Methods for determining the total interplanetary plasma density and radio wave path delay

Abstract

The present disclosure provides a method for determining the total content of interplanetary plasma density and radio wave path delay, and the method for determining the total content of interplanetary plasma density includes: obtaining the plasma density and plasma velocity of the interplanetary plasma at the observation point; determining the initial observation time of the interplanetary plasma according to the plasma velocity; and determining the total content of the interplanetary plasma density according to the plasma density. The method for determining the total content of interplanetary plasma density and radio wave path delay according to the present disclosure solves the problem that the radio wave refraction caused by the interplanetary plasma cannot be accurately determined. The total content of the plasma density between the observation point and the deep space detector can be calculated based on the measured plasma density and velocity, thereby determining the radio wave path delay caused by the plasma.

Description

Technical Field

[0001] The present disclosure relates to the fields of space physics technology and aerospace measurement and control technology, and more specifically, to a method for determining the total density content of interplanetary plasma and the delay of radio wave paths. Background Art

[0002] Interplanetary plasma originates from the solar wind, permeates the entire solar system, and changes with time and location. The presence of interplanetary plasma can cause refraction of radio waves used to measure the distance of deep space probes (also called space probes), affecting the accuracy of ranging.

[0003] In existing deep space exploration experiments, the influence of interplanetary plasma refraction is usually ignored, but such neglect can lead to certain errors in the measurement results. In particular, for deep space probes used to explore celestial bodies such as Mars or farther away, the refraction effect of interplanetary plasma on the radio waves (hereinafter referred to as "radio waves") used to measure deep space probes is obvious. Especially before and after solar eclipse, the refraction of interplanetary plasma can cause large refraction errors in radio waves, and can even cause ranging errors of more than 100m for Mars probes.

[0004] Since the total interplanetary plasma density content is related to the interplanetary plasma delay of radio waves measured by deep space probes, it is necessary to accurately determine the total interplanetary plasma density content in order to determine the interplanetary plasma delay of radio waves measured by deep space probes. Summary of the invention

[0005] In view of the problem that the total content of interplanetary plasma density cannot be accurately determined, which affects the accuracy of ranging, the present disclosure provides a method for determining the total content of interplanetary plasma density and radio wave path delay.

[0006] According to a first aspect of the present disclosure, a method for determining a total content of interplanetary plasma density is provided, the method comprising: obtaining a plasma density and a plasma velocity of the interplanetary plasma at the observation point; determining an initial observation time of the interplanetary plasma according to the plasma velocity of the interplanetary plasma at the observation point, wherein, at the initial observation time, a first time required for the interplanetary plasma to move from the observation point to a position having the same heliocentric distance as the deep space probe along the direction from the sun to the observation point is equal to a second time required for a solar wind spiral to rotate from the observation point to the deep space probe; and determining a total content of the interplanetary plasma density of the interplanetary plasma on a path between the position of the observation point and the position of the deep space probe at the radio wave emission time according to the plasma density of the interplanetary plasma measured at the observation point between the initial observation time and a radio wave emission time of emitting radio waves.

[0007] Optionally, the first time is determined in the following manner: based on the position of the deep space probe and the position of the observation point, a first distance between the deep space probe and the sun and a second distance between the observation point and the sun are determined; based on the difference between the first distance and the second distance and the plasma velocity of the interplanetary plasma at the observation point, the first time is determined.

[0008] Optionally, the second time is determined in the following manner: based on the position of the deep space probe and the position of the observation point, determining the angle between the deep space probe and the observation point relative to the sun; and based on the angle and the angular velocity of the solar wind rotation, determining the second time.

[0009] Optionally, the step of determining the total interplanetary plasma density content of interplanetary plasma on the path between the position of the observation point at the time of radio wave emission and the position of the deep space probe according to the plasma density of the interplanetary plasma measured at the observation point between the initial observation time and the radio wave emission time includes: selecting a plurality of target time points including the initial observation time or the radio wave emission time between the initial observation time and the radio wave emission time; determining a plurality of target positions on the path corresponding to the plurality of target time points one by one according to the plurality of target time points; determining an average plasma density between adjacent target positions among the plurality of target positions according to the average plasma density of the interplanetary plasma measured at the observation point at the plurality of target time points; and determining the total interplanetary plasma density content based on the average plasma density between adjacent target positions among the plurality of target positions and the distance between adjacent target positions among the plurality of target positions.

[0010] Optionally, the average plasma density between adjacent target positions among the plurality of target positions is determined by the following formula:

[0011]

[0012] Among them, d i is the average plasma density between the target position corresponding to the i-th target time point and the target position corresponding to the i-1-th target time point, d oi is the average plasma density measured at the observation point from the i-th target time point to the i-1-th target time point, r n is the heliocentric distance of the observation point, for (r i +r i-1 ) / 2, r iis the heliocentric distance of the target position corresponding to the i-th target time point, i∈[1,n], where n is the number of target time points minus 1.

[0013] Optionally, the total interplanetary plasma density is determined by the following formula:

[0014]

[0015] Where TEC is the total density of the interplanetary plasma, s i is the distance on the path between the target position corresponding to the i-th target time point and the target position corresponding to the i-1-th target time point.

[0016] According to a second aspect of the present disclosure, a method for determining radio wave path delay is provided, the method comprising: determining the total content of interplanetary plasma density on the path between the position of the observation point at the time of radio wave emission and the position of the deep space probe according to the method for determining the total content of interplanetary plasma density as described in the present disclosure; determining the radio wave path delay based on the total content of interplanetary plasma density.

[0017] Optionally, based on the total interplanetary plasma density content, the step of determining the radio wave path delay includes: obtaining an uplink signal frequency and a downlink signal frequency of the transmitted radio wave; and determining the radio wave path delay based on the uplink signal frequency, the downlink signal frequency and the total interplanetary plasma density content.

[0018] According to a third aspect of the present disclosure, there is provided an apparatus for determining a total density content of interplanetary plasma, the apparatus comprising: an acquisition unit configured to acquire a plasma density and a plasma velocity of the interplanetary plasma at an observation point; a time determination unit configured to determine an initial observation time of the interplanetary plasma according to the plasma velocity of the interplanetary plasma at the observation point, wherein, at the initial observation time, a first time required for the interplanetary plasma to move from the observation point to a position having the same heliocentric distance as the deep space probe along the direction from the sun to the observation point is equal to a second time required for a solar wind spiral to rotate from the observation point to the deep space probe; and a density determination unit configured to determine a total interplanetary plasma density content of the interplanetary plasma on a path between a position of the observation point at the time of radio wave emission and a position of the deep space probe according to the plasma density of the interplanetary plasma measured at the observation point between the initial observation time and a time of radio wave emission for emitting radio waves.

[0019] Optionally, the moment determination unit is also configured to determine the first time in the following manner: determine a first distance between the deep space probe and the sun and a second distance between the observation point and the sun based on the position of the deep space probe and the position of the observation point; determine the first time based on the difference between the first distance and the second distance and the plasma velocity of the interplanetary plasma at the observation point.

[0020] Optionally, the moment determination unit is further configured to determine the second time in the following manner: determining the angle between the deep space probe and the observation point relative to the sun based on the position of the deep space probe and the position of the observation point; and determining the second time based on the angle and the angular velocity of the solar wind rotation.

[0021] Optionally, the density determination unit is further configured to: select a plurality of target time points between the initial observation time and the radio wave emission time when the deep space probe emits radio waves, including the initial observation time or the radio wave emission time; determine a plurality of target positions on the path corresponding to the plurality of target time points one by one according to the plurality of target time points; determine an average plasma density between adjacent target positions among the plurality of target positions according to an average plasma density of the interplanetary plasma measured at the observation point at the plurality of target time points; determine the total interplanetary plasma density content based on the average plasma density between adjacent target positions among the plurality of target positions and the distance between adjacent target positions among the plurality of target positions.

[0022] Optionally, the density determination unit is further configured to determine an average plasma density between adjacent target positions among the plurality of target positions by the following formula:

[0023]

[0024] Among them, d i is the average plasma density between the target position corresponding to the i-th target time point and the target position corresponding to the i-1-th target time point, d oi is the average plasma density measured at the observation point from the i-th target time point to the i-1-th target time point, r n is the heliocentric distance of the observation point, for (r i +r i-1 ) / 2, r i is the heliocentric distance of the target position corresponding to the i-th target time point, i∈[1,n], where n is the number of target time points minus 1.

[0025] Optionally, the density determination unit is further configured to determine the total interplanetary plasma density content by the following formula:

[0026]

[0027] Where TEC is the total density of the interplanetary plasma, s i is the distance on the path between the target position corresponding to the i-th target time point and the target position corresponding to the i-1-th target time point.

[0028] According to a third aspect of the present disclosure, a computer-readable storage medium storing a computer program is provided, which, when executed by a processor, implements the method for determining the total content of interplanetary plasma density as described in the present disclosure or the method for determining the radio wave path delay as described in the present disclosure.

[0029] According to a fourth aspect of the present disclosure, a computing device is provided, comprising: a processor; and a memory storing a computer program, wherein when the computer program is executed by the processor, the method for determining the total content of interplanetary plasma density as described in the present disclosure or the method for determining the radio wave path delay as described in the present disclosure is implemented.

[0030] The method for determining the total interplanetary plasma density content and radio wave path delay according to the present disclosure solves the problem that the total interplanetary plasma density content cannot be accurately determined, which affects the accuracy of ranging for deep space probes. The total interplanetary plasma density content between the observation point and the deep space probe can be calculated based on the measured plasma density and velocity observations, thereby determining the radio wave refraction delay caused by the plasma.

[0031] In order to make the above-mentioned objectives, features and advantages of the present disclosure more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 A schematic flow chart of a method for determining the total interplanetary plasma density content according to an embodiment of the present disclosure is shown.

[0034] Figure 2A schematic diagram showing the positions of the sun, deep space probes, and observation points in a method for determining the total content of interplanetary plasma density according to an embodiment of the present disclosure is shown.

[0035] Figure 3 A schematic flow chart of the step of determining the initial observation time in the method for determining the total content of interplanetary plasma density according to an embodiment of the present disclosure is shown.

[0036] Figure 4 A schematic flow chart of the steps of determining the total content of interplanetary plasma density in the method for determining the total content of interplanetary plasma density according to an embodiment of the present disclosure is shown.

[0037] Figure 5 A flowchart diagram showing an example of a method for determining an electric wave path delay according to an embodiment of the present disclosure is shown.

[0038] Figure 6 A schematic block diagram of an apparatus for determining the total interplanetary plasma density content according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the embodiments of the present disclosure clearer, the technical scheme in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments. The components of the embodiments of the present disclosure generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the present disclosure for protection, but merely represents the selected embodiments of the present disclosure. Based on the embodiments of the present disclosure, each other embodiment obtained by those skilled in the art without making creative work belongs to the scope of protection of the present disclosure.

[0040] It should be noted that the term “comprising” will be used in the embodiments of the present disclosure to indicate the existence of the features declared thereafter, but does not exclude the addition of other features.

[0041] The present disclosure relates to a method and device for determining the total content of interplanetary plasma density, a method for determining radio wave path delay, a computer-readable storage medium and a computing device. It is worth noting that before the present disclosure was filed, there was a lack of research on the total content of interplanetary plasma density and on the refraction effect of interplanetary plasma on emitted radio waves, resulting in the inability to eliminate errors in measuring the distance of deep space probes.

[0042] Specifically, radio waves can be transmitted from ground-based radars to deep-space probes, or from deep-space probes to ground-based radars. For example, deep-space probes can forward radio waves transmitted from ground-based radars to deep-space probes back to the ground. In the above radio wave propagation process, radio wave refraction may occur due to the presence of interplanetary plasma, resulting in radio wave path delays, affecting the accuracy of measuring the distance of deep-space probes.

[0043] In view of this, a first aspect of an embodiment of the present disclosure provides a method for determining the total content of interplanetary plasma density, which can determine the total content of interplanetary plasma density for use in determining the radio wave path delay caused by the interplanetary plasma, thereby optimizing the ranging results.

[0044] Figure 1 A schematic flow chart of a method for determining the total content of interplanetary plasma density according to an embodiment of the present disclosure is shown. In this article, a deep space probe may refer to a device for detecting celestial bodies and space, such as a deep space probe. In the following exemplary embodiments, a deep space probe located on Mars is used as an example for description.

[0045] like Figure 1 As shown, the method for determining the total interplanetary plasma density content comprises the following steps:

[0046] In step S10, the plasma density and plasma velocity of the interplanetary plasma at the observation point may be obtained.

[0047] In this step, interplanetary plasma may refer to solar plasma. The observation point may be set on or near the earth, for example, the observation point may be a Sun-Earth Lagrange point. Here, since the observation point is set on or near the earth, the ground radar that transmits radio waves to or receives radio waves from the deep space probe is also located on the earth. Therefore, it can be considered that the distance from the observation point to the deep space probe is the same as the distance from the ground radar to the deep space probe.

[0048] The density and velocity of the plasma can be measured by existing instruments, for example, a plasma measuring instrument such as a Langmuir probe.

[0049] In step S20, the initial observation time of the interplanetary plasma may be determined according to the plasma velocity of the interplanetary plasma at the observation point.

[0050] Here, the initial observation moment can be a moment when, at the initial observation moment, the first time required for the interplanetary plasma to move from the observation point to a position with the same heliocentric distance as the deep space probe along the direction from the sun to the observation point is equal to the second time required for the solar wind spiral to rotate from the observation point to the deep space probe.

[0051] Specifically, the positions of the sun S and the deep space probe P at the time of radio wave emission and the position of the observation point E at the time of observation are as follows: Figure 2 As shown, here, the observation point E can be, for example, the earth. With the sun S as the center, a virtual circle C passing through the observation point E and the detection point P can be obtained. E and virtual circle C P , virtual circle C E and virtual circle C P The radii are the heliocentric distances of the observation point E and the detection point P. Here, although Figure 2 The virtual circle C shown in E and virtual circle C P With different radii, that is, the heliocentric distances of the observation point E and the detection point P are different, but the virtual circle C E and virtual circle C P They may also have the same radius, that is, the observation point E and the detection point P are located on the same virtual circle.

[0052] Here, the radio wave transmission time may be the time when the radio wave is transmitted from the ground radar on the earth to the deep space probe or the time when the radio wave is transmitted from the deep space probe to the ground radar. The radio wave path delay between the ground radar and the deep space probe may be determined based on the total interplanetary plasma density content on the path between the position of the observation point at the time of radio wave transmission and the position of the deep space probe at the time of radio wave transmission, which will be described in detail below in the second aspect of the exemplary embodiment of the present disclosure.

[0053] In this step, the first time can be determined in the following manner: according to the position of the deep space probe and the position of the observation point, a first distance between the deep space probe and the sun and a second distance between the observation point and the sun are determined; based on the difference between the first distance and the second distance and the plasma velocity of the interplanetary plasma at the observation point, the first time is determined.

[0054] by Figure 2 For example, the time for the interplanetary plasma to move from the observation point E to the position P′ having the same heliocentric distance as the deep space probe P can be calculated in the direction SP from the sun S to the observation point P. Specifically, the distance DP from the observation point E to the position P′ can be the difference between the first distance between the deep space probe P and the sun E and the second distance between the observation point E and the sun S, and thus, the first time can be determined according to the distance DP and the plasma velocity.

[0055] The solar wind is a supersonic plasma charged particle flow ejected from the upper atmosphere of the sun, which moves around the sun at a certain angular velocity. In other words, the interplanetary plasma not only moves in the direction from the sun to the observation point, but also moves in a circle with the sun as the center. The solar wind of the same origin forms an Archimedean spiral.

[0056] In this step, the second time can be determined in the following manner: based on the position of the deep space probe and the position of the observation point, determine the angle between the deep space probe and the observation point relative to the sun; based on the angle and the angular velocity of the solar wind rotation, determine the second time.

[0057] Specifically, if Figure 2 As shown, the angle between the deep space probe P and the observation point E relative to the sun S can be the angle ESP, the angular velocity of rotation of the solar wind can be known, and the second time can be the value obtained by dividing the angle ESP by the angular velocity of rotation of the solar wind.

[0058] Since the speed and density of the interplanetary plasma will change with time, at the initial observation time T0 where the first time and the second time are equal, it can be considered that the interplanetary plasma observed at the observation point E is of the same origin as the interplanetary plasma at the deep space probe P. The speed and density of the interplanetary plasma observed at the observation point E can be used to calculate the refraction effect of the interplanetary plasma at the deep space probe P on the radio waves of the deep space probe P.

[0059] As an example, in this step, if Figure 3 As shown, the initial observation time can be determined by:

[0060] In step S21, for any one of the multiple observation times, the first time and the second time at the observation time can be determined according to the position of the deep space detector, the position of the observation point, and the plasma velocity of the interplanetary plasma at the observation point at the observation time.

[0061] For example, observation data of the observation equipment over a period of time can be obtained, multiple observation moments can be selected from the observation data, and the deep space detector position, observation point position, and plasma velocity of the interplanetary plasma at the observation point at each observation moment can be determined, so that the first time and the second time at each observation moment can be calculated based on the method described above.

[0062] In step S22, the first time and the second time of each observation time among the multiple observation times may be compared, and the observation time at which the first time is closest to the second time may be determined as the initial observation time.

[0063] Here, since there may not be an observation moment in which the first time and the second time are strictly equal among all the selected observation moments, the observation moment in which the first time and the second time are closest among all the observation moments can be considered as the initial observation moment in which the first time and the second time are equal. The "closest" mentioned here includes the case where the first time and the second time are strictly equal. Here, a difference threshold can be set for the first time and the second time. When the difference between the closest first time and the second time is less than or equal to the preset difference threshold, the difference between the two can be ignored, and the first time and the second time are considered to be equal. Here, the difference threshold can be set arbitrarily according to actual needs.

[0064] Advantageously, the plurality of observation times may be times within a predetermined period of time before and after the radio wave transmission time at which the radio wave is transmitted.

[0065] For example, on the one hand, a plasma velocity observation sequence of an observation point near the earth within a predetermined time range before and after the radio wave emission time T can be selected, and according to the distance DP, the plasma transport from the observation point E at different observation times to the target orbit where the deep space detector is located (for example, Figure 2 The virtual circle C P On the other hand, the sequence of the second time t2 required for the solar wind spiral to rotate from the observation point E to the direction of the line between the deep space probe point P and the sun point S can be calculated based on the solar wind rotation angular velocity and angle ESP.

[0066] In this way, the observation time closest to the first time t1 in the sequence of the second time t2 can be determined, recorded as T0, and the plasma density of the observation point at this observation time T0 is used as the source of the plasma at the deep space detector.

[0067] It should be noted that in all the calculation processes in this article, the positions of deep space probes and observation points can be uniformly converted to the solar ecliptic coordinate system for calculation.

[0068] In step S30, the total interplanetary plasma density content of the interplanetary plasma on the path between the position of the observation point at the time of radio wave emission and the position of the deep space probe can be determined based on the plasma density of the interplanetary plasma measured at the observation point between the initial observation time and the radio wave emission time.

[0069] As an example, Figure 4 As shown, step S30 may include the following steps:

[0070] In step S31, a plurality of target time points between the initial observation time and the radio wave transmission time of the transmitted radio wave may be selected.

[0071] Specifically, the initial observation time T0 and the radio wave transmission time T n As the start and end time, determine the time range for selecting the target time point, and according to the time of observing the sampling point within the time range, obtain the corresponding target time points as T0, T1…T n-1 , T n Here, the initial observation time T0 can be the radio wave transmission time T n Before, you can also n after.

[0072] In step S32, a plurality of target positions corresponding one-to-one to the plurality of target time points on the path may be determined according to the plurality of target time points.

[0073] Specifically, the position P0 of the deep space probe P at the initial observation time T0 and the observation point E at the radio wave emission time T n Position P n As the starting and ending positions, multiple target positions corresponding to multiple target time points on the path PE are determined. Here, position P0 is the position of the deep space probe P at the initial observation time T0, and the target position P n That is, the observation point E at the time of radio wave emission T n Here, positions P0, P1, P2, P3, ... n-1 , P n The heliocentric distance can be expressed by the following formula (1):

[0074] r i =r i-1 -v i-1 t (1)

[0075] Where i∈[1,n], n is the number of target time points minus 1, r i is the heliocentric distance of the target position at the i-th target time point corresponding to the i-th target time point, r0 is the heliocentric distance of the deep space probe P at the initial observation time T0, r n is the heliocentric distance of the observation point E at the time of radio wave emission Tn, v i-1 is the plasma velocity at the target position corresponding to the i-1th target time point at the i-1th target time point, and t is the time interval between adjacent target time points, for example, it can be a sampling period.

[0076] In addition, considering the target position P corresponding to the i-1th time point at time T0 i-1 and the target position P corresponding to the i-th time point i The average plasma density between i The average plasma density d measured at the observation point at the moment oiTherefore, when the time interval t between adjacent target time points is known, the heliocentric distance r of the i-th target time point can be determined by the following formula (2): i :

[0077]

[0078] Among them, T i is the i-th target time point, is the target position P corresponding to the i-1th time point i-1 and the target position P corresponding to the i-th time point i The angle relative to the sun S, ω is the rotation speed of the solar wind; v i-1 Target position P i-1 and the target position P i The average plasma velocity between , which can be obtained by observation.

[0079] In step S33, an average plasma density between adjacent target positions among the multiple target positions may be determined based on the plasma density of the interplanetary plasma measured at the observation point at the multiple target time points.

[0080] In this step, the average plasma density between adjacent target positions can be determined based on the principle that the change in plasma density satisfies the flux conservation. Specifically, the plasma density within a unit solid angle is conserved. Therefore, the plasma density is inversely proportional to the square of the heliocentric distance and inversely proportional to the speed. Therefore, the average plasma density between the target positions can be calculated using observation data from observation points homologous to those of deep space probes.

[0081] As an example, the average plasma density between adjacent target positions among the plurality of target positions may be determined by the following formula (3):

[0082]

[0083] Among them, d i is the average plasma density between the target position corresponding to the i-th target time point and the target position corresponding to the i-1-th target time point, d oi is the average plasma density of the interplanetary plasma measured at the observation point from the i-th target time point to the i-1-th target time point, which can be considered as the target position P corresponding to the i-th time point i and the target position P corresponding to the i-1th time point i+1 The average plasma density between T i Moment and T i-1 The average plasma density at the time, which can be obtained by observation; r nis the heliocentric distance of the observation point. When the observation point is on or near the earth, the heliocentric distance of the earth can be used as the heliocentric distance of the observation point. Since the heliocentric distance of the earth can be considered a constant, the heliocentric distance of the observation point can also be considered a constant. for (r i +r i-1 ) / 2, r i is the heliocentric distance of the target position corresponding to the i-th target time point, i∈[1,n], n is the number of target time points minus 1. Here, when i is 1, T i-1 The time (i.e., the i-1th target time point) is the T0 time (i.e., the initial observation time) mentioned above; when i is n, T i The time (i.e., the i-th target time point) is T n Time (i.e., the time when the radio wave is transmitted).

[0084] In step S34, the total interplanetary plasma density content may be determined based on the average plasma density between adjacent target positions among the plurality of target positions and the distances between adjacent target positions among the plurality of target positions.

[0085] Specifically, the path length between the corresponding target positions can be calculated using the average plasma density d between adjacent target positions. i , by integrating the plasma density on the path between the deep space detector and the observation point, the total plasma density content between the deep space detector and the observation point is calculated.

[0086] For example, taking the case of a deep space probe located on Mars as an example, using the ephemeris and plasma density (same as electron density) observations of Mars and Earth, the total interplanetary plasma density can be determined by the following formula (4):

[0087]

[0088] Where TEC is the total density of the interplanetary plasma s i is the distance on the path between the target position corresponding to the i-th target time point and the target position corresponding to the i-1-th target time point.

[0089] like Figure 2 As shown, the length of the path PE and the size of the angle SEP can be calculated, and the heliocentric distance r of each target position can be used to calculate the distance between the two targets. i , use the sine theorem and cosine theorem to calculate the length of the distance P1P0 (that is, when i=1, the distance of the target position P1 from the deep space probe P on the path PE) and the size of the angle SEP, so as to further calculate P2P1, P3P2, ...P n-1 P nThe size of, that is, when 1<i≤n, the distance s between the i-th target position and the i-1-th target position on the path PE i .

[0090] A second aspect of an embodiment of the present disclosure provides a method for determining radio wave path delay, the method comprising: determining the total content of interplanetary plasma density on the path between the position of an observation point at the time of radio wave emission and the position of a deep space probe according to the method for determining the total content of interplanetary plasma density as described in the present disclosure; determining the radio wave path delay based on the total content of interplanetary plasma density.

[0091] Specifically, the uplink signal frequency and the downlink signal frequency of the transmitted radio waves can be obtained; based on the uplink signal frequency, the downlink signal frequency and the total interplanetary plasma density content, the radio wave path delay can be determined, specifically, the path delay of the radio wave caused by the refraction of the interplanetary plasma.

[0092] Here, the uplink signal frequency can be the frequency of the radio waves emitted by the ground radar to the deep space probe, and the downlink signal frequency can be the frequency of the radio waves emitted by the deep space probe to the ground radar. Here, the radio waves emitted by the deep space probe to the ground radar can be a forwarding of the uplink radio waves emitted by the ground radar, and the downlink signal frequency can be different from the uplink signal frequency.

[0093] According to the relationship between the total plasma density content and the radio wave delay, the radio wave refraction delay of the uplink signal and the downlink signal are calculated respectively, and the sum of the two is the total radio wave delay.

[0094] As an example, the total radio wave path delay Δs of the radio wave emitted by the ground radar at the time of radio wave emission and then returning to the ground radar after reaching the deep space detector can be determined by the following formula (5):

[0095]

[0096] Among them, Δs is the radio wave path delay of the radio wave transmitted at the time of radio wave transmission, and f 上行 is the uplink signal frequency, f 下行 is the downlink signal frequency, k is the intrinsic coefficient, and TEC is the total density of the interplanetary plasma. In the above formula (3), all physical quantities can be expressed in international units.

[0097] As an example, k may be 40.3. For example, equation (5) may be expressed as the following equation (6):

[0098]

[0099] Where f is the frequency of the radio wave signal, N e is the plasma density at each point on the wave path, s is the wave path PE, ∫s N e ds represents the integral of the plasma density over the electromagnetic wave path PE.

[0100] The above equations (5) and (6) are used to calculate the total radio wave path delay of the radio wave emitted by the ground radar at the time of radio wave emission and then returned to the ground radar after reaching the deep space detector. If only the radio wave path delay Δs of the radio wave emitted from the ground radar to the deep space detector is calculated, 上行 Or just calculate the path delay Δs of the radio wave transmitted from the deep space probe to the ground radar 下行 , the radio wave path delay can be determined by the following equations (7) and (8):

[0101]

[0102]

[0103] Figure 5 A schematic diagram of a method for determining an electric wave path delay according to an embodiment of the present disclosure is shown. Figure 5 In the example shown, the observation point is selected to be on or near the earth, so the position of the earth is taken as the position of the observation point.

[0104] Specifically, in step S1, the positions of the earth and the deep space probe can be converted into the solar ecliptic coordinate system. In step S2, the homology of the deep space probe and the solar wind at the observation point can be analyzed based on the rotational angular velocity of the solar wind and the speed of the observed plasma. In step S3, the intervals between multiple target positions along the radio wave path can be calculated. In step S4, the average plasma density between adjacent target positions can be calculated based on the intervals between the multiple target positions. In step S5, the total interplanetary plasma density content along the radio wave path can be calculated based on the average plasma density between adjacent target positions. In step S6, the plasma radio wave refraction delay amount can be calculated based on the total interplanetary plasma density content.

[0105] According to the method for determining the delay of the radio wave path according to the embodiment of the present disclosure, it is possible to obtain the plasma density and velocity observations actually measured by the plasma measuring instrument based on the plasma in-situ detection data, and calculate the plasma density of each point between the observation point and the deep space probe at a specified time, thereby determining the radio wave refraction delay caused by the plasma, which is used to improve the orbit determination accuracy of the deep space probe.

[0106] A third aspect of the disclosed embodiments provides a device for determining the total content of interplanetary plasma density, such as Figure 6 As shown, the device includes an acquisition unit 100, a time determination unit 200 and a density determination unit 300.

[0107] The acquisition unit 100 may be configured to acquire the plasma density and the plasma velocity of the interplanetary plasma at an observation point.

[0108] The time determination unit 200 can be configured to determine the initial observation time of the interplanetary plasma based on the plasma velocity of the interplanetary plasma at the observation point, wherein, at the initial observation time, the first time required for the interplanetary plasma to move from the observation point to a position with the same heliocentric distance as the deep space probe along the direction from the sun to the observation point is equal to the second time required for the solar wind spiral to rotate from the observation point to the deep space probe.

[0109] The density determination unit 300 can be configured to determine the total interplanetary plasma density content of the interplanetary plasma on the path between the position of the observation point at the time of radio wave emission and the position of the deep space probe based on the plasma density of the interplanetary plasma measured at the observation point between the initial observation time and the radio wave emission time of the transmitted radio wave.

[0110] As an example, the moment determination unit 200 can also be configured to: for any one of the multiple observation moments, determine the first time and the second time at the observation moment based on the deep space probe position, the observation point position, and the plasma velocity of the interplanetary plasma at the observation point at the observation moment; compare the first time and the second time at each of the multiple observation moments, and determine the observation moment that is closest to the first time and the second time as the initial observation moment.

[0111] As an example, the moment determination unit 200 can also be configured to determine the first time in the following manner: determine the first distance between the deep space probe and the sun and the second distance between the observation point and the sun based on the position of the deep space probe and the position of the observation point; determine the first time based on the difference between the first distance and the second distance and the plasma velocity of the interplanetary plasma at the observation point.

[0112] As an example, the moment determination unit 200 can also be configured to determine the second time in the following manner: determine the angle between the deep space probe and the observation point relative to the sun based on the position of the deep space probe and the position of the observation point; and determine the second time based on the angle and the angular velocity of the solar wind rotation.

[0113] As an example, the density determination unit 300 can also be configured to: select multiple target time points between the initial observation time and the radio wave emission time of the radio wave; determine multiple target positions on the path corresponding to the multiple target time points one by one according to the multiple target time points; determine the average plasma density between adjacent target positions among the multiple target positions according to the average plasma density measured at the observation point at the multiple target time points; determine the total interplanetary plasma density content based on the average plasma density between adjacent target positions among the multiple target positions and the distance between adjacent target positions among the multiple target positions.

[0114] As an example, the density determination unit 300 may also be configured to determine an average plasma density between adjacent target positions among the plurality of target positions by the following formula:

[0115]

[0116] Among them, d i is the average plasma density between the target position corresponding to the i-th target time point and the target position corresponding to the i-1-th target time point, d oi is the average plasma density measured at the observation point from the i-th target time point to the i-1-th target time point, r n is the heliocentric distance of the observation point, for (r i +r i-1 ) / 2, r i is the heliocentric distance of the target position corresponding to the i-th target time point, i∈[1,n], where n is the number of target time points minus 1.

[0117] As an example, the density determination unit 300 may also be configured to determine the total interplanetary plasma density content by the following formula:

[0118]

[0119] Where TEC is the total density of interplanetary plasma, s i is the distance on the path between the target position corresponding to the i-th target time point and the target position corresponding to the i-1-th target time point.

[0120] As an example, the device may also include a delay determination unit 400, which may be configured to: obtain an uplink signal frequency and a downlink signal frequency of the transmitted radio wave; and determine the delay of the path of the radio wave transmitted at the time of radio wave transmission based on the uplink signal frequency, the downlink signal frequency and the total interplanetary plasma density content.

[0121] The acquisition unit 100, the time determination unit 200, the density determination unit 300 and the delay determination unit 400 can be based on the above Figures 1 to 5 The method for determining the total density content of interplanetary plasma and the method for determining the delay of an electric wave path in the method embodiment shown execute corresponding steps in the method, for example, through machine-readable instructions executable by an acquisition unit 100, a moment determination unit 200, a density determination unit 300 and a delay determination unit 400. The specific implementation of the acquisition unit 100, the moment determination unit 200, the density determination unit 300 and the delay determination unit 400 can be found in the method embodiment described above, which will not be repeated here.

[0122] A third aspect of an embodiment of the present disclosure provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the method for determining the total content of interplanetary plasma density as described in the present disclosure or the method for determining the radio wave path delay as described in the present disclosure. The specific implementation method can be found in the method embodiment and will not be repeated here.

[0123] A fourth aspect of the embodiments of the present disclosure provides a computing device, the computing device comprising: a processor; a memory storing a computer program, when the computer program is executed by the processor, the method for determining the total content of interplanetary plasma density as described in the present disclosure or the method for determining the delay of an electric wave path as described in the present disclosure is implemented. The specific implementation of the computing device can be found in the method embodiment described above, which will not be repeated here.

[0124] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0125] In the embodiments provided in the present disclosure, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0126] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of the present disclosure.

[0127] In addition, each functional unit in each embodiment of the present disclosure may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0128] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present disclosure, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present disclosure. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0129] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present disclosure, which are used to illustrate the technical solutions of the present disclosure, rather than to limit them. The protection scope of the present disclosure is not limited thereto. Although the present disclosure is described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the aforementioned embodiments within the technical scope disclosed in the present disclosure, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure, and should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be based on the protection scope of the claims.

Claims

1. A method for determining the total content of interplanetary plasma density, characterized in that: The method comprises: Obtain the plasma density and plasma velocity of the interplanetary plasma at the observation point; Determining an initial observation time of the interplanetary plasma according to the plasma velocity of the interplanetary plasma at the observation point, wherein at the initial observation time, a first time required for the interplanetary plasma to move from the observation point to a position having the same heliocentric distance as the deep space probe along the direction from the sun to the observation point is equal to a second time required for the solar wind spiral to rotate from the observation point to the deep space probe; Determine the total interplanetary plasma density on the path between the position of the observation point at the time of radio wave emission and the position of the deep space probe according to the plasma density of the interplanetary plasma measured at the observation point between the initial observation time and the radio wave emission time of the radio wave emission, The first time is determined by: determining a first distance between the deep space probe and the sun and a second distance between the observation point and the sun according to the position of the deep space probe and the position of the observation point; determining the first time based on the difference between the first distance and the second distance and the plasma velocity of the interplanetary plasma at the observation point; The second time is determined by: determining the angle between the deep space probe and the observation point relative to the sun according to the position of the deep space probe and the position of the observation point; determining the second time based on the angle and the angular velocity of the solar wind rotation, Wherein, according to the plasma density of the interplanetary plasma measured at the observation point between the initial observation time and the radio wave emission time of the radio wave emission, the step of determining the total content of the interplanetary plasma density on the path between the position of the observation point at the radio wave emission time and the position of the deep space probe comprises: Selecting a plurality of target time points between the initial observation time and the radio wave emission time, including the initial observation time and the radio wave emission time; Determine, according to the multiple target time points, multiple target positions on the path corresponding one-to-one to the multiple target time points; determining an average plasma density between adjacent target positions among the plurality of target positions according to the average plasma density measured at the observation point at the plurality of target time points; determining the total interplanetary plasma density content based on an average plasma density between adjacent target positions among the plurality of target positions and a distance between adjacent target positions among the plurality of target positions, The average plasma density between adjacent target positions in the plurality of target positions is determined by the following formula: in, For the i The target position corresponding to the target time point is i -The average plasma density between target positions corresponding to 1 target time point, For the i target time point to i - the average plasma density measured at the observation point at a target time point, is the heliocentric distance of the observation point, for( r i + r i-1 ) / 2, r i For the i The heliocentric distance of the target position corresponding to each target time point, i ∈[1, n ], n Subtract 1 from the number of target time points.

2. The method according to claim 1, characterized in that The total interplanetary plasma density is determined by the following formula: in, TEC is the total interplanetary plasma density, For the i The target position corresponding to the target time point is i- The distance between the target positions corresponding to one target time point on the path.

3. A method for determining a radio wave path delay, characterized in that: The method comprises: According to the method for determining the total content of interplanetary plasma density as claimed in claim 1 or 2, determining the total content of interplanetary plasma density on the path between the position of the observation point at the time of radio wave emission and the position of the deep space probe; The radio wave path delay is determined based on the total interplanetary plasma density content.

4. The method according to claim 3, characterized in that Based on the total interplanetary plasma density content, the step of determining the radio wave path delay comprises: Obtain the uplink signal frequency and the downlink signal frequency of the transmitted radio wave; The radio wave path delay is determined based on the uplink signal frequency, the downlink signal frequency and the total interplanetary plasma density content.

5. A device for determining the total content of interplanetary plasma density, characterized in that: The device comprises: An acquisition unit configured to acquire the plasma density and plasma velocity of the interplanetary plasma at an observation point; a time determination unit configured to determine an initial observation time of the interplanetary plasma according to a plasma velocity of the interplanetary plasma at the observation point, wherein at the initial observation time, a first time required for the interplanetary plasma to move from the observation point to a position having the same heliocentric distance as the deep space probe along a direction from the sun to the observation point is equal to a second time required for the solar wind spiral to rotate from the observation point to the deep space probe; a density determination unit configured to determine the total interplanetary plasma density content on the path between the position of the observation point at the time of radio wave emission and the position of the deep space probe according to the plasma density of the interplanetary plasma measured at the observation point between the initial observation time and the radio wave emission time of the radio wave emission, The time determination unit is configured to determine the first time in the following manner: determine a first distance between the deep space probe and the sun and a second distance between the observation point and the sun according to the position of the deep space probe and the position of the observation point; determine the first time based on the difference between the first distance and the second distance and the plasma velocity of the interplanetary plasma at the observation point; The time determination unit is configured to determine the second time in the following manner: determining the angle between the deep space probe and the observation point relative to the sun according to the position of the deep space probe and the position of the observation point; determining the second time based on the angle and the angular velocity of the solar wind rotation; Wherein, the density determination unit is configured to: select a plurality of target time points between the initial observation time and the radio wave emission time, including the initial observation time and the radio wave emission time; determine a plurality of target positions on the path corresponding to the plurality of target time points one by one according to the plurality of target time points; determine an average plasma density between adjacent target positions among the plurality of target positions according to an average plasma density measured at the observation point at the plurality of target time points; determine the total interplanetary plasma density content based on the average plasma density between adjacent target positions among the plurality of target positions and the distance between adjacent target positions among the plurality of target positions; The density determination unit is configured to calculate the average plasma density between adjacent target positions in the plurality of target positions by the following formula: in, For the i The target position corresponding to the target time point is i -The average plasma density between target positions corresponding to 1 target time point, For the i target time point to i - the average plasma density measured at the observation point at a target time point, is the heliocentric distance of the observation point, for( r i + r i-1 ) / 2, r i For the i The heliocentric distance of the target position corresponding to each target time point, i ∈[1, n ], n Subtract 1 from the number of target time points.

6. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for determining the total interplanetary plasma density content according to claim 1 or 2 or the method for determining the radio wave path delay according to claim 3 or 4 is implemented.

7. A computing device, characterized in that: The computing device comprises: processor; A memory storing a computer program, which, when executed by a processor, implements the method for determining the total content of interplanetary plasma density as claimed in claim 1 or 2 or the method for determining the delay of an electric wave path as claimed in claim 3 or 4.

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