As a great challenge facing the world, deep space exploration can only be activated in a few countries with a success rate of about 50%. With the advancement of spacecraft and scientific instruments, the capabilities of small platforms have been greatly enhanced. It is now possible to build micro- and nano-satellites for deep space exploration. As spacecraft become smaller, there is a need for suitable micropropulsion systems. In a research article recently published in Space: Science & Technology, Yanming Wei from the Beijing Institute of Control Engineering (BICE) analyzed micropropulsion systems in conjunction with the various mission requirements of China’s deep space exploration. The deep space missions and platform propulsion systems discussed by the author were mainly based on products developed by the Beijing Institute of Control Engineering (BICE), which specialized in systems control and propulsion of spacecraft and had the accomplishment of 90% of China’s satellites and spacecraft.
First, the author presented several microdrive modules, which are developed to meet the needs of various occasions. Cold gas propulsion has relatively low thrust, but it has high precision and reliability, so the technology is suitable for microsatellites with a mass of less than 10 kg or platforms requiring high precision control. Chemical propulsion has the highest level of thrust and a flexible total impulse. Electric propulsion has a high total impulse and low thrust. For missions at extreme distances, electric propulsion has the advantage of saving fuel for more payloads. Next, the selection of propulsion systems for deep space exploration was discussed. For lunar exploration, Queqiao and Longjiang were equipped with single-propeller systems but with different levels of thrust, since Longjiang’s mass is about an order of magnitude less than Queqiao’s. For Tianqin-1, a scout for gravitational wave detection, realizing drag-free control, is essential, so a cold gas thruster and μCAT were chosen to provide μN-level variable thrust. For deep space missions with separable transfer module, BepiColombo, a collaborative mission of the European Space Agency and the Japanese Space Agency to study Mercury and its environment using two Mercury satellites, is analyzed.
Next, the author introduced 3 types of microdrive modules, namely solid cold gas propulsion module, DNA monopropellant microdrive module and microcathode arc microdrive module (μCAT) propulsion module, which are developed by BICE and have successfully passed flight tests. Packaging the propulsion system into modules can greatly reduce the complexity of the design, manufacturing and testing processes, lowering the technical threshold and promoting cooperation. The solid cold gas micro-propulsion module was developed for formation flying, station keeping and other micronanosatellite tasks, which required a propulsion system with low power consumption, modular design and plug-and-play installation. -and-play. The DNA monpropellant was a mixture of three components: ammonium dinitramide, methanol and water. It was non-toxic and had high density, low freezing point, low volatility and high stability. Thus, the ADN monopropellant micropropulsion module had the advantage of not requiring any particular security during the storage and handling processes. In 2019, the DNA microdrive module successfully passed a flight test on the Ningxia-1 satellite. The μCAT was based on the physical phenomenon of vacuum (cathodic) arcs and was first developed by the George Washington University (GWU) Micropower and Nanotechnology Laboratory. The CAT module did not contain any pressurized parts, the manufacturing process was much simpler compared to other propulsion systems which used a gaseous medium.
Finally, new developments for interstellar missions were discussed. On the one hand, the study of the limit of the solar system is the frontier of astrophysics. China is proposing a mission to study the nose and tail of the heliosphere, which is the boundary between the interstellar medium and plasma from the sun. In the mission, a pair of probes are proposed to launch and then fly a distance of 80 to 150 Au before arriving at the heliosphere. The mission is significant because the edge of the heliosphere has not been fully explored by humanity and the physical property of the boundary remains unknown. On the other hand, propellantless propulsion, for example electric sail (also known as HERTS, Heliopause Electrostatic Rapid Transport System) is a prospective technology for future deep space exploration. The electric sail has many long, thin wires or so-called ties, running from its center. Tethers are charged to thousands of volts, creating high potential regions around them to deflect protons. The device generates thrust by momentum exchange with photons and functions as a virtual sail propelled by the solar wind. In addition, the electric sail can function as a particle probe. As the spacecraft approached termination shock, where the solar wind abruptly decelerated from supersonic to subsonic, the thrust of the electric sail could be expected to drop dramatically. The force and current on the electric sail would provide valuable data for heliosphere research.
Authors: Yanming Wei, Hao Yan, Xuhui Liu, Yang Yu, Jinyue Geng, Tao Chen, Tuoqu Fu, Gaoshi Su, Yu Hu and Daoman Han
Title of the original article: The Microdrive Technology Perspective for China’s Advanced Small Deep Space Platforms
Link to article: https://doi.org/10.34133/2022/9769713
Journal: Space: science and technology
Advanced Space Propulsion Laboratory, Beijing Institute of Control Engineering, Beijing 100090, China
Beijing Engineering Research Center for Efficient and Green Aerospace Propulsion Technology, Beijing 100090, China