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CZ-2D· “Worldskills Shanghai” Launch Vehicle Successfully Chinese Hα Solar Explorer
At 18:51 on October 14, 2021, CZ-2D· “Worldskills Shanghai” Launch Vehicle was launched to the space in Taiyuan Satellite Launch Center. It successfully sent 11 satellites including Chinese Hα Solar Explorer (CHASE) to the intended orbit, and the launch mission had achieved a complete success.
It was the 55th launch of CZ-2D Launch Vehicle, the 143rd flight test of Long March launch vehicles which are developed by Shanghai Academy of Spaceflight Technology as well as the 391st launch of Long March launch vehicles. CZ-2D Launch Vehicle is a room temperature liquid two-stage launch vehicle developed by Shanghai Academy of Spaceflight Technology. It has a takeoff thrust of 300 tons and a carrying capacity of 1.2 tons on the sun-synchronous orbit with a height of 700 km. It has the ability to launch a single satellite or more than one satellite as required by different orbits.
Shanghai Academy of Spaceflight Technology bears the primary responsibility for the development of CHASE. The satellite will realize the world first full-disk Hα waveband spectral imaging, achieve in-orbit maglev control for the first time, and can realize the ultra-high pointing accuracy and stability. The successful launch of CHASE is of great importance for China’s space exploration and development of satellite technology, marking that China has formally entered the “Solar Exploration Era”.
Making constant reform to configuration to seize the multiple satellite launch market
In this launch, CZ-2D carried a disc structure for the first time, which has broken the restriction on satellite quantity and envelope in the former side wall carrying mode. Instead of the greatest number of 5 satellites that can be carried before, this time, the greatest number of satellites that can be carried has reached 10. In order to ensure the safety in the separation of multiple satellites, the designer sorted out the key points and risk points in the whole process of the work, realized several updates of the satellite, and used the round disk for the first time successfully.
Now, CZ-2D Launch Vehicle has played an important role in medium-low orbit launch missions. Brand-new configurations will be developed through continuous researches under the guide of the user tasks. At present, several complex programs for deployment of multiple satellites in various orbits, such as multiple satellite carrying, parallel connection, series connection, series-parallel connection, and combination with a higher stage have been passed the evaluation of the task. Through diversified configurations, the carrying capacity of CZ-2D launch vehicle has broken the limit time after time. Usable space of the nose cone has been further explored. We have grasped some tried and true safety strategies for multiple satellite launching and have had the multiple-configuration nose cone as well as a series of standardized satellite and rocket interfaces. Multiple satellite launching has become normality. It can make the best of the carrying capacity and meet user’s diversified demands to the greatest extent, and can well adapt to the flexible and economic development trend of commercial satellites.
A new requirement for precise landing area-the landing area reduced by more than 80%
Today when launch vehicles are launched frequently, safety of the landing environment has become the focus of attention of the public. In order to reduce the landing area and guarantee the landing safety, this launch is a performance confirmation test in which the grid fin landing area control system is used on CZ-2D launch vehicle for the first time. The outspread grid fin can realize the attitude control of the first sub-stage return, and thus the landing area of the first sub-stage can be reduced by more than 80%. This can make the landing point of the launch vehicle more precise and controllable, and greatly improve the safety and environment of the landing area.
CZ-2D grid fin landing area control system is mainly composed of the heat resistant, light weight, firm and foldable grid fin system that can rotate precisely and the low cost and highly integrated electric system. The grid fin system can be realized on the foldable control surface of the ascending segment of the launch vehicle to avoid the impacts on the satellite launching task. On the return segment, it can finish a series of complicated actions such as unlocking, unfolding, and actuation of control command. Through elaborate designs, material selection and tests of the development team, the control surface can bear a high temperature of more than a thousand degrees centigrade and tons of loads, with a weight of only 1/3 and a cost of only 1/5 of like products, which has granted the launch vehicle a flexible wing.
The grid fin electric system is a brain of grid fin control. It can send a command to guide the control surface to rotate, so that the first sub-stage can fly to the target point. The design team adopted the comprehensive electronic technology from the beginning of the research & development and abandoned the traditional complicated electric design ideas, and integrated the functions of measuring, navigation control, and telemetering into a small box less than 20cm long, which has greatly reduced the size of the system. The research & development team also adopted the commercial components. Through redundancy design, time sequence design and the carrying and flight test of core single units in the preliminary stage, it ensures that the grid fin electric system is light in weight and cheap in price, and has complete functions and sound reliability.
This time, CZ-2D launch vehicle also carries another ten satellites, including SSS-1 satellite, SSS-2A satellite, orbit atmosphere density explorer satellite, commercial meteorological detection satellite, Tianyuan Satellite 1, Jinzijing Satellite 2, low orbit navigation augmentation experiment satellite, two Hede Satellite 2 and traffic experiment satellite.
Realizing solar Hα waveband spectral imaging detection in the world for the first time
The whole CHASE has a weight of 510kg. It runs in the terminator sun-synchronous orbit with a height of 517km. The major scientific load of a satellite is the solar space telescope. This is the world first solar Hα waveband spectral imaging detection in the space. Hα is one of the best spectral lines to study the solar activity with photosphere and chromosphere response. Through the data analysis of the spectral line, we can obtain the changes in the physical quantity such as the atmospheric temperature and speed during solar eruption and study the dynamic process and physical mechanism of solar eruption.
The solar Hα waveband spectral imaging detection of CHASE can realized three scientific goals at one time: observing the photosphere and chromosphere manifestation cast by solar flare and corona substances and revealing the dynamic performance and trigger mechanism of the source region of solar eruption; observing the chromosphere manifestation in the process of formation and evolution of solar filament, and revealing its inner relationship with solar eruption; acquiring the Doppler velocity distribution of full-disk Hα waveband, studying the dynamic process of the lower atmosphere of the sun, providing an important support for solving the scientific problems such as the “physical model for the whole process of energy transfer from the inner to the surface during solar eruption”, and significantly improving China’s international influence in the field of solar physics.
Realizing the first in-orbit application of maglev control to achieve the ultra-high pointing accuracy and stability of satellite
CHASE adopts the satellite platform with ultra-high pointing accuracy and ultra-high stability. As the new generation of satellite platform, it can greatly improve the pointing accuracy and stability of the satellite platforms in China and reach the international advanced level. It adopts the “dynamic-static isolated” new design method. The satellite isolates the platform cabin from the load cabin physically, and blocks the path of transfer of the slight vibration of the platform cabin. It adopts the coordinated control discoupling method to realize active control of the load cabin and servo-actuated control of the platform cabin. Compared with the current state in China, the attitude pointing accuracy and attitude stability of the satellite have been improved by 1~2 magnitudes. It adopts the maglev actuator as the executive body of the load cabin which has the characteristics of high accuracy, big bandwidth, and no self-interference, based on which the ultra-high pointing accuracy and ultra-high stability of the load cabin can be realized. It adopts wireless energy transmission, radio communication and laser communication to realize the reliable transmission of energy and information between two cabins.
The firsthand flight data obtained from the first in-orbit flight of the dual ultra-high satellite platform will greatly reduce the risks of dual ultra-high control technology in the future application. Meanwhile, the in-orbit testing of more than ten new technologies and new products, such as maglev actuator, wireless energy transmission, and laser communication, will make relevant technologies and products more mature and lay a solid technical foundation for the serial development of the dual ultra-high platform. In the future, the dual ultra-high platform technology will also be popularized and applied in the new generation of space missions such as high-resolution ground surveys, large-scale 3D surveying and mapping, 3D solar exploration, and exoplanet discovery to promote China’s leapfrog development in the field of space science and space technology.