A method for retrieving and verifying surface thermal inertia of extraterrestrial bodies

Abstract

The extraterrestrial object surface thermal inertia inversion and verification method comprises the following steps: calculating the thermal diffusivity of the target ground object at different depths by using internal temperature measurement data of the target ground object, combining the experimental measurement value of the heat capacity of the target ground object, and obtaining the calculation value of the thermal inertia of the target ground object; the surface temperature measurement data of the target ground object is obtained by using the thermal imager, and the thermal inertia of the target ground object is calculated according to the thermal inertia theoretical calculation model; the thermal inertia inversion model is fitted and corrected by using the thermal inertia calculated from the internal temperature measurement data, and the calculation accuracy of the thermal inertia based on the surface temperature measurement data is improved. The present application aims to solve the calculation accuracy problem of the thermal inertia inversion method based on the surface temperature measurement data of the thermal imager, and provides technical reserves for the identification and passability analysis of the extraterrestrial object surface dangerous terrain with thermal characteristics.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of surface exploration of extraterrestrial objects, and particularly relates to a method for inverting and verifying thermal inertia of a surface of an extraterrestrial object. BACKGROUND

[0002] In the existing surface exploration of extraterrestrial objects, the identification of terrain and the analysis of passability are both based on the surface geometric features obtained from visible light images. However, the simple visible light vision measurement is easily affected by the light and surface texture, which may cause misjudgment of the passability of the surface geometric features of dangerous terrain (such as slippery / sinking sandy land), and affect the safety of the passage of the surface exploration vehicle of the extraterrestrial planet.

[0003] Thermal inertia is a comprehensive measure of the thermal characteristics of a substance, reflects the ability of the substance to exchange energy with the surrounding environment, and also represents the ability of the surface substance to resist temperature changes from the outside world. It can be approximately considered as representing the granularity of the surface substance. The substance with high thermal inertia has small diurnal temperature difference, such as stone (thermal inertia is usually greater than 1200 J·m -2 ·K -1 ·s -1 / 2 );The substance with low thermal inertia has large diurnal temperature difference, such as dust (thermal inertia is usually less than 150 J·m -2 ·K -1 ·s -1 / 2 )。Under certain surface pressure conditions, the thermal inertia of the terrain composed of particles is a function of particle size, density and aggregation degree. The passability of the Mars rover in the loose sandy terrain is strongly related to the particle size, density and aggregation degree, which indicates that the wheel sinking and slipping during the travel are related to the thermal inertia of the terrain.

[0004] Using the thermal characteristics of the surface of Mars to invert the internal geological features of the surface of Mars for judging dangerous terrain of the surface of Mars and planning the motion trajectory of the Mars rover is the research frontier of the surface exploration of Mars in recent years. NASA and California Institute of Technology have carried out preliminary research. However, due to the difficulty in directly measuring the thermal inertia, the thermal inertia is currently calculated by using the temperature measurement data of the orbiters or the vehicle-mounted thermal imagers. The main problem is that there is a lack of evaluation of the measurement and calculation results, and the calculation accuracy of the thermal inertia cannot be guaranteed, which affects the accuracy of the judgment of dangerous terrain and passability based on the thermal inertia. SUMMARY

[0005] The technical problem solved by this invention is to overcome the shortcomings of existing technologies and propose a method for inverting and verifying the thermal inertia of the surface of extraterrestrial objects. This method involves constructing an experiment to obtain internal temperature measurement data and calculating the thermal inertia of the target object. The calculated value is then compared with the thermal inertia inversion value obtained using a thermal inertia theory calculation model and surface temperature measurement data from a thermal imager. The effectiveness of the thermal inertia inversion based on thermal imager measurement data is evaluated, and the inversion model is corrected to ensure the accuracy of thermal inertia calculation. This provides a technical reserve for identifying hazardous terrain on the surface of extraterrestrial objects and determining their accessibility.

[0006] The technical solution of this invention is:

[0007] A method for inverting and verifying the thermal inertia of an extraterrestrial body surface, comprising:

[0008] N different types of ground features were selected as targets, and the thermal diffusivity D of the targets was calculated using internal temperature data at different depths of the target ground features. h Combined with experimental measurements of the target ground object's heat capacity C h The calculated value P of the thermal inertia of each target feature is obtained. T ;

[0009] Using surface temperature data of the target features, the estimated value P of the thermal inertia of each target feature is obtained. C ;

[0010] Calculate the value P using the thermal inertia of each target feature. T And the estimated value of thermal inertia P for each target feature C The modified thermal inertia inversion model is fitted to obtain the modified thermal inertia inversion model.

[0011] Preferably, the calculated value P of the thermal inertia of the target ground object is obtained. T The method is as follows:

[0012] By selecting two different locations below the Earth's surface at depths (z1, z2), the distances at these two locations over one light period t are obtained. p i temperature values ​​within;

[0013] Using two locations within one optical period t p The thermal diffusivity D of the target ground object is obtained by fitting the i temperature values ​​within the range. h ;

[0014] The heat capacity C of the target ground object was obtained through a volumetric heat capacity measurement experiment. h ;

[0015] Using the obtained thermal diffusivity D of the target ground features h and the obtained target ground heat capacity C h The calculated value P of the thermal inertia of the target object is obtained. T .

[0016] Preferably, a T-type thermocouple is used as the temperature measuring device to obtain i temperature values at two positions within one light period t p ;

[0017] The depth difference between the two positions is not less than 0.1 meters, and the depth of the position with the shallowest depth among the two positions is not greater than 0.1 meters; or, within one light period t p , the maximum temperature difference between the two positions is not less than 10℃.

[0018] Preferably, the method for fitting to obtain the thermal diffusivity D h of the target ground object is as follows:

[0019] Obtain 24 temperature values at two positions within one light period t p , and denote the temperature measurement data as and

[0020] Divide the temperature measurement data and into 6 groups, and each group corresponds to the temperature measurement data at 4 time points at the positions z1 and z2;

[0021] Then, the thermal diffusivity D h of the target ground object is as follows:

[0022]

[0023]

[0024] In the formula, ω = 2π / t p , and k = 0, 1, 2, 3, 4, 5.

[0025] Preferably, the method for obtaining the heat capacity C h of the target ground object is as follows:

[0026] Select a closed and adiabatic container with a volume of V, fill the container with the target ground object, and wrap a heating wire around the container. Heat the target ground object in the container by using an electric heater with a power of P C , measure the temperature rise ΔT C of the target ground object within a heating time Δt, and calculate the heat capacity C h of the target ground object as follows:

[0027]

[0028] Preferably, the calculated value P T of the thermal inertia of the target ground object is as follows:

[0029]

[0030] Preferably, the estimated value P of the thermal inertia of the target ground object is obtained C , in particular:

[0031] 21) calculating the coefficients (A1, A2) of the Fourier series in the thermal inertia theoretical calculation model;

[0032] 22) calculating the initial value B0 of the iterative solution of the thermal inertia according to the surface temperature measurement data

[0033] 23) solving the estimated value P of the thermal inertia of the target ground object C .

[0034] Preferably, the coefficients (A1, A2) of the Fourier series in the thermal inertia theoretical calculation model are, in particular:

[0035]

[0036]

[0037] ψ = arccos (tan δ · tan α)

[0038] wherein α is the local latitude and δ is the solar declination.

[0039] Preferably, the surface temperature measurement data T p ,i = 0, 1, 2, …, 23 of the target ground object measurement point surface position within a light period t i is obtained, and the highest temperature value within the light period is screened to obtain the highest temperature time t max .

[0040] From the surface temperature measurement data T p ,i = 0, 1, 2, …, 23 within a light period t i , two different temperature measurement values are randomly selected, the time corresponding to the two different temperature measurement values is t1, t2, and the absolute value of the temperature difference corresponding to the two different temperature measurement values is calculated

[0041] calculating the initial value B0 of the iterative solution of the thermal inertia, in particular:

[0042]

[0043] ω = 2π / t p

[0044]

[0045] ​​

[0046] In the formula, A is the surface albedo at the target measurement point, C t is the atmospheric transmittance, and S0 is the solar constant.

[0047] According to the following nonlinear equation with P C B as unknown variables, the initial value B0 of the thermal inertia iterative solution is obtained by using the Newton iterative method to obtain the estimated value P C of the target ground object thermal inertia.

[0048]

[0049]

[0050]

[0051] Preferably, the obtained corrected thermal inertia inversion model is specifically:

[0052] The calculated values of the thermal inertia of the N target ground objects are obtained as true values, denoted as

[0053] The estimated values of the thermal inertia of the N target ground objects are obtained, denoted as

[0054] A linear model between the two groups of data of the true values of the thermal inertia of the N target ground objects and the estimated values of the thermal inertia of the N target ground objects is established as follows:

[0055]

[0056] In the formula, k and c are constant parameters to be determined.

[0057] Based on the data The estimated values of the parameters k and c are obtained by using the least square method.

[0058] According to the estimated values of the parameters k and c in the linear model The thermal inertia inversion model based on the surface measurement data of the thermal imager is corrected to obtain a corrected thermal inertia inversion model, which is specifically:

[0059]

[0060] In the formula, P represents the thermal inertia of the target ground object.

[0061] The present application has the following advantages:

[0062] 1) This invention includes a scheme for calculating and inverting the thermal inertia of different geological targets on the surface of extraterrestrial bodies, which can realize the calculation of thermal inertia based on internal temperature measurement data, as well as the solution of thermal inertia based on surface temperature measurement data of thermal imagers.

[0063] 2) This method discloses a method for verifying the thermal inertia of the surface of extraterrestrial objects. This method can further improve the accuracy of the thermal inertia inversion model based on the surface temperature measurement of thermal imagers. It provides a feasible way to identify the internal characteristics of target objects by measuring surface temperature alone, and provides more information for judging the passability of mobile detection. Attached Figure Description

[0064] Figure 1 This is a flowchart illustrating the steps of a method for inverting and verifying the thermal inertia of an extraterrestrial body surface according to the present invention.

[0065] Figure 2 This is a logic block diagram of the thermal inertia calculation method based on internal temperature measurement data in an embodiment of the present invention.

[0066] Figure 3 This is a block diagram of the thermal inertia calculation algorithm based on surface temperature measurement data in an embodiment of the present invention. Detailed Implementation

[0067] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0068] A method for inverting and verifying the thermal inertia of an extraterrestrial body surface, comprising:

[0069] 1) Select N types of ground features with different materials such as coarse sand and fine sand as observation targets, and calculate the thermal inertia based on the internal temperature measurement data: Calculate the thermal diffusivity D of the target ground feature (granular materials such as sand and soil) at different depths using the internal temperature measurement data at the measurement points. h Combined with experimental measurements of the target ground object's heat capacity C h The calculated value P of the thermal inertia of each observed target ground feature is obtained. T ;

[0070] 2) Thermal inertia inversion based on surface temperature data: Using surface temperature data of target objects obtained by a thermal imager, and based on the thermal inertia theoretical calculation model, the estimated value P of the thermal inertia of each observed target object is obtained. C ;

[0071] 3) Evaluation and correction of the thermal inertia inversion model: using the calculated thermal inertia values ​​P for each observed target feature in step 1). T And the estimated value of thermal inertia P for each observed target feature obtained from the thermal inertia inversion model in step 2). C By fitting a modified thermal inertia inversion model, the accuracy of thermal inertia calculation based on surface temperature measurement data is improved, and the modified thermal inertia inversion model is obtained.

[0072] The step 1) obtains the calculated value P of the thermal inertia of the target ground object T The method specifically comprises the following steps:

[0073] 11) Calculating the thermal diffusivity of the target ground object by using the internal temperature measurement data. A T-type thermocouple is used as a temperature measurement device, and two positions z1 and z2 (unit: m) at different depths below the ground surface are selected to arrange the thermocouples (usually, z1 can be selected at a position 0-0.1 m below the ground surface, and the interval between z1 and z2 is not less than 0.1 m (i.e., z2-z1≥0.1 m), or the maximum temperature difference between z1 and z2 positions within one photoperiod is not less than 10 degrees). Then, the temperature values (unit: K) of the target ground object at different depths z1 and z2 measurement positions within one photoperiod t p are obtained, usually, the photoperiod t p is not less than 24 h, and the temperature is sampled at least once per hour, and the average of the temperature sampling values within each hour is taken as the temperature measurement value at the corresponding time. Thus, the temperature measurement data corresponding to different depths z1 and z2 within 24 h can be obtained, which are denoted as and The above temperature measurement data and are divided into 6 groups, and each group corresponds to the temperature measurement data of 4 time points of z1 and z2 positions: for example, 6 groups of temperature measurement data can be selected as follows:

[0074]

[0075] In the formula, k=0, 1, 2, 3, 4, 5, and the thermal diffusivity D h of the target ground object is calculated by using the above 6 groups of temperature measurement data as follows:

[0076]

[0077]

[0078] In the formula, ω≤2π / t p , k=0, 1, 2, 3, 4, 5.

[0079] 12) Obtaining the heat capacity of the target ground object through a measurement experiment of the volume heat capacity. A closed adiabatic container with a volume V is selected, the container is filled with the target ground object, and a heating wire is wound around the container. The target ground object in the container is heated by an electric heating with a power P C , in order to ensure the uniformity of the temperature in the container, a cubic container with a side length of 5-10 cm is generally selected, the temperature difference of the heating is at least greater than 5 degrees, the time is usually greater than 2 hours, the power is 30-40 W, and the temperature rise value ΔT C(To reduce measurement randomness, multiple measurements can be taken and the average value taken), and the heat capacity C of the target feature can be calculated. h as follows:

[0080]

[0081] 13) Using the calculated thermal diffusivity D of the target ground features h And the heat capacity C of the target ground features measured in the experiment h The calculated value P of the thermal inertia of the target object is obtained. T Specifically:

[0082]

[0083] Step 2) obtains the estimated value P of the thermal inertia of the target object. C The method is as follows:

[0084] 21) Calculate the coefficients of the Fourier series in the theoretical calculation model of thermal inertia. Determine the geographical parameters of the theoretical calculation model of thermal inertia, including the optical period t at the target measurement point location. p (Unit: h), local latitude α (unit: rad), solar declination δ (unit: rad), the coefficients of the Fourier series in the theoretical calculation model for thermal inertia are as follows:

[0085]

[0086]

[0087] In the formula, ψ = arccos(tanδ·tanα).

[0088] 22) Calculate the initial value of the thermal inertia using the surface temperature measurement data for iterative solution. B0. The surface position of the target ground object measurement point is obtained using a thermal imager within one optical cycle t. p Temperature value within. Light sampling period t p For a period of 24 hours, the temperature measurement data corresponding to the surface location of the target measuring point is recorded as T. i i = 0, 1, 2, ... 23, filter for the highest temperature value within this photoperiod. Obtain the highest temperature moment tmax; then obtain surface temperature measurement data T within a light cycle. i In the range i = 0, 1, 2, ... 23, arbitrarily select two different temperature measurements, and denote the times corresponding to these different temperature values ​​as t1 and t2 (usually t1 = 13h and t2 = 22h can be selected), and calculate the absolute value of the corresponding temperature difference. Based on the measurement data, calculate the initial value for the iterative solution of thermal inertia. B0 is as follows:

[0089]

[0090] ω=2π / t p

[0091]

[0092]

[0093] In the formula, In order to iteratively solve for the estimated value of thermal inertia P C The initial value in the process, B0, is the value introduced during the calculation process. The relevant dimensionless coefficients; A is the surface albedo at the target measuring point (its value depends on material and color, etc.; the surface reflectance of Martian soil and sand is 0.1–0.3; in practical applications on Mars, the surface albedo can be calculated from remote sensing data), C t S0 is the atmospheric transmittance (set to 0.75 under clear sky conditions), and S0 is the solar constant (valued at 1367 W / m2). 2 ). t1, t2 and t max All times are on the hour. The starting point of the light cycle (i.e., zero o'clock) is deduced by working backward from the solar altitude angle corresponding to the local geographical latitude. For example, in the Northern Hemisphere, noon is defined as the time when the sun is due south (i.e., the sun is at its zenith). Based on this, the zero o'clock and other arbitrary times within the light cycle can be determined. Similarly, the time on Mars can be obtained. A Martian day is approximately 24 hours and 40 minutes. We can approximate a 24-hour cycle to obtain the surface temperature value corresponding to the hour. Thermal inertia is itself an approximate calculation, and the approximation of the time will not affect it.

[0094] 23) Solve for the estimated value of thermal inertia P. C According to the following, P C Let B be a nonlinear equation with unknown variables. Solve for the estimated value of thermal inertia P. C :

[0095]

[0096]

[0097]

[0098] The specific solution process is based on the calculation in 22). Using B0 as the initial value, the estimated value P of the thermal inertia of the target ground object is obtained by solving the problem using the Newton-Raphson iteration method. C .

[0099] The evaluation and correction of the thermal inertia inversion model in step 3) is as follows:

[0100] 31) Select N kinds of coarse sand, fine sand and other different material objects as observation targets, and obtain the thermal inertia calculation values of the N kinds of target objects as real values by using step 1), denoted as

[0101] There is no special constraint for each sample, as long as it is within the scope applicable to the method, the depth is generally 0.1-0.2m, the volume is 5-10cm in length of the bottom edge, and the temperature data is averaged as the temperature value at the current time.

[0102] 32) Obtain the estimated value of the thermal inertia of the N kinds of target objects by using the thermal inertia inversion method based on surface temperature measurement in step 2), denoted as

[0103] 33) Establish a linear model between the real value of the thermal inertia of the N kinds of target objects and the estimated value of the thermal inertia of the N kinds of target objects as follows:

[0104]

[0105] Where k, c are constant parameters to be determined;

[0106] 34) Based on the data The estimated values of parameters k, c can be obtained by using the least square method

[0107] 35) According to the estimated values of parameters k, c in the linear model Correct the thermal inertia inversion model based on the surface measurement data of the thermal imager to obtain the corrected thermal inertia inversion model, which is specifically:

[0108]

[0109] Where P represents the thermal inertia of a certain target object, which is a general calculation formula applicable to any object, and further more accurate thermal inertia estimated values are obtained.

[0110] Embodiment

[0111] The surface of extraterrestrial bodies is covered with sand and gullies, which belongs to a typical unstructured environment. According to the characteristics of the surface topography and geological targets of extraterrestrial bodies, five types of different topography are selected, including sand, slope, hollow, soil surface arranged with stone, and soil arranged with stone inside. The sand is a uniform terrain composed of fine sand with a particle size of about 1-3 mm, the surface is flat, and the vertical height / thickness of the sand is not less than 0.25 m; the slope is a sand with a certain slope, the slope is greater than or equal to 15°, and the vertical height is not less than 0.25 m; the hollow terrain refers to the sand inside which is empty, the surface is flat, and the thickness of the terrain is not less than 0.25 m; the soil surface arranged with stone is a mixture of flat stones of different sizes and soil, the surface is relatively flat, and the thickness of the terrain is not less than 0.25 m; the soil arranged with stone inside is that stones of different sizes are placed inside the soil, which is only soil from the surface, and the thickness of the whole terrain is not less than 0.25 m. The above-mentioned sand, slope, and soil surface arranged with stone can be arranged with thermocouples at a distance of 0.05 m and 0.2 m from the ground surface for internal temperature measurement; for the hollow terrain, the thermocouples can be fixed on the support such as iron wire inserted into the soil for measuring the temperature values at a distance of 0.05 m and 0.2 m from the ground surface; for the terrain with stones arranged inside the soil, if the size of the stone does not affect the arrangement of the thermocouple, it can be arranged in the conventional way, if the stone is large, the thermocouples can be arranged on the upper and lower surfaces of the stone respectively. Figure 1 The surface thermal inertia inversion and verification of extraterrestrial bodies is achieved through steps (1)-(3).

[0112] Step (1), as Figure 2 , the thermal diffusivity of the target ground object is calculated by using the two groups of temperature measurement values at different depths obtained by the T-type thermocouples arranged at the measurement points of the five types of terrain targets, and the thermal inertia of the five types of target ground objects is calculated by combining the experimental measurement values of the thermal capacity of the target measurement point ground object.

[0113] The T-type thermocouples (TC1, TC2) are arranged at different depths (z1=0.05 m and z2=0.2 m) of the five types of terrain target ground object measurement points, and the temperature measurement data of the two places within 24 hours of a photoperiod are recorded to obtain the temperature change curve, and the average temperature is calculated according to the temperature measurement data, and the average temperature at z1=0.05 m and z2=0.2 m is respectively recorded as and The above temperature measurement data is divided into six groups, and each group of data is: where k=0, 1, 2, 3, 4, 5, then the thermal diffusivity D of each type of terrain target ground object is calculated by using the above six groups of temperature measurement data. h As follows:

[0114]

[0115]

[0116] where ω = π / 12, k = 0, 1, 2, 3, 4, 5.

[0117] Then, the heat capacity of the target ground object is obtained through a measurement experiment of the volume heat capacity. A closed adiabatic container with a volume of V is selected, which is filled with the target ground object, and a heating wire is wound around the container. The target ground object is heated by electric heating with a power of P C , and the temperature rise value ΔT C of the target ground object in the heating time Δt is measured, and the heat capacity C h of the target ground object is calculated as follows:

[0118]

[0119] Finally, the calculated heat diffusivity D h of the target ground object and the experimentally measured heat capacity C h of the target ground object are used to obtain the calculated value P T of the heat inertia of the target ground object as follows:

[0120]

[0121] At this point, the calculated values of the heat inertia of the sand ground, the slope, the hollow, the soil surface arranged with stone blocks, and the soil arranged with stone blocks are obtained, which are denoted as

[0122] Step (2), as Figure 3 , according to the heat inertia theoretical calculation model, the surface temperature measurement data of the sand ground, the slope, the hollow, the soil surface arranged with stone blocks, and the soil arranged with stone blocks are used to solve the estimated value P C of the heat inertia.

[0123] First, the geographical parameters of the heat inertia theoretical calculation model are determined, including the photoperiod t p = 24h, the local latitude , and the solar declination The coefficients of the Fourier series in the heat inertia theoretical calculation model are calculated as follows:

[0124]

[0125]

[0126] where ψ = arccos(tanδ·tanα).

[0127] Then, using a thermal imager, the surface temperature values ​​of the five types of terrain target points were acquired within one light cycle of 24 hours. The temperature measurement data were recorded and the temperature change curve was obtained. The average temperature was calculated based on the temperature measurement data and denoted as T. i For i = 0, 1, 2, ... 23, the highest temperature time t within this optical cycle is obtained statistically. max =14h; and select two times with different temperatures, t1=13h and t2=22h, and calculate the absolute value of the corresponding temperature difference. The initial value of the thermal inertia is calculated based on the measurement data for iterative solution. B0 is as follows:

[0128]

[0129] In the formula, surface albedo A = 0.2, and atmospheric transmittance C t =0.75, Solar constant S0 = 1367 W / m 2 ω=π / 12, and

[0130]

[0131] Finally, the unknown variable P is solved according to the following nonlinear equation. C B:

[0132]

[0133] In the formula,

[0134]

[0135] The specific solution process is as follows: Using B0 as the initial value, the estimated value P of the thermal inertia of the target ground object is obtained by solving the problem using the Newton-Raphson iteration method. C .

[0136] Thus, based on the surface measurement data from the thermal imager, the estimated values ​​of the thermal inertia of five types of terrain features—sand, slope, hollow, soil surface with stones, and soil interior with stones—were obtained, denoted as follows:

[0137] Step (3), Evaluation and correction of the thermal inertia inversion model: using the calculated thermal inertia values ​​of the target features in step (1). The accuracy of the thermal inertia inversion model in evaluation step (2) And fit the modified thermal inertia inversion model;

[0138] Calculated using the thermal inertia of the target ground features And the estimated value of thermal inertia obtained by inversion from surface temperature measurement using a thermal imager. Establish the following linear model:

[0139]

[0140] The estimated values of the parameters k and c can be obtained by using the least square method and the thermal inertia inversion model based on the surface measurement data of the thermal imager is corrected as follows:

[0141]

[0142] According to the above model, the corrected thermal inertia values P1, P2, P3, P4 and P5 of the five types of terrain targets and ground objects can be obtained.

[0143] Finally, the accuracy of the thermal inertia inversion model is evaluated by calculating the average relative error and the maximum relative error If the accuracy of the corrected inversion model still cannot meet the task requirements, the fitting correction effect can be improved by increasing the types of terrain and target ground objects.

[0144] Although the present application has been disclosed with reference to the preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not depart from the technical solutions of the present application, shall fall within the protection scope of the present application. In the case of no conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other.

[0145] The contents not described in detail in the specification of the present application are the known technology of the person skilled in the art.

Claims

1. An extraterrestrial object surface thermal inertia inversion and validation method, characterized in that, Comprise: Select N different material ground as target, use target ground measuring point different depth internal temperature data to calculate target ground thermal diffusivity D h , combined with the experimental measurement of target ground heat capacity C h , obtain the calculation value of each target ground thermal inertia P T ; Using the surface temperature measurement data of the target ground object, an estimated value P of the thermal inertia of each target ground object is obtained C ; Using the thermal inertia calculation value P of each target ground object T And the estimated value P of the thermal inertia of each target ground object C Fitting the corrected thermal inertia inversion model to obtain a corrected thermal inertia inversion model; The method for fitting the target ground object thermal diffusivity D is specifically: h ​ Two positions are obtained at one light period t p The temperature measurement data are recorded as and The temperature measurement data and are divided into 6 groups, each group corresponding to the temperature measurement data of 4 time instants for the positions z1 and z2. Dtarget= Dobject+ Dbackground h Specifically: where ω = 2π / t p , k = 0, 1, 2, 3, 4, 5; obtaining an estimated value P of thermal inertia of the target ground object C The method specifically comprises: 21) the coefficients (A1, A2) of Fourier series in the thermal inertia theory calculation model; 22) From the surface temperature measurement data, calculate initial values for the iterative solution of the thermal inertia B0; 23) solving for an estimate of the thermal inertia of the target object P C ; The coefficients (A1, A2) of Fourier series in the thermal inertia theory calculation model, specifically: Ψ = arccos (tan delta tan alpha) Wherein, alpha is the local latitude, and delta is the solar declination.

2. The method of claim 1, wherein, The method comprises the following steps of: obtaining a target ground object thermal inertia calculation value P T , specifically: Selecting two different positions under the ground surface at depths (z1, z2), obtaining a plurality of temperature values at the two positions within one light period t p ​ Using multiple temperature values at two locations within a light period t p to fit for the target ground object thermal diffusivity D h ; Through the measurement experiment of volumetric heat capacity, the heat capacity C of the target ground object is obtained h ; Using the obtained target ground object thermal diffusivity D h and the obtained target ground object heat capacity C h , to obtain a calculated value P of the target ground object thermal inertia T .

3. The method of claim 2, wherein, A T-type thermocouple is used as a temperature measuring device to obtain a plurality of temperature values at two locations within a light period t p . The depth difference between the two positions is not less than 0.1 meters, and the depth of the shallowest position of the two positions is not greater than 0.1 meters; or, one light period t p The maximum temperature difference between the two positions is not less than 10℃.

4. The method of claim 2, wherein, Obtaining the heat capacity C of the target ground object h The method specifically comprises: A closed and heat-insulated container of volume V is selected, which is filled with the target ground object, and a heating wire is wound around it. The target ground object in the container is heated by electric heating with power P C , the temperature rise value ΔT C of the target ground object in the heating time Δt is measured, and the heat capacity C h of the target ground object is calculated as follows:

5. The method of claim 2, wherein, The calculated value P of the target ground object thermal inertia T Specifically:

6. The method of claim 2-5, wherein, Obtain the surface temperature measurement data T of the target ground object measurement point surface position in a light period t p i , i = 0, 1, 2, … 23, filter the highest temperature value in the light period Get the highest temperature moment t max ;​ from a light period t p surface temperature measurement data T i , i = 0, 1, 2, … 23, any two different temperature measurement values are selected, the time corresponding to the two different temperature measurement values is t1, t2, and the absolute value of the temperature difference corresponding to the two different temperature measurement values is calculated Initial values for iterative solution of thermal inertia calculation B0, in particular: ω = 2π / t p In the formula, A is the surface albedo at the target measurement point, C t is the atmospheric transmittance, and S0 is the solar constant. According to the following P C , B is an unknown variable of a nonlinear equation, and the initial value of the iterative solution of the thermal inertia is solved B0, the estimated value P of the target ground object thermal inertia is solved by Newton iteration method C :

7. The method of claim 2-5, wherein, The obtained corrected thermal inertia inversion model is specifically: The thermal inertia calculation values of N target ground objects are obtained as true values, denoted as Obtaining an estimated value of the thermal inertia of N target ground objects, denoted as A linear model between the two groups of data of the real value of the thermal inertia of N target ground objects and the estimated value of the thermal inertia of N target ground objects is established as follows: In the formula, k and c are constant parameters to be determined. Based on data The estimates of the parameters k, c are obtained using the least squares method According to the estimated values of the parameters k and c in the linear model The thermal inertia inversion model based on the surface measurement data of the thermal imager is corrected to obtain a corrected thermal inertia inversion model, and specifically: In the formula, P represents the thermal inertia of the target ground object.

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