As of December 17, 2021, the Wukong satellite has been in orbit for a full 6 years.
As the first satellite launched in the first phase of the Space Science Pilot Project of the Chinese Academy of Sciences, the design life of "Wukong" was originally only 3 years, but until now, the 6-year-old "Wukong" still maintains a strong and energetic vitality, and continues to look at the deep universe for mankind.
At present, the space science pilot project has successfully launched 7 scientific satellites. The Scientific Satellite Integrated Operation And Control Center of the National Space Science Center of the Chinese Academy of Sciences is the "big housekeeper" of these scientific satellites on the ground.
National Space Science Center, Chinese Academy of Sciences, Center for Integrated Operation and Control of Scientific Satellites
Scientific satellite "Remote Controller"
In the early morning of December 17, 2015, Jiuquan Satellite Launch Center.
Chaoxia was still hanging in the sky, and the Long March 2 Ding carrier rocket cut through the long sky and smoothly sent the "Wukong" satellite into the predetermined orbit.
In "Journey to the West", Qitian Great Saint Sun Wukong can turn out 108,000 miles with one heel, and has a sharp "fire eye golden eye", "Wukong" satellite is of course worthy of the name.
The "Wukong" satellite, full name dark matter particle detection satellite, is one of the first four scientific satellites developed by the first phase of the Space Science Strategic Pilot Science and Technology Special Project of the Chinese Academy of Sciences, and is also the dark matter particle detection satellite with the widest range of observation energy segments and the best energy resolution in the world. It orbits the Earth every 95 minutes and observes 5 million high-energy particles in the universe every day.
Profile picture.
1.5 meters long, 1.5 meters wide, 1.2 meters high, and an overall mass of 1.85 tons, "Goku" is not much bigger than a desk in terms of size. But don't underestimate it, "Goku" small body is equipped with nearly 80,000 small detectors, they are "Goku's" "fire eye golden eye", the target of the detection is more than a quarter of the universe, but the "invisible" dark matter to humans.
Of course, "Wukong" collects and detects not dark matter itself, but high-energy gamma rays, electrons and cosmic rays produced after the collision of dark matter particles.
Once a high-energy particle "bumps" into the detector, the scientific data generated by it will be recorded and stored at the first time. When flying over China, Wukong will quickly establish a heaven-earth communication link with three ground stations located in Kashgar, Xinjiang, Sanya, Hainan, and Miyun, Beijing. The scientific data is transmitted along this channel to the ground and aggregated to the Science Satellite Integrated Operation and Control Center in Huairou Science City, Beijing.
In the past, the operation control mode of China's satellites was one satellite corresponding to a ground system, although it could enhance the pertinence of operation management, but there were also shortcomings such as resource allocation efficiency and insufficient data sharing.
The National Space Science Center of the Chinese Academy of Sciences is the general unit of the space science pilot project of the Chinese Academy of Sciences, and the scientific satellites that have been successfully launched and operated in orbit at present include "Mozi", "Shijian No. 1", "Huiyan", "Taiji No. 1" and "Huairou No. 1", as well as the sustainable development science satellite No. 1 that is included in the special management. In order to carry out satellite on-orbit management more efficiently, the National Space Science Center has established a scientific satellite integrated operation and control center to support the daily in-orbit operation of all project satellites.
As a bridge and hub connecting satellite and scientific users, the Operation Control Center has set up two important teams, the Space Science Mission Center and the Data Center, which are responsible for satellite operation management and scientific data processing.
Scientific data "collator"
The purpose of the launch of scientific satellites is to observe space and obtain scientific data. Although there is no "network cable" connection between heaven and earth, the speed of satellite down-transmitting data can not be slow, reaching 150 to 300 megabytes per second, and the peak can even reach 1600 trillion per second, and the future "network speed" will be more impressive. The first to process this data is the data center.
Managing multiple satellites at the same time, the data received by the data center every day is massive, and only one satellite of "Wukong" has to transmit about 16GB of raw scientific data to the ground every day. This raw data cannot be used directly for scientific research and analysis, and needs to be processed by data centers for scientists to carry out follow-up research work.
"Every piece of scientific data cannot be lost!" The daily job of the data center staff Ma Fuli is to deal with these "strings of garbled codes" in the eyes of outsiders. After receiving the original scientific data, he first decompressed and extracted the valid data source package, confirmed that the data fragment was not missing, and then carried out a series of processes such as sorting, time correction, physical quantity conversion, parameter solving, etc., to ensure the integrity and correctness of the scientific data product produced. At present, all satellite science data in orbit managed by the data center has been processed 100% correctly after landing.
After the scientific data products are produced correctly, Ma Welfare distributes the products to the scientific users of different satellites, and simultaneously saves the raw data and data products at all levels to the scientific satellite database.
Zou Ziming, deputy director of the National Space Science Center of the Chinese Academy of Sciences, said that the decentralized storage of satellite scientific data is not conducive to the efficient management and open application of scientific data, and it is inconvenient for scientists to use it. The establishment of a national space science data center is to build a bridge and a platform for scientists to easily use space science data, so that scientific data can play a greater value.
In view of this, the National Space Science Center of the Chinese Academy of Sciences promoted the establishment of the National Space Science Data Center, which is the only national science 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, realizing automatic real-time processing, rapid visualization, storage management, archiving and release, and secure and permanent preservation of satellite scientific data, which has a certain influence in the world. The scientific data of the space science pilot special satellite mission can be retrieved online here, and the database content will continue to be enriched as the number of scientific satellites in orbit and the amount of scientific data increase.
"Data processing and management is the basic work of scientific research, without which there are no high-rise buildings. The more solid the foundation, the brighter the pearls in the crown of science. Zou Ziming said.
Quick Answer "Escort"
The journey of satellites in space is not always smooth, in fact, they face threats from space at every moment. Space debris, cosmic storms, energetic particles... All these may affect the normal operation of the satellite, and the mission center is the mission center that ensures the stable and normal operation of the satellite and can direct the satellite action.
"The Mission Center is the main department responsible for ensuring the safe, reliable and efficient operation of space science satellites in orbit." Zou Ziming introduced that on weekdays, the mission center is like a "health doctor" of the satellite, monitoring the health status of the satellite at all times, and using new technologies such as artificial intelligence and big data to assess and predict the future status of the satellite as much as possible, so as to know it.
Zou Ziming
On the large screen in the mission center, key information about each science satellite in orbit is clear at a glance. While the satellite is transmitting back scientific data, its own operating status data will also be synchronously "reported" to the ground. Over time, the mission center has established a set of "life-cycle health files" for satellites and payloads.
The satellite has been in orbit for a long time, and it is inevitable that there will be a "small disease and small disaster", and the corresponding disposal action is naturally as fast as possible. However, "air diagnosis" is not an easy task, in order to accurately find the "lesion" in a short period of time, and "medicine to cure the disease", it is necessary to have rich theoretical knowledge and operational experience as a support. Over the past 6 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 2021, Wukong entered the "Long Shadow" working mode, that is, each lap of the satellite will enter the shadow area that the sun cannot shine for a long time. Since the main source of power for satellites is solar panel power, in the "long shadow" mode, it is necessary to adjust the power consumption strategy of the satellite, otherwise the load will not work due to insufficient power.
The Mission Center is well aware of this. As early as 2018, they formulated a targeted "Wukong" satellite payload disposal plan. In this "long shadow" mode disposal, Bai Meng, senior engineer of the mission center, and colleagues contacted the satellite developer and various payload units in advance to confirm the disposal plan in time.
Hexadecimal string instructions are the language in which the mission center communicates with satellites. Payload re-energization, initialization, normal observation mode, event table, digital ephemeris... Instructions were quickly sent from the mission center to the ground station, and transmitted to the "brain" of "Goku" through the heaven-earth link. Hundreds of instructions to adjust all the payloads of "Wukong" to the latest working state, to ensure that it continues to perform scientific observation tasks stably.
In the case of sufficient resources for satellite and earth measurement and control, the mission center's control of satellites can reach "minute-level response". This is extremely important for scientific satellites, once there is a scientific opportunistic event that is not included in the daily observation plan, and it is necessary to temporarily carry out emergency observations, the mission center should upload instructions in time to direct the satellite to change its attitude and align itself with the observation target.
In the aurora interference gravitational wave observatory and the Virgo gravitational wave observatory first discovered that the binary neutron star merger gravitational wave event, through the "minute level response", China's first space X-ray astronomical satellite - "Huiyan" successfully monitored the event.
At 00:58 on August 18, 2017, "Wise Eye" transmitted scientific data from daily observation missions to the ground. The data product was distributed to a team of scientists within 2 minutes. After data analysis, scientists found that there may be gravitational wave bursts in a certain area, so they urgently contacted the operation control center.
At 1:40 a.m., the emergency science plan for "two small sky area observations needed to be arranged" was submitted. The task center quickly completes the receipt, review, instruction preparation, instruction inversion, and review of the scientific plan within 10 minutes.
At 1:50, the emergency instruction was successfully uploaded to the "Wise Eye" to observe the designated sky area.
At 2:44, the "wise eye" returned the first batch of gravitational wave event observation data.
At 2:49, the data preprocessing was completed, and the first scientific data products were generated.
At 3 o'clock, the production and distribution of all scientific data products in the event was completed.
The control of the clouds and flowing water ensures that scientists get first-hand data in the first time and quickly carry out scientific research work. That night, the data center provided a total of 1,059 scientific data products for the period of the event, for a total of 23.17GB.
The observations of the "wise eye" have made an important contribution to a comprehensive understanding of the gravitational wave event and the physical mechanism of gravitational wave flash. At this time, the "wise eye" who has made great achievements has just been in orbit for 2 months of trial operation, and is still in the "trial period" of running-in. Its outstanding performance is supported by a powerful technology platform in the Operations Control Center, a perfect and agile collaborative workflow between units, and sensitive and powerful satellite payloads.
In the follow-up mission of the second phase of the space science pilot, the planned launch of the space-based multi-band space variable source monitor satellite and the Einstein probe satellite will have the ability to upload data in real time through the "Beidou" system, which will greatly improve the emergency response capability of the operation control center.
Health care "nurse"
How long can a satellite work in space? This is an economic account, but also a scientific account.
A science satellite is a multi-system device that works together. At the beginning of the project construction, scientists will set a "life" period for the satellite according to the scientific mission goals that need to be completed, and the internal payload units will be designed and manufactured according to this standard.
Increasing the design life of satellites means that their development costs will also increase significantly. However, if the satellite is effectively maintained in orbit and its orbital service exceeds the expected design life, it can greatly save the cost of observation. Beyond the design life, how long the satellites can continue to work healthily depends more on the monitoring, management and assurance of the ground system, and extend their working time as long as possible.
After weighing, when "Wukong" was built, the mission time limit was determined to be 3 years, and its actual cost was much lower than that of similar detectors abroad.
Whether the satellite can extend its life in orbit needs to undergo rigorous evaluation and review by technical experts. After three life extension reviews, "Wukong" has actually worked twice the design life in orbit, and its whole star index rating is still 100 points, which means that "Wukong" has maintained a perfect working state. This proves that in the early development process, from satellite design and load management to a screw and a weld, every detail of "Wukong" has been achieved to the extreme.
Under what circumstances will a satellite be assessed as unable to continue working? Assessments need to be carried out at two levels. First, if the satellite's scientific goals are met, its mission is complete. If, with the extension of the satellite's time in orbit, its "sick" frequency is getting higher and higher, and even some resident faults, after assessment, the status of the satellite and the payload is not suitable for continued work, and the mission period is declared over. If you can carry out good daily management and deal with small accidents in time, you can effectively help satellites delay aging.
In the past 6 years, the fluctuation range of each load of "Wukong" is extremely small, and the working state is very stable. According to the working principle of the load, the longer the observation time in orbit, the more data it accumulates, and the higher the observation accuracy. "Wukong" continues to work on track, which will help scientists make stable use of scientific data, carry out more coherent and in-depth scientific research work, and produce higher-value scientific research results.
"Data needs to be accumulated over a long period of time, observed over a long period of time, which is very critical for scientific research." Zou Ziming said that the process of converting scientific phenomena into scientific data through instrument observation is subject to many conditions, one of the most critical problems is that there must be subtle differences between different instruments. Continuous observation of the same device minimizes these differences and provides scientific research with good and stable scientific data for a long time. Many on-ground telescopes have observation periods of up to several decades.
The 6-year-old "Wukong" still steadily transmits data every day, and the world's most accurate high-energy electron cosmic ray energy spectrum and high-energy helium nucleus cosmic ray energy spectrum drawn by its observation data are constantly growing more accurately, which marks that China's space high-energy particle detection research has ranked among the forefront of the world.
Based on the long-term observation data of "Wukong", Chinese scientists have found that the electron cosmic ray energy spectrum has produced a "bend" at the energy of 1.4 trillion electron volts, and this abnormal fluctuation has never been observed by humans before. The newly discovered "first upturned and then down" energy spectrum structure indicates that there may be an unknown source of cosmic rays, which has yet to be clarified by follow-up research.
Space Observation "Far-Sighted"
The large and small events encountered by science satellites in orbit rely on the management of the operation control center team, and as the number of satellites in orbit increases, the pressure of operation management also increases. In order to improve the efficiency of satellite operation and control, the operation control center takes the basic operation platform as the foundation and optimizes the special software for different satellite support needs, 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 special software can be developed to meet the requirements, which greatly saves resources and costs.
Zou Ziming said that in the future, due to the constraints of space distance, channel rate and other factors, the operation control center must continuously upgrade the existing system to better provide support. Moreover, with the increase in the 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 and control of science satellites more intelligent and reliable.
At present, the average age of the team in the operation control center is only 36 years old, and the young team has strong scientific research and innovation capabilities. Zou Ziming said with great expectation that in the next 5 to 10 years, we are expected to establish China's independent and controllable scientific satellite intelligent control and data application ecosystem, create China's own intellectual property rights of scientific mission planning, payload health management, data processing and analysis tools, etc., promote the co-construction and sharing of data resources and software tools, so that valuable scientific satellites and scientific data can play a greater role.