As the first satellite launched in the first phase of the space science pilot project of China Academy of Sciences, Wukong's design life was originally only three years, but until now, the 6-year-old Wukong is still full of vitality and continues to look into the depths of the universe for mankind.
At present, the space science experimental project has successfully launched seven scientific satellites. The integrated operation control center of scientific satellites in the National Space Science Center of Chinese Academy of Sciences is the "big housekeeper" of these scientific satellites on the ground.
China academy of sciences national space science center scientific satellite integrated transportation control center
Scientific satellite "remote control"
In the early morning of 20 15 12 17, Jiuquan Satellite Launch Center.
Sunglow is still hanging in the horizon, and the Long March II carrier rocket broke through the sky, successfully sending the "Wukong" satellite into the scheduled orbit.
In the The Journey to the West, the Monkey King can turn over 108,000 Li in a somersault, which is very eye-catching. The "Wukong" satellite certainly deserves its name.
"Wukong" satellite, full name of dark matter particle detection satellite, is one of the first four scientific satellites developed in the first phase of space science strategy pilot science and technology project of China Academy of Sciences, and it is also the dark matter particle detection satellite with the widest observation energy range and the best energy resolution in the world. It orbits the earth every 95 minutes and can observe 5 million high-energy particles in the universe every day.
Information picture.
Its length is 1.5m, its width is 1.5m, its height is 1.2m, and its overall mass is1.85t. In terms of volume, Wukong is not much bigger than a desk. But don't underestimate it. Wukong's small body is equipped with nearly 80,000 small detectors. These small detectors are Wukong's eyes, and the detection target is dark matter that accounts for more than a quarter of the universe but is invisible to human beings.
Of course, what Wukong collects and detects is not dark matter itself, but "clues" such as high-energy gamma rays, electrons and cosmic rays generated after dark matter particles collide. Researchers can indirectly find evidence of the existence of dark matter through scientific analysis of the collected data.
Once the high-energy particles "hit" the detector, the scientific data generated by them will be recorded and stored at the first time. When flying over China, Wukong will quickly establish communication links between heaven and earth with three ground stations located in Kashgar, Xinjiang, Sanya, Hainan and Miyun, Beijing. Scientific data are transmitted to the ground along this channel and summarized in the integrated operation control center of scientific satellites in Huairou Science City, Beijing.
In the past, China's satellite operation control mode was that one satellite corresponded to one ground system. Although it can enhance the pertinence of operation management, it also has some shortcomings such as inefficient resource allocation and insufficient data sharing.
The National Space Science Center of China Academy of Sciences is the general undertaking unit of the space science pilot project of China Academy of Sciences. At present, besides Wukong, there are Mozi, Shi Jian No.10, Yan Hui, Taiji No.1 and Huairou No.1, as well as the scientific satellite for sustainable development 1, all of which are specially managed. In order to carry out satellite on-orbit management more efficiently, the National Space Science Center has set up a scientific satellite integrated operation control center to support the daily on-orbit operation of all project satellites.
As a bridge and hub connecting satellites and scientific users, the Transportation Control Center has set up two important teams-Space Science Mission Center and Data Center, which are responsible for satellite operation management and scientific data processing respectively.
Scientific data "proofreader"
The purpose of launching a scientific satellite is to observe space and obtain scientific data. Although there is no "network cable" connection between heaven and earth, the speed of satellite downloading data is not slow, which can reach 150 to 300 megabytes per second, and the peak value can even reach 1600 megabytes per second. The future "network speed" will be even more impressive. The data center processes the data first.
The data center manages multiple satellites at the same time and receives a large amount of data every day. Only one satellite "Wukong" transmits about 16GB of original scientific data to the ground every day. However, these raw data cannot be directly used for scientific research and analysis, and they need to be processed by the data center before scientists can carry out follow-up research.
"Every scientific data can't be lost!" Maffoli, a data center worker, works every day to deal with "a string of garbled codes" in the eyes of these outsiders. After receiving the original scientific data, he first needs to decompress and extract effective data source packages to ensure that data fragments are not missing, and then carry out a series of processing such as sorting, time correction, physical quantity conversion and parameter calculation to ensure the integrity and correctness of the scientific data products produced. At present, the scientific data of all satellites in orbit managed by the data center have been 100% correctly processed after landing.
After the scientific data products are produced correctly, Maffoli will distribute the products to scientific users of different satellites, and at the same time save the original data and data products at all levels in the scientific satellite database.
Zou, deputy director of the National Space Science Center of the Chinese Academy of Sciences, said that the scattered storage of satellite scientific data is not conducive to the efficient management and open application of scientific data, nor is it convenient for scientists to use. The establishment of the National Space Science Data Center is to build a bridge and platform for scientists to use space science data conveniently and make scientific data play a greater role.
In view of this, the National Space Science Center of Chinese Academy of Sciences promoted the establishment of the National Space Science Data Center, which is the only national-level scientific data center in the field of space science in China. At present, the data center has established a business system covering the whole life cycle of data, which has achieved automatic real-time processing, rapid visualization, storage management, filing and release, and safe and permanent preservation of satellite scientific data, and has certain influence in the world. The scientific data of the space science experiment special satellite mission can be searched online here. With the increase of the number of scientific satellites in orbit and the amount of scientific data, the content of the database will be enriched continuously.
"Data processing and management is the basic work of scientific research. Without foundation, there would be no tall buildings. The stronger and more solid the foundation, the more pearls can be produced in the crown of science. " Zou said to him:
Quick response "escort"
Satellite's space journey is not always smooth. In fact, they always face threats from space. Space junk, cosmic storms, high-energy particles ... all these may affect the normal operation of satellites, and it is the mission center that ensures the stable and normal operation of satellites and can direct their actions.
"The mission center is the main responsible department to ensure the safe, reliable and efficient operation of space science satellites in orbit." Zou introduced that on weekdays, the mission center is like a "health doctor" of the satellite, constantly monitoring the health status of the satellite, and using new technologies such as artificial intelligence and big data as much as possible to evaluate and predict the future status of the satellite, so as to be aware of it.
Zou Ziming
On the big screen of the mission center, the key information of each scientific satellite in orbit is clear at a glance. When the satellite returns scientific data, its own operational status data will also be synchronously "reported" to the ground. Over time, the mission center has established a set of "life cycle health records" for satellites and payloads.
Satellite in orbit for a long time, it is inevitable that there will be "minor illnesses and disasters", and the corresponding disposal actions are naturally the sooner the better. However, "remote diagnosis" is by no means easy. In order to accurately find the "focus" in a short period of time and achieve "medicine to cure the disease", we need rich theoretical knowledge and operational experience as support. Over the past six years, with the rich experience of the task center team and the continuous improvement of the emergency plan, the response to emergencies has become more rapid and accurate.
In May of 20021year, Wukong entered the "long shadow" working mode, that is, every circle of the satellite would enter the shadow area outside the sun for a long time. Because the main power supply of the satellite is solar panel, it is necessary to adjust the power consumption strategy of the satellite in the "long shadow" mode, otherwise the load will not work due to insufficient power.
The mission center has a good idea about this. As early as 2065438+2008, they formulated the "Wukong" satellite load disposal plan. Bai Meng, a senior engineer in the mission center, and his colleagues contacted the satellite developer and various load units in advance to determine the disposal plan in time.
Hexadecimal string instruction is the communication language between mission center and satellite. Such as load power-on, initialization, normal observation mode recovery, event list, digital ephemeris and other instructions. It is quickly sent from the mission center to the ground station and transmitted to Wukong's "brain" through the heaven-earth link. Hundreds of instructions, adjust all the loads of Wukong to the latest working state, and ensure that it continues to perform scientific observation tasks stably.
When TT&C resources are sufficient, the mission center can achieve "minute-level response" to satellites. This is extremely important for scientific satellites. In case of a scientific opportunity event that is not included in the daily observation plan and requires temporary emergency observation, the mission center should upload instructions in time to command the satellite to change its attitude and aim at the observation target.
During the first discovery of the gravitational wave event of double neutron stars by the Aurora Interference Gravitational Wave Observatory and the Virgo Gravitational Wave Observatory, the event was successfully monitored by the "Minute Response" of China's first space X-ray astronomical satellite.
Information picture.
At 0: 58 on August 20 18, "Huiyan" transmitted the scientific data of daily observation tasks to the ground. Data products were distributed to the team of scientists within 2 minutes. After data analysis, scientists found that a gravitational wave explosion might occur in a certain area, so they contacted the transportation control center urgently.
1: 40, submit the emergency science plan "Two observations need to be arranged in Xiaotian area". The task center quickly completed the work of receiving, reviewing, instruction preparation, instruction inversion and rechecking of the scientific plan within 10 minute.
At 1: 50, the emergency order was successfully uploaded to Yan Hui to observe the designated sky area.
At 2: 44, Yan Hui sent back the first batch of gravitational wave event observation data.
At 2: 49, data preprocessing was completed and the first batch of scientific data products were generated.
At 3 o'clock, the production and distribution of all scientific data products were completed.
The control of running water ensures that scientists can get first-hand data at the first time and carry out scientific research quickly. That night, the data center provided 1059 scientific data products during the incident, ***23. 17GB.
The observation of "Eye of the Sky" has made an important contribution to a comprehensive understanding of the physical mechanism of gravitational wave events and gravitational wave flashes. At this time, Yan Hui, who has made great contributions, has just been in orbit for 2 months and is still in the "trial period" of running-in. Its excellent performance benefits from the strong technical platform support of the operation control center, the perfect and agile collaborative workflow among all units, and the sensitive and powerful function of satellite load.
In the follow-up mission of the second phase of space science pilot, the planned space-based multi-band space variable source monitoring satellite and Einstein exploration satellite will have the ability to upload data in real time through Beidou system, which will greatly improve the emergency response capability of the operation control center.
Health care "practical nurse"
How long can satellites work in space? This is an economic account as well as a scientific account.
Scientific satellite is a multi-system cooperative equipment. At the beginning of the project construction, scientists will set a "life" period for the satellite according to the scientific mission objectives of the satellite, and all internal load units will be designed and manufactured according to this standard.
Increasing the design life of a satellite means that its development cost will also increase greatly. However, if the satellite's on-orbit operation is effectively maintained and its on-orbit service exceeds the expected design life, the cost required for observation can be greatly saved. How long the satellite can work healthily after its design life depends more on the monitoring, management and guarantee of the ground system to extend the working time as much as possible.
After weighing, when Wukong was built, the mission time limit was determined to be three years, and its actual cost was far lower than that of similar detectors abroad.
Whether a satellite can prolong its in-orbit life needs strict evaluation and evaluation by technical experts. After three life extension evaluations, the actual working time in orbit has reached twice the design life, and its overall index evaluation is still 100, which means that Wukong has always maintained a perfect working state. This proves that in the early development process, from satellite design and load management to a screw and a welding, Wukong has done every detail to the extreme.
Under what circumstances will a satellite be assessed as inoperable? The evaluation needs to be carried out at two levels. First of all, if the scientific goal of the satellite is achieved, its mission is completed. However, if the satellite's "sick" frequency becomes higher and higher with the extension of its in-orbit time, or even some permanent faults occur, after evaluation, the state and load of the satellite are not suitable for continuous work, and the mission period is over. If we can carry out good daily management and deal with minor accidents in time, we can effectively help satellites delay aging.
In the past six years, Wukong's various loads fluctuated very little and his working state was very stable. According to the working principle of load, the longer the on-orbit observation time, the more accumulated data and the higher the observation accuracy. "Wukong" will continue to work in orbit, which will help scientists to use scientific data stably, carry out more coherent and in-depth scientific research, and produce higher-value scientific research results.
"Data needs long-term accumulation and long-term observation, which is very important for scientific research." Zou said that the process of transforming scientific phenomena into scientific data through instrument observation is restricted by many conditions, and one of the most critical problems is that there must be subtle differences between different instruments. Continuous observation of the same equipment can minimize these differences and provide good and stable scientific data for scientific research for a long time. Many telescopes on the ground can observe for decades.
Six-year-old Wukong still sends back data steadily every day, and the world's most accurate high-energy electron cosmic ray spectrum and high-energy helium nuclear cosmic ray spectrum drawn by his observation data are more and more accurate, which indicates that China's space high-energy particle detection research has been at the forefront of the world.
Scientists in China, based on the long-term observation data of Wukong, found that the energy spectrum of electron cosmic rays produced a "kink" at the energy of 1.4 trillion electron volts, which was an abnormal fluctuation never observed by human beings before. However, the newly discovered "top-down" energy spectrum structure indicates that there may be unknown cosmic ray sources, which need further study.
Space observation "farsightedness"
The major events and minor events encountered by scientific satellites in orbit depend on the management of the operation control center team. With the increase of the number of satellites in orbit, the pressure of operation management also increases. In order to improve the efficiency of satellite operation control, based on the basic operation platform, the operation control center optimizes special software for different satellite support requirements, forming a technical system of "public platform+task plug-in". For the operation and management of newly launched satellites in the future, as long as the existing system is adapted, a small amount of newly developed special software can meet the requirements, which greatly saves resources and costs.
Zou said that due to the constraints of space distance, channel rate and other factors, the operation control center must constantly upgrade the existing system to provide better support. Moreover, with the increasing number of space science satellites in orbit in China, the operation control center needs to adopt artificial intelligence, machine learning, big data, cloud platform and other technologies on a large scale to make the daily operation control of scientific satellites more intelligent and reliable.
At present, the average age of the transportation control center team is only 36 years old, and the young team has strong scientific research and innovation ability. Zou said with great expectation that in the next five years to 10, we are expected to establish an autonomous and controllable scientific satellite intelligent management and data application ecosystem, build scientific mission planning, load health management, data processing and analysis tools with independent intellectual property rights, promote the sharing of data resources and software tools, and make valuable scientific satellites and scientific data play a greater role.