Space

Voyager 1 leaves the Solar System?

Artist's impression of Voyager 1 (Image: NASA)
Artist's impression of Voyager 1 (Image: NASA)
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Model of the Voyager spacecraft (Image: NASA)
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Model of the Voyager spacecraft (Image: NASA)
Digital model of the Solar System as seen from the outside (Image: NASA)
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Digital model of the Solar System as seen from the outside (Image: NASA)
Gold-plated record carried by Voyager 1 containing greetings to any alien civilization that finds it (Image: NASA)
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Gold-plated record carried by Voyager 1 containing greetings to any alien civilization that finds it (Image: NASA)
Model of the Voyager spacecraft (Image: NASA)
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Model of the Voyager spacecraft (Image: NASA)
Panoramic view of the Solar System as seen by Voyager 1 (Image: NASA)
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Panoramic view of the Solar System as seen by Voyager 1 (Image: NASA)
Earth (circled) as seen from Voyager 1 (Image: NASA)
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Earth (circled) as seen from Voyager 1 (Image: NASA)
Artist's impression of the Voyager 1 spacecraft passing Saturn (Image: NASA)
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Artist's impression of the Voyager 1 spacecraft passing Saturn (Image: NASA)
Relative positions of the Voyager and Pioneer interstellar probes (Image: NASA)
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Relative positions of the Voyager and Pioneer interstellar probes (Image: NASA)
Old heliosphere model (Image: NASA)
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Old heliosphere model (Image: NASA)
New heliosphere model showing "froth" made of magnetic bubbles (Image: NASA)
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New heliosphere model showing "froth" made of magnetic bubbles (Image: NASA)
Comparison of the old and new heliosphere models with the new one showing magnetic "froth" (Image: NASA)
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Comparison of the old and new heliosphere models with the new one showing magnetic "froth" (Image: NASA)
Artist's impression of Voyager 1 (Image: NASA)
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Artist's impression of Voyager 1 (Image: NASA)
Artist's concept of the two Voyager spacecraft in the heliosheath (Image: NASA)
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Artist's concept of the two Voyager spacecraft in the heliosheath (Image: NASA)
Astrospheres, bubbles of gas and charged particles surrounding stars in a manner similar to the heliosphere around the Solar System (Image: NASA)
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Astrospheres, bubbles of gas and charged particles surrounding stars in a manner similar to the heliosphere around the Solar System (Image: NASA)
Heliosphere diagram (Image: NASA)
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Heliosphere diagram (Image: NASA)
Rising cosmic ray counts as Voyager 1 approaches interstellar space (Image: NASA)
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Rising cosmic ray counts as Voyager 1 approaches interstellar space (Image: NASA)
Direction of solar and interstellar magnetic fields (Image: NASA)
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Direction of solar and interstellar magnetic fields (Image: NASA)
Behavior of the Sun's magnetic field and charged particles as Voyager passes through the "magnetic highway" (Image: NASA)
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Behavior of the Sun's magnetic field and charged particles as Voyager passes through the "magnetic highway" (Image: NASA)
Magnetic field strength and direction of the region Voyager 1 is passing through (Image: NASA)
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Magnetic field strength and direction of the region Voyager 1 is passing through (Image: NASA)
Artist's impression of Voyager 1 in the "magnetic highway" (Imaeg: NASA)
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Artist's impression of Voyager 1 in the "magnetic highway" (Imaeg: NASA)
Voyager's low-energy charged particle instrument (Image: NASA)
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Voyager's low-energy charged particle instrument (Image: NASA)
Voyager probes in the heliosheath (Image: NASA)
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Voyager probes in the heliosheath (Image: NASA)
Voyager 1 instruments (Image: NASA)
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Voyager 1 instruments (Image: NASA)
Voyager 1 launching September 5, 1977 (Image: NASA)
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Voyager 1 launching September 5, 1977 (Image: NASA)
Heliosphere and the bow shock wave (Image: NASA)
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Heliosphere and the bow shock wave (Image: NASA)
Case for Voyager 1's gold-plated record with instructions on how to play is and a map showing Earth's location (Image: NASA)
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Case for Voyager 1's gold-plated record with instructions on how to play is and a map showing Earth's location (Image: NASA)
Plasma flow near Voyager 1 (Image: NASA)
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Plasma flow near Voyager 1 (Image: NASA)
Simplified view of the heliosphere (Image: NASA)
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Simplified view of the heliosphere (Image: NASA)
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Changes in cosmic rays and protons as Voyager 1 passes through the heliosheath (Image: NASA)
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Changes in cosmic rays and protons as Voyager 1 passes through the heliosheath (Image: NASA)

Has Voyager 1 left the Solar System? Is it officially the first spacecraft to reach interstellar space? It depends on whom you ask. NASA says no, but W.R. Webber of the New Mexico State University Department of Astronomy and F.B. McDonald of the University of Maryland Institute of Physical Science and Technology say yes. They contend that the unmanned, nuclear-powered probe left the Solar System on August 25, 2012 at a distance of 121.7 AU (18.2 billion km) from the Sun when its instruments on board detected a major shift in cosmic ray intensity.

Voyager 1 is one of the two Voyager deep space probes sent by NASA to study the outer planets and the frontiers of the Solar System. The 722 kilogram (1,590 lb) spacecraft was launched 35 years ago on September 5, 1977 and is powered by three radiothermal generators. In 1979, it flew by Jupiter and in 1980 it visited Saturn. As it did so, the giant planets sent Voyager on a one-way slingshot trajectory toward interstellar space at a speed of 17.043 km/s (38,120 mph) relative to the Sun.

Changes in cosmic rays and protons as Voyager 1 passes through the heliosheath (Image: NASA)
Changes in cosmic rays and protons as Voyager 1 passes through the heliosheath (Image: NASA)

At its current distance, Voyager 1 is so far away that it takes radio signals almost 17 hours to reach Earth. This puts the probe a long way from any real estate, but according to scientists the Solar System extends even to that tremendous distance. For astronomers, the Solar System’s boundary is the point where the Sun is no longer able to push out the incredibly tenuous bubble of gas that surrounds it called the heliosphere and where its magnetic sphere no longer dominates. It is this boundary that Weber and McDonald claim that Voyager has passed.

According to them, Voyager 1 experienced a dramatic shift in radiation on August 25, 2012. Previously, the radiation detected was dominated by what are called Anomalous Cosmic Rays (ACR), which are cosmic ray particles that have become trapped by the Sun’s magnetic field. However, on that day, the intensity of the ACRs dropped to less than one percent within hours and over the next few days decreased by a factor of up to 500. Meanwhile, the intensity of Galactic Cosmic Rays (GCR), which are cosmic rays from outside the Solar System, doubled.

Artist's concept of the two Voyager spacecraft in the heliosheath (Image: NASA)
Artist's concept of the two Voyager spacecraft in the heliosheath (Image: NASA)

"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 Webber.

However, NASA disagrees with the findings, saying in a statement: "The Voyager team is aware of reports today that NASA's Voyager 1 has left the solar system," said Edward Stone, Voyager project scientist based at the California Institute of Technology, Pasadena, California. "It is the consensus of the Voyager science team that Voyager 1 has not yet left the solar system or reached interstellar space. In December 2012, the Voyager science team reported that Voyager 1 is within a new region called 'the magnetic highway' where energetic particles changed dramatically. A change in the direction of the magnetic field is the last critical indicator of reaching interstellar space and that change of direction has not yet been observed."

Voyager 1 is currently the most distant man-made object to leave Earth and NASA says that the probe will have enough power to transmit signals until 2025. After that, it’s next port of call will be the star AC+79 3888, 17.6 light years away in the constellation of Camelopardalis, which Voyager 1 will pass within 1.6 light years of in 40,000 years.

Weber and McDonald’s findings will be published in the journal Geophysical Research Letters.

The video below outlines the Voyager missions.

Sources: American Geophysical Union, NASA

ScienceCasts: Voyager

9 comments
Australian
An amazing reminder of just how powerful that great ball of fire in the sky really is! A shame Voyager will only be alive another decade or so. I guess the reality is it would be a millenia or greater until it had something meaningful to report back!
Slowburn
Too bad that Voyager is not equipped to do some universal constant experiments.
Pecos Pete
Amazing accomplishment !
Charles Barnard
I have to agree with NASA. Though it won't be until V1 reaches the other side of the new region and beyond (there may be multiple layers to the region) I consider the boundary region 'part' of the Solar System as much as the slipstream around a vehicle is 'part' of the vehicle. Technically it's not part of the Solar System OR interstellar space, but since it travels with and is part of the Solar System's movement, it makes more sense to consider it 'part' as it is 'attached.'
Slowburn
re; Australian We don't actually know that the space Voyager is passing through is empty. the data Voyager is sending back may not be exciting but it is meaningful.
Richard Handel
WOW !!!!!! That's all I've got people !!!! WOW !!!!
Bruce H. Anderson
What I find most interesting is that the "magnetic highway" region Voyager is passing through was unknown until recently, at least according to other published reports. There seems to be plenty to discover out there.
Stewart Mitchell
If we live in a binary star system , it will be almost impossible to measure the boundary.
Liaquat Ali
Great achievement, may be one of its kind of human miracles. I am astonished of the technology, how from so far that antenna of voyager 1 keeping pin point contact from its earth based station specially at such huge velocity? Please could anybody from NASA explain in detail, how they are able to do that? Thanks and tons of greetings to such a gigantic achievement.