Research On High Accuracy Measurement System Of Formation Spacecraft With 100 Astronomical Units

As one of the important activities of human space exploration,deep space exploration is the most direct way for human beings to know themselves and the universe.Deep space exploration farthest to 100 astronomical units has been the frontier research in the field of international space science.During the exploration mission,how to achieve accurate spacecraft information including distance,speed,and angle at such a long distance,how to improve the success rate,and how to accomplish as many scientific exploration missions as possible in a single mission are all issues that need to be considered in the 100 astronomical units exploration.This dissertation proposes deep space exploration by formation spacecraft to perform deep space exploration mission.The main contents are as follows.1.The high accuracy measurement system includes the ranging system for ground stations to spacecraft,the measurement system for formation spacecraft network and the uplink very long baseline interferometry system for ground station to spacecraft.The deep space measurement system improves performance at extremely long distance,low signal to noise ratio and long transmitting delay environment.To ensure engineering realizability of this innovation,it designs a series of high accuracy measurement algorithms to support formation missions.And these algorithms can apply to high accuracy measurement between ground station and spacecraft and that between spacecrafts.2.In the deep space ranging system,a parallel composite pseudo noise code is proposed to solve the problem of short unambiguity ranging distance,and complex ranging system design.This method modulates two different spread spectrum codes on the in-phase channel and quadrature channel.Compared with the traditional ranging method,the parallel composite ranging code shortens the acquisition time,improves the ranging distance and ensures the measurement accuracy at the same level of traditional ranging system.Based on the parallel composite code,the prototype is designed to test the performance.3.The main propose of formation spacecraft nework is to maintain a stable configuration and complete the data transmission of multiple spacecrafts in a short time.Therefore,the system should achieve time synchronization,baseline measurement and high speed communication between spacecraft network.Thus,this dissertation designs the integrated signal for telemetry,tracking,command and communication in the interspacecraft links.The integrated signal can accomplish high accuracy ranging,high accuracy time synchronization and high speed communication at the same frequency.Moreover,it improves the robustness of communication signal under high dynamic environment,simplifies the design of receiving channel and shortens switching time between multiple spacecrafts.Based on the integrated signal,the loose coupling and tight coupling two modes are designed for different situations.Besides,the prototype is designed to achieve performance analysis of the novel signal.4.After completing the measurement of radial parameters,we propose angle measurement algorithms to acquire tangential parameters.For the angle measurement between ground stations and spacecraft,we update the traditional downlink very long baseline interferometry(VLBI)to uplink VLBI.Compared the traditional method,this method improves the signal-to-noise ratio,reduces the requirements for ground stations and enhences measurement accuracy.In terms of the problem of integer ambiguity in interferometry,this dissertation proposes multi-frequency and multi-baseline algorithm to solve it.For the angle measurement of inter-spacecrafts,the multi-channel time division algorithm is applied to reduce the influence of different channels.Besides,the angle measurement performance is also analyzed under different environment.This dissertation builds the 100 astronomical units measurement system based on the combination of system design,theoretical calculation,simulation analysis and experimental test.Each subsystem has accomplished physical demonstration and performance tests.And the experimental results show that the measurement system has high performance,high frequency utilization and high function integration.Therefore,the subsystem can provide an advanced design concept for future deep space missions...