An orbit control safe shutdown time calculation method suitable for deep space exploration

Abstract

The application discloses a kind of orbit control safety shutdown time calculation methods suitable for deep space exploration, belong to.The method first calculates the theoretical velocity increment of orbit control, determines the bottom engine, orbit control engine and attitude control engine and related engine thrust and specific impulse parameters;Second, the actual orbit control velocity increment is obtained, to determine the orbit control nominal start-up duration;Then, calculate time error deviation, give the engine shutdown time and forced shutdown time of orbit control process;If it is a conventional orbit control task, the above two time as the final safety shutdown time;For safety-related orbit control tasks, give a plurality of groups of shutdown time and forced shutdown time under nominal condition and pull bias condition, finally determine the safety shutdown time of safety-related orbit control task.The application selects appropriate shutdown time and forced shutdown time, to ensure the orbit safety and mission safety of probe.

Description

TECHNICAL FIELD

[0001] The present application relates to an orbit control safety shutdown time calculation method suitable for deep space exploration, belonging to the technical field of spacecraft orbit control. BACKGROUND

[0002] Orbit control is the most common flight maneuver in the on-orbit flight mission of a probe. As deep space exploration missions gradually exhibit the characteristics of multiple targets and multiple tasks, dozens of orbit control tasks may be involved in future exploration missions. The implementation results of previous orbit control tasks directly affect subsequent orbit control strategies. For example, if the firing time of previous orbit control is too long, it will cause changes in key parameters such as orbit configuration and propellant consumption, affecting subsequent key exploration links. Therefore, the completion of each orbit control will directly determine whether the entire mission can be carried out normally according to the plan.

[0003] During orbit control execution, the on-time of the orbit control engine directly affects the final orbit control effect. Usually, the orbit control velocity increment is determined by integrating the acceleration meter measurement results, and the orbit control engine is automatically triggered to shut down when the target velocity increment is reached. However, due to the measurement error of the acceleration meter itself, the calculation bias of the on-board computer, and the control error of the orbit control execution mechanism, the probe may not be able to accurately shut down according to the intended target velocity increment during orbit control. In order to ensure the safety of the probe's orbit and the implementation of subsequent tasks according to the intended target, the orbit control engine is set to have a prohibited shutdown time T offmin and a forced shutdown time T offmax , which are uploaded to the control system computer as orbit control on-time safety thresholds to protect the safety of the probe's orbit and the mission. The design process of the prohibited shutdown time T offmin and the forced shutdown time T offmax differs for different types of orbit control tasks. Orbit control includes different types of orbit control such as midcourse correction, braking, de-orbiting, lifting orbit, and phase adjustment.

[0004] In early lunar exploration missions, the safety design of orbit control is achieved by the forbidden shutdown firing duration ratio factor and the forced shutdown firing duration ratio factor in orbit control. The ratio factor is determined by formula or engineering experience, which is risk-free for most orbit controls. However, for some orbit controls involving safety, it is not safe to determine only by formula or engineering experience. According to engineering experience, the forced shutdown firing duration ratio factor of the Russian Luna-25 probe was set to 1.5 before the deorbiting process, resulting in the probe eventually crashing into the moon and the mission failing. Therefore, for such dangerous orbit controls, the working conditions need to be set according to the range of engine thrust, specific impulse and probe mass, and the reasonable setting of forbidden shutdown time and forced shutdown time is confirmed by multiple orbit extrapolations to confirm the safety of the orbit and the absence of risk of collision with celestial bodies and escape.

[0005] Orbit controls involving safety include braking, deorbiting, etc. For such orbit controls, the engine forbidden shutdown time T offmin and the forced shutdown time T offmax The rationality of the parameter design will affect the implementation results of the orbit control:

[0006] 1) If the orbit control start time is short, it will cause changes in the orbit period, orbit altitude and orbit configuration after control, such as braking. If the forbidden shutdown time T offmin is designed to be small, the speed increment is low after triggering the engine shutdown at this time point, and the probe cannot enter the range of the influence of the moon's gravitational field to normally orbit the moon, or the orbit altitude is high after triggering the shutdown at this time, and the semi-major axis and period change, which has a direct impact on the subsequent key links.

[0007] 2) If the orbit control start time is long, the orbit altitude after control is too low, resulting in a small altitude margin for the subsequent deorbiting task or an orbit altitude lower than the safety threshold, which poses a risk of crashing into the moon. For deorbiting, if the forced shutdown time T offmax is designed to be large, the subsequent deorbiting task risk will increase after the probe's flight orbit altitude is reduced after triggering the shutdown, and even a collision with the celestial body surface may occur.

[0008] Therefore, for orbit control tasks involving safety, further orbit safety analysis and subsequent task safety analysis are needed. SUMMARY

[0009] The technical problem solved by the present application is to overcome the shortcomings of the prior art and provide an orbit control safety shutdown time calculation method suitable for deep space exploration, which ensures the orbit safety and mission safety of the probe by selecting appropriate forbidden shutdown time and forced shutdown time.

[0010] The technical solution of the present application is:

[0011] A method for calculating safe shutdown time of orbit control for deep space exploration, comprising:

[0012] S1: determining initial mass m0 and initial mass deviation Δm0 of the probe before orbit control;

[0013] S2: performing accurate orbit determination on the probe according to nominal orbit control time, and predicting orbit elements at the orbit control time, calculating theoretical velocity increment of orbit control according to orbit control target, and determining parameters of the submergence engine, the orbit control engine and the attitude control engine, and related engine thrust and specific impulse parameters;

[0014] S3: calculating submergence velocity increment and aftereffect velocity increment according to the theoretical velocity increment and the above-mentioned engine specification parameters, obtaining actual orbit control velocity increment, and determining nominal start time of orbit control;

[0015] S4: dividing the orbit control task into regular orbit control task and orbit control task involving safety according to the orbit control target;

[0016] S5: for the two kinds of orbit control tasks, calculating time error deviation according to the nominal start time of orbit control, and giving engine prohibited shutdown time T offmin and forced shutdown time T offmax of the orbit control process; if it is a regular orbit control task, the given engine prohibited shutdown time T offmin and forced shutdown time T offmax are taken as the final safe shutdown time;

[0017] S6: for the orbit control task involving safety: determining a set of safety threshold constraints, giving multiple sets of prohibited shutdown time T offmin and forced shutdown time T offmax under nominal working condition and deviation working condition through orbit dynamics simulation, comparing the prohibited shutdown time T offmin and forced shutdown time T offmax given in step S5, and determining the safe shutdown time of the orbit control task involving safety.

[0018] Further, in step S3, the method for calculating the submergence velocity increment and the aftereffect velocity increment is:

[0019] The velocity increment of the submergence engine is:

[0020]

[0021] In the formula, t c is the total working time of the submergence engine, and F cTo execute the submerged engine thrust, I c The specific impulse of the orbit control engine;

[0022] The mass of the probe after submersion is calculated And it is updated as the initial mass of the orbit control;

[0023] The post-effect velocity increment is:

[0024] ΔV h = ΔV s1 + ΔV s2 + ΔV s3 + ΔV p

[0025] In the formula, ΔV s1 , ΔV s2 , ΔV s3 The velocity increment caused by the delay of the control system generating the shutdown instruction, the delay of sending the shutdown instruction, and the delay of executing the shutdown instruction; The velocity increment caused by the post-effect impulse I p of the thrust reduction process of the engine after shutdown.

[0026] Further, in step S3, the actual orbit control velocity increment is:

[0027] ΔV = ΔV0- ΔV c - ΔV h

[0028] In the formula, ΔV0is the theoretical velocity increment of the orbit control;

[0029] The nominal start-up duration of the orbit control is:

[0030]

[0031] In the formula, g is the gravitational acceleration, F g is the thrust of the orbit control engine, and Δm is the propellant consumption during the orbit control process, which is expressed as:

[0032]

[0033] Further, in step S2, the engine use strategy for the orbit control and the attitude control engine use strategy during the orbit control process are determined according to the probe engine use principle, and the submerged engine thrust F c and the deviation ΔF c , the submerged engine specific impulse I c and the deviation ΔI c , the orbit control engine thrust F g and the deviation ΔF g , and the orbit control engine specific impulse I gand bias ΔI g , attitude control engine thrust F z and bias ΔF z , attitude control engine specific impulse I z and bias ΔI z .

[0034] Further, in step S5, according to the orbit control nominal start-up time length, the time error bias is calculated, specifically:

[0035] The time error bias is caused by the parameter uncertainty caused time deviation, the time error caused by the sinking, the attitude control caused time error;

[0036] The parameter uncertainty caused time deviation dt g is the sum of the time error caused by the probe mass deviation, the orbit control engine thrust deviation, the orbit control engine specific impulse deviation;

[0037] The time error caused by the sinking dt c is the sum of the time error caused by the probe mass deviation, the sinking engine thrust deviation, the sinking engine specific impulse deviation;

[0038] The attitude control caused time error dt z is the time deviation caused by the attitude control engine maintaining the probe attitude.

[0039] Further, in step S5, according to the calculated time error bias, the engine prohibition shutdown time T offmin and the forced shutdown time T offmax of the orbit control process are given:

[0040] T offmin = t-dt g -dt c -dt z

[0041] T offmax = t+dt g +dt c +dt z

[0042] In the formula, t is the orbit control nominal start-up time length.

[0043] Further, in step S6, the safety threshold constraint set is determined, and the constraints in the set include:

[0044] Constraint one: the additional consumption amount caused by the shutdown time length design is less than the probe propellant remaining amount;

[0045] Constraint two: constraints for different orbit control mission objectives: for the gravitational capture mission, the minimum firing time for the probe to capture the target celestial body's gravitational region is given; for the orbit lowering mission, the safe minimum threshold of the orbit altitude is given; for the orbit control mission with multiple targets in orbit, the safe distance threshold between two probes is given; if there are complex requirements related to the mission, a set of constraints on orbit, time and fuel consumption is given.

[0046] Further, in step S6, for the orbit control mission related to safety: a plurality of sets of forbidden shutdown times T offmin and forced shutdown times T offmax are given by orbit dynamics simulation under the nominal condition and the pull-off condition, wherein the pull-off condition includes at least two conditions, i.e., a condition considering the minimum thrust, the maximum specific impulse and the maximum initial mass of the probe, and a condition considering the maximum thrust, the minimum specific impulse and the minimum initial mass of the probe.

[0047] Further, in step S6, the orbit dynamics simulation under the nominal condition and all the pull-off conditions satisfies a set of safety threshold constraints.

[0048] Further, in step S1, the initial mass m0 of the probe before orbit control is determined, and the calculation method is as follows:

[0049] m0=m fs -Δm g -Δm z -Δm other

[0050] In the formula, m fs is the mass characteristic measurement data of the probe before launch, Δm g is the orbit control propellant consumption, Δm z is the attitude control propellant consumption, and Δm other is the factor affecting the mass of the probe due to possible spacecraft separation and inter-spacecraft separation.

[0051] Compared with the prior art, the present application has the following advantages:

[0052] The present application improves the reliability of the probe shutdown time design by theoretically calculating the orbit control safety time and verifying it through multi-condition simulation analysis, and realizes the safe shutdown of the probe during the orbit control in the process of in-orbit flight. BRIEF DESCRIPTION OF DRAWINGS

[0053] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a better understanding of the preferred embodiments, and are not to be considered limitations of the present application. Moreover, throughout the drawings, like reference numerals refer to similar components. In the drawings:

[0054] Figure 1 This is a flowchart of the track control safety shutdown time calculation method according to an embodiment of the present invention. Detailed Implementation

[0055] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0056] This invention proposes a method for calculating the safe shutdown time of orbit control systems applicable to deep space exploration, such as... Figure 1 As shown, it includes:

[0057] S1: Based on the pre-launch mass characteristic measurement data m fs Orbit control propellant consumption Δm g Attitude control propellant consumption Δm z And factors that may affect detector quality, such as spacecraft-rocket separation, inter-spacecraft separation, and sample transfer Δm. other Determine the initial mass m0 = m before orbit control of the probe. fs -Δm g -Δm z -Δm other and initial mass deviation Δm0;

[0058] S2: Based on the nominal orbit control time, accurately determine the probe's orbit in advance and predict the orbital elements F = (a, e, i, Ω, ω, γ) at the orbit control time, where a, e, i, Ω, ω, γ represent the orbital semi-major axis, eccentricity, orbital inclination, right ascension of the ascending node, argument of perigee, and true anomaly, respectively. Calculate the theoretical velocity increment ΔV0 for orbit control based on the orbit control target and the current orbit determination data. Based on the theoretical velocity increment ΔV0, determine the engine usage strategy for orbit control and the attitude control engine usage strategy during the orbit control process, and determine the thrust F of the bottom-diving engine. c and deviation ΔF c Specific impulse of bottom-dwelling engine I c and deviation ΔI c Orbit control engine thrust F g and deviation ΔF g Track control engine specific impulse I g and deviation ΔI g Attitude control engine thrust F z and deviation ΔF z Attitude control engine specific impulse I zand the deviation ΔI z The engine thrust and specific impulse related parameters are determined by the ground thermal test results.

[0059] S3: According to the theoretical speed increment in the orbit control process, the engine selection, calculate the orbit control speed increment after deducting the sinking speed increment and the aftereffect speed increment ΔV = ΔV0- ΔV c -ΔV h .

[0060] The speed increment of the sinking engine is expressed as:

[0061]

[0062] Where, t c is the total working time of the sinking engine, such as using two engines to sink for 30s, then t c = 60s. Calculate the mass of the probe after sinking and update it as the initial mass of the orbit control.

[0063] The aftereffect speed increment is expressed as:

[0064] ΔV h = ΔV s1 + ΔV s2 + ΔV s3 + ΔV p

[0065] Where, ΔV s1 , ΔV s2 , ΔV s3 are the speed increments caused by the control system generating shutdown instruction delay, sending shutdown instruction delay, and shutdown instruction execution delay; is the speed increment caused by the aftereffect impulse I p of the engine thrust decline process after shutdown.

[0066] The orbit control start-up time can be expressed as:

[0067]

[0068] Where, g is the gravitational acceleration, taking 9.80665 m / s 2 , Δm is the propellant consumption in the orbit control process, expressed as:

[0069]

[0070] S4: According to the different of orbit control target, the orbit control task is divided into regular orbit control task and orbit control task involving safety. Orbit control task contains different types of orbit control such as midcourse correction, braking, deorbit, phasing, lifting, etc. Orbit control involving safety contains braking, deorbit, etc. which may deviate from celestial body gravity sphere and impact the moon, etc. which directly lead to the failure of exploration mission. Orbit control task also includes orbit control task of multiple probes running simultaneously in orbit.

[0071] S5: For the two types of orbit control tasks in step S4, according to the orbit control strategy and the selection of engine, the engine prohibited shutdown time T offmin and forced shutdown time T offmax of the orbit control process are calculated, which contains time error caused by parameter uncertainty, sinking, attitude control, actuator, etc.

[0072] 1) According to theoretical analysis and a large number of test verification, combined with engineering experience, the time error dt g caused by parameter uncertainty can be expressed as the sum of time error caused by probe mass deviation, orbit control engine thrust deviation and orbit control engine specific impulse deviation,

[0073]

[0074] where m and dm are the mass and mass deviation of the probe after sinking, F g and dF g are the thrust and thrust error of the orbit control engine, I g and dI g are the specific impulse and specific impulse error of the orbit control engine, and ΔV is the orbit control velocity increment. It should be noted that when the probe uses 2 x 150 N engines to work, the thrust and deviation should be the sum of the two engines.

[0075] 2) The time error caused by sinking can be expressed as the sum of the time error caused by the probe mass deviation, the sinking engine thrust deviation and the sinking engine specific impulse deviation,

[0076]

[0077]

[0078] where m c and dm c are the initial mass m0 and the initial mass deviation, F c and dF c are the thrust and thrust error of the sinking engine, dI c is the specific impulse error of the sinking engine, and ΔV cThe increment of the descent velocity.

[0079] 3) The attitude control engine works to generate additional thrust, which affects the minimum and maximum transfer time due to the need to maintain the probe attitude during the orbit control process. The time error caused by attitude control is:

[0080]

[0081] where m is the mass of the probe after descent, ΔV1 is the attitude control velocity increment, which can be considered according to the maximum orbit control velocity increment. T max The maximum disturbance torque of the orbit control process, D is the force arm of the probe attitude control engine.

[0082] 4) The time error caused by the actuator includes the time delay of the control system generating the shutdown instruction, the time delay of the control system sending the shutdown instruction, dt s3 , the execution time delay of the engine shutdown instruction, and the aftereffect impulse I p caused by the thrust drop process after the engine is turned off. This part of the time error has been considered by deducting the aftereffect velocity increment in step S3, which will not be considered again here.

[0083] 5) The forbidden shutdown time and the forced shutdown time can be represented as the relationship between the nominal on-time t of the orbit control and the time error dt g , dt c , dt z ,

[0084] T offmin = t-dt g -dt c -dt z

[0085] T offmax = t+dt g +dt c +dt z

[0086] S6: For orbit control tasks involving safety, determine the safety threshold constraint according to different orbit control task objectives. In order to ensure the executability of the subsequent tasks of the probe, it is necessary to make a fine budget of the propellant consumption, and to ensure that the additional consumption m f caused by the shutdown time design is less than the remaining amount of propellant of the probe It should be noted that the remaining amount of propellant of the probe needs to be updated according to the previous orbit control execution during the execution of the task in the flight mission. For the gravity capture task, the minimum firing time t min is given to capture the probe in the gravity region of the target celestial body; for the orbit lowering task, the safety minimum threshold h minFor multi-target on-orbit orbit control tasks, a safe distance threshold d between two probes is given min If subsequent tasks have complex task requirements such as timing and point landing, the constraint set of orbit elements and time is given through dynamic simulation data. The above type of orbit control safety threshold can be expressed as a set of constraint terms:

[0087]

[0088] S7: According to the deviation range of engine thrust, specific impulse and probe initial mass, set the simulation working condition, verify the orbit control safety and task safety. In addition to the nominal working condition, consider two kinds of pull bias working conditions of minimum thrust, maximum specific impulse and maximum initial mass of the probe, and maximum thrust, minimum specific impulse and minimum initial mass of the probe. The orbit dynamics simulation of the nominal working condition and the two kinds of pull bias working conditions should meet the safety threshold constraint set C determined in step S6, that is:

[0089]

[0090] By adjusting the forbidden shutdown time T offmin and the forced shutdown time T offmax in the orbit dynamics simulation, so that the above constraints are met, three groups of forbidden shutdown time T offmin and forced shutdown time T offmax under the nominal working condition and the two kinds of pull bias working conditions are given;

[0091] By comparing the multiple groups of forbidden shutdown time T offmin and forced shutdown time T offmax given in steps S5 and S7, the safe shutdown time of the orbit control task involving safety is finally determined. Among them, the forbidden shutdown time T offmin takes the maximum value of the calculation value in step S5 and the three groups of simulation values in step S7, and the forced shutdown time T offmax takes the minimum value of the calculation value in step S5 and the three groups of simulation values in step S7, to ensure the safe execution of the probe orbit control process.

[0092] The orbit control safety shutdown time calculation method proposed in the application can be applied to complex deep space exploration tasks, especially for orbit control tasks involving safety. By selecting appropriate forbidden shutdown time and forced shutdown time, the orbit safety and task safety of the probe can be ensured while achieving the orbit control target, and the safety of the detection task implementation is improved.

[0093] The above-described embodiments are only the preferred specific embodiments of the application, and the usual changes and substitutions made by those skilled in the art within the scope of the technical solutions of the application should be included in the protection scope of the application.

Claims

1. An orbit control safe shutdown time calculation method suitable for deep space exploration, characterized in that, Comprise: S1: determine the initial mass m0 and the initial mass deviation Δm0 before the probe orbit control; S2: according to the nominal orbit control time, the probe is accurately determined, and the orbit root number at the orbit control time is predicted, the theoretical velocity increment of orbit control is calculated according to the orbit control target, and the submergence engine, orbit control engine and attitude control engine, and the related engine thrust and specific impulse parameters are determined; S3: according to the theoretical velocity increment, the above-mentioned engine specification parameters, the submergence velocity increment and the aftereffect velocity increment are calculated, the actual orbit control velocity increment is obtained, and the nominal orbit control start time is determined; S4: according to the orbit control target, the orbit control task is divided into regular orbit control task and orbit control task related to safety; S5: for two kinds of orbit control tasks, according to the nominal start-up time of the orbit control, the time error deviation is calculated, and the engine prohibition shutdown time T of the orbit control process is given offmin and the forced shutdown time T offmax ; if it is a conventional orbit control task, the given engine prohibition shutdown time T offmin and the forced shutdown time T offmax are taken as the final safe shutdown time; S6: For orbit control tasks involving safety: determine a set of safety threshold constraints, give a plurality of sets of forbidden shutdown times T offmin and forced shutdown times T offmax under nominal and off-nominal conditions by orbit dynamics simulation, compare with the engine forbidden shutdown times T offmin and forced shutdown times T offmax given in step S5 to determine the safety shutdown times for orbit control tasks involving safety.

2. The orbit control safe shutdown time calculation method of claim 1, wherein, In step S3, the method for calculating the submergence velocity increment and the aftereffect velocity increment is: The velocity increment of the submergence engine is: In the formula, t c is the total working time of the bottom-sinking engine, F c is the thrust of the bottom-sinking engine, I c is the specific impulse of the bottom-sinking engine; Calculating the mass of the probe after sinking and updating it as the initial mass for orbit control; The aftereffect velocity increment is: ΔV h = ΔV s1 + ΔV s2 + ΔV s3 + ΔV p where ΔV s1 , ΔV s2 , ΔV s3 is the speed increment caused by the shutdown instruction generation delay, the shutdown instruction sending delay, and the shutdown instruction execution delay of the control system; is the speed increment caused by the aftereffect impulse I p of the thrust decline process after the engine is shut down.

3. The method for calculating the safe shutdown time of track control according to claim 2, characterized in that, In step S3, the actual orbit control velocity increment is: AV = AV0- AV c - AV h In the formula, ΔV0 is the theoretical velocity increment of orbit control; The nominal orbit control start time is: where g is the acceleration due to gravity, F g is the orbit control engine thrust, and Δm is the propellant consumption during the orbit control process, I g is the specific impulse of the orbit control engine, and is expressed as:

4. The method of claim 2, wherein, In step S2, the engine use strategy for orbit control and the attitude control engine use strategy in the orbit control process are determined according to the detector engine use principle, and the execution of the bottoming engine thrust F c and the deviation ΔF c , the specific impulse I c and the deviation ΔI c , the orbit control engine thrust F g and the deviation ΔF g , the orbit control engine specific impulse I g and the deviation ΔI g , the attitude control engine thrust F z and the deviation ΔF z , the attitude control engine specific impulse I z and the deviation ΔI z are determined.

5. The method of claim 1, wherein, In step S5, according to the nominal orbit control start time, the time error deviation is calculated, which is: The time error deviation caused by the parameter uncertainty, the time error caused by the submergence, and the time error caused by the attitude control are divided; Time bias dt due to parameter uncertainty g Sum of time errors due to probe mass bias, orbit control engine thrust bias, orbit control engine specific impulse bias: where dm is the mass deviation after the probe has landed, dF g is the thrust error of the orbit control engine, dI g is the specific impulse error of the orbit control engine; Time error caused by subsidence dt c Sum of time errors caused by probe mass deviation, subsidence engine thrust deviation, subsidence engine specific impulse deviation: where dm c is the initial mass deviation of the probe, F c and dF c are the thrust and thrust error of the descent engine, respectively, dI c is the specific impulse error of the descent engine, F g is the orbit control engine thrust; Time error dt due to attitude control z Time offset created by maintaining the probe attitude for attitude control of the engine: where dF z is the attitude control engine thrust error, T max is the maximum disturbance torque of the orbit control process, D is the force arm of the probe attitude control engine.

6. The method of claim 5, wherein, In step S5, the engine shutdown time T is given for the orbit control process according to the calculated time error deviation offmin and the forced shutdown time T offmax : T offmin = t - dt g - dt c - dt z T offmax = t + dt g + dt c + dt z In the formula, t is the nominal orbit control start time.

7. The method of claim 1, wherein, In step S6, the safety threshold constraint set is determined, and the constraints in the set include: Constraint one: the additional consumption caused by the shutdown time design is less than the probe propellant reserve; Constraint two: the constraint for different orbit control task targets: for gravity capture task, the minimum ignition time of the probe in the target celestial body gravity area is given; for the orbit lowering task, the safety minimum threshold of the orbit height is given; for the orbit control task of multiple targets in orbit, the safety distance threshold between two probes is given; if there are complex requirements related to the task, the constraint set of orbit, time and fuel consumption is given.

8. The method of claim 1, wherein, In step S6, for the orbit control task involving safety: a plurality of sets of forbidden shutdown time T offmin and forced shutdown time T offmax under nominal conditions and under a plurality of perturbed conditions are given by orbit dynamics simulation, wherein the plurality of perturbed conditions at least include two conditions, a first condition considering minimum thrust, maximum specific impulse and maximum initial mass of the probe, and a second condition considering maximum thrust, minimum specific impulse and minimum initial mass of the probe.

9. The method of claim 1 or 8, wherein, In step S6, the orbit dynamics simulation of the nominal working condition and all the pull bias working conditions meets the safety threshold constraint set.

10. The method of claim 1, wherein, In step S1, the initial mass m0 of the probe before orbit control is determined, and the calculation method is: m0= m fs -Δm g -Δm z -Δm other where m fs is the pre-launch mass property measurement data for the probe, Δm g is the on-orbit control propellant consumption, Δm z is the attitude control propellant consumption, Δm other is the factor that can affect the probe mass due to possible spacecraft separation, inter-satellite separation.

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