"The fleet is full of messengers with lights": Voyager flew out of the solar system for the first time.

Voyager program is an unmanned exploration program of NASA, including Voyager-1 and Voyager -2. They were all launched in 1977, and the planets in the solar system were detected at the end of 1970. Although the Voyager program was originally designed to detect Jupiter and Saturn, both spacecraft eventually reached the edge of the solar system and continued to send back relevant information.

"Voyager-1" was originally planned as a part of "Sailor", and its design adopted the new technology of gravity acceleration at that time. Fortunately, this mission happened to encounter a planetary geometric arrangement that only happened once every 176 years: "The spacecraft only needs a small amount of fuel for channel correction, and the rest of the time can be accelerated by the gravity of the planets. A spacecraft can visit the four gaseous giants of the solar system: Jupiter, Saturn, Uranus and Neptune. "

Voyager 1 and Voyager 2 were designed for this opportunity, and their launch times were accurately calculated. Thanks to this once-in-a-century opportunity, it only takes 12 years for two sister spacecraft to visit four planets instead of the usual 30 years.

Voyager-1 was launched from Cape Venal Space Base in Kana, Florida on September 5, 1977. It is still running normally. It is the man-made spaceship farthest from the earth in history and the first one to leave the solar system.

Voyager-1 started shooting Jupiter from 1979 to 1. On March 5 of the same year, it was the closest to Jupiter, only 349,000 kilometers. Voyager-1 completed an in-depth study of Jupiter's satellites, rings and magnetic fields during its 48-hour short flight, took high-resolution photos, and discovered volcanic activity on Io.

Voyager-1 passed Saturn in1980 165438+ 10, and the highest cloud from Saturn in June165438+10/2/ It detected that the structure of Saturn's rings was more complicated than expected, and also observed the dense atmosphere on Titan. However, this decision to approach Titan caused the traveler-1 to be affected by extra gravity, which eventually led the satellite to leave the ecliptic (that is, the orbital level of the planets in the solar system) and terminated its planetary exploration mission.

Voyager 2 was launched on August 20, 1977 on/kloc-0, and it is still in normal operation. This is the longest-running space probe in history. Its design is basically the same as that of its sister ship Voyager-1, but the difference is that Voyager -2 follows a slow flight trajectory so that it can stay on the ecliptic and accelerate its flight to Uranus and Neptune at 198 1 by Saturn's gravity.

Because of this, Voyager 2 is not as close to Titan as Voyager 1. However, it became the first spacecraft to visit Uranus and Neptune, and in 176, it completed the voyage feat of visiting four gas giants with a once-in-a-lifetime planetary geometric arrangement.

The closest time for Voyager 2 to Jupiter was1July 9, 979, passing 570,000 kilometers from the cloud top of Jupiter. This exploration discovered several rings around Jupiter and took some photos of Io.

Voyager 2 was closest to Saturn on August 25th, 198 1. It uses radar to detect Saturn's upper atmosphere and measure data such as temperature and density.

Voyager 2 was closest to Uranus on198665438+1October 24th, and immediately discovered 10 previously unknown natural satellites. It also detected the unique atmosphere formed by the inclination of Uranus' rotation axis of 97.77, and observed its planetary ring system.

Voyager 2 was closest to Neptune on1August 25th, 989. Because this is the last planet it can visit, NASA decided to adjust the route of Voyager 2 to a place close to Triton, and it found Neptune's big black spot in its exploration.

Both Voyager 1 and Voyager 2 have obtained a lot of information about gas planets in the solar system, which helps astronomers to greatly increase their understanding of them. The change of satellite orbit is also used by scientists to study the existence of celestial bodies outside Neptune.

201June1July, NASA announced that after 35 years of flight, Voyager-1 had left the solar system and entered interstellar space for the first time. Ed Si Tong, a scientist who participated in the Voyager project, said: "The first messenger sent by human beings to interstellar space is already at the edge of the solar system. Once in interstellar space, it will take 40,000 years to reach the next planetary system. "

20 12 On August 25th, Voyager-1 became the first spacecraft to cross the solar circle and enter the interstellar medium.

In June of 20 13, Voyager-1 entered the solar sheath, which was more than 186 billion kilometers away from the sun (124.5 astronomical units). This is the area between the terminal shock wave zone and interstellar space (or interstellar matter) in the solar system, which is a vast area and is influenced by the sun and the Milky Way at the same time. It takes more than 17 hours for sunlight to reach the spacecraft.

2065438+On September 12, 2003, NASA confirmed that Voyager-1 had been flying for 39 years, about 20.6 billion kilometers away from the Earth, and finally became the first man-made object to fly out of the solar system.

A spokesman for NASA said: "Voyager has reached a space that the probe has never reached, which is a milestone in the history of human science development." A series of related data prove that "Voyager-1" has now left the top layer of the solar circle composed of hot and active particles wrapped around the solar system and entered the cold and dark interstellar space.

By June of 20 13, Voyager 2 was about152.4 billion kilometers away from the sun (about 10 1.9 astronomical unit) and had also entered the solar sheath. 20 1 18 10/5 October, Voyager 2 became the second man-made object to fly out of helium and enter interstellar space after Voyager 1. Helium layer is the protective layer of particles and magnetic fields caused by the sun.

Ed Si Tong, a scientist of NASA's Voyager Program, said: "Travelers constantly surprise us, which means we have a lot to learn. I'll be surprised if Voyager 2 sends back the same thing as Voyager 2, because it's great. But now what we see is the scene of different times in the solar system activity cycle, so we can understand the different and the same places. "

Voyager 1 and Voyager 2 are still moving out of the solar system, and Voyager-1 is the man-made spacecraft farthest from the earth at present.

By the end of 20 18, 10 and 18, the traveler-1 is 21500 million kilometers away from the sun. Thanks to several gravitational accelerations, Voyager-1 has flown faster than any existing human aircraft, which makes its sister ship Voyager -2 (launched two weeks in advance) never surpass it. Their power comes from the thermal energy brought by the decay of radioactive materials, which reduces about 4 watts of energy every year.

Although all the "travelers" left the helium layer, NASA revised the statement in February 20 18, and still said that their statement of leaving the solar system was inaccurate. Scientists say it may take nearly 30,000 years for Voyager 2 to fly away from the sun.

"Voyager -2" transmitted signals to the earth until the 2020s; In 2036, the power transmitted by the "Voyager-1" signal will be exhausted. After the battery is exhausted, it will continue to move to the center of the Milky Way, but it will not send data back to Earth. Voyager-1 It is estimated that it will reach the theoretical Oort Cloud in about 300 years, and it will take 30,000 years to pass.

Oort Cloud, also known as Aupic-Oort Cloud, is theoretically a spherical cloud around the sun, which is mainly composed of ice asteroids. Oort Cloud is located in interstellar space, which is about 654.38+ million astronomical units (about 2 light years) farthest from the sun, which is half the distance between the sun and proxima centauri. The Kuiper belt and discrete disk, which are also composed of celestial bodies outside Neptune, are less than one thousandth of the distance from the sun. The outer edge of Oort Cloud marks the structural edge of the solar system and the edge of the sphere of influence of solar gravity.

Since Voyager 2' s mission to visit the planet has ended, Voyager 1 was described by NASA as Ad Astra's mission, although it will not go to any specific star for 40,000 years. But "Voyager-1" will pass Gliese 445, which is currently located in Ophiuchus, with a distance of 1.6 light years. The star is moving towards the solar system at the speed of 1 19 km/s, and NASA said, "Travelers are destined to roam the Milky Way, perhaps forever."

Since the birth of civilization, interstellar space outside the solar system has been a mysterious dark vacuum for human beings on earth, and its secret was finally revealed today by the first two intrepid spacecraft that are about to leave the solar system.

The edge of the solar system, far from the protection of the sun, seems to be a cold, empty and dark place. For a long time, humans thought that this vast space between the solar system and the nearest star was a terrible void.

Until recently, the edge of the solar system was a dark space, and humans could only peep from a distance. Astronomers often ignore this and prefer to aim their telescopes at nearby stars, galaxies and nebulae.

However, as mentioned above, in the past few years, Voyager 1 and Voyager 2 have flown to a strange area that we call interstellar space, and the images sent back have given mankind a glimpse of the true face of this vast space for the first time. As the first human-built object far away from the solar system, these two spacecraft are exploring unknown areas billions of miles away from the Earth. Before that, human spacecraft had never flown so far into space.

Voyager revealed that there is an invisible area outside the boundary of the solar system, but the substance is quite active, chaotic and agitated. At the same time, the solar circle formed by the sun and its planets will produce bow shock waves when it collides with interstellar matter in interstellar space.

Michelle bannister, an astronomer who studies the outer region of the solar system at the University of Canterbury in Christchurch, New Zealand, said, "If you look at different parts of the electromagnetic spectrum, you will find that those parts of space are very different from the darkness we see with our naked eyes. Here, electromagnetic phenomena is very active, interacting and promoting each other. You can imagine the rushing river formed by Niagara Falls rushing down. "

However, unlike the rushing water under Niagara Falls, the turbulence in the outer solar system is the result of the solar wind. The so-called solar wind is an ultra-high-speed charged particle stream, or plasma stream, which is constantly ejected from the sun to the periphery. When the solar wind reaches the edge of the solar system, it will slow down and collapse, mixing with the gas, dust and cosmic rays flowing between galaxies, which is also the "interstellar medium". The solar wind will increase or decrease due to the intensity of solar activity.

In the past 100 years, mainly relying on the observation of radio telescopes and X-ray telescopes, scientists have sketched a composition map of interstellar medium, revealing that the interstellar medium consists of extremely dispersed ionized hydrogen atoms, cosmic dust and cosmic rays, and dense interstellar molecular clouds. Molecular clouds are places where new stars are born. Our solar system was formed by the collapse of a huge molecular cloud 4.5 billion years ago.

However, the exact nature of the interstellar medium outside the solar system is still a mystery to a great extent, mainly because the whole solar system, that is, the sun and its eight planets, and an extremely distant dense disk-shaped region, called the Kuiper Belt, are all wrapped in a huge protective bubble formed by the solar wind. This balloon-like bubble is called heliosphere.

When the sun and many of its planets move rapidly in the Milky Way, this big bubble formed by the solar wind is like an invisible barrier, which resists the interstellar medium and keeps most harmful cosmic rays and other substances out of the solar system. When Voyager 2 flew out of the solar system, it measured the explosion of cosmic rays, and bubbles in the solar circle prevented cosmic rays from entering the solar system, thus protecting life on earth.

But the life-saving characteristics of the solar circle (heliosphere) also make it more difficult to study the interstellar space outside this bubble. Even from the inside of the solar system, it is difficult to determine the size and shape of the solar circle.

Elena Provonikova, a postdoctoral researcher at Johns Hopkins University's Applied Physics Laboratory, said, "It's like being in your own home and wondering what the house looks like. You have to look outside to really judge. The only way to know what the solar circle looks like is to get out of the solar system, then look back and take an image of it from outside the solar circle. "

This is not an easy task. Compared with the whole galaxy, the solar system is like something smaller than a grain of rice, floating in the middle of the Pacific Ocean. For human beings, the outer edge of the solar circle (heliosphere) is so far away that it took more than 40 years for two spacecrafts "Voyager-1" and "Voyager -2" to arrive here after taking off from the earth.

Voyager-1 crossing the solar system in a straight line first entered interstellar space in 20 12, and Voyager -2 also entered interstellar space in 20 18. At present, the two artificial spacecraft are about 65.438+0.3 billion miles away from the Earth and 65.438+0.65438+0 billion miles away from the Earth, respectively, and continue to fly to outer space farther away from the solar system. When they fly away from the solar system, they also send back more data to the earth continuously.

Voyager, which has reached the age of no doubt, reveals the true face of the boundary between the solar circle and the interstellar medium, and provides new clues for human beings to understand how the solar system was formed and why life can exist on earth. In fact, it is not until now that human beings have discovered that the edge of the solar system is not a clear boundary, but an active chaotic region, which stirs the rotating magnetic field, the storm of colliding stars, the storm of high-energy particles and the rotating radiation.

The size and shape of bubbles in the solar circle will change with the change of solar wind output, and will also change with different regions of the cross star medium in the solar system. When the solar wind rises or falls, it will also change the external pressure on the bubbles in the solar circle.

In 20 14, solar activity surged, leading to solar storms sweeping through interplanetary space. The storm first hit Mercury and Venus at a speed of 800 kilometers per second. Two days later, after crossing 65.438+0.50 billion kilometers, a solar storm surrounded the earth. Fortunately, the earth's magnetic field can block the solar wind and protect life on earth from the powerful radiation damage of the solar wind.

A day later, this powerful solar storm roared from Mars, crossed the asteroid belt and headed for the distant gas giants (Jupiter, Saturn and Uranus). More than two months later, it pounced on Neptune, and its orbit was nearly 4.5 billion kilometers away from the sun.

After more than six months, the solar storm finally reached the space called "terminal shock wave" more than 30 billion kilometers away from the sun/kloc-0. Here, the solar magnetic field driving the solar wind becomes so weak that the pressure of the interstellar medium interacts with the solar wind, thus slowing down the speed of the storm.

The speed of the solar storm reaching the terminal shock zone will slow down to less than half of the previous speed, just as the Atlantic hurricane weakens into a tropical storm. At the end of 20 15, this solar storm caught up with the irregular Voyager 2, the size of a car. The sensor in Voyager -2, driven by slowly decaying plutonium battery, has been working for more than 40 years. It quickly detected the solar storm and found that the volume of solar wind plasma increased dramatically.

Voyager 2 then sent the data back to Earth. Even at the speed of light, it takes 18 hours to reach the earth. Astronomers can receive the information of Voyager in the distance, thanks to the huge dish-shaped satellite array 70 meters high and the application of a series of advanced technologies. These technologies were unimaginable when Voyager 1977 left the earth, let alone invented.

When the solar storm met Voyager 2, the spacecraft was still in the solar system. More than a year later, the last dying afterwind of the solar storm caught up with the traveler-1, and it entered interstellar space as early as 20 12 years ago.

The two spacecraft take different routes to cross the solar system, one is 30 degrees above the ecliptic plane of the solar system and the other is 30 degrees below the ecliptic. The solar storm that broke out in 20 14 met two travelers at different times and in different areas, which provided useful clues for studying the nature of heliopause (also translated as heliopause, the boundary where the solar wind meets the interstellar medium).

According to the data sent back by Voyager, this turbulent boundary, called the top of the solar wind layer, is millions of kilometers thick, covering the solar circle (heliosphere) with a surface area of several billion square kilometers.

The solar circle (heliosphere) is unexpectedly large, which shows that the density of interstellar medium in this part of the galaxy is lower than people think.

When the sun runs in the interstellar space of the Milky Way, it will cut a path, just like a ship sailing in the water will leave a "bow wave", and it will also form a wake behind it, which may have one or more tails similar to the shape of a comet. However, both travelers took off from the "nose" of the solar bubble, so they didn't provide any data about the tail of the solar circle.

Provo Nikova, a researcher at Hopkins University, said, "According to Voyager, the top of the solar wind layer is about one astronomical unit thick. But this is not the real surface of the solar circle. This is a field with complicated activities. We don't know what happened there. " One astronomical unit represents the average distance between the earth and the sun, which is 93 million miles.

In this boundary area between solar system and interstellar space, not only the solar wind and interstellar wind (particle flow from interstellar space) collide with each other to produce turbulence, but also the particles in the solar wind and interstellar medium seem to exchange charge and momentum. In this way, some interstellar medium will be transformed into solar wind, which can increase the outward thrust of bubbles in the solar circle.

Although solar storms can provide interesting data, surprisingly, solar storms have little effect on the overall size and shape of bubbles in the solar circle. It seems that what happens outside the circle has a much more important influence on the solar circle than what happens inside. The solar wind will not obviously affect the bubbles in the solar circle with the increase or decrease of time. However, if the solar bubble enters a certain area of the Milky Way, the density of the interstellar wind it encounters will affect the increase or decrease of the solar circle.

In addition, there are still many unsolved problems surrounding and protecting the solar bubble in our solar system. For example, is this bubble formed by the solar wind a special phenomenon in the universe or a pattern?

When the solar system runs in the interstellar medium of the Milky Way, the bubbles in the solar circle around the solar system will form a long tail. Provo Nikova believes that increasing the understanding of the solar circle will increase the understanding of whether human beings are lonely and intelligent life in the universe. She said: "The study of our own galaxy will tell us what conditions life needs in other star systems."

This is largely because the solar wind prevents the interstellar medium from entering the solar system, and also prevents the deep space radiation that threatens the life of the earth and the impact of deadly high-energy particles (such as cosmic rays). Cosmic rays are charged high-energy subatomic particles coming from deep space and approaching the speed of light. Cosmic rays are produced when stars explode, galaxies collapse into black holes and other catastrophic cosmic events occur. The interstellar space outside the solar system is full of high-speed subatomic particles, which will cause fatal radiation damage to an unprotected planet.

Jamie Rankin, a researcher in solar physics at Princeton University, was the first scientist to write a doctoral thesis based on the interstellar data collected by Voyager. He said, "Voyager's data clearly tells us that 90% of the cosmic radiation is filtered out by the sun. Without the protection of the solar wind, I don't know if we humans can survive. "

During this period, there are three other NASA spacecraft about to enter interstellar space, namely "Pioneer 10", "Pioneer 1 1" (Pioneer 1 1) and "New Horizon". On the huge boundary of the solar circle, these tiny detectors can only provide extremely limited information. Fortunately, more extensive observations can be made in space closer to the earth.

In 2008, NASA launched a microsatellite "interstellar boundary explorer" (Ibex) orbiting the Earth to draw the boundary between the solar circle and interstellar space. Ibex detected a particle belt called "high energy neutral atom" ejected from the interstellar boundary.

Rankin said: "You can think of Ibex mapping as some kind of Doppler radar that measures the apparent velocity of stars, and travelers are like a ground weather station." She used data from Voyager, Ibex and related fields to analyze smaller-scale solar storms.

Rankin is writing a paper based on the solar storm data of 20 14 years. There is evidence that the solar circle is shrinking when the traveler-1 crosses the boundary of the solar circle. But when Voyager 2 crossed the border, the solar circle was expanding. "This is a very dynamic boundary. Surprisingly, Ibex's 3D map captured this discovery, which allowed us to track the reaction of Voyager at the scene when the incident occurred. "

Ibex also observed how active the boundary of the solar circle was. In the first year, Ibex discovered a huge band of high-energy neutral atoms, which meandered through the boundary of the solar circle. This neutral atomic band will change with time, and some features will appear and disappear in just six months. This zone is located at the front end of the solar stratosphere, where solar wind particles will be reflected back to the solar system from the edge of the solar sphere by the galactic magnetic field.

With the continuous progress of human space technology, although more and more advanced spacecraft will explore the depths of the universe in the future, Voyager's great Long March story is still very long and will not end. Although these two human spacecraft have left the solar circle (heliosphere), they are still within the sphere of influence of the sun. Even in this marginal zone, which is very far away from the sun, you can still see the sun's rays with the naked eye and recognize the sun. Moreover, the gravity of the sun is far beyond the solar circle, which can accommodate a cloud-like celestial body called Oort Cloud, which is a very sparse and huge spherical cloud composed of ice, dust and space debris.

Although the matter in Oort Cloud floats in distant interstellar space, it still moves around the sun. Some comets passing through the solar system come from Oort Cloud, but it's too far for humans to send probe spacecraft to Oort Cloud, 300 billion to10.5 trillion kilometers away. Voyager-1 entered interstellar space in 20 12 and left the sun 100 astronomical unit, but it will take 300 years to fly to the huge Oort cloud.

These extremely distant celestial bodies have remained basically unchanged since the formation of the solar system, and they may hold the code of how planets form and why life can appear in the universe. With each wave of new data, new solutions appear.

There may be a layer of hydrogen covering part or all of the solar circle, and its influence on the solar circle has not been deciphered. In addition, the solar circle seems to be passing through an interstellar cloud cluster in the Milky Way, which is composed of particles and dust left over from ancient cosmic events, which is the so-called local interstellar cloud cluster in astronomy. How this interstellar cloud affects the boundary of the solar circle and the earth creatures living in it remains to be studied.

This interstellar cloud can change the size and shape of the solar circle. It may have different temperatures, different magnetic fields, different ionizers and all these different parameters. This is very exciting, because this is an unknown field, and human beings still know very little about the interaction between the sun and our own galaxy (the Milky Way).

Finally, it is worth mentioning that Voyager 1 and Voyager 2 both carried a gold-plated copper disc record with pictures and sounds from the earth. There are symbols and charts on the cover to explain how to operate this record and indicate the location of the earth in detail.

The greeting of Voyager's record is: "The children of the earth say hello to you". Jimmy Carter, then president of the United States, said on behalf of mankind: "This is a gift from a distant small world. It records our voices, our science, our images, our music, our thoughts and feelings. We are trying to live our time and enter your time. "

These information are combined into a time capsule, and any interstellar civilization, aliens and even future humans who get this golden record can restore the information of the "Voyager" program.

The question is, according to the "dark forest" law of the universe in "Three-body", if the earth coordinates are exposed to aliens who have mastered advanced civilization, will human beings encounter disaster?

But in any case, Voyager, the two car-sized spaceships, connected with a small parabolic antenna by metal bolts, will be the pioneer of mankind rushing out of the solar system one day and bravely breaking into the magnificent and unfamiliar unknown Xinghai ahead. On the long journey of human beings to explore infinite space, they are like "a fleet full of messengers with lights, approaching the dark details" ...