Research On Satellite Constellation Design For Complex Observation Tasks

With the development of economy and technology,satellites play an increasingly important role in human life.They have been widely used in weather prediction,earthquake monitoring,military reconnaissance,remote sensing imaging,global communications,global navigation and many other fields.With the increasing demand for earth observation applications,single Earth observation satellites have gradually been unable to meet the requirements of complex observation tasks.The demand for the coordinated observation between satellites is an inevitable trend.At present,a design method of remote sensing satellite single satellite orbit has been mature,but the calculation of single satellite revisit time has not considered the satellite payload.When considering the satellite payload,the calculation method of satellite revisit time is less.The model is not accurate at the same time.There are few researches on the design methods of remote sensing satellite constellations,mainly foucus on using heuristic algorithms to generate constellations.The main methods are divided into two parts.The first method often uses a constellation configuration,that is,the 3+4N constellation model.The coverage rate and percentage of coverage time are the main indicators to evaluate the constellation.The second method mainly uses the 6N constellation model,which is more versatile,but it does not contain any information about the constellation configuration.At the same time,the design of constellations is mainly focused on the design of communication satellites and navigation satellites.Since communication satellites and navigation satellites often use the earth orbit,remote sensing satellites often use low earth orbit because of the limitation of ground resolution,so this research is not universal.At the same time for single satellite and constellation coverage calculation(instantaneous coverage rate,cumulative coverage),the commonly used method is grid point method.This method is relatively simple model,but with the classification accuracy,computational efficiency decreased when calculating the remote sensing satellite for long time accumulation of coverage.It will take long time for grid point method.Aiming at complex observation tasks(high time resolution,high spatial resolution and high spectral resolution),this paper puts forward the method to generate the satellite constellation for the Earth observation.The main lines of this paper are as follows: first,the performance of the single satellite is analyzed with the payload.For the calculation of single satellite’revisit time to the ground,we propose a fast calculation method to calculate the minimum tilt angle corresponding to the desired revisit time;for single satellite of coverage calculation to the ground,this paper proposes a precise and efficient calculation method,which is named latitude strip method.Secondly,we quantify the performance of the remote sensing task and evaluate the performance of the single satellite.If a single satellite can’t meet the mission requirements,we will generate satellite constellations that meet the mission requirements according to the single satellite.By analyzing the ground track of a single satellite,a method of generating orbit satellite constellations which share the same ground track with a single satellite is proposed.The constellation can improve the time resolution.At last,the remote sensing satellite constellations are designed to meet the task requirements for high space,time and spectral resolution tasks.The main works of this paper are as follows:1.The design methods of the repeat ground track orbit and the sun synchronous repeating ground track orbit are summarized.Remote sensing satellites use different types of orbits when carrying different loads.According to the orbit design method of reference literature,problem model,and considering the J2 perturbation case,summarizes the design method of orbit and sun synchronous orbit.Finally,the set of regression track under different track parameters is given,which is convenient for the track designers to compare and verify.2.An accurate and efficient method for calculating the coverage rate of the satellite to the ground target is proposed.In this paper,a method of covering calculation by using the trajectory of sliding ground is proposed,and the latitutude-strip method is used.The method divides the target area into several latitude stripes and obtains the longitude interval of the target region.In a repeat cycle of a satellite orbit,the coverage of each latitude stripe is calculated according to the geometric relationship of the spherical surface.When calculating the coverage interval of the next orbit period,we can get the coverage of the whole simulation period by sliding the coverage interval of the last period.The simulation results show that compared with the traditional grid point method,the latitudinal strip method is accurate and efficient.3.The method to calculate the relationship between the desired repeat cycle and the minimum tilt angle is proposed.The conventional method to calculate the revisit time are numerical methods which is based on statistics.This method is based on numerical statistics,the efficiency is low,and can not statistics a lot of points.In this paper,through the analysis of remote sensing satellite in a repeat cycle after the equator,the equator is divided into several intervals,through the analysis of space and satellite width size and tilt angle,the revisit time on the equatorial satellite can be obtained.According to this method,when the satellite payload parameters are determined,the satellites can easily get the relationship between the desired repeat cycle and the minimum tilt angle.The simulation results show that this method has high calculation efficiency and can help track designers to design better track.4.A method to generate common ground track constellation based on single satellite is proposed.In this paper,a design method of the common ground track constellation based on single satellite is given.Firstly,analyzes the geometric relationship between different orbit plane satellite ground track,by setting the satellite satellite phase,run the same or different ground track,thereby reducing the revisit time and space on the Equator.By establishing the mathematical relation between the Q value and the sun synchronous repeat ground track orbit,the design method of the constellation of the same orbit and the different orbit plane is given.By the method proposed in this paper,according to the mission requirements,the satellite constellation can be quickly obtained according to the single satellite.Aiming at the complex observation mission,this manuscript gives the design method of remote sensing satellite constellation system which is generated by a single satellite.The experimental results show that the method is efficient and reliable.It has been applied to projects such as high special resolution projects.