As the first Sun-only "cameraman" in the history of Chinese satellites, the "Xihe" has created many "firsts".
In the near future, "Xihe" will receive the first batch of observation data.
The research team will publish the observation data at home and abroad after scientifically calibrated processing.
◎Reporter Jin Feng
Imitate Xihe and control Tianma, aiming to herd the stars in the sky.
"Xihe" is the goddess of the sun and the goddess who set the calendar in ancient mythology.
On October 14th, China's first solar exploration science and technology experimental satellite named "Xihe" was successfully launched at the Taiyuan Satellite Launch Center, which marked China's formal entry into the era of "sun exploration".
As the first Sun-only "cameraman" in the history of Chinese satellites, the "Xihe" has created many "firsts".
After the "Xihe" launch mission is completed, the R&D team of Nanjing University will immediately carry out the on-orbit test work of the "Xihe" with the satellite system, measurement and control system and ground system teams. The first batch of observation data will be obtained in the near future, and scientific calibration will be carried out. After the treatment, it will be announced to home and abroad.
First launch
Spatial detection of solar Hα band spectral imaging
Since the 1960s, countries around the world have successively launched more than 70 solar exploration satellites.
For example, the "Ulysses" probe, which was launched in 1990 and achieved solar polar orbit detection for the first time; the "Parker" probe, which was launched in 2018 and first approached the sun (9 solar radii) to detect the sun; 2020; Launched in 2010 and plans to acquire the solar polar region image for the first time and detect solar wind plasma and high-energy particles at a close distance, such as the "Solar Orbiter".
Why are humans so fascinated by the sun?
Li Chuan, chief designer of the science and application system of "Xihe" and associate professor of Nanjing University, told the reporter of Science and Technology Daily: "The sun is the closest star to the earth, and it is the only star that can achieve high-temporal-spatial resolution observations. It is our understanding of the universe. A window, through its observation and research, can understand some basic astrophysical processes, such as the generation and evolution of magnetic fields, the acceleration and propagation of particles, the physical mechanism of celestial explosions, etc. Secondly, solar eruptions are catastrophic space weather. Observing and studying the sun has great application value for the early warning and forecast of disastrous space weather."
So, what is the difference between a satellite that detects the sun and a satellite that detects the moon and Mars?
Li Chuan said: “Because the sun’s radiation is very strong, the radiation intensity in the earth’s orbit is 1.36 kilowatts per square meter, so the solar space telescope on the Xihe needs to consider temperature control first, and it must pass the filter. Only allow the required band to enter the telescope system, and then control the telescope system within the operating temperature range through related thermal control technology; in addition, it is also necessary to focus on stray light suppression, and use coatings, diaphragms, etc. to reduce the scattered light in the system. drop to lowest."
Hα is one of the best spectral lines for studying solar activity in the photosphere and chromosphere response. The "Xihe" will be the first to realize the space detection of solar Hα band spectral imaging in the world.
"The Hα line wing reflects the information of the sun's photosphere, while the center of the line reflects the information of the chromosphere. The spectral imaging of a spectral line can obtain information of different levels of the photosphere and the chromosphere, which is equivalent to making a longitudinal section of the sun. Analysis." Li Chuan said.
First adopted
New method of overall design of "movement and static isolation non-contact"
The relevant person in charge of the Eighth Academy of China Aerospace Science and Technology Corporation introduced that traditional satellites adopt the design method of fixed connection between the platform cabin and the payload cabin. Therefore, the vibration of the movable parts of the platform cabin will inevitably be transmitted to the payload cabin, resulting in a decrease in the observation quality of the telescope in the payload cabin. .
This time, the "Xihe" satellite development team adopted the new method of "dynamic and static isolation non-contact" overall design for the first time in the world. The micro vibration sources such as flywheels and solar panels were concentrated in the platform cabin, and the solar Hα spectrometer was placed in the load cabin. , And for the first time in orbit applied maglev control technology and actuators to physically isolate the platform cabin from the load cabin.
The "maglev actuator" is an important part of maglev control, and it has also become the "stability maintenance" of the "Xihe" load compartment.
The relevant person in charge of the Eighth Academy of China Aerospace Science and Technology Corporation introduced that in order to allow the maglev actuator to have high precision, large bandwidth, and its own non-interference capabilities, the team adopted a closed magnetic circuit optimization design to successfully achieve high magnetic field uniformity and achieve a large bandwidth Isolate the effect of platform cabin flexibility and micro-vibration interference; through low noise, low ripple, high-precision power amplifier drive current precision control, ultra-high-precision drive current output is achieved, and the control accuracy is two orders of magnitude higher than traditional methods, ensuring Loads such as the solar space telescope can obtain a super-quiet and ultra-stable working environment, which greatly expands the detection capability and application scope of such loads as the telescope.
First proposed
"Active control of the load compartment, slave control of the platform compartment"
As the first "cameraman" dedicated to the sun in the history of Chinese satellites, researchers have designed many observation methods for the "Xihe" solar Hα spectrometer. Sometimes it is necessary to calibrate the sun in flat field, that is, to control the attitude of the satellites to point to the sun in turn 9 different areas of the disk; sometimes it is necessary to control the satellite's attitude for continuous sweep observation of the sun; sometimes it is necessary to perform dark-field calibration of the satellite, that is, to control the satellite's attitude to point to a specific area in space.
“The platform cabin is like an airplane. The control subsystem is the driver. It is necessary to ensure that the airplane runs stably on the route, and the load is the passengers.” Administrative command of the Xihe satellite platform cabin control subsystem of the Eighth Academy of China Aerospace Science and Technology Corporation Lin Rongfeng drew an analogy. Although the "passenger" is very picky, the R&D team designed 5 different pointing modes to respond and switch in a timely manner, so that the platform cabin can easily cope with the various work requirements of the load and ensure stable and continuous observation of the sun. .
In addition, the load compartment and platform compartment of the "Xihe" have two states, locked and unlocked.
"When the two cabins are locked, the control of the platform cabin is actually the control of the entire star. But once the two cabins are unlocked, the situation is very different." The "Xihe" satellite platform of the Control Institute of the Eighth Academy of China Aerospace Science and Technology Corporation Nie Zhanghai, technical leader of the cabin control subsystem, said, “The load cabin and the platform cabin have relative movement. The platform cabin must track the load cabin in real time, but the gap between the two cabins is only 5 mm. There was a collision between the two cabins."
How to realize the coordinated control of the two cabins?
After countless researches and tests, the “Xihe” first proposed a new method of “active control of the load compartment and slave control of the platform compartment” for the first time in the world. The attitude control force and the position control force are distributed to the corresponding large-bandwidth ultra-high-precision maglev actuator, which realizes the stable control of the two cabins.
First realized
Satellite high-power, high-reliability, and high-efficiency wireless energy transmission
The load compartment and platform compartment are in a non-contact state, and traditional power supply methods cannot meet the energy transmission needs.
How to solve the problem of energy access in the load compartment?
How to realize the energy distribution of the whole star?
After many demonstrations and comparisons, the research team of the 811 Institute of the Eighth Academy of China Aerospace Science and Technology Corporation (hereinafter referred to as the 811 Institute) proposed a magnetic induction coupling wireless energy transmission technology, which was the first to achieve high-power, high-reliability, and high-efficiency wireless energy transmission technology on a satellite. Applications.
"From energy input to energy output, the overall conversion efficiency of the entire link reaches more than 80%. In the magnetic field coupling part, the magnetic transmission efficiency reaches more than 95%, realizing high-efficiency and low-heat energy transmission. The application of this technology allows satellites The wireless energy transmission technology has been fully verified and laid the foundation for the application of other types of wireless energy transmission technology." said Zhang Junting, the chief designer of the wireless transmission subsystem of the "Xihe" 811 Institute.
According to the characteristics of the satellite's uninterrupted energy demand in orbit, satellite working status and orbital illumination, the developers of 811 also upgraded the "brain" power controller of the satellite power system.
Zhou Chengzhao, the chief designer of the power supply subsystem of the 811 "Xihe", said: "The team upgraded the original scattered energy collection, storage, control and distribution management model to an integrated intelligent management model, which solved the problem of combining the platform cabin and the load cabin. The technical problems of power supply, sub-cabin power supply, and energy transmission in space provide a steady stream of energy for the payload module, while greatly improving the handling and response capabilities of on-orbit failures and guaranteeing the lifetime of satellites in orbit."
In addition, the satellite adopts two "mutual backup" wireless communication methods, laser communication and microwave communication, and sets up a 5G high-speed communication channel between the two cabins, which further improves the efficiency and reliability of inter-cabin communication.