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Voyager 2 was 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. 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.
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 and 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.'
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Saturn were one of
the first images of the sixth planet taken by Voyager 2 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. 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. 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.
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As 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.
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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.
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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. As Voyager 2 probe was launched on August 20 in 1977, about two weeks before Voyager 1. It is now 9 billion 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’ travelling an speed of light’. 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.
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'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. As Voyager 2 probe was launched on August 20 in 1977, about two weeks before Voyager 1. It is now 9 billion 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’ travelling an speed of light’. 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.
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