Voyager 2's First Reports from Interstellar Space Surprise Scientists

Katie Ramirez
November 5, 2019

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.

According to the scientists, this jump was detected by one of the instruments on Voyager 2 and is evidence of the probe making its way "from the hot, lower-density plasma characteristic of the solar wind to the cool, higher-density plasma of interstellar space". And, interestingly, what Voyager 2's five instruments picked up shows a smoother, thinner heliopause, with a stronger magnetic field. Voyager scientists published their results in five papers published Tuesday in Nature Astronomy (1, 2, 3, 4, 5). But testing those ideas directly is obviously a real challenge, given that doing so requires sending hardware to the edge of the Solar System.

While scientists were aware of the inner layer, the presence of the outer layer became evident only after Voyager 2 crossed into interstellar space. This is the point where the solar wind piles up against the approaching wind of particles in interstellar space, which Prof Gurnett likens to the effect of a snow plow on a city street.

The new boundary layers suggest there are stages in the transition from our solar bubble to the space beyond that scientists did not previously understand.

Voyager 2 left Earth's orbit in 1977 a month before its twin Voyager 1, but took seven years longer to reach the heliosphere's outer limit some 18 billion kilometres (more than 11 billion miles) away. It then made for the southern hemisphere of the heliosphere (the outermost region of the solar system, sometimes referred to it as "the bubble"), straight for interstellar space.

Therefore, the structure of the heliosphere is being unfolded.

It took both spacecraft less than a day to travel through the entire heliopause.

"Voyager 2's interstellar arrival is a significant milestone because we are now able to look at our own star from outside in rather than inside out, and from not just one, but two perspectives", Rankin said. Voyager 1 passed into the ISM at 122.6 AU.

Voyager 2's exit out of the bubble was not without surprises.

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"Inside, the magnetic field comes from the Sun, carried out by the ionized solar wind, and outside the magnetic field is what is in the local region of the Milky Way galaxy", Stone said. In every of people situations, the photo voltaic affect recovered, with cosmic rays dropping back again on to their gradual development and solar particles returning to their regular ranges.

Other results from the new analyses also show a complicated the relationship between interstellar space and our solar system at its edges.

Scientists are interested in the heliopause because it presents an opportunity to learn more about the sun, interstellar space and the interactions between them.

The two spacecraft are now more than 10 billion miles from Earth. This suggests that something is compressing the plasma outside the heliosphere, but scientists don't know what. "This is somewhat similar to what you might find out in the galaxy", says Gurnett. Previous models heavily predicted that heightened solar activity during Voyager 1's crossing in 2012 should have pushed the bubble's boundary farther out. "The speed of the plasma was essentially zero", Krimigis said.

The mission teams expect another 5 years or so of data from the two craft before they run out of power, which is not quite enough time to reach a part of space that is truly devoid of the Sun's influence.

"The heliopause is an obstacle to the interstellar flow", Stone added. By contrast, Voyager 2 experienced to chase the edge of the photo voltaic affect at a time when solar action was larger.

When there's some converse of developing a focused probe to cross a various portion of the changeover spot, we're probable to be still left parsing the Voyager information for decades to occur. Voyager 2 launched two weeks ahead of Voyager 1, on a special course to explore Uranus and Neptune. It is as yet the main shuttle to have visited those planets. An accompanying standpoint implies that Voyager 2 is going to be the last spacecraft to cross this boundary for at least 25 many years. It is now NASA's longest-running mission.

"When the two Voyagers were launched, the Space Age was only 20 years old", Stone went on. "And some of them, only about 30 per cent of what's outside, can actually reach Earth". The changes confirmed that the spacecraft entered a new region of space.

In the future, the researchers want to send more probes in different directions towards the edges of our solar system to study these boundary layers in more detail.

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