluids, including plasmas, form boundaries", Gurnett said.
"Voyager 2's entry into the ISM occurred at 119.7 Astronomical Units (AU), a little more 0.002 light years from the Sun".More news: Melbourne Cup: Vow and Declare wins Australia's most prestigious horse race
More news: Missing New Hampshire couple found buried on beach likely murdered, police say
More news: ISIS chief Baghdadi's sister captured by Turkey in Syria
Currently, Voyager 1 is located more than 22 billion kilometers (13.6 billion miles) from the Sun, and Voyager 2 is 18.2 billion kilometers (11.3 billion miles) from it.
"In a historical sense, the old idea that the solar wind will just be gradually whittled away as you go further into interstellar space is simply not true", says Don Gurnett. "The two Voyagers will outlast Earth", said Kurth. Explorer 2 propelled two weeks in front of Voyager 1 on an exceptional course to investigate Uranus and Neptune. The data also suggests the heliosphere has varied thickness, with Voyager 1 sailing 10 AU farther than its "sibling", despite initial thoughts that Voyager 2 would break through the ISM first.
But that won't necessarily mean we wouldn't like to know more. They send out small puffs that keep the spacecraft oriented, meaning their antennae are still directed at Earth.
During that transition, Voyager 1 saw a gradual increase of high-energy cosmic rays, but these were punctuated by two spikes where high-energy cosmic rays suddenly rose.
"There appears to be a region just outside the heliopause where we're still connected - there's still some connection back to the inside", Edward Stone, a physicist who has worked on the Voyager missions since 1972, said in the call.
'And the probability of them running into anything is nearly zero'.
It entered interstellar space, and now, a year later, scientists have published five papers in Nature Astronomy about their findings.