Space-based Asteroid Monitoring System

Abstract

This invention relates to the field of asteroid monitoring technology and proposes a space-based networked asteroid monitoring system, characterized by comprising: a monitoring satellite configured to perform the following actions: acquiring optical measurement data of near-Earth asteroids; transmitting the optical measurement data to a ground control station; and a ground control station configured to determine the orbit of the near-Earth asteroid based on the optical measurement data.

Description

Technical Field

[0001] This invention generally relates to the field of asteroid monitoring technology. Specifically, this invention relates to a space-based networked asteroid monitoring system. Background Technology

[0002] Asteroids are the most numerous type of small celestial body in the solar system, mainly distributed in the asteroid belt between the orbits of Mars and Jupiter and the Kuiper Belt beyond Neptune. As of October 27, 2021, a total of 607,011 asteroids have been discovered and numbered, and 536,397 asteroids have not been numbered. Among them, 27,868 are near-Earth asteroids, including 2,309 potentially hazardous asteroids.

[0003] To prevent and warn of the threat of near-Earth asteroid impacts, countries around the world have conducted research on asteroid monitoring, early warning, and prevention. Based on different observation platforms, these systems are divided into ground-based and space-based monitoring systems; based on different technological principles, they can be categorized into optical observation, radar detection, and infrared spectral observation.

[0004] Ground-based optical observation systems are currently a widely used observation method. They determine the asteroid's position by repeatedly photographing the same area of ​​the sky at different times using optical telescopes established at different ground stations, utilizing sunlight reflected from the asteroid's surface. Ground-based optical observation systems have advantages such as low investment cost, long observation distance, and mature technology. However, they are also easily limited by time and geographical location, and can only search the sky at night and under clear skies. Furthermore, ground-based optical observation systems have measurement blind spots for near-Earth hazardous asteroids. In recent years, several near-Earth hazardous asteroids have failed to be tracked in time, due to the limitations of time and space coverage in ground-based measurements. Summary of the Invention

[0005] To at least partially solve the aforementioned problems in the prior art, this invention proposes a space-based network asteroid monitoring system, comprising:

[0006] The monitoring satellite is configured to perform the following actions:

[0007] To acquire optical measurement data of near-Earth asteroids; and

[0008] Transmit the optical measurement data to the ground control station; and

[0009] A ground control station is configured to determine the orbit of the near-Earth asteroid based on the optical measurement data.

[0010] In one embodiment of the present invention, the orbit of the monitoring satellite is configured as a sun-synchronous orbit, wherein the semi-major axis and inclination of the orbit are configured such that the right ascension variation of the ascending node of the orbit is the same as the direction and rate of the Earth's annual rotation around the Sun.

[0011] In one embodiment of the present invention, configuring the running track includes:

[0012] Considering the J2 term, the precession of the right ascension rate of the ascending node over one period can be expressed as follows:

[0013]

[0014] in R represents the right ascension variability of the ascending node, n represents the mean orbital angular velocity, J2 represents the second-order zonal harmonic coefficient of the Earth's gravitational field, and R... e denoted by 'a', 'a' by 'e', ​​and 'e' by 'e'.

[0015] In one embodiment of the present invention, the monitoring satellite includes an optical camera, the optical camera being configured to:

[0016] Staring mode, wherein the optical camera is configured to be steerable for tracking observations of a single near-Earth asteroid; and

[0017] The census mode, wherein the optical camera is configured to make observations in a direction along the running track or in a direction perpendicular to the running track.

[0018] In one embodiment of the present invention, the monitoring satellite acquires optical measurement data of near-Earth asteroids including:

[0019] The optical camera is used to acquire CCD camera negatives;

[0020] The near-Earth asteroids and background stars in the CCD camera film are resolved and extracted.

[0021] A matching algorithm between the background stars and the star catalog is constructed, along with the measurement coordinates of the CCD camera film, to calculate the position of the near-Earth asteroid on the celestial sphere.

[0022] In one embodiment of the present invention, the ground control station determines the orbit of the near-Earth asteroid based on the optical measurement data, including initial orbit determination and precise orbit determination. The initial orbit determination includes the following steps:

[0023] The dynamic relationship of the near-Earth asteroid is expressed as follows:

[0024]

[0025] The F and G series are dimensionless;

[0026] The fundamental equations for determining the initial orbit, considering the J2 term perturbation effect of the central celestial body, the Sun, are expressed as follows:

[0027] as well as

[0028] The initial orbital basic equations are solved iteratively.

[0029] In one embodiment of the present invention, precise trajectory determination includes the following steps:

[0030] The differential equation of motion for the near-Earth asteroid is expressed as follows:

[0031]

[0032] in, The vector r represents the gravitational pull of the Sun's mass, and r represents the position vector of the asteroid. Indicates the speed of the asteroid. Represents the asteroid's acceleration vector; r0 and This represents the state quantity at the initial moment. Indicates the error term;

[0033] The measurement equation for the near-Earth asteroid is expressed as follows:

[0034] Y = H(X,t) + V

[0035] Where Y represents the measured value of the observed quantity, H(X,t) represents the theoretical value of the observed quantity, and V represents the measurement error; and

[0036] The linearized equations for determining the precise orbit are expressed as follows:

[0037]

[0038] Where O represents the observed value, T represents the theoretical value, and ΔX represents the orbital improvement.

[0039] In one embodiment of the present invention, the error term includes perturbation error of the solar non-spherical gravitational field, perturbation error of major planets, perturbation error of solar radiation pressure, and error of general relativistic effects.

[0040] The present invention has at least the following beneficial effects: the present invention can greatly improve the space asteroid monitoring capability by performing space-based network multi-satellite measurements, precise orbit calculations and early warnings. Attached Figure Description

[0041] To further illustrate the advantages and other features of the various embodiments of the present invention, a more specific description of the embodiments of the present invention will be presented with reference to the accompanying drawings. It is understood that these drawings depict only typical embodiments of the invention and are therefore not intended to limit its scope. In the drawings, identical or corresponding parts will be indicated by the same or similar reference numerals for clarity.

[0042] Figure 1 The diagram illustrates a space-based network asteroid monitoring system according to one embodiment of the present invention. Detailed Implementation

[0043] It should be noted that the components in the various figures may be shown exaggeratedly for illustrative purposes and are not necessarily to scale. In each figure, the same reference numerals are used for components that are identical or have the same function.

[0044] In this invention, unless otherwise specified, "arranged on," "arranged above," and "arranged on" do not exclude the possibility of an intermediate element between them. Furthermore, "arranged on or above" merely indicates the relative positional relationship between two components, and in certain cases, such as when the product orientation is reversed, it can also be converted to "arranged below or under," and vice versa.

[0045] In this invention, the various embodiments are merely intended to illustrate the solutions of the invention and should not be construed as limiting.

[0046] In this invention, unless otherwise specified, the quantifiers “a” and “one” do not exclude scenarios involving multiple elements.

[0047] It should also be noted that, in the embodiments of the present invention, only a portion of the components or parts may be shown for clarity and simplicity. However, those skilled in the art will understand that, under the teachings of the present invention, necessary components or parts can be added as needed for specific scenarios. Furthermore, unless otherwise stated, features in different embodiments of the present invention can be combined with each other. For example, a feature in the second embodiment can replace a corresponding or functionally identical or similar feature in the first embodiment, and the resulting embodiment will also fall within the scope of disclosure or description of this application.

[0048] It should also be noted that, within the scope of this invention, the terms "same," "equal," and "equal to" do not imply that the two values ​​are absolutely equal, but rather allow for a certain reasonable margin of error. In other words, the terms also encompass "substantially the same," "substantially equal," and "substantially equal to." Similarly, in this invention, the directional terms "perpendicular to," "parallel to," etc., also encompass the meanings of "substantially perpendicular to" and "substantially parallel to."

[0049] Furthermore, the numbering of the steps in the methods of the present invention does not limit the execution order of the method steps. Unless otherwise specified, the method steps may be executed in different orders.

[0050] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0051] Figure 1 The diagram illustrates a space-based network asteroid monitoring system according to one embodiment of the present invention.

[0052] The satellite platform of the space-based asteroid monitoring system can be deployed in a sun-synchronous orbit to ensure that the telescope detection has a good phase.

[0053] In near-circular orbits, only the J2 term needs to be considered, and the precession of the right ascension rate of the ascending node over one period can be expressed as follows:

[0054]

[0055] By configuring the semi-major axis and inclination of the orbit so that the rate of change of the right ascension of the ascending node is the same as the direction and rate of the Earth's annual rotation around the Sun, a sun-synchronous orbit is formed.

[0056] Optical cameras are deployed on the satellite platform according to space measurement needs. The installation of the optical cameras is mainly divided into a staring mode and a survey mode. The optical cameras are configured as follows: in staring mode, the optical cameras are configured to be steerable for tracking and observing individual near-Earth asteroids; and in survey mode, the optical cameras are configured to be non-steerable, typically conducting observations along or perpendicular to the orbital direction.

[0057] The optical camera obtains the film captured by the CCD camera through optical observation. The film processing requires the use of astronomical positioning methods to distinguish and extract the GEO target and background stars in the original CCD. By establishing a matching algorithm between the star target and the precise star catalog and the mode of CCD measurement coordinates, the position of the GEO target on the celestial sphere can be calculated.

[0058] The first step in the calculation process is to consider the effects of various observations. Since the positions in the star catalog are reference epoch mean positions, it is necessary to consider the effects of Earth's rotation and attitude, proper motion, radial velocity, annual aberration, gravitational deflection, annual parallax, and other effects.

[0059] Optical measurement data of asteroids can be obtained through multi-satellite networking. The satellite platform returns the optical measurement results to the ground control station via telemetry data. The asteroid's orbit is then calculated at the control station. The orbit calculation is divided into initial orbit determination and precise orbit determination.

[0060] The initial trajectory can be determined using a two-body model, where the dynamic relationship expression satisfies the F\G expansion:

[0061]

[0062] To facilitate calculation, the F and G series have been dimensionless.

[0063] When performing the initial orbit calculation, the perturbation effect of the J2 term of the central celestial body, the Sun, was taken into account. Substituting this into the geometric measurement relation expression, the basic equation for the initial orbit calculation was obtained:

[0064]

[0065] The above is a linear equation in form, which can be solved using least squares in the case of multiple measurements. However, since the coefficients are still functions of unknowns, it is essentially a nonlinear equation, and therefore the above solution requires iterative processing.

[0066] Precision track improvement is a multivariable nonlinear iterative process for dynamic systems.

[0067] The differential equation satisfied by the motion of an asteroid can be expressed as follows:

[0068]

[0069] in, The vector r represents the gravitational pull of the Sun's mass, and r represents the position vector of the asteroid. Indicates the speed of the asteroid. Represents the asteroid's acceleration vector; r0 and This represents the state quantity at the initial moment. These mainly include perturbations of the Sun's non-spherical gravitational field, perturbations of large planets, perturbations of solar radiation pressure, and effects of general relativity. For asteroids with large masses, radiation pressure can generally be disregarded.

[0070] The relationship between observations and satellite state quantities is generally described by, for example, the following nonlinear equation, where Y represents the measured value of the observation, H(X,t) represents the theoretical value of the corresponding observation, and V represents the measurement error:

[0071] Y = H(X,t) + V

[0072] The linearized equation for determining the orbit can be expressed as follows, where O is the observed value and T is the theoretical value:

[0073]

[0074] In the formula It is obtained by numerical integration from the variational equation; ΔX represents the orbital improvement.

[0075] In satellite orbit determination, both the dynamic equations and the measurement equations are nonlinear systems. Therefore, after linearization, the optimal parameter estimation can be performed using the linear estimation problem to obtain the orbital improvement amount for each time.

[0076] Although various embodiments of the invention have been described above, it should be understood that they are presented by way of example only and not as limitations. It will be apparent to those skilled in the art that various combinations, modifications, and alterations can be made without departing from the spirit and scope of the invention. Therefore, the breadth and scope of the invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should be defined solely by the appended claims and their equivalents.

Claims

1. A space-based networked asteroid monitoring system, characterized in that, include: The monitoring satellite is configured to perform the following actions: Acquire optical measurement data of near-Earth asteroids; as well as The optical measurement data is transmitted to the ground control station. The orbit of the monitoring satellite is configured as a sun-synchronous orbit, wherein the semi-major axis and inclination of the orbit are configured such that the right ascension variability of the ascending node of the orbit is the same as the direction and rate of the Earth's annual rotation around the Sun. as well as A ground control station is configured to determine the orbit of the near-Earth asteroid based on the optical measurement data, including initial orbit determination and precise orbit determination, wherein initial orbit determination includes the following steps: The dynamic relationship of the near-Earth asteroid is expressed as follows: The F and G series are dimensionless; The fundamental equations for determining the initial orbit, considering the J2 term perturbation effect of the central celestial body, the Sun, are expressed as follows: as well as The initial orbital basic equations are solved iteratively. Precision trajectory determination includes the following steps: The differential equation of motion for the near-Earth asteroid is expressed as follows: in, The vector r represents the gravitational pull of the Sun's mass, and r represents the position vector of the asteroid. Indicates the speed of the asteroid. Represents the asteroid's acceleration vector; r0 and This represents the state quantity at the initial moment. Indicates the error term; The measurement equation for the near-Earth asteroid is expressed as follows: Y = H(X,t) + V Where Y represents the measured value of the observed quantity, H(X,t) represents the theoretical value of the observed quantity, and V represents the measurement error; and The linearized equations for determining the precise orbit are expressed as follows: Where O represents the observed value, T represents the theoretical value, and ΔX represents the orbital improvement. The configuration of the running track includes: Considering the J2 term, the precession of the right ascension rate of the ascending node over one period can be expressed as follows: in R represents the right ascension variability of the ascending node, n represents the mean orbital angular velocity, J2 represents the second-order zonal harmonic coefficient of the Earth's gravitational field, and R... e denoted by 'a', 'a' by 'e', ​​and 'e' by 'e'.

2. The space-based networked asteroid monitoring system according to claim 1, characterized in that, The monitoring satellite includes an optical camera, which is configured to: Staring mode, wherein the optical camera is configured to be steerable for tracking observations of a single near-Earth asteroid; and The census mode, wherein the optical camera is configured to make observations in a direction along the running track or in a direction perpendicular to the running track.

3. The space-based networked asteroid monitoring system according to claim 2, characterized in that, The monitoring satellite acquires optical measurement data of near-Earth asteroids, including: The optical camera is used to acquire CCD camera negatives; The near-Earth asteroids and background stars in the CCD camera film are resolved and extracted. A matching algorithm between the background stars and the star catalog is constructed, along with the measurement coordinates of the CCD camera film, to calculate the position of the near-Earth asteroid on the celestial sphere.

4. The space-based networked asteroid monitoring system according to claim 3, characterized in that, The error terms include perturbation errors of the Sun's non-spherical gravitational field, perturbation errors of major planets, perturbation errors of solar radiation pressure, and errors caused by general relativistic effects.

Images