CN115600070B - Method for predicting polar orbit satellite encountering polar photoelectrons - Google Patents

Abstract

The invention discloses a prediction method for a polar-orbiting satellite encountering an aurora electron, comprising: calculating the spatial position geographic coordinates of the polar-orbiting satellite in orbit at a fixed time interval; converting the spatial position geographic coordinates of the polar-orbiting satellite into geomagnetic coordinates ; Based on the auroral belt boundary model, input the geomagnetic activity Kp index to determine the polar and equatorial boundaries of the auroral belt area; based on the geomagnetic coordinates of the polar orbiting satellite and the auroral belt area, determine the orbital position of the polar orbiting satellite in the auroral belt area, The longest duration of polar-orbiting satellites in the auroral belt area and the probability of polar-orbiting satellites encountering auroral electrons are obtained. The invention can quickly analyze the spatial position, duration and encounter probability of polar-orbiting satellites encountering auroral electrons under different geomagnetic activity conditions, and provide a basis for evaluating the charging and discharging risks of polar-orbiting satellites.

Description

A Forecasting Method for Polar Orbiting Satellites Encountering Auroral Electrons

technical field

The invention relates to the technical field of polar-orbiting satellites, in particular to a method for predicting when a polar-orbiting satellite encounters aurora electrons.

Background technique

The aurora is a phenomenon in which particles in the magnetosphere enter the atmosphere and stimulate the atmosphere to emit light. It can be clearly seen in the aurora photos taken by satellites. The aurora appears in an oval strip surrounding the magnetic poles of the earth, called the auroral belt. The auroral belt is about 20° away from the geomagnetic pole and moves slightly to the night side. Among them, the aurora appears most frequently and has the greatest intensity near midnight. In the northern and southern polar regions, the southern and northern lights with similar shapes and similar evolution processes can be observed at the same time. This is the phenomenon of conjugate aurora excited by magnetospheric particles falling to the north and south poles along the same magnetic force line.

Fallout particles (especially electrons) that cause aurora can act on the surface of satellites operating in low-Earth polar orbits, bringing the risk of surface charging and discharging effects.

In low Earth orbit, solar ultraviolet radiation can ionize oxygen and nitrogen atoms in Earth's neutral atmosphere, forming a plasma. Since the plasma in the LEO orbit mainly comes from the ionization of solar ultraviolet radiation, the plasma density varies with the solar cycle and local time. Normally, the ionospheric cool plasma in the LEO orbit generally does not cause serious satellite charging problems, but during geomagnetic activity, the hot plasma of the keV level injected from the magnetotail can be injected into the poles along the Earth's magnetic field lines. At very low altitudes, low-Earth polar-orbiting satellites may encounter these hot plasmas, and especially the electrons in them may cause serious charging problems for the satellites. The on-orbit data measured by the U.S. Defense Meteorological Satellite DMSP (orbit about 840km, inclination 99°) currently operating in a near-Earth polar orbit shows that the energy of auroral sedimentation electrons that may be encountered in the two-pole auroral belt area (magnetic latitude 55°-75°) It can reach the order of several keV. It should be pointed out that due to the convergence of the magnetic field lines at the two poles of the earth, the flux of electrons deposited in the aurora may obviously exceed the GEO orbit.

At present, in the field of engineering applications, there is a lack of prediction methods for the location and duration of polar-orbiting satellites that may encounter auroral sinking electrons in the polar regions.

Contents of the invention

Aiming at the above-mentioned problems existing in the prior art, the present invention provides a method for predicting when a polar-orbiting satellite encounters an auroral electron.

The invention discloses a method for predicting that a polar-orbiting satellite encounters an aurora electron, comprising:

Calculate the geographic coordinates of the space position of the polar-orbiting satellite in orbit at a fixed time interval;

Convert the spatial location geographic coordinates of polar-orbiting satellites into geomagnetic coordinates;

Based on the boundary model of the auroral zone, the geomagnetic activity Kp index is input to determine the polar and equatorial boundaries of the auroral zone;

Based on the geomagnetic coordinates of the polar-orbiting satellites and the coordinates of the auroral belt area, the orbital position of the polar-orbiting satellites in the auroral belt is determined, and the longest duration of the polar-orbiting satellites in the auroral belt and the probability of polar-orbiting satellites encountering auroral electrons are obtained statistically.

As a further improvement of the present invention, the calculation of the spatial position geographical coordinates of the polar-orbiting satellite in orbit includes:

Obtaining orbit parameters of polar-orbiting satellites; wherein, the orbit parameters include perigee height, apogee height and inclination;

Input the orbit parameters of the polar-orbiting satellites into the SGP4 orbit calculation program, and output the spatial position geographic coordinates of the polar-orbiting satellites at different times on the orbit according to a fixed time interval; wherein, the spatial position geographic coordinates include longitude, latitude and altitude ; Preferably, the fixed time interval is 60s, and 1440 geographic coordinate points of the spatial positions of polar-orbiting satellites in orbit are output in one day.

As a further improvement of the present invention, the conversion of the spatial position geographic coordinates of the polar-orbiting satellites into geomagnetic coordinates includes:

Based on the geomagnetic coordinate calculation program, the spatial position geographic coordinates of the polar-orbiting satellites are converted into the geomagnetic coordinates adopted by the aurora belt model, and the magnetic local time information of the polar-orbiting satellites in the geomagnetic coordinate system is obtained; preferably, it can be converted on the geomagnetic coordinate system. Geomagnetic coordinate points of 1440 polar orbiting satellites.

As a further improvement of the present invention, the calculation formulas for the polar and equatorial boundaries of the auroral belt region are:

θ _m ＝A _0m +A _1m cos[15(t+α _1m )]+A _2m cos[15(2t+α _2m )]+A _3m cos[15(3t+α _3m )]

AL＝18-12.3Kp+27.2Kp ² -2Kp ³

In the formula, _{m =} 0 or 1 _, corresponding to the polar direction and the equatorial direction respectively; The geomagnetic latitude of the equator toward the boundary; when t is the magnetic place, A _im and α _im respectively represent the amplitude with the geomagnetic latitude and the phase expressed in decimal hours, and the coefficients A _im and α _im of the equation are third-order polynomials of the AL index, i takes 0-3, which means the order, and there are a series of coefficient b _im values for each A _im and α _im . ;The AL index is used to describe the intensity of geomagnetic disturbance during the auroral activity. The AL index can be calculated by the Kp index. The Kp index ranges from 0 to 9. 0 means that the geomagnetic activity is very calm, and 5 or greater than 5 means that it is in a state of geomagnetic storm; The Kp index is the average value of the maximum disturbance of the horizontal component of the geomagnetic field in mid-latitudes for 3 hours around the world; the input geomagnetic Kp index can be selected according to actual needs. If you need to realize the prediction of a certain day in the future (such as tomorrow), you can use the future geomagnetic Kp The predicted value of the index, and based on the Kp index, determine the polar and equatorial boundaries of the auroral belt area; if it is necessary to realize the worst-case assessment of the longest duration and probability of polar-orbiting satellites encountering auroral electrons, the Kp index can be selected The maximum value of is used as an input parameter.

As a further improvement of the present invention, the calculation method for the longest duration of the polar-orbiting satellite in the auroral belt region includes:

Count the continuous geomagnetic coordinate points of the satellite space position in the auroral belt;

Select the track segment with the most continuous geomagnetic coordinate points in the satellite space position;

The total duration of the trajectory segment is determined based on the set fixed time interval (60s), which is the longest duration of the polar-orbiting satellite in the auroral zone.

As a further improvement of the present invention, the calculation method of the probability that the polar-orbiting satellite encounters the auroral electrons includes:

Obtain the number M of geomagnetic coordinate points of all spatial positions generated by polar-orbiting satellites within a day;

Count all coordinate points N of polar-orbiting satellites located in the auroral belt area within one day;

Calculate the probability P=N/M that the polar-orbiting satellite encounters the auroral electron.

Compared with prior art, the beneficial effect of the present invention is:

The present invention converts the space position coordinates of the polar-orbiting satellite into the geomagnetic coordinates of the distribution of the auroral belt by determining the position of the boundary of the auroral zone under different geomagnetic activity conditions; The spatial position, duration and encounter probability of Aurora Electronics are quickly analyzed to provide a basis for assessing the risk of charging and discharging of polar-orbiting satellites.

Description of drawings

Fig. 1 is a flow chart of a method for predicting a polar-orbiting satellite encountering an aurora electron disclosed in an embodiment of the present invention;

Fig. 2 is the boundary of the aurora belt and the sub-satellite point of the orbital motion of the polar orbiting satellite disclosed by an embodiment of the present invention;

Fig. 3 is a situation where a polar-orbiting satellite encounters an auroral belt under the condition of Kp=5 disclosed by an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Below in conjunction with accompanying drawing and take the low earth polar orbit satellite of 1100km/86.4 ° as an example, the present invention is described in further detail:

As shown in Fig. 1, the present invention provides a kind of 1100km/86.4 ° low-Earth polar-orbiting satellite encounters the prediction method of aurora electron, comprises:

Step 1. Obtain orbital parameters such as perigee height, apogee height, and inclination angle of the near-Earth polar-orbiting satellite; and input them into the SGP4 orbit calculation program in sequence, and obtain the orbital parameters of the near-Earth polar-orbiting satellite at different times in the orbit at a time interval of 60s The longitude, latitude, and altitude information corresponding to the spatial location.

Step 2. Use the geomagnetic coordinate calculation program to convert the geographical coordinates of the spatial position of the near-Earth polar-orbiting satellite into geomagnetic coordinates, that is, based on the longitude, latitude and height information of the near-Earth polar-orbiting satellite in the geographic coordinate system, the position of the near-Earth polar-orbiting satellite is obtained. Magnetic local time information under the geomagnetic coordinate system; among them, the geomagnetic coordinate points of 1440 polar-orbiting satellites can be obtained in one day.

Step 3. Using the auroral belt boundary model proposed by Starkov, calculate the polar and equatorial boundaries of the auroral belt region under the condition of the geomagnetic Kp index; where,

The geomagnetic parameter that the auroral belt boundary model relies on is the AL index, which describes the intensity of geomagnetic disturbance during auroral activity; the AL index can be calculated from the Kp index, and the formula is as follows:

AL＝18-12.3Kp+27.2Kp ² -2Kp ³

The auroral belt boundary θ (geomagnetic latitude) given by the model can be expressed as:

θ _m ＝A _0m +A _1m cos[15(t+α _1m )]+A _2m cos[15(2t+α _2m )]+A _3m cos[15(3t+α _3n )]

Among them, A _im and α _im represent the amplitude with geomagnetic latitude and the phase expressed in decimal hours, respectively, and t is the magnetic local time. m=0/1 correspond to polar and equatorial auroral boundaries respectively. The coefficients A _im and α _im of the equation are third-order polynomials of the AL index:

There are a series of coefficient b _im values for each A _im and α _im ; see Table 1 for details.

Table 1

Wherein, as shown in Figure 2, the intervals formed by the upper and lower wavy lines (thick black dots) obtained by the present invention are respectively the auroral belts of the north and south poles, and the thin black dots are sub-satellite points of satellite orbital motion, a total of 1440 sub-satellite points . As shown in Figure 3, it is the case of the satellite encountering the auroral belt under the condition of Kp=5. In the figure, two oval strips enclose the auroral belt area, and the * point is the sub-satellite point of satellite orbital motion.

Step 4. Based on the geomagnetic coordinates of the polar-orbiting satellite and the auroral belt area, determine the orbital position of the polar-orbiting satellite in the auroral belt area, and obtain the longest duration of the polar-orbiting satellite in the auroral belt area and the time at which the polar-orbiting satellite encounters aurora electrons probability;

specific:

The calculation method for the longest duration of a polar-orbiting satellite in the auroral belt area, including:

Count the continuous geomagnetic coordinate points of the space position of the polar orbiting satellite in the auroral belt area;

Select the track segment with the most continuous geomagnetic coordinate points in the satellite space position;

The total duration of the trajectory segment is determined based on the set fixed time interval (60s), which is the longest duration of the polar-orbiting satellite in the auroral zone.

The calculation method for the probability of a polar-orbiting satellite encountering an auroral electron, including:

Obtain the number M of geomagnetic coordinate points of all spatial positions generated by polar-orbiting satellites within a day;

Count all coordinate points N of polar-orbiting satellites located in the auroral belt area within one day;

Calculate the probability P=N/M that the polar-orbiting satellite encounters the auroral electron.

Under different geomagnetic Kp conditions, the longest duration of polar-orbiting satellites in the auroral belt area and the probability of polar-orbiting satellites encountering auroral sedimentation electrons are shown in Table 2:

Table 2

maximum duration Probability of Encountering the Aurora Belt Kp=0 4 minutes 3.9% Kp=5 10 minutes 8.6% Kp=9 10 minutes 10.3%

The advantages of the present invention are:

The present invention converts the space position coordinates of the polar-orbiting satellite into the geomagnetic coordinates of the distribution of the auroral belt by determining the position of the boundary of the auroral zone under different geomagnetic activity conditions; The spatial position, duration and encounter probability of Aurora Electronics are quickly analyzed to provide a basis for assessing the risk of charging and discharging of polar-orbiting satellites.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (7)

1. A method for predicting polar satellite encounter with polar photoelectrons, comprising:

calculating the geographic coordinates of the in-orbit running space position of the polar orbit satellite according to a fixed time interval;

converting the space position geographic coordinates of the polar orbit satellite into geomagnetic coordinates;

inputting a geomagnetic activity Kp index based on the polar band boundary model, and determining polar and equatorial boundaries of a polar band region;

and determining the orbit position of the polar orbit satellite in the polar light band area based on the geomagnetic coordinates and the polar light band area coordinates of the polar orbit satellite, and counting the longest duration time of the polar orbit satellite in the polar light band and the probability of the polar orbit satellite encountering polar light electrons.

2. The method of predicting when a polar orbiting satellite encounters an aurora electronic as in claim 1, wherein said calculating the geospatial position of the orbital motion of the polar orbiting satellite comprises:

acquiring the orbit parameters of the polar orbit satellite; wherein the orbit parameters include a perigee height, a apogee height, and an inclination angle;

inputting the orbit parameters of the polar orbit satellite into an SGP4 orbit calculation program, and outputting the spatial position geographical coordinates of the polar orbit satellite at different moments on the orbit according to a fixed time interval; wherein the spatial location geographic coordinates include longitude, latitude, and altitude.

3. A method of predicting exposure of a polar satellite to an aurora of claim 2, wherein the fixed time interval is 60s.

4. The method of predicting polar orbiting satellite encounter with polar photoelectrons of claim 1, wherein said converting the spatial position geographical coordinates of the polar orbiting satellite into geomagnetic coordinates comprises:

and converting the space position geographical coordinates of the polar orbit satellite into geomagnetic coordinates adopted by the polar light band model based on a geomagnetic coordinate calculation program to obtain magnetic geotime information of the polar orbit satellite in a geomagnetic coordinate system.

5. The method of predicting the encounter of a polar satellite with an aurora electron according to claim 1, wherein the polar and equatorial boundaries of the aurora zone are calculated by the formula:

θ _m ＝A _0m +A _1m cos[15(t+α _1m )]+A _2m cos[15(2t+α _2m )]+A _3m cos[15(3t+α _3m )]

AL＝18-12.3Kp+27.2Kp ² -2Kp ³

wherein m =0 or 1, respectively corresponding to the polar and equatorial directions; theta.theta. _m The magnetic latitude of the polar or equatorial boundary, A _im And alpha _im Respectively representing the amplitude of the satellite magnetic latitude and the phase represented by decimal hours, and when t is the magnetic place, i is 0-3 to represent the order; AL is the intensity of the geomagnetic disturbance for each A _im And alpha _im All have a series of coefficients b _im The value is obtained.

6. The method of predicting the encounter of a polar satellite with an aurora of claim 1, wherein the method of calculating the longest duration that the polar satellite is in an aurora zone comprises:

counting continuous geomagnetic coordinate points of the space positions of polar orbit satellites in the polar light band region;

selecting a track section with the most continuous geomagnetic coordinate points in the satellite space position;

the total duration of the trajectory segment is determined based on a set fixed time interval, i.e., the longest duration of the polar orbiting satellite in the polar band region.

7. The method for predicting the polar orbiting satellite encountering an aurora electron according to claim 1, wherein the method for calculating the probability that the polar orbiting satellite encounters an aurora electron comprises:

acquiring the number M of geomagnetic coordinate points of all spatial positions generated by a polar orbit satellite in one day;

counting all coordinate points N in the polar light band region within one day;

and calculating the probability P = N/M that the polar orbit satellite encounters the polar light electrons.

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