Planck's Mission ―― Excavating "Creating Relics"
Before the Planck satellite, humans launched spacecraft to investigate the microwave background of the universe. The cosmic background detector was launched in1989165438+1October 18, and the anisotropy of the cosmic microwave background was determined. The microwave background radiation map of the whole sky universe taken by this satellite is a "baby photo" of the universe when it was only 380,000 years old. It faithfully reproduces the oldest radiation phenomenon in space at that time and directly connects human beings with the early universe. Unfortunately, the "cosmic background detector" lacks enough resolution to answer some important questions and can't provide some missing details for cosmologists. The wilkinson microwave anisotropy probe, launched on June 30th, 20001year, measured the cosmic microwave background in more detail, but its resolution is still not high enough to answer all the questions in people's minds. Therefore, scientists need to do further fine measurement and accurate research on the cosmic microwave background radiation.
According to the most influential "Big Bang" theory in modern cosmology, our universe was produced by a very small point explosion about 65.438+0.37 billion years ago, and the universe is still expanding. This theory has been confirmed by a large number of astronomical observations, but it has not solved the problems of the shape, structure and future of the universe. In May 2004, American Physical Review magazine published Neil, an astrophysicist at Montana State University. Professor Cornish's new research work is to use the data of cosmic microwave background radiation to find evidence that the universe is like a spherical mirror room. He believes that multiple national images of the same object in the universe can be presented in different places in time and space. The mirror room effect may mean that the universe is finite, but it produces the feeling that the universe is infinite. Cornish said: "There is no indication that the universe is finite, but this does not prove that it is infinite."
It seems that to solve the mystery of the origin and evolution of the universe, it is necessary to deeply study and analyze the clues hidden in its early microwave radiation. Scientists are eager to get clearer images of celestial background radiation, so as to confirm the prediction of photon polarization in background radiation in the theory of "cosmic inflation", better analyze and judge the properties of the early universe, such as the density of protons and electrons, the energy distribution between matter and radiation, and eliminate the differences in the theory of cosmic evolution. All this is waiting for the launch of a new generation of cosmic microwave background radiation detection satellite "Planck".
The uniqueness of "Planck"
Planck satellite program originated from two research projects put forward by the European Space Agency in 1994, which were originally called "cosmic background radiation anisotropy satellite" and "background anisotropy measurement satellite" respectively. Because of the similar goals, 1996 was merged into an exploration mission and named after the famous German scientist Planck.
The main structure of Planck satellite is cylindrical, with a height of 4.2 meters and a maximum diameter of 4.2 meters. The launch mass is about 1.9 tons, including service cabin and payload cabin. The service cabin is equipped with power supply, attitude control, data processing and communication systems, and scientific instruments with low temperature requirements; Payload cabin includes telescope, optical console, some instruments that need cooling and cooling system.
Detect the temperature of the universe
"Planck" satellite will search the whole space, study the cosmic matter, and measure the subtle changes of the radiation temperature of the cosmic microwave background with unprecedented accuracy, because the temperature difference reveals the density differences in different areas of the early universe, and the high-density areas will eventually form the large-scale structures of the universe such as galaxies or galaxy groups that we see today, helping astronomers develop and verify the existing cosmological theories. In order to accomplish this task, Planck satellite carried a telescope with a diameter of1.5m. By using high-sensitivity sensors named "low-frequency instrument" and "high-frequency instrument" placed in the cabin, the telescope can collect cosmic microwave background radiation, and its instantaneous sensitivity is more than 10 times higher than that of "cosmic background detector".
Carrying the coldest detector
In order to accurately measure the temperature of microwave background radiation, the detector on Planck satellite must be cooled to near absolute zero. The low frequency instrument developed by the French Institute of Astrophysics works at -253℃. The high frequency instrument developed by the Italian Institute of Extraterrestrial Radiation Technology runs at -272.9℃. In order to keep the instrument at such a low temperature, technicians adopted a complicated cooling system. The black shielding plate installed on the surface of the satellite is actually an effective radiator, which can cool the detector to 60 K; Then the hydrogen adsorption cooler can cool the detector to 20 K; Then the detector is cooled to 4k by a mechanical cooler; Finally, the detector is cooled to about1100mk by mixing normal helium and rare helium isotopes.
Have the sharpest "vision"
The angular resolution of Planck satellite is higher, which is more than 50 times higher than that of Cosmic Background Detector. The satellite can draw a cosmic microwave background map with an angular resolution over 10 arc minute, determine the spatial curvature of the universe, and distinguish the temperature difference of one millionth degree in a certain sky area. Moreover, the drawn cosmic microwave background map can automatically remove the spectral radiation from the cosmic background signal from the galaxies outside the galaxy.
More than one million kilometers away from the earth.
The Planck satellite will be separated from the Ariane -5 rocket shortly after launch. After 4-5 months of launch, the satellite will maneuver, reach L2 of the Sun-Earth system directly, and enter the Lissajous orbit around L2. The orbital period of the satellite is about 6 months and the design life is 2 years.
L2 is actually an imaginary point in space, which is about 1 15× 106km away from the earth. When the satellite is in L2 environment, it can maintain stable radio communication with the Earth and ensure uninterrupted observation time, so L2 becomes the best site selected by the international astronomical observation plan.
The European Space Operations Center in darmstadt will communicate with satellites through the Novos ground station near Australia. The satellite around L2 has three hours to get in touch with the ground every day, when the scientific data recorded the day before will be sent back to the ground, and the instructions for the next autonomous control period will be transmitted to the satellite.
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Max. Planck (1858 ~ 1947) is a great physicist in modern Germany and the founder of quantum theory. Planck's most important achievement in physics is to put forward the famous Planck radiation formula and create the concept of energy quantum. At the end of 19, when people explained the blackbody radiation experiment with classical physics, the famous so-called "ultraviolet disaster" appeared. Although Riley? Jenkins (1877 ~ 1946) and Wayne (1864 ~ 1928) put forward two formulas respectively, trying to find out the law of blackbody radiation, but compared with the experiment, Rayleigh? Jenkins formula only applies to the low frequency range, and Wien formula only applies to the high frequency range. Planck systematically studied thermal radiation from 1896. After several years of hard work, he finally deduced a formula that was consistent with the experiment. He published a three-page paper entitled "On the Perfection of Wien Spectral Equation" in the Bulletin of the German Physical Society in late 1900 10, and put forward the blackbody radiation formula for the first time. On February 4th, 65438+65438, at the regular meeting of the German Physical Society, Planck gave a report on the energy distribution in the normal spectrum. In this report, he excitedly expounded his most amazing discovery. He said that in order to get the correct radiation formula in theory, it must be assumed that the energy radiated (or absorbed) by matter is not continuous, but one after another, which can only be an integer multiple of a certain minimum value. This minimum value is called energy quantum, and the radiation frequency is the minimum value of energy of V ε=hν. Among them, H Planck called it the fundamental action quantum at that time, and now it is called Planck constant. Planck constant is the most important physical constant in modern physics, which indicates that physics has changed from a "classical larva" to a "modern butterfly". 1906, Planck systematically summarized his work in the book "Lecture on Thermal Radiation", which provided an important foundation for opening up a new way to explore the laws of microscopic matter movement.
19 18 Planck won the Nobel Prize in Physics.