Schematic diagram of Hubble space telescope
The telescope was named after Edwin Hubble because Hubble discovered the expansion of the universe in 1929. The purpose of scientists developing this telescope is to observe the edge of the universe and help find the answers to some of the deepest questions of mankind.
According to the data, the Hubble Space Telescope is the largest telescope put into orbit. The total length of the telescope is 12.8m, the diameter of the lens barrel is 4.28m, the diameter of the main mirror is 2.4m, the shell diameter is 3m, and the total weight is about11.5t. This is a complete space observatory with excellent performance. With its help, we can observe the light emitted by the universe 65.438+0.4 billion light years away. It can observe any star in the constellation alone; It can study and determine the size and origin of the universe, as well as the age and distance scale of the universe; It can also analyze extragalactic galaxies, determine the distance between planets and galaxies, study planets, black holes, quasars and the solar system, and draw a map of the universe and a meteorological map of planets of the solar system.
Experts pointed out that the telescope consists of three parts, the first part is an optical part, the second part is a scientific instrument, and the third part is an auxiliary system, including two solar panels with a length of 1 1.8m and a width of 2.3m, which can provide 2.4kW of power and two parabolic antennas for communication with the ground. The front of the lens barrel is the optical part, and the back is the annular cabin. In this cabin, a group of scientific instruments are placed on the focal plane of the telescope's main mirror, and the solar panel and antenna protrude from the middle of the cylinder.
The optical part of the telescope is the heart of the whole instrument. It is composed of two hyperboloid mirrors, one is the primary mirror with a diameter of 2.4m, and the other is the secondary mirror with a diameter of 0.3m, which is installed about 4.5m in front of the primary mirror. The light projected on the primary mirror is first reflected on the secondary mirror, and then emitted from the secondary mirror to the central hole of the primary mirror, passing through the central hole and reaching the focal plane of the primary mirror, forming high-quality images for various scientific instruments to carry out precise processing, and the obtained data are transmitted back to the ground through the relay satellite system.
In addition to the optical part, another main part of the telescope is eight scientific instruments installed on the focal plane of the main mirror, namely:
(1) wide-field planetary camera.
It has high sensitivity and extremely wide observation band, from ultraviolet to infrared; You can not only observe the planets in the solar system, but also observe the Milky Way and extragalactic galaxies. The photos are very clear.
(2) dim celestial cameras.
It is two independent and similar complete celestial bodies and detection systems, which can detect stars as dark as 23~29.
(3) Dark and weak celestial spectrograph.
It can be used for spectral analysis of radiation from ultraviolet to near infrared band, and can also measure their deflection.
(4) High resolution spectrograph.
It can observe the ultraviolet spectrum, and can observe darker and farther celestial bodies.
(5) High-speed photometer.
It can accurately measure celestial bodies in visible and ultraviolet bands, determine the photometric standard of star targets, and further identify celestial bodies observed by people in the past.
(6) Precision-guided remote sensor.
There are three precision-guided remote sensors on the telescope, which are used for the telescope orientation system and the precise measurement and positioning of celestial bodies.
In fact, these scientific instruments were equipped for the telescope in the first few years of its operation. In order to make the space telescope make full use of the latest technological achievements, these instruments on the focal plane are designed to be combined and replaced in various ways. Telescopes can be repaired and replaced by astronauts on the space shuttle during operation. If necessary, the whole telescope can also be transported back to the ground by the space shuttle for overhaul and then put into orbit. According to the design requirements, the life of space telescope is at least 15 years, and it is estimated that it can actually reach several decades.
When it was found that the observation distance of the telescope was not far enough, the excitement caused by the first celestial image suddenly turned into extreme worry. The telescope that was originally expected to observe1400 million light years can only observe 4 billion light years now! Later, it was found that the edge of the main lens was worn too flat, and it was worn off by 0.25 mm To make matters worse, every time the solar panel crosses the boundary between day and night (90 minutes), it will bend, resulting in blurred vision images jumping. As a result, various descriptions of the bad situation were added to the Hubble telescope, and critics even began to question whether NASA should continue to exist.
Three years later, NASA overhauled the seriously ill Hubble telescope, costing $250 million and lasting 1 1 day. Astronauts installed corrective optical components called "eyes" and inflexible solar panels to prevent the image from jumping. In addition, an improved camera was installed.
The following February, 1997, NASA carried out the second maintenance at a cost of $350 million. This time, the astronauts installed two new instruments, which improved the data collection ability of the telescope by nine times. A near-infrared camera and a multi-celestial spectrograph extend the telescope's capability to the infrared range longer than the wavelength of visible red light in the electromagnetic spectrum. The other is the imaging spectrometer of the space telescope, which is called the "color vision" of the Hubble telescope. Different from the previous spectrograph, it can observe as many as 5 12 different celestial bodies at a time and find clues to determine the composition, speed and temperature of these celestial bodies.
In order to expand the data storage capacity, NASA also installed a solid-state tape data recorder. Compared with the technology used before, these new instruments have artificial intelligence and can work together or with other cameras originally installed on the telescope. Simultaneous imaging at different wavelengths is very beneficial for astronomers to study a celestial body more deeply.
Facts have proved that "Hubble" does provide a lot of basis for human exploration of space. First of all, Hubble helped solve some problems that have puzzled astronomers for a long time, and derived a new overall theory to explain these results. One of Hubble's main tasks is to photograph butterflies with the Hubble Space Telescope.
Hubble telescope will have a far-reaching impact on the study of black holes.
Nebula can measure the distance of Cepheid variable more accurately than before, which allows us to determine the numerical range of Hubble constant more accurately, so as to have a more correct understanding of the expansion rate and age of the universe. Before the launch of Hubble, the statistical error of Hubble constant was estimated to be 50%, but after Hubble re-measured the distance of Cepheid variable in Virgo galaxy cluster and other distant galaxy clusters, the accuracy of the measured value could be within 10%. This is consistent with the results measured by other more reliable technologies after Hubble launch.
Hubble has also been used to improve the estimation of the age of the universe, and the future of the universe is also one of the questioned issues. Astronomers from the high redshift supernova search team and the supernova cosmology project used telescopes to observe distant supernovae and found that the expansion of the universe may actually be accelerating. This acceleration has been confirmed by Hubble and other ground-based telescopes, but the reason for the acceleration is still difficult to understand.
Hubble's high-resolution spectra and images clearly confirm the popular theory that black holes exist in galactic nuclei. In the early 1960s, it was only a hypothesis that black holes would be found in the cores of some galaxies. It was not until the 1980s that some galactic cores were identified as candidates for black holes. However, Hubble's work has made the core of galaxies a common cognition. In the future, the Hubble project will focus on the close relationship between the mass of black holes in the core of galaxies and the properties of galaxies. Hubble's research on black holes in galaxies will have a far-reaching impact on the relationship between the development of galaxies and the central black holes.
Schematic diagram of the space shuttle Columbia.
As an undeniable fact, the Hubble Space Telescope has reached an "advanced age". During more than ten years in space, it has undergone four overhauls, namely 1993, 1997, 1999 and 200 1 year. Although Hubble has taken on a brand-new look after each overhaul, especially in 200 1 year, scientists used the space shuttle Columbia for the fourth overhaul, installed a mapping camera, replaced the solar panel, replaced the power control device that had been working for 1 1 year, and activated the near-infrared camera and multi-target spectrometer in a "dormant" state.
In the near future, NASA will gather experts and astronauts from all walks of life to discuss when and how to let NASA's favorite son Hubble die. Although people are still reluctant to part with it, there is not much time left for Hubble, and it may be replaced by the "first line" this year or later.
At present, the United States is actively planning to develop a new generation of space telescopes to replace the Hubble telescope still in orbit. It is reported that the diameter of the primary mirror of the new generation telescope is 7.5 meters, the observation range is 4-6 times larger than that of Hubble, and the clarity is no less than that of Hubble. The new generation telescope is expected to weigh 3000 kg, while Hubble weighs 10000 kg. Making such a big and light lens requires a great breakthrough and progress in materials.
Hubble left a gap of 1 ~ 1 billion years when exploring the early universe. A new generation of telescopes will fill this gap, study the early universe and observe the formation of galaxies. "Hubble" specializes in observing the universe with short waves in ultraviolet and visible light, while the new generation of telescopes use the infrared part of the electromagnetic spectrum with longer wavelength to explore the universe in depth. Because the galaxy is far away from the earth during the expansion of the universe, the light it emits becomes red light with long wavelength and is transmitted to the earth in the form of infrared rays.
Experts pointed out that the new generation of telescopes will not orbit the earth like Hubble, but will stably occupy the orbit of about1.5000 km between the earth and the sun and outside the moon, making a telescope array. Experts predict that its final spatial resolution can be nearly 1000 times better than that of Hubble telescope.
As the successor of Hubble Space Telescope, which will end its observation activities in 20 10, it is planned to launch in 2010/year. However, the launch was rescheduled to 20 13 due to the impact of life extension measures such as the maintenance of Hubble Space Telescope.
Since the launch of the world's first space probe in 1959, human beings have successively launched probes and visited the moon, seven planets in the solar system, asteroids and comets. Some probes have also flown outside the solar system to reveal more distant mysteries of deep space, among which the investigation on the moon is the most detailed, and even astronauts have been sent to the moon for field investigation.
Schematic diagram of extraterrestrial galaxies
These probes have made great achievements, greatly expanded the range of human activities, uncovered many mysteries of the moon and planets of the solar system, answered many mysteries debated by astronomers in the past, and promoted the development of space science in a deeper and wider field.
The main purposes of detecting extraterrestrial planets are: to study the origin and present situation of the moon and solar system; Through the investigation and study of planets of the solar system and its satellites, the formation and evolution of the earth's environment are further revealed. Understand the evolution of the solar system and explore the origin and evolutionary history of life; Make use of the special environment of space to carry out various scientific experiments and directly serve the national economy.