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This article comes from the official account of Wechat: ID:fanpu2019, by Wang Shanqin

Voyager 1 helps humans to further study the Jupiter system and the Saturn system with higher quality data. The meaning of the picture of the earth-"dim blue dot" taken during its long-distance roaming goes beyond astronomy and has become one of the important starting points for human beings to think philosophically about the universe, the earth and human beings themselves. Voyager 1 is also the first man-made object to leave the solar system and the farthest man-made object from Earth so far. Its success also directly laid a solid foundation for Voyager 2 to complete the feat of "Planetary Journey".

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As the pathfinder of the "Planetary Tour" project, the success of Pioneer 10 and Pioneer 11 opened two skylights for mankind to explore exoplanets (Jupiter, Saturn, Uranus and Neptune). However, on December 16, 1971, before the two probes were launched, NASA announced the cancellation of the planetary tour project. It was only two years after the project was officially launched (1969).

The "Planet Tour" project was cancelled because of the funding. At that time, the budget of the project was as high as $1 billion, equivalent to more than $5 billion today. On the other hand, funding for NASA has been decreasing year by year since 1965; after the success of the Apollo moon landing program in 1969, President Nixon, who took office in the same year, further cut the annual funding of NASA. In 1971, NASA could only choose between the space shuttle program and the Planetary Tour project. NASA chose the space shuttle program.

Voyager: the resurrection of "Planetary Journey" the cancellation of the "Planetary Journey" project is undoubtedly a great tragedy.

Fortunately, when NASA's Exoplanet working Group (Outer Planets Working Group) recommended the Planetary Tour project in 1969, it also recommended an alternative: a project to explore only Jupiter and Saturn, which had a much lower budget. In 1971, at the last discussion and voting meeting of the "Planetary Tour" project, while adopting the project, the expert group also highlighted this option. NASA also spoke highly of the options when he finally decided to cancel the Planet Tour project.

This option wins the chance of rebirth for the Planet Tour project. In January 1972, the Jet Propulsion Laboratory (JPL) began to turn to the preparation of this alternative project; in May of the same year, NASA formally approved this alternative project, which is the Mariner Jupiter-Saturn (Mariner Jupiter-Saturn,MJS) project.

The MJS project will launch two identical detectors, with the second as a spare for the first. When the MJS project was proposed, JPL already operated Mariners 1-9 to explore Mercury, Venus and Mars, and Mariner 10 was about to be launched. As a result, the two detectors of the MJS project were named Mariner 11 and Mariner 12, respectively. The budget for the project is $360 million.

Because Mariner 11 and Mariner 12 of the MJS project explored exoplanets, which were quite different from other probes in the Mariner series, they were renamed "Voyager 1" and "Voyager 2" respectively on March 7, 1977, so they are no longer part of the Mariner series, but are still operated by the JPL team.

The target of Voyager 1 is Jupiter, Saturn and Titan, whose orbit code is "JST". These three letters are the initials of the above three celestial bodies.

Orbital diagrams of Voyager 1 and Voyager 2. Voyager 1 moves in the direction of "JST" and Voyager 2 moves in the direction of "JSX". There are two possibilities for X, including the Titan flyby mission (for Voyager 1 failure) and the X=TB representation for Uranus flyby mission (for Voyager 1 success). The timescale on the track is measured in 0.5 years. Photo Source: NASA; translator: Wang Shanqin

Structure and instrument Voyager 1 has a mass of 825.5 kg, of which the ship itself weighs 721.9 kg. It has 16 MR-103 hydrazine thrusters for attitude control, 8 standby thrusters, three-axis stabilized gyroscopes, celestial coordinate reference equipment, radio communication systems, energy systems, 11 scientific instruments, solid motors for midway orbit change and 8 propulsion rocket motors.

Model pictures of Voyager 1 and 2. Source: NASA / JPL Voyager 1's radio communication system includes a parabolic high gain antenna with a diameter of 3.7m, which receives signals from three deep space network sites (DSN) on Earth and sends the resulting data to DSN.

On July 9, 1976, an engineer and Voyager's unfinished high-gain antenna. Image source: NASA / JPL Voyager 1 also has a data memory, the Digital Tape Recorder (DTR), which can hold 64 kilobytes of data, which allows it to delay sending images. For comparison, there is no DTR on Pioneer 10 and 11, and the filmed data must be sent immediately.

Voyager 1's electricity is provided by three radioisotope thermomotors (RTG). Each RTG contains 24 compressed plutonium-238 oxide spheres, so it is also known as a plutonium nuclear battery. At the time of launch, the heat generated by the RTG can produce about 470 watts of electric power. Due to the decay of radioactive material, the power of RTG will continue to decrease.

The scientific instruments of Voyager 1 include Imaging Science system (Imaging Science System), Radio Science system (Radio Science System), Infrared interference Spectrometer (Infrared Interferometer Spectrometer), Ultraviolet Spectrometer (Ultraviolet Spectrometer), Triaxial Flux Gate Magnetometer (Triaxial Fluxgate Magnetometer), Plasma Spectrometer (Plasma Spectrometer), Low Energy charged Particle equipment (Low Energy Charged Particle Instrument), Cosmic Ray system (Cosmic Ray System), Planetary Radio Astronomical Survey (Planetary Radio Astronomy Investigation) system, Optical polarizer system (Photopolarimeter System), Plasma Wave Subsystem (Plasma Wave Subsystem).

The structure of Voyager 1 and 2? photo Source: NASA / JPL in Voyager 1's instrument, the imaging science system is responsible for capturing the image. it weighs 38.2kg and includes a long focal narrow field of view camera and a short focal wide field of view camera with a telescope caliber of 17.7cm and 5.7cm respectively. The filters on both cameras cover multiple bands from ultraviolet to visible light. Through these filters, the camera can take monochromatic images and be combined by astronomers into magnificent color images with a resolution of up to thousands of meters per pixel.

According to previous calculations, the launch time window for the original Planetary Tour project and Voyager 1 and 2, which were later replacements, were between 1976 and 1980. On September 5, 1977, Voyager 1 was launched on board the Hercules 3 E-Centaur (Titan IIIE-Centaur) rocket. Sixteen days earlier (August 20, 1977), Voyager 2 had been launched with the same rocket. Voyager 1 was delayed several times before launch, causing this reverse order. However, under the design of orbital dynamics experts, Voyager 1 will pass through the asteroid belt and visit Jupiter and Saturn earlier than Voyager 2.

Voyager 1 was launched on a rocket. Photo: Voyager 1 enters the asteroid belt on December 10, NASA1977. On December 19, 1977, Voyager 1 flew in front of Voyager 2. Voyager 1 left the asteroid belt on September 8, 1978.

Flyby Jupiter system on January 6, 1979, Voyager 1 began to observe Jupiter.

On February 25, 1979, Voyager 1 photographed Jupiter containing parts of the Great Red spot. Voyager 1 is 9.2 million kilometers from Jupiter at this time. The resolution of the image is 160 km. Photo Source: during the 28 days from January 6 to February 3, NASA / JPL1979, Voyager 1 continued to take several pictures of Jupiter. During this period, Voyager 1 flew from 5800 kilometers to 3100 kilometers from Jupiter. Later, the photos were stitched together into a movie.

Voyager 1 is a film made up of photos taken between January 6 and February 3, 1979. In order to reflect changes in the characteristics of the same side, photos taken every 10 hours (Jupiter's rotation cycle) are selected to piece together the video. During this period, the position of Jupiter's Great Red spot is almost unchanged, but it rotates at a high speed, and clouds at different latitudes show different characteristics of movement. The black dots in the video are projections of Jupiter's moons, and the white dots are Jupiter's moons themselves. Video source: NASA / JPL1979 Voyager 1 entered the Jupiter system on February 10, 2000. In early March, it found a thin ring around Jupiter, which was less than 30 kilometers thick. This is the first time that Jupiter has been confirmed to have rings. On March 4 and 5, 1979, Voyager 1 discovered Io XIV and Io XVI respectively.

Voyager 1 reaches the near arch point of Jupiter at 12:05:26 on March 5, NASA / JPL1979, about 280,000 kilometers from the top of Jupiter's cloud. Before and after flying by Jupiter, it took a large number of high-quality images, detecting Jupiter's magnetic field, gravity field, atmosphere, and so on.

A pseudo-color map of the Great Red spot of Jupiter obtained by Voyager 1. After NASA / JPL flew over Jupiter, Voyager 1 flew over Io (distance 2.057 km) and Europa (distance 73.376 km) on the same day.

Voyager 1 takes a group photo of Jupiter, Io (left) and Europa (right) in March 1979. Image source: NASA compared to Pioneer 10 and Pioneer 11 flew over Io (357,000 km and 314,000 km, respectively), while Voyager 1 was much smaller than Io (2.057 km), so a large number of details of Io were observed.

The image of Io captured by Voyager 1 at a distance of 450,000 kilometers on March 5, 1979 (left) is combined with the heart-shaped area of material falling back from the eruption of the Pele volcano (right). Near the Pell crater is the Loki volcano. The black crack in the center of the heart-shaped area is a crater, and the material that erupts after the eruption lags behind, forming a heart-shaped area. Photo Source: NASA / JPL Voyager 1 directly captured the eruption of volcanoes on Io. This is the first time that a volcanic eruption has been found on a celestial body outside the earth. Interestingly, just before this discovery, astronomers had predicted the existence of volcanic activity on Io from theoretical calculations. Studies show that Io is the most volcanically active celestial body in the solar system. Sulfur-rich material from volcanoes above it falls on its surface, forming red, orange and yellow surfaces.

Part of Io (left) photographed by Voyager 1 on March 4, 1979 and part of Io (right) photographed by Voyager 1 on March 5, 1979. At that time, Voyager 1 was 490, 000 kilometers and 1285, 000 kilometers from Io. The picture on the left shows the Loki volcano erupting with material thrown to a height of more than 160 kilometers. Image source: NASA / JPL although Voyager 1 flew past Pioneer 10 and Pioneer 11 (32.1-58.67 km), it still achieved higher-resolution images with its high-quality imaging system. The images it took showed that Europa had crisscross cracks on its surface. Astronomers at the time inferred that the cracks came from surface faults or tectonic processes.

Voyager 1 photographed Europa at a distance of 286.9252 million kilometers on March 2, 1979. The dark lines on the surface are cracks on Europa. Photo: on March 6, NASA / JPL1979, Voyager 1 flew over Ganymede (distance 11.471 million km) and Callisto (distance 12.64 million km). Because the flying distance is much smaller than Pioneer 10 and Pioneer 11, it has obtained higher-quality images of Ganymede and Callisto.

Part of Ganymede (left) photographed by Voyager 1 on March 5, 1979 and part of Callisto (right) shot by Voyager 1 on March 6, 1979. When taking photos, Voyager 1 was 246,000 kilometers away from Ganymede and 200,000 kilometers from Callisto. Photo Source: NASA / JPL although Voyager 1 observed Jupiter for about 3 months, it only took 48 hours before and after reaching its near arch point to detect Jupiter's magnetic field and radiation. Detailed observations of Jupiter's rings and moons last only a few days. During this period, Voyager 1 discovered eight moons of Jupiter.

During several months of imaging observation and several days of close observation, Voyager 1 obtained a large amount of data about the Jupiter system, which provided an important basis for planetary scientists to further study the Jupiter system.

Flyby Saturn system on April 9, 1979, Voyager 1 completed orbit correction and flew to Saturn. To avoid hitting Titan, it made another orbital correction on October 10, 1979. On August 22, 1980, Voyager 1 began to observe Saturn.

On November 12, 1980, Voyager 1 entered the Saturn system and flew over Titan on the same day, the closest distance to the surface of Titan was only 3915 km, which was 1 × 90 of the distance Pioneer 11 flew over Titan (36.2962 km).

Voyager 1 shot Titan at a distance of 435,000 kilometers on November 12, 1980. The top of Titan is thick with fog. Image source: data from the NASA / JPL Voyager 1 spectrometer show that Titan's atmosphere contains methane, ethane, a variety of other organic compounds and large amounts of nitrogen. However, the thick organic haze in Titan's atmosphere still makes the image obtained by Voyager 1 look unfeatured.

Based on Voyager 1 radio occultation data, astronomers inferred that Titan has a diameter of 5152 km, a surface temperature of about 94 K and an atmospheric pressure of 1.47 bar (1 bar = 100,000 Pascal, Earth's standard atmospheric pressure is 1.01325 bar). Its data also show that Titan has a dense atmosphere and may have liquid matter on its surface.

On November 12, 1980, Voyager 1 flew over Enceladus (distance 41.567 km). At 23:46:30 on the same day, Voyager 1 reached Saturn's near arch (the closest point to the center of celestial gravity), when it was 126, 000 kilometers from Saturn's cloud top.

Voyager 1 photographed Saturn's rings on November 13, 1980, when it was 1.5 million kilometers away from Saturn. Photo: on November 13, NASA / JPL1980, Voyager 1 flew over Enceladus (8.844 km), Enceladus (20.204 km), Rhea (7.398 km) and Rhea (88.044 km) in the same day.

On November 12, 1980, Voyager 2 filmed Enceladus (left, 425,000 km) and Enceladus (right, 1.2 million km). In these images, Herschel crater (Crater Herschel) at the upper right of Enceladus and Ithaca Grand Canyon (Ithaca Chasma) above Enceladus are clearly visible. Source: NASA / JPL

On November 12, 1980, Voyager 2 photographed Enceladus (left, 240,000 km) and Rhea (right, 73,000 km). Many craters on their surface are clearly visible. Photo Source: NASA / JPL1980 November 14, 2006, Voyager 1's observation mission of the Saturn system ends. During the flyby of the Saturn system, Voyager 1 observed the chemical composition of Saturn's upper atmosphere, the complex structure of Saturn's rings, Saturn's aurora, Titan and several other previously identified moons. Five new moons of Saturn and Saturn's G rings were also discovered.

Voyager 1 photographed Saturn's rings on November 16, 1980, when it was 5.3 million kilometers away from Saturn. The sun shines on Saturn's shadow and casts its shadow on Saturn's rings. Image source: when NASA / JPL Voyager 1 flew over Titan at close range, Titan's gravity caused it to skim over Saturn's south pole and fly away from the ecliptic plane (the orbital plane of the earth is the ecliptic plane, and the orbital plane of other planets in the solar system is basically coplanar with the ecliptic plane), and then fly out of the solar system.

Family Photo and dim Blue Dot of the Solar system on February 14, 1990, Voyager 1, which has drifted in the open solar system for more than 12 years, is about 6 billion kilometers from Earth. At this time, it is 32 degrees above the ecliptic, suitable for photographing several planets in the solar system. The Voyager team gave orders to point it in the direction of the sun and took 60 pictures to form a family picture of the solar system. To avoid being overexposed by the sun, the exposure time of each photo is only 0.005 seconds.

This family photo shows Jupiter, Earth, Venus, Saturn, Uranus and Neptune in the solar system. Mercury is too close to the sun to be identified. Mars' position at the time made it only a crescent in Voyager 1's perspective, so it could not be identified.

Voyager 1 takes a family photo of the solar system on February 14, 1990. From left to right are JUPITER, EARTH, VENUS, SATURN, URANUS and NEPTUNE. ? photo Source: NASA / JPL in this set of family photos, the most famous is the image of the earth. In the picture of the earth, the earth is only a tiny bright spot of 0.12 pixels, almost overwhelmed by the colored band of light formed by the camera reflecting sunlight.

In the image of the Earth taken by Voyager 1 on February 14, 1990, the pale spot in the bright reddish band on the far right is our Earth. Source: NASA / JPL this photo aroused the deep thinking of the famous astronomer, astrobiologist, popular science writer and science fiction writer Carl Sagan,1934-1996. He called the Earth in the picture "dim blue dots" (Pale Blue Dot) and published the book "dim blue dots: looking forward to man's home in space" (Pale Blue Dot: A Vision of the Human Future in Space) in 1994.

In this book, Sagan said passionately, "think about that point again." That's here, that's home, that's us. At this point, everyone you love, everyone you know, everyone you've ever heard of, everyone, no matter who, will spend their lives here. "" Some people say that astronomy is humble and builds character. Perhaps nothing shows more about the stupidity of human conceit than this distant picture of our tiny world. For me, this photo underscores our responsibility to be friendlier to each other and to protect and cherish this bleak blue dot-the only home we know so far. " [note 1]

The marriage of the picture taken by Voyager 1 and the book written by Sagan gave the earth the nickname "dim blue dot". The name spread quickly and broke the circle, and became one of the most important entry points for human beings to think about the earth and the universe.

Flying out of the frontier of the solar system, astronomers launched the Voyager Interstellar Mission (VIM) for Voyager in 1989 after completing a mission to explore the exoplanet system. At that time, Voyager 1 was 40 astronomical units (1 astronomical unit 1.496 billion kilometers) from Earth.

VIM mainly detects phenomena related to the solar wind. VIM is divided into three stages: detecting terminal shock wave (Termination Shock), detecting heliospheric sheath (Heliosheath), and exploring interstellar space.

The heliosphere (heliosphere) is a huge bubble formed around the sun by solar wind (light gray area in the image below). Its boundary with interstellar space is the heliopause (Heliopause), where solar wind particles stop. When the solar wind blows near the top of the heliosphere, it will come into contact with the interstellar medium and be blocked by the interstellar medium to form a terminal shock wave, which is called the "terminal shock region".

At one end of the direction of solar motion, the area between the terminal shock region and the heliospheric top is shaped like a scabbard or sword scabbard, so it is called the heliospheric sheath.

Schematic diagrams of heliospheric layer, terminal shock wave, heliospheric sheath, heliospheric top, and bow shock. Photo Source: NASA / Goddard / Walt Feimer; Translation: Wang Shanqin, therefore, in the direction away from the sun, from inside to outside are the terminal shock region, heliospheric sheath and heliopause. The heliospheric top strikes the interstellar medium and forms a bow shock wave (Bow shock). According to some astronomers, interstellar space lies beyond the top of the heliosphere.

Voyager 1 surpassed Pioneer 10 on February 17, 1998, when it was about 69.419 astronomical units (about 104.1 billion kilometers) from Earth. Since then, it has been the farthest spacecraft from the sun.

On December 17, 2004, Voyager 1 entered the heliosphere sheath through the terminal shock zone. In June 2012, astronomers noticed a sharp increase in the number of high-energy particles received by Voyager 1 from interstellar space, so they judged that Voyager 1 was about to pass through the heliopause.

Voyager 1 passes through the heliosphere top on August 25, 2012, when it is 121astronomical units (about 181.5 billion kilometers) from Earth. Voyager 1 became the first spaceship ever to enter interstellar space on this day, according to some astronomers. [note 2]

To celebrate Voyager 1's arrival in interstellar space, astronomers took radio images of Voyager 1 using a very long Array (VLBA) on February 21, 2013.

Radio photos of Voyager 1 taken by the very long Array (VLBA) on February 21, 2013. Photo: NRAO / AUI / NSF as of February 18, 2023, Voyager 1 is 159.1 astronomical units (about 238.01 billion kilometers) from the sun. Now, its speed relative to the sun is 17 kilometers per second (3.57 astronomical units per year), which is much faster than the third cosmic speed (the speed to get rid of the sun's gravity and out of the solar system), so it will stay away from the sun. And will continue to move towards the center of the Milky way galaxy. It can also fly out of the Milky way and roam the universe outside the Milky way.

Gold discs sent to aliens to give potential aliens a chance to learn about Earth, astronomers placed a gold-plated copper disk 12 inches (30 centimeters) in diameter on Voyager 1 and 2. It records the location of the earth and human information. These two gold-plated copper plates are the famous "gold records".

The Golden record on Voyager 1. Photo Source: NASA / JPL Gold record includes greetings in 55 languages (including Mandarin, Cantonese, Hokkienese and Wu), 35 sounds of life on Earth, 90 minutes of "Earth Voice" (including whales, babies crying, waves crashing against the coast and 27 world famous songs on Earth). Among them are Chinese guqin music "running Water", Mozart's "Magic Flute", etc.) (including human mathematics, physics, the solar system and its internal planets, Earth animals, plants, DNA, human anatomy and reproduction, topography and scenery in parts of the earth, food, architecture, daily human life, etc.), as well as audio recordings of greetings from some politicians of the time.

The meaning of the message on the gold record? picture Source: the dumbbell shape of the solar system and 15 lines and the lower right corner of the NASA / JPL album cover is the same as the nameplates of Pioneer 10 and 11, its significance has been introduced in the article introducing Pioneer 10 ("exploring the Frontiers of the Solar system: pioneer 10, Planetary Journey"), and will not be repeated here.

In the upper left corner of the album cover are the drawings and stylus of the phonograph record. The binary symbol around it indicates the time of rotation of the record, from which it can be calculated that the time of rotation of the record is 3.6 seconds. Below the big circle is the side view of the record and stylus, which shows that it takes about an hour to play the record.

The upper-right corner of the album cover shows the waveform of the image signal, the binary symbol of the scanning time (8 milliseconds), and the method of drawing the lines that make up the image. The bottom indicates that if the decoding is correct, the picture is a circle.

Brilliant achievements and great sacrifices although Voyager 1 was not the first probe to detect the Jupiter and Saturn systems up close, it got better images of the two system members than Pioneers 10 and 11. In addition, it discovered Io's volcanic eruption, Jupiter's rings, Jupiter's eight new moons, Titan at close range, Saturn's G-rings, Saturn's five new moons, and so on. Its observations of the Jupiter system and the Saturn system have further deepened human understanding of the physical, chemical and even biological properties of these two gaseous giant planets, their moons and rings.

Voyager 1's "family photos" of Jupiter (top right), Io (top left), Europa (middle), Ganymede (lower left) and Callisto (lower right). These pictures are not taken from the same photo, but are made up of multiple photos. They are not proportional in size in the picture. Source: the meaning of the picture of the Earth ("dim blue dot") taken by NASA Voyager 1 during a long-distance roam goes beyond astronomy: after Sagan's contagious expression spread widely, this image of "dim blue dot" has become one of the important starting points for human philosophical thinking about the universe, the earth and human itself, giving people a direct understanding of the smallness, loneliness, fragility and value of the earth. It also gives mankind an intuitive understanding of the vastness of the universe.

In addition, Voyager 1 is the first man-made object to leave the solar system. It is also by far the farthest man-made celestial body from the earth. Because of its huge speed, all other man-made celestial bodies that have lifted off are unable to break its distance record.

Although Voyager 1 has made many outstanding achievements, it has paid its own price. Because it detects Titan at close range, its orbit changes significantly under the gravitational pull of Titan, making it impossible to travel to Uranus and Neptune after flying over Saturn. This is a plan that has been worked out from the very beginning.

At that time, the Voyager team even made a plan: if Voyager 1 failed to explore Titan, Voyager 2 would repeat Voyager 1's mission. We are lucky that Voyager 1 successfully completed the exploration plan of Titan, so that Voyager 2 can achieve the mission of exploring Uranus and Neptune, thus basically realizing the previously ambitious planetary tour. In other words, Voyager 2's feat of accomplishing "Planetary Journey" should feel the sacrifice and accomplishment of Voyager 1.

Annotation

[note 1] original text: "Consider again that dot. That's here, that's home, that's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. "" It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known. " Readers interested in other paragraphs can go to the following link: https://www.goodreads.com/ quotes / 337712-from-this-distant-vantage-point-the-earth-might-not-seem.

[note 2] astronomers dispute the boundaries of interstellar space. Some astronomers believe that the heliopause is not the dividing line between the solar system and interstellar space. This is because astronomers believe that there are a large number of small celestial bodies orbiting the sun further away, forming a region called the Oort cloud. If the outer edge of the Oort Cloud is used as the frontier of the solar system, Voyager 1 will need to fly for nearly 30,000 years to leave the boundary of the solar system and enter interstellar space.

[note 3] for the distance between Voyager 1 (and Voyager 2) and other information, see:

Https://voyager.jpl.nasa.gov/mission/status/

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