An efficiency evaluation method and system for a near-earth asteroid space-based monitoring and early warning system

Abstract

The application provides a performance evaluation method and system for a near-earth asteroid space-based monitoring and early warning system. The method constructs a value-keeping sky area model and a scanning strategy through a unified coordinate system and time system. The state quantity is obtained by recursively interpolating the asteroid orbit within the task period. The candidate events are coarsely screened using the orbital geometry and luminosity conditions. Then, the secondary determination is combined with the visible or infrared flux calculation, signal-to-noise ratio and platform constraints to generate an effective observation event list, and finally the catalog completion rate and early warning rate are evaluated. The advantage of the application is that the performance of different deployment schemes can be quantitatively evaluated. Simulation shows that the early warning rate of the leading and trailing orbit dual-telescope scheme reaches 90.93%, which is significantly better than the sun-earth L1 point scheme. In addition, after using the performance simulation acceleration method, the number of single-target determinations is greatly reduced, and the running time is shortened from about 9 hours to about 10 minutes, which meets the requirements of rapid comparison of multiple schemes.

Description

Technical Field

[0001] This application pertains to the fields of asteroid defense, asteroid monitoring and early warning, and aerospace, and specifically relates to a method and system for evaluating the effectiveness of a space-based monitoring and early warning system for near-Earth asteroids. Background Technology

[0002] Near-Earth asteroids are defined as those with a perihelion distance of less than 1.3 AU. These asteroids may impact Earth, thus posing a potential hazard. The core task of an asteroid monitoring and early warning system is not only to detect targets but also to provide a sufficiently long warning time before the target impacts Earth, and to provide observational data support for subsequent orbit determination, risk assessment, and emergency response. Existing monitoring systems mainly rely on ground-based optical surveys, which have advantages such as mature technology, large aperture, and convenient follow-up observations. However, they are limited by diurnal variations, weather, atmospheric absorption, lunar background, and blind spots in the direction of the sun, making it difficult to maintain long-term stable coverage of targets near the sun and those with low albedo.

[0003] Space-based visible and infrared telescopes can complement ground-based systems in terms of observation time, location, and wavelength. Infrared observations, utilizing asteroid thermal radiation, offer better detection potential for low-albedo targets and those near the Sun. Earth-Sun L1 points, Earth-leading orbits, Earth-following orbits, and other special orbital configurations can monitor potential threat areas around Earth and near the Sun from different geometric locations. Therefore, during the mission validation phase of space-based monitoring, it is necessary to establish a unified method for evaluating the effectiveness of different orbital configurations.

[0004] Current space-based monitoring effectiveness assessment methods typically suffer from the following shortcomings: First, some methods rely primarily on geometric visibility or visible light stellar magnitude determination, failing to adequately characterize the combined effects of asteroid thermal radiation, solar reflected radiation, phase angle, and low-albedo targets. Second, different modeling calibers are often used for the monitored sky area, solar avoidance angle, Earth avoidance angle, instantaneous field-of-view scanning, and revisit rhythm under different orbital configurations, making rigorous comparisons between different schemes difficult. Third, long-term simulations of large-scale near-Earth asteroid samples require extensive and repeated determinations of targets, time steps, platform positions, and scanning directions, resulting in high computational costs and making it difficult to support rapid iteration with multiple parameters, orbits, and strategies.

[0005] Therefore, a method for evaluating the effectiveness of space-based monitoring and early warning is needed. This method should unify the modeling of target populations, orbital platforms, telescope parameters, visible / infrared detectability, scanning strategies, and effectiveness indicators. Furthermore, it should improve the efficiency of large-sample simulations through pre-calculation and interpolation, thereby providing support for the design of space-based near-Earth asteroid monitoring systems, parameter sensitivity analysis, and selection of multi-platform collaborative schemes. Summary of the Invention

[0006] To overcome the aforementioned shortcomings, this application proposes a performance evaluation method for a space-based monitoring and early warning system for near-Earth asteroids, including: Step S1: Obtain near-Earth asteroid orbit data and telescope platform ephemeris data, and unify the coordinate system and time system; establish a monitoring sky area model according to different orbit configurations, construct a scanning grid and repeated access strategy, and generate a platform-time-pointing lookup table; Step S2: For each near-Earth asteroid, perform orbit recursion during the mission's lifetime and store the target state as sparse nodes on the simulation timeline; during the performance statistics phase, interpolate the sparse nodes according to the required simulation time to obtain the target's ensemble state quantities, including: target position, heliocentric distance, observation distance, and phase angle. Step S3: Use the target's relative ecliptic longitude, ecliptic latitude, observation distance, heliocentric distance and phase angle to perform a coarse screening of candidate events, and exclude moments that are not located in the monitored sky area, do not meet the avoidance constraints, do not fall into the scanning field of view, or do not meet the preliminary judgment conditions of the visible light apparent magnitude threshold / infrared flux threshold. Step S4: For candidate events that pass the coarse screening, perform visible light band apparent magnitude and signal-to-noise ratio calculation, or perform infrared band thermal radiation / reflected radiation flux calculation, and combine platform avoidance constraints, instantaneous field of view constraints and detection thresholds for secondary judgment to obtain valid observation events; Step S5: Write all visible moments into the list of valid observation events; Step S6: Based on the list of valid observation events, determine whether each asteroid has been discovered, whether it has been warned, and whether it is a target approaching from the direction of the sun; calculate the cataloging completeness rate and warning rate.

[0007] As an improvement to the above method, the monitored area model in step S1 is represented as follows: ; in, k Indicates the first k A telescope platform or deployment plan; l and β These represent ecliptic longitude and ecliptic latitude relative to Earth, respectively. and They represent the first k The observable boundaries of the telescope platform in the ecliptic longitude direction; and They represent the first k The observable boundaries of the telescope platform in the ecliptic latitude direction; Represents the geometrically observable function after integrating avoidance angle, occlusion, and attitude constraints; when When, it indicates that the direction is at time. t Satisfy platform geometric constraints; when When, it indicates that the direction is at time.t The effects of constraints are unobservable.

[0008] As an improvement to the above method, the target state is calculated in step S2 as follows: For each simulation time The state of the target relative to the Sun, Earth, and observation platform is represented as follows: ; in, Indicates the simulation time The position vector of a near-Earth asteroid relative to the Sun; Indicates the simulation time The position vector of the telescope platform relative to the sun; Indicates the distance from the target to the telescope. Indicates the heliocentric distance of the target. This indicates the phase angle.

[0009] As an improvement to the above method, the calculation of apparent magnitude and signal-to-noise ratio in the visible light band and the method for determining effective observation events in step S4 include: For the visible light band, the apparent magnitude is calculated based on the target's absolute magnitude, heliocentric distance, observation distance, and phase function. The target at time... The apparent magnitude is represented as: ; in, H The absolute magnitude of a near-Earth asteroid; This represents the phase function; if the target is within the current instantaneous field of view and simultaneously satisfies the threshold constraints of solar avoidance, Earth avoidance, and apparent star avoidance, it is determined to be a valid visible light observation. ; in, Indicates the first k The telescope platform at the j Each scan points downwards at time [time]. The visible light observation results of the target; target indicates the target's location; Indicates the first k Each telescope platform at any time Corresponding to the j The instantaneous field of view area pointed to by each scan; This represents the geometrically observable function after considering the combined avoidance angle, occlusion, and attitude constraints. Indicates the first k The limiting magnitude of a telescope platform in the visible light band; Indicates the target at time. The observed signal-to-noise ratio; Indicates the first kEach telescope platform must meet the minimum signal-to-noise ratio threshold required for effective detection; if any condition is not met, then... .

[0010] As an improvement to the above method, the calculation of infrared thermal radiation / reflected radiation flux in step S4 includes: For the infrared band, the asteroid radiation received by the telescope includes the asteroid's own thermal radiation and the reflection of solar radiation from its surface, both of which are represented as: ; in, Indicates the target at wavelength Place, moment The total radiant flux received by the telescope platform; This refers to the thermal radiation flux calculated based on the NEATM thermal model; This represents the reflected flux of solar radiation on the asteroid's surface. Based on the solar constant, target heliocentric distance, geometric albedo, emissivity, and beam parameters or The temperature distribution on the illuminated surface of the asteroid is calculated using the phase angle, and the infrared thermal radiation flux is obtained by integrating over the visible surface; the temperature of the target surface element is also calculated. Represented as: ; in, A For Bond's albedo; Solar irradiance at 1 AU; e For emissivity; s The Stefan-Boltzmann constant; The target heliocentric distance; i The angle of incidence on the surface; Integrating the surface elements of the target visible from the telescope platform yields the thermal radiation flux of the target in the infrared band: ; in, Indicates the distance from the target to the telescope; This refers to the visible area on the target's surface that can be observed by the telescope platform. (T) Indicates temperature as T A blackbody at wavelength Planck radiation function at the location; ψ This represents the angle between the normal to the surface element of the target and the direction in which the surface element points towards the telescope platform; dA Represents the area of ​​the target surface element; The reflected flux of solar radiation from the target surface is calculated based on the target albedo, solar spectral irradiance, heliocentric distance, observation distance, and the phase angle between the sun, target, and telescope platform, and is expressed as: ; in, Indicates the target at wavelength Spectral albedo at that location; This represents the solar spectral irradiance at a location of 1 AU; This indicates the area on the target surface that is illuminated by the sun. This represents the reflection phase function, used to describe the distribution characteristics of surface reflected radiation as a function of the solar incident direction, observation direction, and phase angle.

[0011] As an improvement to the above method, step S4 combines platform avoidance constraints, instantaneous field-of-view constraints, and detection thresholds for a secondary precise determination, expressed as: ; in, Indicates the first k The telescope platform at the j Each scan points downwards at time [time]. The visible light observation results of the target; target indicates the target's location; Indicates the first k Each telescope platform at any time Corresponding to the j The instantaneous field of view area pointed to by each scan; This represents the geometrically observable function after considering the combined avoidance angle, occlusion, and attitude constraints. Indicates the first k Each telescope platform at wavelength Infrared flow detection threshold at the location; Indicates the target at wavelength Place, moment The total radiant flux received by the telescope platform; if any of the above conditions are not met, then .

[0012] This application also provides a performance evaluation system for a space-based monitoring and early warning system for near-Earth asteroids, used to implement the above method, the system comprising: The Near-Earth Asteroid Collaborative Monitoring and Planning Module is used to acquire near-Earth asteroid orbital data and telescope platform ephemeris data, unify the coordinate system and time system; establish a monitoring sky area model according to different orbital configurations, construct a scanning grid and repeated access strategy, and generate a platform-time-pointing lookup table; The asteroid orbit sparse interpolation and state reconstruction module is used to perform orbit recursion for each near-Earth asteroid during the mission's lifetime, storing the target state as sparse nodes on the simulation timeline; in the performance statistics phase, the sparse nodes are interpolated according to the required simulation time to obtain the target's ensemble state quantities, including: target position, heliocentric distance, observation distance, and phase angle. The multi-constraint candidate event coarse screening module is used to coarsely screen candidate events using the target's relative ecliptic longitude, ecliptic latitude, observation distance, heliocentric distance and phase angle, and exclude moments that are not located in the monitored sky area, do not meet the avoidance constraints, do not fall into the scanning field of view, or do not meet the preliminary judgment conditions of visible light apparent magnitude threshold / infrared flux threshold. The multi-parameter accurate determination and event extraction module is used to perform visible light band apparent magnitude and signal-to-noise ratio calculations or infrared band thermal radiation / reflected radiation flux calculations on candidate events that have passed the coarse screening. It also performs secondary determinations by combining platform avoidance constraints, instantaneous field of view constraints and detection thresholds to obtain valid observation events. The module for generating a list of valid observation events is used to write all visible moments into the list of valid observation events. The asteroid discovery and warning and approach attribute assessment module is used to determine whether each asteroid has been discovered, whether it has been warned, and whether it is a target approaching from the direction of the sun, based on the list of valid observation events; and to calculate the cataloging completeness rate and warning rate.

[0013] Compared with existing technologies, the advantages of this application are: 1. A unified modeling method for the standby sky area, scanning grid, and revisit rhythm under multi-orbit configurations is proposed. This method unifies different platforms such as the Sun-Earth L1 point, Earth pilot orbit, and Earth follower orbit into a computational framework for platform ephemeris, standby sky area, scanning direction, and constraint avoidance, making different deployment schemes comparable.

[0014] 2. An effective observational determination method that takes into account both visible light apparent magnitude and infrared radiation flux determination is proposed. This method simultaneously considers the target's solar reflected radiation, the asteroid's own thermal radiation, phase angle, observation distance, heliocentric distance, telescope sensitivity, scanning strategy, and platform avoidance constraints. It not only determines whether the target is geometrically visible, but also whether it meets the visible light apparent magnitude threshold or the infrared radiation flux threshold.

[0015] 3. A high-performance simulation acceleration method suitable for large-scale near-Earth asteroid samples is proposed. By pre-calculating platform geometry and scanning direction, target state interpolation, candidate event coarse screening, and a small number of precise judgments, the method avoids repetitive calculations for each target, each time point, and each direction, significantly improving the simulation efficiency of multiple schemes.

[0016] 4. A multi-indicator comprehensive evaluation method for monitoring and early warning tasks is proposed. This method simultaneously outputs information such as cataloging completeness rate, overall early warning rate, solar direction early warning rate, and orbit update capability, which can serve the selection of schemes and parameter optimization under different mission objectives.

[0017] 5. The space-based observation evaluation method designed in this invention can quantitatively evaluate the monitoring and early warning effectiveness of different space deployment schemes and collaborative observation strategies. Under the conditions of point source sensitivity of 5σ and 150 μJy, the early warning rate of the dual-telescope scheme with pilot and trailing orbits (observation area 90°) reaches 90.93%, and the early warning rate in the solar direction reaches 91.50%, which is significantly higher than the 67.32% and 72.93% of the Sun-Earth L1 point scheme, respectively. After adopting the performance simulation acceleration method, the number of single-target visibility determinations is reduced from 901,621 to the order of 1,803, and the overall runtime is shortened from about 9 hours to about 10 minutes, which can meet the needs of rapid comparison and evaluation of multiple schemes. Attached Figure Description

[0018] Figure 1 The diagram shown is the overall flowchart for evaluating the effectiveness of space-based monitoring and early warning of near-Earth asteroids. Figure 2 The diagram shown is a description of the monitored celestial area (monitoring celestial sphere). Figure 3 The diagram shown is a description of the monitored sky area (opposition ecliptic longitude). Figure 4 The diagram shows a multi-orbit configuration for guarding the sky. Figure 5 The diagram shows a schematic of the Earth navigation orbit scanning strategy. Figure 6 The image shown is a visibility analysis diagram in the visible light band. Figure 7 The image shown is a visibility analysis diagram in the infrared band. Figure 8 The diagram shown is a flowchart of the large-sample performance simulation calculation. Detailed Implementation

[0019] The technical solution of this application will be described in detail below with reference to the accompanying drawings.

[0020] This invention proposes a performance evaluation method for a space-based monitoring and early warning system for near-Earth asteroids. This method addresses the design requirements of space-based visible and infrared telescope missions, establishing a complete workflow comprising target sample input, orbital platform modeling, monitoring area division, scanning strategy design, visibility determination, acceleration performance simulation, index statistics, and parameter optimization, including: 1. Establish a unified description method for the guarded sky area and scanning strategy under multi-track configuration.

[0021] 2. Establish a detectability determination method that takes into account visible light reflection, infrared thermal radiation, phase angle, telescope sensitivity, and observation geometry.

[0022] 3. Establish accelerated simulation methods for pre-calculation, interpolation, and secondary fine-tuning of large-scale near-Earth asteroid samples.

[0023] This invention supports unified performance evaluation for various platform configurations, including the Sun-Earth L1 point, Earth pilot orbit, and Earth follower orbit; it can simultaneously handle visible light apparent magnitude constraints and infrared radiation flux constraints; it can incorporate solar reflection and asteroid thermal radiation into the same detectability determination; it can reduce redundant calculations in large-sample simulations through pre-calculation storage and interpolation determination; and it can output indicators such as cataloging completeness rate, overall early warning rate, solar direction early warning rate, average early warning time, effective observation count, and orbit update capability, providing quantitative basis for the demonstration of monitoring system schemes.

[0024] Example 1 like Figure 1 As shown, this invention proposes a method for evaluating the effectiveness of a space-based monitoring and early warning system for near-Earth asteroids, efficiently providing analytical results on the effectiveness of space-based observation equipment in monitoring and early warning of near-Earth asteroids. The specific technical solution is as follows: Step 1: Input data acquisition and unified coordinate modeling.

[0025] The process involves acquiring a near-Earth asteroid sample set, telescope platform orbit, telescope payload parameters, and mission constraints, including mission time constraints, Earth-Sun avoidance angle constraints, observation target constraints, and attitude pointing constraints. These constraints are then uniformly transformed to the heliocentric ecliptic J2000 coordinate system or another designated inertial coordinate system. Near-Earth asteroid samples may include orbital elements, epochs, and absolute stellar values. H Geometric albedo Cluster parameters or Rotation or thermophysical parameters are used to calculate the equivalent diameter of the asteroid: Telescope platform parameters include platform position vector Velocity vector Platform orbit type, attitude pointing constraints, solar avoidance angle, Earth avoidance angle, and mission lifetime; telescope payload parameters may include instantaneous field of view, spectral range, and limiting star view, etc. Point source sensitivity Integration time, pointing switching time, pixel scale, detector noise, and signal-to-noise ratio threshold.

[0026] Step 2: Modeling the multi-orbit configuration of the sky area.

[0027] Establish a monitoring celestial sphere based on the relative geometry of the Sun, Earth, and telescope. Using the ecliptic plane as the reference plane, define the direction from the Sun to the Earth as the reference axis, and utilize the ecliptic longitude relative to the Earth. l He Huang Wei β Describe the area of ​​the sky that the telescope is monitoring, such as Figure 2 and Figure 3 As shown. For different orbital configurations, candidate guarded sky regions are first generated under the relative geometry model of the Sun-Earth-telescope platform. The candidate region does not directly adopt a single, fixed, mature template, but is based on the... k The orbital position, relative offset to Earth, solar avoidance constraints, Earth avoidance constraints, and platform attitude reachability constraints of each telescope platform or deployment scheme are parameterized. Subsequently, solar avoidance zones, Earth avoidance zones, and unreachable regions of the platform attitude are further eliminated to obtain the effective guarded sky area that satisfies both geometric and observational constraints. For example... Figure 4 As shown.

[0028] For telescope platforms in Earth-leading or trailing orbits, the monitored area can be set up according to the platform's offset distance from Earth and the mission objective, including a solar proximity area, an Earth periphery area, or alternating front and rear monitored areas. For Sun-Earth L1 point orbits, a ring-shaped or sector-shaped monitored area can be set up according to the solar avoidance angle, the Earth avoidance angle, and the scattering suppression capability of the platform's optical system. The monitored areas for different configurations are represented as follows:

[0029] in, k Indicates the first k A telescope platform or deployment plan; l and β These represent ecliptic longitude and ecliptic latitude relative to Earth, respectively. and They represent the first k The observable boundaries of the telescope platform in the ecliptic longitude direction; and They represent the first k The observable boundaries of the telescope platform in the ecliptic latitude direction; This represents the geometrically observable function after considering the combined avoidance angle, occlusion, and attitude constraints. When When, it means that the direction satisfies the platform geometric constraints at time t; when When, it indicates that the direction is at time. t The effects of constraints are unobservable.

[0030] Step 3: Design the scanning grid and revisit strategy.

[0031] Each guarded area The instantaneous field of view of the telescope is gridded. Let the angular widths of the instantaneous field of view of the telescope in the ecliptic longitude and ecliptic latitude directions be respectively... and Considering the overlap rate of adjacent fields of view Then, the scan step size is obtained: like Figure 5 As shown, a pointing grid is generated based on the scan step size. Each pointer corresponds to an instantaneous field of view unit, and the scanning order and integration time are specified by the task. Pointer switching time and revisit interval Develop a time-series scanning plan. For sky survey missions requiring trajectory correlation, the same sky region can be set. n Second revisit, interval between adjacent revisits overnight confirmation interval These rules ensure that performance evaluation considers not only whether the target is instantly visible, but also whether the target can form an effective observation trajectory or an observation arc across the night.

[0032] Step 4: Asteroid and observation platform status recursion.

[0033] The near-Earth asteroid and telescope platform states are recursively calculated throughout the mission's lifespan. For long-term cataloging simulations, a recursive orbital model sufficient to support geometric visibility and brightness determination accuracy can be used; for high-precision early warning simulations, a dynamic model incorporating solar gravity, planetary perturbations, lunar perturbations, relativistic corrections, and necessary non-gravitational terms can be used. For each simulation time point... Calculate the target's state relative to the Sun, Earth, and observation platform:

[0034] in, Indicates the simulation time The position vector of a near-Earth asteroid relative to the Sun. Indicates the simulation time The position vector of the telescope platform relative to the sun, Indicates the distance from the target to the telescope. Indicates the heliocentric distance of the target. This represents the phase angle. Further calculations are made of the target's relative ecliptic longitude and latitude within the monitored celestial sphere, and it is determined whether the target falls within the instantaneous field of view corresponding to the current scan direction.

[0035] Step 5: Visibility calculation in the visible light band.

[0036] like Figure 6 As shown, for the visible light band, the apparent magnitude is calculated based on the target's absolute magnitude, heliocentric distance, observation distance, and phase function. The target at time... The apparent magnitude can be expressed as:

[0037] Where H represents the absolute magnitude of a near-Earth asteroid; This represents the phase function. If the target is within the current instantaneous field of view and simultaneously satisfies the threshold constraints for solar avoidance, Earth avoidance, and apparent star detection, it is determined to be a valid visible light observation.

[0038] in, Indicates the first k The telescope platform at the j Each scan points downwards at time [time]. The visible light observation results of the target; target indicates the target's location; Indicates the first k Each telescope platform at any time Corresponding to the j The instantaneous field of view area pointed to by each scan; Indicates the first k The limiting magnitude of a telescope platform in the visible light band; Indicates the target at time. The observed signal-to-noise ratio; Indicates the first k Each telescope platform must meet the minimum signal-to-noise ratio threshold required for effective detection. If any condition is not met, then... .

[0039] Step 6: Infrared band visibility calculation.

[0040] For the infrared band, the asteroid radiation received by the telescope includes the asteroid's own thermal radiation and the reflection of solar radiation from its surface, both of which are represented as:

[0041] in, Indicates the target at wavelength Place, moment The total radiant flux received by the telescope platform; The thermal radiation flux is calculated based on the NEATM thermal model. This represents the reflected flux of solar radiation on the asteroid's surface. For example... Figure 7 As shown, when using NEATM, the parameters can be determined based on the solar constant, target heliocentric distance, geometric albedo, emissivity, and beam parameters. or The temperature distribution on the illuminated surface of the asteroid is calculated using the phase angle, and the infrared thermal radiation flux is obtained by integrating over the visible surface. The temperature of a surface element of the target can be expressed as:

[0042] in, A For Bond's albedo, The solar irradiance at 1 AU is... e For emission rate, s The Stefan-Boltzmann constant is... For the target heliocentric distance, i Let be the incident angle on the surface. Integrating over the visible surface elements of the target from the telescope platform yields the target's thermal radiation flux in the infrared band:

[0043] in, Indicates the distance from the target to the telescope; This refers to the visible area on the target's surface that can be observed by the telescope platform. (T) Indicates temperature as T A blackbody at wavelength Planck radiation function at the location; ψ dA represents the angle between the normal of the target surface element and the direction pointing from the element to the telescope platform; dA represents the area of ​​the target surface element. The reflected flux of solar radiation from the target surface can be calculated based on the target albedo, solar spectral irradiance, heliocentric distance, observation distance, and the phase angle between the sun, target, and telescope platform, and is expressed as: ; in, Indicates the target at wavelength Spectral albedo at that location; This represents the solar spectral irradiance at a location of 1 AU; This indicates the area on the target surface that is illuminated by the sun. This represents the reflection phase function, used to describe the distribution characteristics of surface reflected radiation as a function of the solar incident direction, observation direction, and phase angle. If the reflection term is relatively small compared to the thermal radiation term within the selected infrared band, it can also be set... It equals 0.

[0044] Further consideration is given to infrared field-of-view constraints, platform avoidance constraints, and infrared flux detection thresholds. If the target is within the current instantaneous field of view and simultaneously satisfies both the observation platform avoidance constraint and the infrared flux threshold constraint, then it is determined to be a valid infrared observation.

[0045] in, Indicates the first k Each telescope platform at wavelength The infrared flow detection threshold at the location. If any of the above conditions are not met, then .

[0046] Step 7: Accelerated methods for large-sample performance simulation.

[0047] To address the high computational complexity resulting from direct determination of each target, time step, and direction, this invention, building upon the aforementioned orbital data acquisition, monitored sky area modeling, scanning grid construction, asteroid and telescope platform state recursion, and visible / infrared band visibility calculation, proposes an accelerated simulation method combining pre-calculation storage, interpolation coarse screening, and secondary precise determination. The computational flow is as follows: Figure 8 As shown.

[0048] 1. Acquire near-Earth asteroid orbital data and telescope platform ephemeris data, and unify the coordinate system and time system; establish a monitoring sky area model based on different orbital configurations, construct a scanning grid and repeated access strategy, and generate a platform-time-pointing lookup table.

[0049] 2. For each near-Earth asteroid, orbit recursion is performed during the mission's lifetime, and the target state is stored as sparse nodes on the simulation timeline. During the performance statistics phase, the sparse nodes are interpolated according to the required simulation time to obtain geometric state quantities such as target position, heliocentric distance, observation distance, and phase angle.

[0050] 3. Use the target's relative ecliptic longitude, ecliptic latitude, observation distance, heliocentric distance, and phase angle to perform a rough screening of candidate events, and quickly eliminate moments that are not located in the monitored sky area, do not meet the avoidance constraints, do not fall within the scanning field of view, or do not meet the preliminary judgment conditions of the visible light apparent magnitude threshold / infrared flux threshold.

[0051] 4. For candidate events that pass the coarse screening, further calculations are performed on the apparent magnitude and signal-to-noise ratio in the visible light band, or on the thermal radiation / reflected radiation flux in the infrared band. These calculations are then combined with platform avoidance constraints, instantaneous field-of-view constraints, and detection thresholds to make a second, more accurate determination, thus obtaining valid observation events.

[0052] 5. Write all visible moments into the event list. Subsequent metric statistics will be completed directly based on the event list, and the visibility determination of each point will no longer be repeated.

[0053] Step 8: Cataloging, early warning, and calculation of solar direction early warning indicators.

[0054] Based on the list of valid observation events, determine whether each asteroid has been discovered, whether a warning has been issued, and whether it is a target approaching from the direction of the Sun.

[0055] set up The total number of samples, To meet the target number of discovery rules, The number of targets that meet the threat conditions in the task definition. The cataloging completeness rate C and the early warning rate W are expressed as follows: (The original text is incomplete and cannot be translated accurately.) For a solar orientation warning scenario, let's set... This represents the number of threatening targets originating from the vicinity of the sun or whose solar distance angle is less than a threshold. Let the number of targets that are detected in advance and meet the early warning rules be denoted as follows: Then the early warning rate for the solar direction is: Simultaneously, the average warning time, maximum warning time, median warning time, number of effective observations, number of orbit updates, increase in observation arc length, and stratified indicators for different size ranges are statistically analyzed. For impactors or near-Earth rendezvous targets, the warning time can be defined as the time difference between the first effective detection time and the target's distance threshold to Earth, the perigee time, or the impact time. in, The time of perigee, the time of entering 0.05 AU, the time of entering the Earth-Moon distance, or the time of entering the atmospheric boundary can be selected according to the needs of the mission.

[0056] Example 2 A telescope platform will be deployed at the Sun-Earth L1 point or in front of or behind the Earth's orbit, with an orbital offset distance of 0.1–0.2 AU relative to the Earth. The telescope will employ mid-infrared or visible light bands for detection, with an instantaneous field of view of 4.5° × 9.0°, a point source sensitivity threshold of 150 μJy, an integration time of 120 s, a pointing switching time of 15 s, and solar avoidance and Earth avoidance angles of 45° and 10°, respectively.

[0057] A sample of near-Earth asteroids with a diameter of at least 50 m was selected. Each target in the sample was included with its orbital elements, absolute magnitude, and albedo. For each asteroid, its orbit was recursively calculated over the 5-year mission lifespan to obtain its position, distance, phase angle, and celestial coordinates relative to the telescope.

[0058] The Earth navigation platform's monitoring area was set to ±45° of ecliptic longitude and ±45° of ecliptic latitude relative to the Earth, and a scanning grid was divided according to a 4.5° × 9.0° field of view. Each grid was scanned cyclically in a fixed order, and the target was required to obtain at least two valid observations within a specified time window to be counted as an orbit update event. Six observations within 30 days were counted as discovery events.

[0059] For infrared band observations, for each candidate observation event, first determine whether the target is located within the current field of view and meets the avoidance angle constraint; then use NEATM to calculate the target's thermal radiation flux, while superimposing the solar reflection term; when the total infrared flux is greater than 150 μJy, it is recorded as a valid infrared observation.

[0060] The cataloging completeness rate, overall warning rate, and solar direction warning rate distribution are statistically analyzed based on the list of valid observation events. If parameter sensitivity analysis is required, other conditions can be kept constant, and the field of view size, point source sensitivity, ecliptic longitude range, ecliptic latitude range, and revisit interval can be changed respectively. The impact of each parameter on the indicators can then be ranked and output.

[0061] This invention addresses the problems in existing space-based monitoring effectiveness assessments, such as incomplete physical models, incomparability between different orbital configurations, high computational costs for large-sample simulations, and limited statistical indicators. It establishes a complete space-based monitoring and early warning effectiveness assessment process. By unifying visible light apparent magnitude, infrared thermal radiation, solar reflectance, phase angle, telescope sensitivity, observation geometry, and scanning strategy into the determination of effective observation events, the effectiveness of assessments for low-albedo asteroids, targets in the vicinity of the Sun, and short-term threats can be improved.

[0062] This invention enables the comparison of different space-based orbit configurations, such as the Sun-Earth L1 point, the Earth-leading orbit, and the Earth-following orbit, under the same data caliber, thereby avoiding comparison biases caused by differences in sky area definition, scanning rhythm, or visibility criteria.

[0063] This invention transforms repetitive geometric and brightness calculations into reusable lookup tables and candidate event lists through pre-calculation storage, interpolation coarse screening, and secondary precise judgment. For large-scale sample and multi-parameter combination simulations, the calculation of a single scheme can be reduced from hours to minutes, making it suitable for rapid sensitivity analysis and strategy iteration during the task demonstration phase.

[0064] The cataloging completeness rate, early warning rate, and solar direction early warning rate output by this invention can be directly used to evaluate the monitoring system's ability to support daily cataloging tasks, solar direction blind spot filling tasks, and short-term early warning tasks.

[0065] This invention is applicable not only to single platforms but also to collaborative observation across multiple platforms. By unifying event lists and indicator statistics, the marginal contribution of newly added platforms to long-term cataloging, daily early warning, and orbit updates can be quantified, providing quantitative evidence for the joint deployment of multiple space-based platforms.

[0066] In this invention, based on the Granvik (2018) asteroid swarm model, simulations were conducted on 230,330 near-Earth asteroids with a diameter greater than 50m. Taking the Earth-leading orbit as an example, it was divided into three configurations according to the range of the monitored sky area: EL1, EL2, and EL3. EL1 covers the region of ecliptic longitude from -45° to 0° on the side facing the Sun on the Earth side, EL2 covers the region of ecliptic longitude ±45°, and EL3 further adopts the region of ecliptic longitude ±45° and ±135°~180° alternating between the monitored and monitored areas. At the same time, the Earth-following orbit ET was introduced as a collaborative observation platform. Under the conditions of uniform point source sensitivity of 5σ, 150 μJy, and ecliptic latitude ±45° for the monitored sky area, the cataloging completeness rates of the EL1, EL2, EL3, and Sun-Earth L1 point schemes were 29.67%, 37.97%, 41.58%, and 54.73%, respectively; the warning rates were 55.81%, 70.23%, 64.23%, and 67.32%, respectively; and the warning rates for the solar direction were 86.88%, 75.83%, 67.02%, and 72.93%, respectively. After further considering collaborative observation, the early warning rates of the EL1+L1, EL2+L1, and EL3+L1 schemes increased to 77.28%, 84.10%, and 78.71%, respectively, and the early warning rates for the solar direction increased to 91.02%, 86.52%, and 81.32%, respectively. The cataloging completeness rates of the EL1+ET and EL2+ET dual-telescope schemes reached 43.56% and 52.77%, respectively, with early warning rates of 70.11% and 90.93%, and solar direction early warning rates of 92.08% and 91.50%, respectively. Meanwhile, direct calculations took approximately 9 hours, while the efficiency acceleration method of this invention only requires 10 minutes. The results demonstrate that the method of this invention can quickly and effectively evaluate the performance differences of various space-based observation configurations, such as pilot orbits, follower orbits, and Sun-Earth L1 points, in terms of general survey cataloging, threat early warning, and solar direction target early warning, and provides quantitative basis for the optimal deployment scheme of space-based monitoring systems.

[0067] Example 3 This application also provides a performance evaluation system for a space-based monitoring and early warning system for near-Earth asteroids, used to implement the above method. The system includes: The Near-Earth Asteroid Collaborative Monitoring and Planning Module is used to acquire near-Earth asteroid orbital data and telescope platform ephemeris data, unify the coordinate system and time system; establish a monitoring sky area model according to different orbital configurations, construct a scanning grid and repeated access strategy, and generate a platform-time-pointing lookup table; The asteroid orbit sparse interpolation and state reconstruction module is used to perform orbit recursion for each near-Earth asteroid during the mission's lifetime, storing the target state as sparse nodes on the simulation timeline; in the performance statistics phase, the sparse nodes are interpolated according to the required simulation time to obtain the target's ensemble state quantities, including: target position, heliocentric distance, observation distance, and phase angle. The multi-constraint candidate event coarse screening module is used to coarsely screen candidate events using the target's relative ecliptic longitude, ecliptic latitude, observation distance, heliocentric distance and phase angle, and exclude moments that are not located in the monitored sky area, do not meet the avoidance constraints, do not fall into the scanning field of view, or do not meet the preliminary judgment conditions of visible light apparent magnitude threshold / infrared flux threshold. The multi-parameter accurate determination and event extraction module is used to perform visible light band apparent magnitude and signal-to-noise ratio calculations or infrared band thermal radiation / reflected radiation flux calculations on candidate events that have passed the coarse screening. It also performs secondary accurate determinations by combining platform avoidance constraints, instantaneous field of view constraints and detection thresholds to obtain valid observation events. The module for generating a list of valid observation events is used to write all visible moments into the list of valid observation events. The asteroid discovery and warning and approach attribute assessment module is used to determine whether each asteroid has been discovered, whether it has been warned, and whether it is a target approaching from the direction of the sun, based on the list of valid observation events; and to calculate the cataloging completeness rate and warning rate.

[0068] This application may also provide a computer device, including: at least one processor, memory, at least one network interface, and a user interface. The various components in this device are coupled together via a bus system. It is understood that the bus system is used to implement communication between these components. In addition to a data bus, the bus system also includes a power bus, a control bus, and a status signal bus.

[0069] The user interface can include a display, keyboard, or clicking device. Examples include a mouse, trackball, touchpad, or touchscreen.

[0070] It is understood that the memory in the embodiments disclosed in this application may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory may be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced Synchronous DRAM (ESDRAM), Synchlink DRAM (SLDRAM), and Direct Rambus RAM (DRRAM). The memories described herein are intended to include, but are not limited to, these and any other suitable types of memory.

[0071] In some implementations, the memory stores elements such as executable modules or data structures, or subsets thereof, or extended sets thereof: operating systems and applications.

[0072] The operating system includes various system programs, such as the framework layer, core library layer, and driver layer, used to implement various basic business functions and handle hardware-based tasks. The application programs include various applications, such as media players and browsers, used to implement various application functions. Programs implementing the methods of the embodiments of this disclosure can be included in the application programs.

[0073] In the above embodiments, the processor can also invoke programs or instructions stored in memory, specifically programs or instructions stored in an application program, for the following purposes: Follow the steps described above.

[0074] The above methods can be applied to or implemented by a processor. The processor may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above methods can be completed by integrated logic circuits in the processor's hardware or by software instructions. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic diagrams disclosed above. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the disclosed methods can be directly implemented by a hardware decoding processor, or by a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above methods.

[0075] It is understood that the embodiments described in this application can be implemented using hardware, software, firmware, middleware, microcode, or a combination thereof. For hardware implementation, the processing unit can be implemented in one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), general-purpose processors, controllers, microcontrollers, microprocessors, other electronic units for performing the functions described in this application, or combinations thereof.

[0076] For software implementation, the technology of this application can be implemented by executing the functional modules (e.g., procedures, functions, etc.) of this application. The software code can be stored in memory and executed by a processor. The memory can be implemented in the processor or outside the processor.

[0077] This application may also provide a non-volatile storage medium for storing a computer program. When the computer program is executed by a processor, it can implement the steps in the above method embodiments.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application do not depart from the spirit and scope of the technical solutions of this application, and should all be covered within the scope of the claims of this application.

Claims

1. A method for evaluating the effectiveness of a space-based monitoring and early warning system for near-Earth asteroids, comprising: Step S1: Obtain near-Earth asteroid orbit data and telescope platform ephemeris data, and unify the coordinate system and time system; Based on different orbital configurations, a monitoring sky area model is established, a scanning grid and a repeated access strategy are constructed, and a platform-time-pointer lookup table is generated; Step S2: Perform orbit recursion for each near-Earth asteroid during the mission's lifetime and store the target state as sparse nodes on the simulation timeline. In the performance statistics stage, sparse nodes are interpolated according to the required simulation time to obtain the target's set state variables, including: target position, heliocentric distance, observation distance, and phase angle; Step S3: Use the target's relative ecliptic longitude, ecliptic latitude, observation distance, heliocentric distance and phase angle to perform a coarse screening of candidate events, and exclude moments that are not located in the monitored sky area, do not meet the avoidance constraints, do not fall into the scanning field of view, or do not meet the preliminary judgment conditions of the visible light apparent magnitude threshold / infrared flux threshold. Step S4: For candidate events that pass the coarse screening, perform visible light band apparent magnitude and signal-to-noise ratio calculation, or perform infrared band thermal radiation / reflected radiation flux calculation, and combine platform avoidance constraints, instantaneous field of view constraints and detection thresholds for secondary judgment to obtain valid observation events; Step S5: Write all visible moments into the list of valid observation events; Step S6: Based on the list of valid observation events, determine whether each asteroid has been discovered, whether it has been warned, and whether it is a target approaching from the direction of the sun; calculate the cataloging completeness rate and warning rate.

2. The effectiveness evaluation method for a space-based monitoring and early warning system for near-Earth asteroids according to claim 1, characterized in that, The monitored area model in step S1 is represented as follows: ； in, k Indicates the first k A telescope platform or deployment plan; λ and β These represent ecliptic longitude and ecliptic latitude relative to Earth, respectively. and They represent the first k The observable boundaries of the telescope platform in the ecliptic longitude direction; and They represent the first k The observable boundaries of the telescope platform in the ecliptic latitude direction; Represents the geometrically observable function after integrating avoidance angle, occlusion, and attitude constraints; when When, it indicates that the direction is at time. t Satisfy platform geometric constraints; when When, it indicates that the direction is at time. t The effects of constraints are unobservable.

3. The effectiveness evaluation method for a space-based monitoring and early warning system for near-Earth asteroids according to claim 1, characterized in that, The target state is calculated in step S2 as follows: For each simulation time The state of the target relative to the Sun, Earth, and observation platform is represented as follows: ； in, Indicates the simulation time The position vector of a near-Earth asteroid relative to the Sun; Indicates the simulation time The position vector of the telescope platform relative to the sun; Indicates the distance from the target to the telescope. Indicates the heliocentric distance of the target. This indicates the phase angle.

4. The effectiveness evaluation method for a space-based monitoring and early warning system for near-Earth asteroids according to claim 1, characterized in that, The visible light band apparent magnitude and signal-to-noise ratio calculation, and the effective observation event determination method in step S4 include: For the visible light band, the apparent magnitude is calculated based on the target's absolute magnitude, heliocentric distance, observation distance, and phase function. The target at time... The apparent magnitude is represented as: ； in, H The absolute magnitude of a near-Earth asteroid; This represents the phase function; if the target is within the current instantaneous field of view and simultaneously satisfies the threshold constraints of solar avoidance, Earth avoidance, and apparent star avoidance, it is determined to be a valid visible light observation. ； in, Indicates the first k The telescope platform at the j Each scan points downwards at time [time]. The visible light observation results of the target; target indicates the target's location; Indicates the first k Each telescope platform at any time Corresponding to the j The instantaneous field of view area pointed to by each scan; This represents the geometrically observable function after considering the combined avoidance angle, occlusion, and attitude constraints. Indicates the first k The limiting magnitude of a telescope platform in the visible light band; Indicates the target at time. The observed signal-to-noise ratio; Indicates the first k Each telescope platform must meet the minimum signal-to-noise ratio threshold required for effective detection; if any condition is not met, then... .

5. The effectiveness evaluation method for a space-based monitoring and early warning system for near-Earth asteroids according to claim 1, characterized in that, The calculation of infrared thermal radiation / reflected radiation flux in step S4 includes: For the infrared band, the asteroid radiation received by the telescope includes the asteroid's own thermal radiation and the reflection of solar radiation from its surface, both of which are represented as: ； in, Indicates the target at wavelength Place, moment The total radiant flux received by the telescope platform; This refers to the thermal radiation flux calculated based on the NEATM thermal model; This represents the reflected flux of solar radiation on the asteroid's surface. Based on the solar constant, target heliocentric distance, geometric albedo, emissivity, and beam parameters η The temperature distribution on the illuminated surface of the asteroid is calculated using the phase angle, and the infrared thermal radiation flux is obtained by integrating over the visible surface; the temperature of the target surface element is also calculated. Represented as: ； in, A For Bond's albedo; Solar irradiance at 1 AU; ε For emissivity; σ The Stefan-Boltzmann constant; The target heliocentric distance; θ The angle of incidence on the surface; Integrating the surface elements of the target visible from the telescope platform yields the thermal radiation flux of the target in the infrared band: ； in, Indicates the distance from the target to the telescope; This refers to the visible area on the target's surface that can be observed by the telescope platform. (T) Indicates temperature as T A blackbody at wavelength Planck radiation function at the location; ψ This represents the angle between the normal to the surface element of the target and the direction in which the surface element points towards the telescope platform; dA Represents the area of ​​the target surface element; The reflected flux of solar radiation from the target surface is calculated based on the target albedo, solar spectral irradiance, heliocentric distance, observation distance, and the phase angle between the sun, target, and telescope platform, and is expressed as: ； in, Indicates the target at wavelength Spectral albedo at that location; This represents the solar spectral irradiance at a location of 1 AU; This indicates the area on the target surface that is illuminated by the sun. This represents the reflection phase function, used to describe the distribution characteristics of surface reflected radiation as a function of the solar incident direction, observation direction, and phase angle.

6. The effectiveness evaluation method for a space-based monitoring and early warning system for near-Earth asteroids according to claim 1, characterized in that, In step S4, a secondary precise determination is performed by combining platform avoidance constraints, instantaneous field-of-view constraints, and detection thresholds, as follows: ； in, Indicates the first k The telescope platform at the j Each scan points downwards at time [time]. The visible light observation results of the target; target indicates the target's location; Indicates the first k Each telescope platform at any time Corresponding to the j The instantaneous field of view area pointed to by each scan; This represents the geometrically observable function after considering the combined avoidance angle, occlusion, and attitude constraints. Indicates the first k Each telescope platform at wavelength Infrared flow detection threshold at the location; Indicates the target at wavelength Place, moment The total radiant flux received by the telescope platform; if any of the above conditions are not met, then .

7. A performance evaluation system for a space-based monitoring and early warning system for near-Earth asteroids, used to implement the method described in any one of claims 1-6, characterized in that, The system includes: The Near-Earth Asteroid Collaborative Monitoring and Planning Module is used to acquire near-Earth asteroid orbital data and telescope platform ephemeris data, unify the coordinate system and time system; establish a monitoring sky area model according to different orbital configurations, construct a scanning grid and repeated access strategy, and generate a platform-time-pointing lookup table; The asteroid orbit sparse interpolation and state reconstruction module is used to perform orbit recursion for each near-Earth asteroid during the mission's lifetime, storing the target state as sparse nodes on the simulation timeline; in the performance statistics phase, the sparse nodes are interpolated according to the required simulation time to obtain the target's ensemble state quantities, including: target position, heliocentric distance, observation distance, and phase angle. The multi-constraint candidate event coarse screening module is used to coarsely screen candidate events using the target's relative ecliptic longitude, ecliptic latitude, observation distance, heliocentric distance and phase angle, and exclude moments that are not located in the monitored sky area, do not meet the avoidance constraints, do not fall into the scanning field of view, or do not meet the preliminary judgment conditions of visible light apparent magnitude threshold / infrared flux threshold. The multi-parameter accurate determination and event extraction module is used to perform visible light band apparent magnitude and signal-to-noise ratio calculations or infrared band thermal radiation / reflected radiation flux calculations on candidate events that have passed the coarse screening. It also performs secondary determinations by combining platform avoidance constraints, instantaneous field of view constraints and detection thresholds to obtain valid observation events. The module for generating a list of valid observation events is used to write all visible moments into the list of valid observation events; and The asteroid discovery and warning and approach attribute assessment module is used to determine whether each asteroid has been discovered, whether it has been warned, and whether it is a target approaching from the direction of the sun, based on the list of valid observation events; and to calculate the cataloging completeness rate and warning rate.

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