The statements in this article are based on reliable sources and are repeated at the end of this article
According to its manufacturer, the world's largest digital camera has been officially commissioned and is ready to start traveling to the target location to shoot what it claims to be "the most realistic night sky ever." This is what not so long ago, American engineers and scientists announced the completion of the Space and Time Survey Camera (LSST), which is about three tons or more and looks like a car-sized tool, which is designed to capture new information about cosmic objects, as well as the nature of dark matter and dark energy. [Beer]
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Twenty years of exploration and construction
The project, which has been going from demonstration to finished product for about 20 years, is about to set off for the Vera Rubin Observatory at the top of the Cerro Pachón mountain in Chile, which rises to more than 2,700 meters above sea level. By the end of 2024, the Simeone Survey Telescope will be connected to the facility, and its twin five- and three-foot-wide lenses will begin a decade-long exploration of the sky, covering the solar system, the Milky Way, and beyond.
To achieve these ambitious goals, this supercam is more than just a simple enlarged version of a point-and-shoot digital camera. Although we don't usually see a physical shutter in the lens of a smartphone, in a DSLR camera, the shutter is an integral part. In contrast, the shutter speed of the LSST camera is relatively slow, which is one of the challenges it faces in achieving these goals.
This is because the camera is extremely slow and carefully controlled in reading data, a process that has been described by the scientists responsible for the design and construction of some of the camera's features, which takes only 2 seconds to read after a 15-second exposure. This slow-down processing allows the operator to deal with a lower level of noise floor, about 6 to 7 electrons, in order to capture the darker starry sky. In fact, this is also the difficulty of traditional astronomical observations.
"We need more efficient sensors so that we can tell what's actually dark in a dark sky and what's actually obscured by noise floor, so we can measure very faint objects in the sky," the design scientists explained. "During this 2-second reading, we need to block more light from entering the camera, which is why we have a specially designed special shutter. ”
To improve the operator's ability to capture dim object measurements in low-light environments, the research team took an innovative step to reduce the temperature of the LSST camera's focal area to extremely low temperatures, specifically -100°C or 173K, effectively suppressing the thermal motion of atoms in the area and optimizing measurement accuracy.
Cosmologists are preparing to use LSST cameras to explore the solar system in an unprecedented and comprehensive way. This ambitious research program is expected to increase our knowledge of known objects in the solar system tenfold, helping us unravel the mysteries of the origin of the solar system and enable real-time monitoring of any asteroids that could potentially threaten Earth's safety.
The person in charge of coordinating this cutting-edge project has emphasized that with the help of such tools, humanity can observe the universe more comprehensively and deeply than ever before, and thus broaden the understanding of fundamental physics. With the imminent launch of this project, humanity will hopefully open a new chapter in answering some of the most profound and impactful questions in the fields of physics and astronomy.
The reason for this reasoning is precisely because the data it can collect can be said to be "groundbreaking". Because of the unique characteristics of this data, we will be able to conduct a really in-depth study of the expansion of the universe and dark energy, said the deputy director of the Rubin Observatory and the head of the camera project, who told the reporters who went to interview, that data processing is also a difficulty, because of the terrifying pixel content, the data can be 20 terabytes in size in a day, which is a challenge for storage and analysis.
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Difficult design, transportation and installation
Although this camera can be used as a powerful assistant for scientists to solve the mystery of dark energy and the universe, it still has a long way to go before it is "fully realized". It will start from its laboratory in Menlo Park, California, and end at the observatory at the top of Cerro Pachón in the Andes Mountains, at an altitude of more than 2,700 meters. Later in 2024, the camera is expected to be securely hoisted from the top of the telescope to begin its journey into the universe.
However, its transportation problems are not only due to its large size, but also to the sophistication of its internal structure. The focal plane of the camera is made up of 201 highly customized CCD sensors closely aligned, each with a flatness of about 5 microns precisely controlled at one-tenth the width of a human hair.
It is important to know that the thickness of the ordinary A4 paper we use every day is usually between 50 and 100 microns, but the spacing between these sensors is extremely small, and it can be damaged due to any collision and contact. Therefore, during manufacturing and transportation, it has become a difficult task to ensure that these sensitive parts do not collide in any way.
Although the project team has tested the camera's intended transport path with a "quality simulant" consistent with its weight and shape. The simulator has a built-in accelerometer to simulate and measure the various stresses that will be applied to the LSST camera, especially during air transport to Chile.
The head of the laboratory said: "Although the results of this test project were extremely successful, we have made great efforts to reduce the uncertainty in the transportation process. Still, seeing it loaded onto a plane and shipped to Chile is worrying. ”
When the camera is successfully deployed in the environment it relies on, such as a cooling unit that lowers its image sensor to -100 degrees Celsius, it is up and running. Scientists then conduct a series of tests to ensure that the camera performs up to standard and that the entire telescope system works together.
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A new chapter in astronomy and the science of the universe
Although the project is not yet fully completed, and it is even expected that the first images will not be shown to the public until the spring of 2025, this is still something that researchers are looking forward to. Many people have been working on this project for more than a decade, and they are very enthusiastic about the results to come, and the camera and its first photos are already in the spotlight.
There are many people who may not understand this product, after all, we can now claim that the sensor on a small mobile phone can be called "100 million pixels", why such a "merely" 3.2 billion pixel camera, it will weigh several tons. That's because people don't really think about an order of magnitude of the problem. You think that 3.2 billion is 32 times that of 100 million, but in fact, if you want to improve a little later, you need hundreds of times thousands of times more piles, and the function is beyond everyone's imagination.
The completion of this machine marks a major breakthrough in the field of astronomical observation of large instruments. By repeatedly scanning the same sky, scientists are given the ability to accurately monitor all changes in the region over many years to come. With this technology, scientists will be able to capture transient events such as changes in brightness of supernovae, observe the bending of light from celestial objects beyond visual range due to the gravitational pull of matter, including dark matter, and track the increase in distances between galaxies.
In fact, this kind of work is also a lot of astronomical observation methods, including the continent of some high-level survey telescopes are used in this way, through the record of the same sky in the same sky different light and dark brightness performance, the trajectory of the stars, by studying the changes of these things in the orbit of "time", so as to analyze the laws of the movement of celestial bodies, and discover those phenomena that we cannot directly verify, such as those changes in waves and forces that we cannot directly observe.
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The difference between a large optical camera and a radio telescope
Some people may wonder what is the difference between this so-called largest astronomical camera and our world's largest telescope, known as the "eye of the sky". In fact, the difference between this is not small, for example, China's Tianyan FAST, located in Guizhou, with its amazing 500-meter aperture pride in the world, has become the world's largest single-aperture radio telescope, which is designed to focus on helping us receive radio signals from the universe.
Then, with its help, the human "gaze" was able to travel through the stars, capturing the faint radio signals in the depths of the universe. Whether it is searching for pulsars, delving into the mysteries of gas galaxies, searching for clues to cosmic microwave background radiation, or even searching for the call of extraterrestrial civilizations, FAST is leading the development trend of radio astronomy with its extraordinary sensitivity and wide frequency coverage.
The difference is the "astronomical camera" equipped with this superpixel. The combination of optical and near-infrared observation capabilities, as well as the wide field of view and ultra-high image resolution of the giant sensor, will reveal a magnificent picture of the universe, whether it is the dancing trajectory of an asteroid, the brilliant explosion of a supernova, or the violent explosion of an active galactic nucleus. Through the in-depth mining of massive data, it can provide new breakthrough insights for the study of cosmology, astronomy and physics.
The two can be described as focusing on the capture and study of radio signals, and the other focusing on large-scale astronomical monitoring and time-domain astronomy research in the optical and near-infrared bands. Although the two explore in completely different ways, they have the same goal in the end, jointly building a new chapter in human exploration of the universe. In the days to come, let's look forward to these astronomical tools to bring us more mysteries and surprises about the universe.
Resources:
Chinese Academy of Sciences - 3.2 billion pixels, the world's largest digital camera unveiled ---- Chinese Academy of Sciences
The Paper - The Vera Rubin Observatory is screening out two supermassive black holes from massive data