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

Pioneer 10 is the first probe to successfully detect Jupiter at close range, and it is also the first probe to successfully detect exoplanets (Jupiter, Saturn, Uranus and Neptune). Its success has accumulated valuable experience for subsequent exoplanet probes. Mankind has entered the era of exoplanet exploration, its starting point is Pioneer 10, "Pioneer" well-deserved. Its success has created the first oasis in the desert in the field of exoplanet exploration.

After the launch of the satellite, humans began to launch unmanned probes to detect planets in the solar system at close range. Among these planets, the exploration of "exoplanets" (Jupiter, Saturn, Uranus and Neptune) is more challenging because, first, they are farther than the "inner planets" and therefore require more powerful rockets and more advanced orbital control technologies; second, because they are farther away, the radiation of the sun near them is weaker, so other sources of energy other than solar cells are needed to power the instruments.

Mankind has not retreated because of these difficulties. Through the cooperation of scientists and engineers, mankind finally successfully launched a series of detectors, realized the great feat of close detection of four exoplanets, and made a qualitative leap in the understanding of exoplanets. Pioneer 10 (Pioneer 10) is the first in this series of detectors, and the first to be successful.

Pioneer 10 and the artistic imagination of Jupiter. Source: Rick Guidice Origin: an once-in-a-century opportunity in 1964, Gary Flandro,1934-, an aerospace engineer at NASA's Jet Propulsion Laboratory (JPL), pointed out that in the late 1970s, Jupiter, Saturn, Uranus and Neptune were on the same side and almost in line. If the probe could be launched in that direction a few years in advance, the probe could pass the four giant planets in turn around 1980 and detect them closely by flyby.

With this scheme, the probe can not only fly by four exoplanets in turn, but also increase the speed of the probe by the gravitational acceleration effect of each exoplanet, thus saving a lot of fuel and nearly half of the flight time.

This happens only once every 175 years, so this opportunity is very precious. To this end, NASA launched a program to explore exoplanets. After discussion, experts initially plan to launch four probes, two of which explore Jupiter, Saturn and Pluto, and two explore Jupiter, Uranus and Neptune. This is the famous "Planet Tour" (Planetary Grand Tour) project. [note 1] Pluto was also among the "nine planets" at the time, so it was also one of the core observation targets of the "planetary tour" project.

In order to provide valuable experience for the Zhuangyou project, NASA's Ames Research Center (ARC) proposed the Galactic Jupiter probe (Galactic Jupiter Probes) project in 1964. The project will launch two identical probes to cross the asteroid belt and explore Jupiter. Of the two detectors, one acts as a backup for the other-if one fails, the other completes the former's task.

In February 1969, NASA approved the project. The two probes of the project were named Pioneer 10 and Pioneer 11 shortly before their launch. They started numbering from "10" because NASA has launched several pioneer probes since 1958, and their numbers are 0, 1, 2, 3, 4, Pmur1, Pmur3, 5, Pmur30, Pmur31, 6 (A), 7 (B), 8 (C), 9 (D) and E. These probes were used to explore the moon and to study the properties of the sun, with some successes and some failures.

Pioneer 10 and Pioneer 11 were initially numbered F and G. They are the first and second probes in the pioneer series to explore exoplanets, respectively. All Pioneer series probes are operated by ARC's Pioneer team.

An artistic imagination of the shape of Pioneer 6-13. On the far left are Pioneers 6, 7, 8 and 9, the second on the left are Pioneers 10 and 11, and the third and far right are Pioneers 12 and 13, respectively. Image source: NASA structure and instrument Pioneer 10 is an unmanned spacecraft. It has the following important components: power supply, propulsion and attitude control system, scientific instruments and antennas.

In order to solve the problem of solar energy shortage in the outer solar system, Pioneer 10 installed four radioisotope thermal motors (radioisotope thermoelectric generators,RTG) using compressed plutonium-238 oxide spheres, so the power supply is also known as plutonium nuclear batteries. They are placed on two three-bar trusses with an angle of 120 degrees, far enough from the instrument on the detector, like two tentacles protruding from a snail. At the time of launch, the heat generated by the RTG can produce about 155W of electric power. Due to the decay of radioactive material, the power of RTG will continue to decline, but when flying to Jupiter, its output power is still 140W, while the normal operation of the detector only needs 100W.

Two of the four radioisotope thermomotors of pioneers 10 and 11 were placed on an extension truss. Image source: https://history.nasa.gov/ SP-349 / ch3.htm Pioneer 10 is equipped with six MR-103 hydrazine thrusters, which are matched in three pairs to change speed, control attitude and adjust rotation speed. The 36kg propellant inside the thruster is packed in a spherical box with a diameter of 42 centimeters.

The instruments on Pioneer 10 are: helium vector magnetometer (Helium Vector Magnetometer,HVM), four-spherical plasma analyzer (Quadrispherical Plasma Analyzer), charged particle equipment (Charged Particle Instrument,CPI), cosmic ray telescope (Cosmic Ray Telescope,CRT), Geiger tube telescope (Geiger Tube Telescope,GTT), capture radiation detector (Trapped Radiation Detector,TRD), meteoroid probe (Meteoroid Detectors), asteroid / meteoroid probe (Asteroid / Meteoroid Detector) AMD), ultraviolet photometer (Ultraviolet Photometer), imaging polarization photometer (Imaging Photopolarimeter,IPP) and infrared radiometer (Infrared Radiometer).

Figure: the structure diagram of Pioneer 10 (also Pioneer 11). What is not marked in the middle of the main antenna (high gain antenna) is the medium gain antenna. Photo: NASA,Vectors by Mysid; Wang Shanqin Translation Pioneer 10's radio communication system includes a parabolic high-gain antenna with a diameter of 2.7m and a medium-gain antenna. The antenna is used to receive the signal instructions sent by the deep space network station (DSN) on Earth and to send the obtained data to the DSN.

According to the name of the instrument, we will find that most of them will be used to detect cosmic rays, various charged particles, plasmas, magnetic fields, meteors and asteroids. The rest of the equipment is responsible for taking ultraviolet, visible and infrared images.

The imaging polarization photometer on Pioneer 10 consists of a small telescope with an aperture of only 2.54 centimeters (1 inch) and two detectors. The two detectors match the red filter and the blue filter respectively. After entering the telescope, the light passes through the filter and then images on the detector. By combining the images obtained by the two detectors, the almost real color of the target can be synthesized.

After all the instruments and spare parts are installed, Pioneer 10 has a length of 2.9 meters (from the gain antenna to the tail of the ship) and a maximum diameter of 2.7 meters (that is, the diameter of the high-gain antenna). Before launch, Pioneer 10 had a mass of 258 kilograms.

Pioneer 10, which is nearing completion. Photo: NASA Ames Research Center Pioneer 10 launches on March 3, 1972 (UTC), when the Pioneer 10 launches on an Atlas-Centaur rocket. The rocket has customized a powerful third-stage solid motor for Pioneer 10, which can accelerate the probe to 14.4 kilometers per second, which is one of the important guarantees that Pioneer 10 can fly to Jupiter.

Pioneer 10 was launched on an Atlas-Centaur rocket. Image source: NASA Ames Resarch Center (NASA-ARC) because of its high speed, Pioneer 10 entered interplanetary space in only 19 minutes (the space between planets is called interplanetary space; the space between stars is called interstellar space; the two are not the same and should not be confused). Eleven hours later, Pioneer 10 passed through the moon and became the fastest man-made celestial body so far.

The rocket also rotates Pioneer 10 around the symmetrical axis of the high-gain antenna at a speed of 60 revolutions per minute. As the three trusses (the third truss is used to hold the helium vector magnetometer) protrude, its speed drops to 4.8 revolutions per minute, and it continues to rotate at that speed. One purpose of rotation is to control stability, and the other is to enable the detector to change the direction of the telescope or detector near the target area for a wider range of imaging or measurement.

Within 10 days of launch, the instruments on Pioneer 10 were activated successively. While traveling through interplanetary space, Pioneer 10 became the first probe to detect interplanetary helium atoms and detected high-energy aluminum and sodium ions from the solar wind.

The artistic imagination of Pioneer 10. Image: just 12 weeks after the launch of NASA / Don Davis, Pioneer 10 passed through the orbit of Mars and flew toward the asteroid belt between Mars and Jupiter. There are a large number of asteroids here, hence the name.

On July 15, 1972, Pioneer 10 entered the asteroid belt, becoming the first spacecraft to enter the asteroid belt.

On August 7, 1972, Pioneer 10 detected a shock wave generated by a violent solar wind burst at a distance of 2.2 astronomical units (3.3 billion kilometers) from the sun, providing important data for the study of solar physics.

Pioneer 10 was not hit by large dust particles during its passage through the asteroid belt, indicating that the interior of the asteroid belt is very empty. During this period, Pioneer 10 accurately determined the density of dust particles of different sizes in the asteroid belt and measured the intensity of light ("zodiacal light") formed by scattering sunlight by dust particles in interplanetary space.

On February 15, 1973, Pioneer 10 safely crossed the asteroid belt to Jupiter, by which time it had flown about 435 million kilometers.

Pioneer 10 flew by the Jupiter system on November 6, 1973, and Pioneer 10 was 2500 kilometers from Jupiter. The Pioneer team issued instructions to begin testing its imaging system, and then successfully obtained an image of Jupiter. As it approached Jupiter, it photographed a large number of crescent-shaped Jupiter; as it was about to enter Jupiter's shadow, it saw the "crescent moon" getting thinner and thinner.

Jupiter was photographed several times during Pioneer 10's approach to Jupiter, showing a phenomenon similar to that of the lunar phase. Image source: on November 26, NASA1973, the number of solar wind particles detected by Pioneer 10 decreased sharply, and the temperature increased about 100 times, meaning it reached the edge of Jupiter's magnetosphere and began to enter Jupiter's magnetosphere. At the edge of Jupiter's magnetic field, the solar wind strikes the magnetosphere, forming a bow shock wave; the magnetosphere blocks the solar wind, which greatly reduces the speed of the solar wind. On this day, the Pioneer team received 12 images of Jupiter taken by Pioneer 10. A day later, Pioneer 10 passed through Jupiter's magnetopause.

On November 29, 1973, Pioneer 10 passed through the orbit of all Jupiter's outer moons. Starting on December 1, Pioneer 10, close enough to Jupiter, took pictures of Jupiter that surpassed the best image quality available to telescopes on Earth at the time.

On December 3, 1973, Pioneer 10 began flying over the Jupiter system. It flew over Callisto (distance 139.23 million km), Ganymede (distance 44.625 million km), Europa (distance 321,000 km) and Io (distance 357,000km) at 12:26:00, 13:56:00, 19:26:00 and 22:56:00 of the day, respectively.

The trajectory of Pioneer 10 from December 2 to 6, 1973 and the position of Jupiter and its four moons when it flew over the Jupiter system on December 4, 1973. Image source: Tomruen; Wang Shanqin translates images of Ganymede taken by Pioneer 10 showing lower albedo in the center and near the South Pole and brighter North Pole.

Pioneer 10 shot Ganymede on December 3, 1973. Image source: NASA Pioneer 10 is always too far away from Europa, so people can't analyze enough detail from its images. However, the images still show that Europa's overall albedo is relatively high and has some wide dark areas. These characteristics were further confirmed by other detectors later.

An image of Europa taken by Pioneer 10 on December 3, 1973. Image: 02:26:00 on December 4, NASA1973, Pioneer 10 reaches its near wood point (the closest point in the object's orbit around Jupiter), 13.2252 kilometers from Jupiter's cloud top. At this point, its speed is 35 kilometers per second. Ten minutes later, Pioneer 10 crossed the equatorial plane of Jupiter. About 78 minutes later, it entered behind Jupiter (relative to the direction of Earth's line of sight at that time) and conducted a radio masking experiment.

Jupiter was photographed during Pioneer 10's flyby. The black dot in the picture is the projection of Io. Source: NASA during its proximity to Jupiter, Jupiter's radiation intensity to Pioneer 10 was about 10 times the expected intensity. The strong radiation seriously interfered with several instruments of Pioneer 10, causing them to temporarily fail, and led to a large number of instruction errors. Fortunately, the radiation intensity suddenly dropped a few minutes before the system was about to be completely scrapped, and the Pioneer team corrected most of the wrong instructions through emergency commands.

Since then, the Pioneer team analyzed the reason for the sudden drop in radiation and found that Jupiter's magnetic field is a circumferential magnetic field around the equator and wobbles. This made Jupiter's magnetic field stop hanging over Pioneer 10 at some point, and the latter narrowly escaped death.

Although Jupiter's strong radiation interfered with Pioneer 10, six of the 11 instruments were still working, and the imaging system sent back about 500 images of Jupiter and some of its moons to Earth. The highest resolution of these images is 320 kilometers per pixel.

On January 1, 1974, Pioneer 10 ended its mission to explore the Jupiter system and began its interstellar mission. [note 2] on March 31, 1997, the Pioneer completed all missions on the 10th.

Pioneer 10 was once the farthest man-made body from the sun. Voyager 1 surpassed Pioneer 10 on February 17, 1998, when the two were about 69.419 astronomical units (104.1 billion kilometers) from Earth. Since then, Pioneer 10 has been the second farthest man-made body from the sun. In April 2023, Voyager 2 will overtake Pioneer 10, making it the third-farthest man-made object from the sun.

On April 27, 2002, the ground received its data for the last time, when it was 80.22 astronomical units from Earth. On January 23, 2003, the ground received its weak signal for the last time. On February 7, 2003, it could not be reached from the ground.

A gold-plated aluminum plate containing some important information is placed on Pioneer 10, a metal plate for aliens. This is the first time that humans have placed an information card on the probe to let aliens know the information about the earth. Since then, Pioneer 11, Voyager 1 and Voyager 2 have adopted a similar scheme, in which the brand on Pioneer 11 is exactly the same as that on Pioneer 10. [note 3]

The brand on Pioneer 10 weighs about 120 grams, and its width, height and thickness are 22.86 cm, 15.24 cm and 1.27 mm, respectively.

The nameplate carried on Pioneer 10. Source: at the top left of the NASA brand is a picture of the super-fine structure transition of the hydrogen atom. When the spin direction of the electrons of a hydrogen atom changes, the period of the photons emitted is 0.704 nanoseconds, and 1 nanosecond is equal to 1 billionth of a second. This information allows aliens to understand one of the ways in which humans measure time. At the midpoint of the line between two hydrogen atoms, there is a very short vertical line, which represents the binary 1.

The center of many lines on the left side of the sign represents the solar system. The longest line extending from this center to the right represents the relative distance between the sun and the center of the Milky way; the other 14 lines scattered from the center represent the relative distance between the Earth and 14 pulsars. These 14 lines are made up of binary numbers that represent the rotation period of the corresponding pulsar. Aliens can find the corresponding pulsar through the cycle, thus determining the location of the solar system.

The portraits on the sign represent the contours of adult men and women on the earth. The man raised his right hand as a sign of friendship. The symbol on the parallel line between a woman's head and feet indicates a binary 8, indicating that the woman is about 8 feet (168 centimeters) tall. Part of the overlap with the portrait is the outline of Pioneer 10, which is strictly proportional to the size of the person.

At the bottom of the sign is the solar system, and from left to right are the Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto; the curve represents the trajectory of Pioneer 10: from Earth, fly by Jupiter and leave the solar system. The symbols above or below the planets represent the binary number of their relative distance from the sun, in units 0.1 times the average radius of Mercury's orbit.

A nameplate placed on Pioneer 10. Image source: NASA / HQ Pioneer 10 is now heading towards the star Aldebaran Aldebaran (Alpha Taurus). Aldebaran is a red giant about 65 light-years from the solar system (nearly 10 trillion kilometers a light-year), and Pioneer 10 takes more than 2 million years to reach it.

In 2019, someone used data on the position, speed and direction of stars from the Gaia satellite to infer more "optimistic" results: in about 90,000 years, Pioneer 10 will fly by the dwarf star HIP 117795, the closest light-year away; this is the closest star it will encounter in the next few million years. However, 0.75 light-years is about 50,000 times the distance between the earth and the sun (150 million kilometers), and the alien planet cannot be that far away from the parent star. So it will take longer for Pioneer 10 to be intercepted by aliens, if any.

The moon covers Aldebaran. Image source: Christina Irakleous is fruitful and significant. Pioneer 10 created many firsts: it was the first probe to detect an exoplanet, it was the first probe to pass through the asteroid belt, it was the first probe to explore the Jupiter system at close range, it was the first man-made celestial body to reach the third cosmic speed so that it could leave the solar system, and it was the first probe to use a nuclear battery. It is the first exoplanet probe to achieve gravity-assisted acceleration and orbit change, and so on.

Its exploration of Jupiter has realized the dream of observing Jupiter at close range and achieved fruitful results. From the beginning of the observation to the end of the observation, in nearly 60 days, the Pioneer team issued about 16000 instructions for Pioneer 10 to carry out various observation tasks. During this period, it passed through the bow shock waves of Jupiter's magnetosphere 17 times, took about 500 images of Jupiter and its moons, and measured or observed various properties of Jupiter, such as magnetosphere, radiation belt, magnetic field, atmosphere, gravitational field, and so on. it has greatly deepened man's understanding of Jupiter's system and opened a precedent in all aspects of Jupiter's research.

The success of Pioneer 10 has accumulated valuable experience for probes such as Pioneer 11 (exploring Jupiter and Saturn), Voyager 1 (exploring Jupiter and Saturn), Voyager 2 (exploring Jupiter, Saturn, Uranus and Neptune), Galileo (probing Jupiter), Juno (probing Jupiter), Cassini-Huygens (probing Saturn and Titan) and New Horizon (probing Pluto). To be their forerunner.

In order to commemorate the contribution of Pioneer 10, the United States Postal Service issued a commemorative stamp with Pioneer 10 as the theme on February 10, 1975.

The Pioneer 10 stamp issued in 1975. Image source: US Post Office; Hi-res scan of postage stamp by Gwillhickers Pioneer 10 ushered in the era of human exploration of exoplanets, creating the first oasis in the desert of exoplanet exploration. Since then, with the success of other exoplanet probes, more oases have emerged.

Annotation

[note 1] the English word Grand Tour originally means that Europeans or Englishmen patrol the whole European continent, which corresponds to the Chinese word for "Zhuang you".

[note 2] as early as when it was out of the asteroid orbit, the Pioneer team had chosen a path so that it could accelerate and change its orbit and leave the solar system with the help of the "gravitational slingshot" effect produced by Jupiter's strong gravity. Pioneer 10 made this plan when it flew over Jupiter, making it the first exoplanet probe to achieve gravitational acceleration.

[note 3] the idea of placing metal plates on Pioneers 10 and 11 was first proposed by Eric Boggs (Eric Burgess,1920-2005). He hopes that advanced intelligent life (aliens) will intercept probes roaming in space in the future, know through the brand that there is another group of intelligent life living on the earth in the solar system, and know the information about the earth and human beings. Boggs shared the idea with Carl Sagan (Carl Sagan,1934-1996). Sagan was so interested in the idea that he formally applied to NASA to implement the plan. NASA approved the idea. Sagan worked with Frank Drake (Frank Drake,1930-2022) to design the brand. The illustrations on the sign were carried out by Linda Salzman Sagan,1940-, Sagan's wife at the time.

[note 4] the wavelength of the electromagnetic wave generated by this transition is 21.106 cm, the frequency is 1420.405 MHz, and the corresponding period is 0.704 nanoseconds.

[note 5] Bailer-Jones, Coryn A. L. & Farnocchia, Davide, Future Stellar Flybys of the Voyager and Pioneer Spacecraft, Research Notes of the American Astronomical Society, 2019, 3, 59. For an extended version of this paper, see arXiv:1912.03503 (https://arxiv.org/ abs / 1912.03503).

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