Calculation method of geosynchronous orbit satellite threat zone and its spatial physical range

Abstract

The present invention proposes the concept of abnormal approach threat zone of geosynchronous orbit (GEO) satellite and its calculation method, including the concept of upper / lower threat zone of GEO satellite, the spatial position relationship and regional range of upper / lower threat zone; the longitude range and duration calculation method of upper / lower threat zone of GEO satellite; for the working mode of optical imaging satellite, the concept and calculation method of safety window in threat zone are proposed; the threat distance and solar illumination angle threshold are set, and the longitude range, duration and safety window in threat zone are solved. The benefit effect of the present invention is: the concept of abnormal approach threat zone of geosynchronous orbit and safety window in threat zone is expressed in a quantitative way, and the proposed calculation method of spatial area range, longitude range, duration and safety window in threat zone of threat zone is reliable and accurate, and has important application value in the security defense of GEO high-value targets.

Description

Technical Field

[0001] The present invention belongs to the field of spacecraft safety management, specifically to the concept of geosynchronous orbit threat zone and a method for calculating the space physical range. Background Art

[0002] Since the beginning of the 21st century, with the progress of human exploration of space and the increasing frequency of space activities, space launch activities have continued to increase, generating a large amount of space debris and space garbage, making space safety issues increasingly serious and posing a threat to spacecraft in orbit. As the most valuable spacecraft, the safety issues of geosynchronous orbit satellites are particularly prominent. The safety protection measures for geosynchronous orbit satellites are still insufficient in terms of protection, especially in terms of preventing fine measurement, and there is a lack of effective measures. Summary of the invention

[0003] The purpose of the present invention is to provide a method for calculating the threat zone of a geosynchronous orbit satellite and its spatial physical range, which can effectively solve the problems of the above-mentioned background technology.

[0004] To solve the above problems, the present invention proposes a method for calculating the threat zone of a geosynchronous orbit satellite and its spatial physical range, which includes the following steps:

[0005] The concept of geosynchronous orbit (GEO) satellite threat zone is predefined, and a method for calculating the spatial position relationship and regional range of the upper / lower threat zones of geosynchronous orbit (GEO) satellites is proposed. According to the working characteristics of optical payloads, a method for calculating the safety window in the geosynchronous orbit (GEO) satellite threat zone is proposed.

[0006] The specific steps are as follows:

[0007] Definition of Geosynchronous Orbit (GEO) Satellite Threat Zone: The geosynchronous orbit satellite threat zone refers to the physical area in space and time where a geosynchronous orbit satellite is at risk of collision when approached closely by other satellites and where onboard sensors can perform fine imaging measurements.

[0008] Definition of GEO satellite upper threat zone and lower threat zone: The physical area where the orbit height of geosynchronous orbit observation satellite is higher than that of GEO target star, which creates collision risk and has conditions for refined imaging, and the approach distance is less than the distance threshold is the upper threat zone; the physical area where the orbit height of geosynchronous orbit observation satellite is lower than that of GEO target star, which creates collision risk and has conditions for refined imaging, and the approach distance is less than the distance threshold is the lower threat zone.

[0009] Definition of the safety window in the geosynchronous orbit (GEO) satellite threat zone: When a geosynchronous orbit observation satellite enters the GEO target star threat zone, the time gap caused by the observation satellite's optical payload avoiding direct sunlight is the safety window in the threat zone.

[0010] The calculation method of the longitude range and duration of the threat zone on the geosynchronous orbit (GEO) satellite is designed according to the predefined concept: when the radial distance between the observation satellite and the target satellite is equal to d, the spatial position is A, and the fixed position of the geostationary orbit target satellite is B. The distance between AB and BC is d, the longitude range of the subsatellite points of A and B is ∠AOB, and the longitude range of the upper threat zone is is 2ω, then:

[0011] ω=F(R+h1,R,d)

[0012] Where F is the sine function of ∠AOB, then:

[0013]

[0014] Since the radius of the earth r (6378.137 km) and the height of the synchronous orbit h (35786 km) are constants, then R = r + h. Substituting them in, we get:

[0015]

[0016] The geostationary orbit period T (23 hours, 56 minutes and 4 seconds) and the radius of the Earth r (6378.137 kilometers) are constants. Define the orbit period T of the observation satellite above the synchronous orbit u The angular velocity of the geostationary satellite is υ, and the angular velocity of the observation satellite is υ u , the gravitational constant μ is:

[0017] υ=2π / T=(μ / (r+h) 2 ) 1 / 2

[0018] υ u =2π / T u =(μ / (r+h+h1) 2 ) 1 / 2

[0019] The angular velocity difference between the observation satellite and the geostationary orbit target satellite:

[0020] Δυ=2π / T-2π / T u

[0021] =(μ / (r+h) 2 ) 1 / 2 -(μ / (r+h+h1) 2 ) 1 / 2

[0022] When the satellite does not change its orbit, it drifts westwards and enters the threat zone for:

[0023]

[0024] The longitude range and duration calculation method of the threat zone under the geosynchronous orbit (GEO) satellite is designed according to the predefined concept: in terms of time and space, the orbital height of the geosynchronous orbit observation satellite is the orbital height of the GEO target satellite. The orbital period of the geosynchronous orbit observation satellite is T d , and the height difference from the GEO target satellite orbit is h2, then the longitude range of the observation satellite entering the target satellite threat area is:

[0025]

[0026] The relative angular velocity between the observation satellite and the GEO target satellite is:

[0027] Δυ=2π / T d -2π / T

[0028] =(μ / (r+h-h2) 2 ) 1 / 2 -(μ / (r+h) 2 ) 1 / 2

[0029] When the satellite does not change its orbit, it drifts eastward and enters the threat zone for:

[0030]

[0031] According to the working characteristics of the optical payload, a calculation method for the safety window in the geosynchronous orbit (GEO) threat zone is designed. The optical payload solar avoidance angle is α. When the angle between the observation satellite's direction vector to the sun and the radial line connecting the observation satellite and the target star is less than α, the optical payload should avoid direct sunlight and will not have the conditions for observation and imaging. This creates a safe period for the observed satellite. After the orbits of the observation satellite A and the target satellite B are determined, their motion and spatial position relationship mainly changes with time. Define the epoch time t, the spatial position of satellite A is P A (t), the spatial position of satellite B is P B (t), the distance threshold of the threat zone of satellite B is d. Since the change caused by the difference in the positions of satellites A and B is small compared with the average distance between the sun and the earth (149.6 million kilometers), the sun direction vectors of satellites A and B are approximately the same at the same time, defined as Therefore, the solar direction angle φ of the observation satellite A to the target satellite B can be expressed as:

[0032]

[0033] in, is the direction vector of star A to star B.

[0034] When the sun avoidance angle of the optical payload of star A is α, the calculation conditions of the safety window are as follows:

[0035]

[0036] The beneficial effects of the present invention are as follows: the concepts of the abnormal proximity threat zone of the geosynchronous orbit and the safety window within the threat zone are expressed in a quantitative manner; the proposed calculation method of the spatial area range, longitude range, duration and safety window within the threat zone is accurate and reliable, and has important application value in the security defense of GEO high-value targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the physical spatial scope of the threat area on the GEO satellite;

[0038] Figure 2 Schematic diagram of the physical space scope of the threat area under the GEO satellite;

[0039] Figure 3 Schematic diagram of the solar avoidance range of the threat area on the GEO satellite;

[0040] Figure 4 Schematic diagram of the solar avoidance range of the GEO satellite's lower threat area;

[0041] Figure 5 An example of calculating the safety window within a GEO satellite threat zone. DETAILED DESCRIPTION

[0042] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Note that the following embodiments are merely illustrative in nature, and the present invention is not intended to limit its applicable objects or uses, and the present invention is not limited to the following embodiments.

[0043] A method for calculating the threat zone of a geosynchronous orbit satellite and its spatial physical range includes predefined concepts: the concept of upper / lower threat zones of GEO satellites, the spatial position relationship and regional range of the upper / lower threat zones; a method for calculating the longitude range and duration of the upper / lower threat zones of GEO satellites; a concept and calculation method for a safety window in the threat zone are proposed for the working mode of optical imaging satellites; the threat distance and solar illumination angle thresholds are set, and the longitude range, duration and safety window of the threat zone are designed and calculated, as follows:

[0044] Definition of Geosynchronous Orbit (GEO) Satellite Threat Zone: The geosynchronous orbit satellite threat zone refers to the physical area in space and time where a geosynchronous orbit satellite is at risk of collision when approached closely by other satellites and where onboard sensors can perform fine imaging measurements.

[0045] GEO satellite upper threat zone, lower threat zone definition: The geosynchronous orbit observation satellite orbit altitude is higher than the GEO target star, there is a risk of collision, there are fine imaging conditions, and the physical area range of the approach distance is less than the distance threshold is the upper threat zone, such as Figure 1 As shown in the figure, the geosynchronous orbit observation satellite has an orbit height lower than the GEO target satellite, which generates collision risk and has fine imaging conditions. The physical area with a proximity distance less than the distance threshold is the lower threat area, such as Figure 2 shown.

[0046] Definition of the safety window in the geosynchronous orbit (GEO) satellite threat zone: When a geosynchronous orbit observation satellite enters the GEO target star threat zone, the time gap caused by the optical payload of the observation satellite to avoid direct sunlight is the safety window in the threat zone. Figure 3 As shown, the security window in the lower threat area is as follows Figure 4 shown.

[0047] Using the open source space target orbit data (TLE) on the Internet, the threat zone with a GEO satellite approaching distance threshold of 320 kilometers is selected, and a geostationary orbit satellite with a fixed longitude near 90° east longitude is selected. The calculation results of the threat zone for the satellite with Norad number 41745 are shown in the following table.

[0048]

[0049] Referring to the orbital positions of the observed satellite and the 41745 satellite, the distance of the 41745 satellite to the observed satellite and the solar illumination curve are shown in the figure below. If the solar avoidance angle of the 41745 satellite is set to 40°, the safety window of the observed satellite is the green part in the figure. Under the condition of selecting the 320-kilometer threshold of the observed satellite threat area, the 41745 satellite has two safety windows in its threat area, such as Figure 5 As shown, they are: 9Apr 202110:18:43 (UTC) to 11Apr 2021 1:47:52 (UTC), 11Apr2021 19:29:42 (UTC) to 12Apr 2021 2:44:34 (UTC).

Claims

1. A method for calculating the threat zone of geosynchronous orbit satellites and their spatial physical range, characterized in that: The steps include: (1) Predefined concepts: (a) Geosynchronous orbit satellite threat zone: The geosynchronous orbit satellite threat zone refers to the physical area in space and time where the geosynchronous orbit satellite target satellite is approached by other satellites at close range and there is a risk of collision. The onboard sensors can be used for fine imaging measurement. (b) Geosynchronous orbit satellite upper threat zone and lower threat zone: The upper threat zone is the physical area where the orbital altitude of the geosynchronous orbit observation satellite is higher than the geosynchronous orbit satellite target satellite, there is a risk of collision, there are conditions for fine imaging, and the approach distance is less than the distance threshold. The lower threat zone is the physical area where the orbital altitude of the geosynchronous orbit observation satellite is lower than the geosynchronous orbit satellite target satellite, there is a risk of collision, there are conditions for fine imaging, and the approach distance is less than the distance threshold. (c) Safety window in the geosynchronous orbit satellite threat zone: The time gap caused by the geosynchronous orbit observation satellite entering the geosynchronous orbit target satellite threat zone due to the need for the optical payload of the geosynchronous orbit observation satellite to avoid direct sunlight is the safety window in the threat zone. (2) Design a method for calculating the longitude range of the upper threat zone and the duration of the threat zone based on a predefined concept: When the radial distance between the geosynchronous orbit observation satellite and the geosynchronous orbit target satellite is equal to d, the spatial position of the geosynchronous orbit observation satellite is A, and the fixed position of the geosynchronous orbit target satellite is B; the distance between AB and BC is d, the longitude range ω of the subsatellite points A and B is ∠AOB, and the longitude range of the upper threat zone is is 2ω; then: ω=F(R+h1,R,d) Where F is the sine function of ∠AOB, then: Since the radius of the earth r = 6378.137 km and the height of the synchronous orbit h = 35786 km are constants, then R = r + h. Substituting them in, we get: The geostationary orbit period T = 23 hours 56 minutes 4 seconds and the radius of the earth r = 6378.137 kilometers are constants; define the orbital period T of the geostationary observation satellite above the synchronous orbit u The angular velocity of the target satellite in geosynchronous orbit is υ, and the angular velocity of the observation satellite in geosynchronous orbit is υ u , the gravitational constant μ, when the geosynchronous orbit observation satellite A is located above the geosynchronous orbit, h1 is its height above the geosynchronous orbit, then: u=2π / T=(μ / (r+h) 2 ) 1 / 2 u u =2π / T u =(μ / (r+h+h1) 2 ) 1 / 2 The relative angular velocity between the geosynchronous orbit observation satellite and the geosynchronous orbit target satellite is: Δυ=2π / T-2π / T u =(μ / (r+h) 2 ) 1 / 2 -(μ / (r+h+h1) 2 ) 1 / 2 When the geosynchronous observation satellite does not change its orbit, it drifts westward and enters the threat zone for: (3) Design the longitude range of the threat zone under the geosynchronous orbit satellite and the calculation method of the threat zone duration according to the predefined concept: In terms of time and space, the orbital altitude of the geosynchronous orbit observation satellite is lower than the orbital altitude of the geosynchronous orbit satellite target satellite; the orbital period of the geosynchronous orbit observation satellite is T d , and the orbital height difference with the geosynchronous orbit satellite target satellite is h2, then the longitude range of the geosynchronous orbit observation satellite entering the geosynchronous orbit satellite target satellite threat area is: The relative angular velocity between the geosynchronous orbit observation satellite and the geosynchronous orbit target satellite is: Δυ=2π / T d -2π / T =(μ / (r+h-h2) 2 ) 1 / 2 -(μ / (r+h) 2 ) 1 / 2 When the geosynchronous observation satellite does not change its orbit, it drifts eastward and enters the threat zone for: (4) According to the working characteristics of the optical payload, a calculation method for the safety window in the geosynchronous orbit threat zone is designed: the optical payload solar avoidance angle is α. When the angle between the direction vector of the geosynchronous orbit observation satellite to the sun and the radial line connecting the geosynchronous orbit observation satellite and the target satellite is less than α, the optical payload avoids direct sunlight and does not have the conditions for observation and imaging. This creates a safe period for the geosynchronous orbit satellite target satellite. After the orbits of the geosynchronous orbit observation satellite A and the geosynchronous orbit satellite target satellite B are determined, their motion and spatial position relationship mainly changes with time. Define the epoch time t, the spatial position of satellite A is P A (t), the spatial position of satellite B is P B (t), the distance threshold of the threat zone of satellite B is d; since the change caused by the difference in the positions of satellites A and B is small compared with the average distance of 149.6 million kilometers between the sun and the earth, the sun direction vectors of satellites A and B are approximately the same at the same time, defined as Therefore, the solar direction angle φ of the geosynchronous orbit observation satellite A to the geosynchronous orbit target satellite B can be expressed as: in, is the direction vector of star A to star B; When the sun avoidance angle of the optical payload of star A is α, the calculation conditions of the safety window are as follows:

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