Method for determining content of elemental iron in lunar soil based on reflection spectrum absorption depth

Abstract

This invention provides a method for determining the content of elemental iron in lunar soil based on the absorption depth of reflectance spectra, comprising the following steps: (1) preparing a series of simulated lunar soil samples with different elemental iron contents as standard samples; (2) collecting the reflectance spectra of each standard sample and calculating the absorption depth of the absorption band at a wavelength of 2000 nm for each standard sample; (3) fitting the conversion relationship between the elemental iron content in the sample and the absorption depth with the elemental iron content in the sample as the ordinate and the absorption depth as the abscissa; (4) collecting the reflectance spectra of the lunar soil samples, calculating the absorption depth of the absorption band at a wavelength of 2000 nm for the reflectance spectra of the lunar soil samples, and then calculating the elemental iron content in the lunar soil samples using the conversion relationship between the elemental iron content in the samples and the absorption depth. This invention enables the non-destructive, simple, efficient, and low-cost determination of the elemental iron content in lunar soil.

Description

Technical Field

[0001] This invention belongs to the field of lunar soil composition analysis and relates to a method for determining the content of elemental metallic iron in lunar soil based on the absorption depth of reflectance spectroscopy. Background Technology

[0002] Due to the lack of an atmosphere and magnetic field protecting the lunar surface, it is directly exposed to the space environment, subjected to high-speed impacts from meteorites and micrometeorites, as well as continuous bombardment from cosmic rays and solar wind particles. These effects induce the formation of elemental metallic iron. Electron microscopy studies have revealed that this space-weathered elemental metallic iron (Fe)... 0 The particle size of lunar regolith typically ranges from tens to hundreds of nanometers. As lunar regolith is exposed to the space environment for longer periods, it gradually matures, and the content of elemental metallic iron generated within it also increases. Conversely, the content of elemental metallic iron can reflect the maturity of lunar regolith. Therefore, the abundance of elemental metallic iron is of great significance for assessing space weathering and the evolution of lunar regolith.

[0003] Currently, there are three common methods for obtaining the abundance of elemental metallic iron in lunar samples. Method 1 first uses chemical testing to determine the total iron (FeO) content in the sample, and then uses iron Mössbauer spectroscopy to obtain the percentage of elemental metallic iron in the total iron (FeO). 0 The percentage of FeO (FeO) in the sample can be used to calculate the content of elemental metallic iron in the sample, based on the total iron content, the percentage of elemental metallic iron in the total iron content, and the actual mass of the specific sample. Method 2 first uses chemical testing to obtain the total iron (FeO) content in the sample, then performs magnetic testing, using ferromagnetic resonance (FMR) to test the signal intensity (IL) of iron in the lunar soil sample. s Method 1: Substitute the total iron content and iron signal intensity value obtained from the test into an empirical formula to calculate the content of elemental metallic iron. Method 2: Measure the reflectance spectrum of the sample, and then use the reflectance value combined with the Hapke radiative transfer model to invert the content of elemental metallic iron in the sample.

[0004] Methods 1 and 2 both require chemical analysis to determine the FeO content in the whole rock. This chemical analysis is typically destructive, may contaminate the sample, and is complex and time-consuming, making it less than ideal for rare lunar samples. Furthermore, the high cost of Mössbauer spectroscopy would make the testing of elemental iron in lunar soil prohibitively expensive, hindering its widespread application. Method 2's FMR can only detect elemental iron particles with a diameter of approximately 4–33 nm, failing to detect those larger than 33 nm. Therefore, FMR-based calculations cannot accurately represent the total elemental iron content in the sample. Method 3, before using the Hapke model to invert the elemental iron content, requires detailed determination of the optical parameters of all minerals composing the lunar soil sample, involving tedious and complex preparatory work. Furthermore, the study found that the Hapke model has a good inversion effect on nanoscale elemental iron with small particle size, but the inversion results for elemental iron with a particle size greater than 50 nm are not ideal. Therefore, for lunar soil samples containing a large amount of coarse elemental iron, the inversion results will have a large error compared with the actual elemental iron content.

[0005] In summary, existing research methods have significant limitations, including being destructive, having large errors, being complex and cumbersome to operate, and being too costly, resulting in their limited application in the study of elemental iron content in lunar regolith. In the coming years, my country will continue its lunar exploration program, launching the Chang'e 6 probe to complete lunar polar sample return, launching an asteroid probe to complete near-Earth asteroid sampling and main-belt comet exploration, completing Mars sample return, and exploring the Jupiter system, among other key technological challenges. Against the backdrop of deep space exploration, a comprehensive and in-depth understanding of lunar regolith composition will contribute to the development of lunar science and the smooth progress of lunar engineering projects. Therefore, developing simple, efficient, low-cost, and non-destructive methods for testing elemental iron content in lunar regolith is particularly necessary. Summary of the Invention

[0006] To address the limitations of existing methods for testing the content of elemental iron in lunar samples, such as destructive nature, large errors, complex and cumbersome operation, and high cost, this invention provides a method for determining the content of elemental iron in lunar soil based on reflectance spectral absorption depth. This method enables non-destructive, simple, efficient, and low-cost determination of the content of elemental iron in lunar soil without the aid of other auxiliary means.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for determining the content of elemental iron in lunar soil based on reflectance spectral absorption depth includes the following steps:

[0009] (1) Preparation of standard samples

[0010] A series of simulated lunar soil samples with different contents of elemental metallic iron were prepared as standard samples;

[0011] (2) Spectral testing and absorption depth calculation

[0012] The reflectance spectra of each standard sample were collected, and the absorption depth of the absorption band at a wavelength of 2000 nm for each standard sample was calculated using Equation (III).

[0013]

[0014] In equation (III), d is the absorption depth of the absorption band of the reflection spectrum at a wavelength of 2000 nm, and λ l , λ r and λ est R represents the wavelengths of the left shoulder, right shoulder, and lowest point of the absorption band at a wavelength of 2000 nm in the reflection spectrum. l R r and R est These represent the reflectance of the left shoulder, right shoulder, and lowest point of the absorption band at a wavelength of 2000 nm in the reflectance spectrum, respectively.

[0015] (3) Determine the conversion relationship between elemental iron content and absorption depth.

[0016] Plot the relationship between the elemental iron content in the sample and the absorption depth of the absorption band of the sample's reflectance spectrum at 2000 nm wavelength as the x-axis. Then, fit the formula to obtain the conversion relationship between the elemental iron content in the sample and the absorption depth of the absorption band of the sample's reflectance spectrum at 2000 nm wavelength.

[0017] (4) Test the elemental iron content in lunar soil samples

[0018] The reflectance spectrum of the lunar soil sample was collected. Based on the reflectance spectrum of the collected lunar soil sample, the absorption depth of the absorption band at a wavelength of 2000 nm of the reflectance spectrum of the lunar soil sample was calculated by Equation (III).

[0019] Based on the absorption depth of the absorption band of the lunar soil sample at a wavelength of 2000 nm, the content of elemental iron in the lunar soil sample is calculated using the conversion formula between the content of elemental iron in the sample determined in step (3) and the absorption depth of the absorption band of the sample's reflection spectrum at a wavelength of 2000 nm.

[0020] In step (2) of the above technical solution, the process for determining the calculation formula of the absorption depth of the absorption band of the reflection spectrum at a wavelength of 2000 nm is as follows:

[0021] First, assume that the equation of the straight line connecting the left and right shoulders of the absorption band at a wavelength of 2000 nm in the reflection spectrum is as shown in equation (I).

[0022] f(λ)=aλ+b(I)

[0023] In equation (I), λ is the wavelength, a and b are constants, and f(λ) is the corresponding reflectivity.

[0024] Then, the absorption depth d of the absorption band at a wavelength of 2000 nm in the reflection spectrum can be represented by equation (II).

[0025] d=f(λ est )-R est (II)

[0026] In equation (II), λ est R represents the wavelength corresponding to the lowest point (the bottom of the absorption valley) of the absorption band at a wavelength of 2000 nm in the reflection spectrum. est This represents the reflectance corresponding to the lowest point (the bottom of the absorption valley) of the absorption band at a wavelength of 2000 nm in the reflectance spectrum.

[0027] If the wavelengths and reflectance corresponding to the left shoulder, right shoulder, and bottom of the absorption band (absorption valley) at a wavelength of 2000 nm in the reflection spectrum are known, then according to formulas (I) to (II), the absorption depth d of the absorption band at a wavelength of 2000 nm in the reflection spectrum can be expressed by formula (III).

[0028]

[0029] In equation (III), d is the absorption depth of the absorption band of the reflection spectrum at a wavelength of 2000 nm, and λ l , λ r and λ est R represents the wavelengths of the left shoulder, right shoulder, and lowest point of the absorption band at a wavelength of 2000 nm in the reflection spectrum. l R r and R est These represent the reflectance of the left shoulder, right shoulder, and lowest point of the absorption band at a wavelength of 2000 nm, respectively.

[0030] In the above technical solution, when collecting the reflectance spectra of each standard sample and lunar soil sample, the reflectance spectra of each standard sample and lunar soil sample are collected in the 400-2150nm wavelength range.

[0031] In the above technical solution, the reflectance spectra of various standard samples and lunar soil samples can be collected using a visible-near-infrared spectrophotometer.

[0032] In step (1) of the above technical solution, a feasible method for preparing a series of simulated lunar soil samples with different contents of elemental metallic iron is as follows:

[0033] ① Weigh out graphite and simulated lunar soil and put them into a crucible. Place the crucible in a high-temperature atmosphere furnace and heat the furnace to 1550-1600℃ under vacuum conditions. Hold the temperature for 3-4 hours. Remove the crucible and quench it to cool. This will give you a glassy sample containing elemental iron.

[0034] ② The glassy sample containing elemental iron is crushed and then magnetically separated using a magnetic separator to obtain magnetic and non-magnetic samples.

[0035] ③ The total iron content of the magnetic sample was determined by inductively coupled plasma optical emission spectrometry, and the proportion of elemental metallic iron in the magnetic sample was determined by iron Mössbauer spectroscopy. The mass percentage of elemental metallic iron in the magnetic sample was then calculated.

[0036] ④ Mix magnetic and non-magnetic samples of different mass ratios evenly to obtain a series of simulated lunar soil samples with different contents of elemental metallic iron.

[0037] Furthermore, in the above technical solution, the simulated lunar soil is simulated lunar soil CLRS-2.

[0038] In the above technical solution, when collecting the reflectance spectra of each standard sample and lunar soil sample, the reflectance spectra of each standard sample and lunar soil sample are collected at least 3 times (e.g., 3 to 5 times). The average value of the reflectance spectral signals of each standard sample collected in each collection and the average value of the reflectance spectral signals of each lunar soil sample collected in each collection are used as the absorption depth of the absorption band of the reflectance spectra of each standard sample and lunar soil sample at a wavelength of 2000 nm.

[0039] In step (3) of the above technical solution, after plotting the relationship between the content of elemental iron in each standard sample and the absorption depth of the absorption band of the reflection spectrum of each standard sample at a wavelength of 2000 nm, the conversion relationship between the content of elemental iron in the sample and the absorption depth of the absorption band of the reflection spectrum of the sample at a wavelength of 2000 nm is obtained by second fitting.

[0040] Compared with the prior art, the technical solution provided by the present invention has the following beneficial technical effects:

[0041] 1. This invention provides a method for determining the content of elemental metallic iron in lunar soil based on the absorption depth of the reflectance spectrum. The method uses the absorption depth value of the absorption band at a wavelength of 2000 nm in the reflectance spectrum of the lunar soil sample as a basis to determine the content of elemental metallic iron in the sample. The entire determination process only requires a visible-near-infrared spectrophotometer for reflectance spectrum acquisition, without the need for other auxiliary testing methods. This not only reduces testing costs but also prevents contamination of the precious lunar soil sample, making it a non-destructive and pollution-free test. Furthermore, no pretreatment of the lunar soil sample is required before reflectance spectrum acquisition, nor is it necessary to test the optical parameters of the constituent minerals of the lunar soil. The operation is simple and quick, avoiding a large amount of complicated preparation work. Thirdly, because this method only requires collecting the reflectance spectrum data of the lunar soil sample, the required amount of lunar soil sample is small, requiring only milligrams of sample for determination. Fourth, this method uses reflectance spectroscopy to test the content of elemental metallic iron. Since reflectance spectroscopy is not easily affected by sample particle size, it is applicable to a wide range of lunar soil samples. This can solve the shortcomings of existing FMR-based methods, which cannot detect elemental metallic iron with a particle size greater than 33 nm, and the problem that the method combining reflectance values ​​and the Hapke radiative transfer model has unsatisfactory inversion results for elemental metallic iron with a particle size greater than 50 nm.

[0042] 2. The method of the present invention only requires reflectance spectral data in the ~2000nm band, which requires a small amount of spectral data. Therefore, the method of the present invention can also be applied to the interpretation of remote sensing spectral data, which is of great significance for a deeper understanding of the material composition and evolution process of the moon. Attached Figure Description

[0043] Figure 1 Figures (a) and (b) are photographs of the non-magnetic and magnetic samples prepared in the examples, respectively.

[0044] Figure 2 Figures (a) and (b) show the magnetic and non-magnetic samples prepared in the examples, respectively. 57 The Mössbauer spectrum of Fe resonance absorption, (a) the red sub-spectrum (the sub-spectrum pointed to by the arrow in the figure) corresponds to elemental metallic iron, and (b) the sub-spectrums are all Fe. 2+ No signal of elemental iron was detected.

[0045] Figure 3 These are the reflectance spectra of samples C1 to C9, where the numbers on each reflectance spectrum curve represent the percentage content of elemental iron in the sample.

[0046] Figure 4 This is a graph showing the fitting relationship between the content of elemental iron and the absorption depth. Detailed Implementation

[0047] The following examples further illustrate the method for determining the content of elemental metallic iron in lunar soil based on the absorption depth of reflectance spectroscopy provided by this invention. It should be noted that the following examples are only for further illustration of this invention and should not be construed as limiting the scope of protection of this invention. Any non-essential improvements and adjustments made to this invention by those skilled in the art based on the above description are still within the scope of protection of this invention.

[0048] In the following embodiments, the instrument used to acquire the sample spectra was a Cary 500 visible-near-infrared spectrophotometer. Each sample was tested three times, and the average value of the spectral signals obtained from the three tests was used as the final signal value.

[0049] Example

[0050] In this embodiment, the method for determining the content of elemental metallic iron in lunar soil based on the absorption depth of reflectance spectroscopy, as described in this invention, is provided.

[0051] 1. Preparation of standard samples

[0052] In this step, multiple simulated lunar soil samples with different amounts of elemental metallic iron are prepared, i.e., multiple standard samples with different amounts of elemental metallic iron are prepared. The initial raw materials used in the preparation include: high-titanium lunar maria simulated lunar soil CLRS-2 prepared by the Institute of Geochemistry, Chinese Academy of Sciences, and high-purity graphite purchased from the market. The mineral composition of the simulated lunar soil CLRS-2 mainly includes basic volcanic glass, ilmenite, olivine, pyroxene, and plagioclase, and its chemical composition is shown in Table 1.

[0053] Table 1. XRF test results (wt.%) of simulated lunar soil CLRS-2

[0054]

[0055]

[0056] The preparation process of several simulated lunar soil samples with different contents of elemental metallic iron is as follows:

[0057] (1) Weigh graphite and simulated lunar soil CLRS-2 in a mass ratio of 1.0:27.0, put them into a crucible, place the crucible in a high-temperature atmosphere furnace, keep the high-temperature atmosphere furnace under vacuum conditions, heat to 1600℃, keep it at the temperature for 4h, take the crucible out of the high-temperature atmosphere furnace, and quickly quench and cool it to obtain a glassy sample containing elemental metallic iron.

[0058] (2) The glassy sample containing elemental iron was crushed, and the glass was magnetically separated using a magnetic separator to separate the magnetic (C) elements. h ) and non-magnetic (C n Separate the parts of ).

[0059] The separated magnetic (C) h ) and non-magnetic (C n (See part of the photos) Figure 1 , where C n Photographs of the samples Figure 1 As shown in Figure (a), C h Photographs of the samples Figure 1 As shown in Figure (b), the color in Figure (b) is significantly darker than that in Figure (a). This is because C h This is caused by the presence of opaque elemental iron in the sample.

[0060] (3) Determination of C using inductively coupled plasma optical emission spectrometry (OES) h Sample and C n The total iron (FeO) content of the sample was determined by iron Mössbauer spectroscopy (FeMS). h Sample and C n The percentage of elemental iron in a sample is the product of the total iron content of the sample and the percentage of elemental iron in the sample.

[0061] C h Sample and C n The sample 57 Fe resonance absorption Mössbauer spectrum as shown Figure 2 As shown, figures (a) and (b) represent C respectively. h Sample and C n In the sample, the red sub-spectrum in (a) corresponds to elemental metallic iron, and the sub-spectrums in (b) are all Fe. 2+ No signal of elemental iron was detected. The analytical test results are shown in Table 2. As can be seen from Table 2, sample C... n The sample contained 0 wt.% elemental iron and C. h The content of elemental iron in the sample was 0.36 wt.%.

[0062] Table 2C h Sample and C n The content of elemental iron in the sample

[0063]

[0064] Note: Fe 0 Short for elemental iron

[0065] (4) Weigh C according to a certain proportion h Sample and C nThe samples were then thoroughly mixed to obtain samples C1 to C9 with elemental iron contents of 0 wt%, 0.05 wt.%, 0.10 wt.%, 0.15 wt.%, 0.20 wt.%, 0.25 wt.%, 0.30 wt.%, and 0.36 wt.%, respectively. These constitute nine standard samples with different elemental iron contents. The specific sampling ratios are shown in Table 3.

[0066] Table 3 shows the C values ​​for preparing samples C1 to C9 with different iron contents. h With C n Mixing ratio of samples

[0067]

[0068] 2. Spectral testing and absorption depth calculation

[0069] (1) The reflectance spectra of samples C1 to C9 in the 400–2150 nm wavelength range were collected one by one using a visible-near-infrared spectrophotometer. The reflectance spectra of samples C1 to C9 are shown in the figure below. Figure 3 As shown, Figure 3 The numbers on each reflectance spectrum curve represent the percentage content of elemental iron in the sample.

[0070] (2) Based on the spectral data of each sample collected in step (1), calculate the absorption depth d of the absorption band of the reflection spectrum of each sample at a wavelength of 2000 nm. The formula for calculating d is as shown in equation (III):

[0071]

[0072] In equation (III), λ l , λ r and λ est These represent the wavelengths of the left shoulder, right shoulder, and lowest point (bottom of the absorption valley) of the absorption band at a wavelength of 2000 nm in the reflection spectrum; R l R r and R est The values ​​represent the reflectance of the left shoulder, right shoulder, and lowest point (bottom of the absorption valley) of the absorption band at a wavelength of 2000 nm for samples C1 to C9. Table 4 shows the wavelength (λ), reflectance (R), and absorption depth (d) values ​​corresponding to the left and right shoulders of the absorption band at a wavelength of 2000 nm for samples C1 to C9.

[0073] Table 4 shows the absorption band characteristics of samples C1 to C9 at a wavelength of 2000 nm.

[0074]

[0075] 3. Determine the conversion relationship between the elemental iron content M and the absorption depth d.

[0076] Plot the relationship between the elemental iron content in samples C1–C9 and the absorption depth of the absorption band at 2000 nm using the reflectance spectrum of the samples as the x-axis. Then, perform a quadratic fitting to obtain the conversion formula between the elemental iron content M and the absorption depth d of the reflectance spectrum at 2000 nm: M = 0.35d. 2 -0.94d + 0.63, the fitting result is as follows Figure 4 As shown. By Figure 4 It can be seen that the coefficient of determination R of the fitting function 2 The value of 0.95 indicates that the fitting effect is very good.

[0077] 4. Testing the elemental iron content in an unknown lunar soil sample.

[0078] (1) The reflectance spectra of lunar soil samples in the 400–2150 nm band were collected using a visible-near-infrared spectrophotometer;

[0079] (2) Analysis of the characteristics of the absorption band at 2000 nm wavelength in the reflectance spectrum of the lunar soil sample collected in step (1), including: the wavelength λ corresponding to the left shoulder, right shoulder and lowest point of the absorption band (bottom of the absorption valley) at 2000 nm wavelength. l , λ r and λ est The reflectance R corresponding to the left shoulder, right shoulder, and lowest point (bottom of the absorption valley) of the absorption band at a wavelength of 2000 nm. l R r and R est The absorption depth d of the absorption band at a wavelength of 2000 nm in the reflectance spectrum of the lunar soil sample was calculated according to formula (III).

[0080] (3) Based on the absorption depth of the absorption band of the lunar soil sample at a wavelength of 2000 nm, the conversion relationship between the elemental iron content M in the sample determined in step 3 and the absorption depth d of the absorption band of the sample's reflectance spectrum at a wavelength of 2000 nm is M = 0.35d. 2 The elemental iron content in the lunar soil sample can be calculated by using -0.94d + 0.63.

Claims

1. A method for determining the content of elemental metallic iron in lunar soil based on reflectance spectral absorption depth, characterized in that, Includes the following steps: (1) Preparation of standard samples A series of simulated lunar soil samples with different contents of elemental metallic iron were prepared as standard samples; (2) Spectral testing and absorption depth calculation The reflectance spectra of each standard sample were collected, and the absorption depth of the absorption band at a wavelength of 2000 nm for each standard sample was calculated using Equation (III). In equation (III), d is the absorption depth of the absorption band of the reflection spectrum at a wavelength of 2000 nm, and λ l , λ r and λ est R represents the wavelengths of the left shoulder, right shoulder, and lowest point of the absorption band at a wavelength of 2000 nm in the reflection spectrum. l R r and R est These represent the reflectance of the left shoulder, right shoulder, and lowest point of the absorption band at a wavelength of 2000 nm in the reflectance spectrum, respectively. (3) Determine the conversion relationship between elemental iron content and absorption depth. Plot the relationship between the elemental iron content in the sample and the absorption depth of the absorption band of the sample's reflectance spectrum at 2000 nm wavelength as the x-axis. Then, fit the formula to obtain the conversion relationship between the elemental iron content in the sample and the absorption depth of the absorption band of the sample's reflectance spectrum at 2000 nm wavelength. (4) Test the elemental iron content in lunar soil samples The reflectance spectrum of the lunar soil sample was collected. Based on the reflectance spectrum of the collected lunar soil sample, the absorption depth of the absorption band at a wavelength of 2000 nm of the reflectance spectrum of the lunar soil sample was calculated by Equation (III). Based on the absorption depth of the absorption band of the lunar soil sample at a wavelength of 2000 nm, the content of elemental iron in the lunar soil sample is calculated using the conversion formula between the content of elemental iron in the sample determined in step (3) and the absorption depth of the absorption band of the sample's reflection spectrum at a wavelength of 2000 nm. When collecting the reflectance spectra of each standard sample and lunar soil sample, the reflectance spectra of each standard sample and lunar soil sample were collected in the 400-2150 nm wavelength range.

2. The method for determining the content of elemental metallic iron in lunar soil based on the absorption depth of reflectance spectroscopy according to claim 1, characterized in that, The method for preparing a series of simulated lunar soil samples with different contents of elemental metallic iron in step (1) is as follows: ① Weigh out graphite and simulated lunar soil and put them into a crucible. Place the crucible in a high-temperature atmosphere furnace and heat the furnace to 1550-1600℃ under vacuum conditions. Hold the temperature for 3-4 hours. Remove the crucible and quench it to cool. This will give you a glassy sample containing elemental iron. ② The glassy sample containing elemental iron is crushed and then magnetically separated using a magnetic separator to obtain magnetic and non-magnetic samples. ③ The total iron content of the magnetic sample was determined by inductively coupled plasma optical emission spectrometry, and the proportion of elemental metallic iron in the magnetic sample was determined by iron Mössbauer spectroscopy. The mass percentage of elemental metallic iron in the magnetic sample was then calculated. ④ Mix magnetic and non-magnetic samples of different mass ratios evenly to obtain a series of simulated lunar soil samples with different contents of elemental metallic iron.

3. The method for determining the content of elemental metallic iron in lunar soil based on the absorption depth of reflectance spectroscopy according to claim 2, characterized in that, The simulated lunar soil is simulated lunar soil CLRS-2.

4. The method for determining the content of elemental metallic iron in lunar soil based on the absorption depth of reflectance spectroscopy according to any one of claims 1 to 3, characterized in that, When collecting the reflectance spectra of each standard sample and lunar soil sample, the reflectance spectra of each standard sample and lunar soil sample were collected at least three times. The average value of the reflectance spectral signals of each standard sample and the average value of the reflectance spectral signals of each lunar soil sample were used as the absorption depth of the absorption band at a wavelength of 2000 nm for calculating the reflectance spectra of each standard sample and lunar soil sample.

5. The method for determining the content of elemental metallic iron in lunar soil based on the absorption depth of reflectance spectroscopy according to any one of claims 1 to 3, characterized in that, In step (3), after plotting the relationship between the content of elemental iron in each standard sample and the absorption depth of the absorption band of the reflection spectrum of each standard sample at a wavelength of 2000 nm, the conversion relationship between the content of elemental iron in the sample and the absorption depth of the absorption band of the reflection spectrum of the sample at a wavelength of 2000 nm is obtained by quadratic fitting.

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