Nasa confirms Voyager 1 probe has LEFT the solar system 35 years after its mission to explore space began

Thirty-five years after its launch, Voyager 1 has left the solar system.
Researchers say drastic changes in radiation levels measured by the probe confirm it has travelled beyond the influence of the Sun.
Mission scientists today confirmed the probe is 'in a new region' - although scientists are continuing to debate whether Voyager 1 has reached interstellar space or entered a separate, undefined region beyond the solar system.

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Nasa's Voyager 1 probe has finally left the solar system, mission scientists have confirmed

VOYAGER'S HISTORY

Nasa's robotic space probes Voyager 1 and 2, both weighing 1,592 lb (722 kg), prepared for launch in 1977 on missions to locate and study the outer Solar System and eventually interstellar space.
Voyager 2 launched on August 20, 1977, before Voyager 1.
Voyager 1 launched on September 5, 1977 moving faster than its sister probe and eventually passing it.
On June 15, 2012, NASA scientists reported that Voyager 1 may be very close to entering interstellar space and becoming the first man-made object to leave the Solar System.
Voyager 2 will have to be turned off by 2020, and Voyager 1 will have to be turned off by 2025.

The results confirm the probe has left the heliosphere.
The heliosphere is a region of space dominated by the Sun and its wind of energetic particles, and which is thought to be enclosed, bubble-like, in the surrounding interstellar medium of gas and dust that pervades the Milky Way galaxy.
On August 25, 2012, NASA’s Voyager 1 spacecraft measured drastic changes in radiation levels, more than 11 billion miles from the Sun.

Anomalous cosmic rays, which are cosmic rays trapped in the outer heliosphere, all but vanished, dropping to less than 1 percent of previous amounts.

At the same time, galactic cosmic rays - cosmic radiation from outside of the solar system - spiked to levels not seen since Voyager’s launch, with intensities as much as twice previous levels.
The findings have been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.
'Within just a few days, the heliospheric intensity of trapped radiation decreased, and the cosmic ray intensity went up as you would expect if it exited the heliosphere,' said Bill Webber, professor emeritus of astronomy at New Mexico State University in Las Cruces.
He calls this transition boundary the 'heliocliff.'
In the article, the authors state: 'It appears that [Voyager 1] has exited the main solar modulation region, revealing [hydrogen] and [helium] spectra characteristic of those to be expected in the local interstellar medium.'

However, Webber said scientists are continuing to debate whether Voyager 1 has reached interstellar space or entered a separate, undefined region beyond the solar system.
'It’s outside the normal heliosphere, I would say that,' Webber said.
'We’re in a new region. And everything we’re measuring is different and exciting.'

The 'magnetic highway': Here the sun's magnetic field lines are connected to interstellar magnetic field lines, allowing particles from inside the heliosphere to zip away and particles from interstellar space to zoom in

Late last year researchers said NASA's long-running Voyager 1 spacecraft has entered a new layer of the solar system that scientists hadn't known was there, researchers say.
Scientists have dubbed this region the ‘magnetic highway’ and say it's the last stop before interstellar space, or the space between stars.
'We do believe this may be the very last layer between us and interstellar space,’ said Edward Stone, Voyager project scientist based at the California Institute of Technology, in Pasadena, California.
‘This region was not anticipated, was not predicted.’
Therefore, it's hard to determine how soon the spacecraft will leave the solar system altogether, Stone said at the time.
‘It may take two months, it may take two years,’ he added.

The outer limits: This artist's concept shows NASA's two Voyager spacecraft exploring a turbulent region of space known as the heliosheath, the outer shell of the bubble of charged particles around our Sun

Space weather: Voyager is bathed in solar wind from the southern hemisphere flowing northward

In a release, Nasa said it was referring to this new region as a magnetic highway for charged particles because our Sun's magnetic field lines are connected there to interstellar magnetic field lines.
This connection allows lower-energy charged particles from inside our heliosphere - the bubble of charged particles the Sun blows around itself - to zoom out, and allows higher-energy particles from outside to stream in.
Before entering this region, the charged particles bounced around in all directions, as if trapped on local roads inside the heliosphere.

VOYAGER'S LOW-ENERGY CHARGED PARTICLE INSTRUMENT

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It was data taken from Voyager's low-energy charged particle instrument that showed it first entered the magnetic highway region in July.

The instrument includes a stepper motor that turns the platform on which the sensors are mounted, so that the field of view rotates through 360 degrees.

This motor was tested for 500,000 steps, enough to reach the orbit of Saturn, and has now completed over 6 million steps.

The old-fashioned capacitor bank underneath the motor stores energy needed to provide a 15.7-watt pulse every 192 seconds.

However, because the direcrtion of the magnetic field lines has remained the same, the Voyager team believed the new region is still inside our solar bubble.
They predict the direction of these magnetic field lines will change when the craft breaks out into interstellar space.
Since December 2004, when Voyager 1 crossed a point in space called the termination shock, the spacecraft has been exploring the heliosphere's outer layer, called the heliosheath.
In this region, the stream of charged particles from the sun, known as the solar wind, abruptly slowed down from supersonic speeds and became turbulent.
Voyager 1's environment was consistent for about five and a half years.
The spacecraft then detected that the outward speed of the solar wind slowed to nothing.
The intensity of the magnetic field also began to increase at that time.
Data from two instruments aboard voyager that measure charged particles showed it first entered the magnetic highway region on July 28 last year.
The region ebbed away and flowed toward Voyager 1 several times.
The spacecraft entered the region again August 25 and the environment has been stable since.

'If we were judging by the charged particle data alone, I would have thought we were outside the heliosphere,' said Stamatios Krimigis, chief scientist on the low-energy charged particle instrument.
'But we need to look at what all the instruments are telling us and only time will tell whether our interpretations about this frontier are correct.'
Spacecraft data revealed the magnetic field became stronger each time Voyager entered the highway region; however, the direction of the magnetic field lines did not change.

'We are in a magnetic region unlike any we've been in before - about ten times more intense than before the termination shock - but the magnetic field data show no indication we're in interstellar space,' said Leonard Burlaga, a member of the team that looks after Voyager's magnetometer.
'The magnetic field data turned out to be the key to pinpointing when we crossed the termination shock. And we expect these data will tell us when we first reach interstellar space.'
Voyager 1 and its sister probe Voyager 2 launched 35 years ago on a tour of the outer planets.
Voyager 2 launched on August 20, 1977, about two weeks before Voyager 1.
It is now 9billion miles from the sun. Voyager 1 launched on September 5, 1977, moving faster than its sister probe and eventually passing it.
It is now more than 11 billion miles from the sun. The signal from Voyager 1 takes approximately 17 hours to travel to Earth.
After hurtling into space, both probes have continued to travel toward the fringes of the solar system.

Interstellar missions: A map of the Voyager tours through outer space

Saturn: an image of the sixth planet taken by Voyager 2

Neptune: An image of the eight planet taken by Voyager 2

The Voyagers are NASA's longest-running spacecraft, and will continue traveling after they have left the solar system.
As soon as Voyager 1 breaks through to interstellar space, it will be the first man-made object to leave the solar system, Stone said.
However, it would take at least 40,000 years before either probe came close to another star, Stone said.
Long before that both Voyagers will run out of power and transmit their findings back home before shutting off for good.
‘We will have enough power for all the instruments until 2020; at that point we will have to turn off our first instrument,’ Stone said.
Voyager 1 will have to be turned off by 2025.