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The Moon-based Earth observation geometry. The mean Earth-Moon distance is about 384,405 km. The inclination of obliquity to ecliptic is 23.5?, while the value of lunar orbit to ecliptic is 5.15?.
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The Moon is a potential new platform for Earth observation. The advantages of its large-scale observational scope, long temporal duration, and multi-layer detecting of the Earth will undoubtedly advance our understanding of the Earth system. To carry out the observations from a Moon-based optical sensor, the geolocation error caused by exterior ori...
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... Moon-based Earth observation geometry is shown in Figure 2. Different from satellite platforms, the Moon-based Earth observation geometry has its peculiarities. ...
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... Earth-Moon angle is the major factor and different Earth-Moon angle leads to different variation of the image offsets. The MAE variations caused by angular errors are given in Figure 12. Similar to the analysis of the position error, we compare two cases. ...
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... to the analysis of the position error, we compare two cases. Figure 12 depicts the variation of the MAE caused by the angu- lar elements. From Figure 12(a,b), equipping sensors at the origin of the lunar disc will result in smal- ler offsets in x-axis direction and there is no offset in the y-axis direction. ...
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... 12 depicts the variation of the MAE caused by the angu- lar elements. From Figure 12(a,b), equipping sensors at the origin of the lunar disc will result in smal- ler offsets in x-axis direction and there is no offset in the y-axis direction. The reason is the Earth is always around the zenith of the sensor, the azimuth angle varies from 0° to 360°, while the azimuth angle range is only 2° at the high latitude of the Moon. ...
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... the same azimuth angular error, if the angular variation range is smaller, the effect of the error will be larger. For the elevation angular error, the offsets of both x-axis and y-axis remain the same, which is not significant influenced by the observation distance and Earth-Moon angle (Figure 12(c,d)). ...
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... resolution is considered as one of the most significant parameters for the optical sensor, which describes the ability to distinguish the objects. For a Moon-based optical sensor, the relation- ship between the spatial resolution and geolocation error is an important issue that has never been Figure 12. Comparison of the geolocation error caused by the angular errors between the 0° and 60°N cases during one orbital period. ...
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... for the case of equipping sensors near the centre of the lunar disc, the angular errors of the Moon-based sensor also show the systematic feature. Just because of this feature, the MAE is representative for the measurements of the offsets both in x-axis and y-axis of the image during one orbital period (Figures 11 and 12). Analysing the MAE variation, our results indicate that equipping sensors near the centre of the lunar disc have complex variation of the geolocation error. ...
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Citations
... Although research outcomes related to the observational geometry of Earth-Moon space that considered the phase angle have been published, they have predominantly focused on lunar-based observations [23,24]. Therefore, there is a need to develop a comprehensive observational geometry model specifically designed for Earth-Moon space, incorporating high-precision phase angle parameters. ...
As a radiant light source within the dynamic range of most spacecraft payloads, the Moon provides an excellent reference for on-orbit radiometric calibration. This research hinges on the precise simulation of lunar spectral irradiances and Earth-based Moon observation geometry. The paper leverages the Hapke model to simulate the temporal changes in lunar spectral irradiances, utilizing datasets obtained from the Lunar Reconnaissance Orbiter Camera (LROC). The research also details the transformation process from the lunar geographic coordinate system to the instantaneous projection coordinate system, thereby delineating the necessary observational geometry. The insights offered by this study have the potential to enhance future in-orbit spacecraft calibration procedures, thereby boosting the fidelity of data gathered from satellite observations.
... Moreover, because the lunar surface has a large load capacity, various types of equipment can be placed to collect various types of data. In addition, compared to the current satellite-based platforms, the advantages of Moonbased platform also have been summarized and clarified in existing literature (Huang, 2008;Guo et al., 2018Guo et al., , 2020Ye et al., 2018aYe et al., , 2018bYe et al., , 2019. ...
As a platform for longer-term continuous moon-based earth radiation observation (MERO) which includes reflected solar short-wave (SW) radiation and long-wave infrared (LW) radiation, the huge lunar surface space can provide multiple location choices. It is important to analyze the influence of lunar surface position on irradiance which is the aim of the present work based on a radiation heat transfer model. To compare the differences caused by positions, the site of 0°E 0°N was selected as the reference site and a good agreement of the calculation results was verified by the comparison with the NISTAR’s actual detected data. By analyzing the spatial characteristics of the irradiance, the results showed that the irradiance on the lunar surface was of circular distribution and the instrument that was placed in the region of 65°W–65°E and 65°S–65°N could detect the irradiance most effectively. The relative deviation between the reference site and the marginal area (region of > 65°S or 65°N or > 65°W or 65°E) was less than 0.9 mW·m−2 and the small regional differences make a small-scale network conducive to radiometric calibration between instruments. To achieve accurate measurement of the irradiance, the sensitivity design goal of the MERO instrument should be better than 1 mW·m−2 in a future actual design. Because the lunar polar region is the priority region for future exploration, the irradiance at the poles has also been analyzed. The results show that the irradiance changes periodically and exhibits complementary characteristics of time. The variation range of irradiance for short-wave radiation is greater than long-wave radiation and the irradiance of SW reaches the maximum at different times. The MERO at the polar region will provide valuable practical experiment for the follow-up study of the moon-based earth observation in low latitudes.
... Through numerous experiments and a series of simulation images, it was proved that the lunar observatory had continuous observation characteristics and wide swath. Guo et al. [8] presented a geometric image model and evaluated the influence of the exterior orientation elements on the geolocation errors of an optical sensor. Yuan and Liao [9] analyzed in detail four influence factors on Moon-based microwave radiation imaging, including the time zone correction, relative movement of the Earth-Moon, atmospheric radiative transfer effect, and ionosphere effect. ...
... As the wavelength increases beyond 10 μm, the radiant energy shows a decreasing trend. In formulas (7) and (8), is the radiance at the entrance pupil of the Moon-based Earth observation platform (Figure 7), E is the irradiance of the focal plane of the thermal infrared sensor, and the DN of formula (8) is the final image of the thermal infrared sensor from the Moon-based Earth observation platform. First, Figure 7 is used to calculate the irradiance of the focal plane of the thermal infrared sensor for the Moonbased Earth observation platform by formula (7). ...
As a unique natural satellite of the Earth, the Moon has always attracted much attention, and one subject of interest is the establishment of an Earth observation platform on the Moon. Compared with the existing spaceborne and airborne observation platforms, a Moon-based Earth observation platform would have the unique advantage of the ability to obtain global and large-scale observation data. At present, the study on Moon-based Earth observations is in theory, so it is necessary to use simulation methods to understand the observation performance of a Moon-based Earth observation platform. In this study, a method for Moon-based Earth observation imaging simulation in the thermal infrared band is developed to study the Moon-based thermal infrared imaging process. The method comprises three parts, including the estimation of Moon-based imaging coverage, the acquisition of the radiation intensity at the entrance pupil, and the simulated image output from the Moon-based thermal infrared sensor. Then, the simulated results are validated with the existing spaceborne observation data. Results show that the absolute error of Moon-based thermal infrared simulations is between 1.3-5.7 K, the RMSE is between 1.38 - 3.12 K, and the relative error is between 0.44% - 2.12%, indicating that the thermal infrared imaging model can more realistically simulate the true conditions of ground surface and that a Moon-based Earth observation platform could observe the Earth in the thermal infrared band.
... Ye et al. [20] analyzed the pointing error of line-of-sight vector. Guo et al. [21] revealed the relationship between the geolocation error and exterior orientation elements' error, giving guidance to spatial resolution selection. ...
... Another important feature is the changing orbital inclination, leading to the changing observation angle for the certain position on Earth. Maximum orbital inclination relative to the Earth Equator varies between 28° and -28° during every 18.6 years, while the minimum ranges from 18° to -18° about 9.3 years later [21]. Such orbital inclination is enough to cover the total Arctic or Antarctic region during one orbital period. ...
The effects of temporal sampling interval on the Moon-based Earth observation geometry is analyzed in this study based on three observation angles, namely viewing zenith angle, solar zenith angle, and relative azimuth angle. According to the definitions of these three angles, the calculation method for these angles and their variations between adjacent temporal samplings are deduced. Further, the effects of the different positions of the lunar surface on the observation angles are derived. The results show that the variations of the nadir point and subsolar point determine the variations of the viewing zenith angle and solar zenith angle respectively, while the relative azimuth angle needs to consider the relative variations of the Moon-based platforms nadir point and the subsolar point. By evaluating the variations of these three observation angles, it is found that the effects of the temporal sampling interval will have significant impacts on the relative azimuth angle of the observed points at mid-low latitude regions, especially near the regions of the Moon-based platforms nadir point and the subsolar point. In conclusion, the observation angles can characterize the Moon-based Earth observation geometry, and enlarging the temporal sampling interval will lead to the obvious impacts on the observation geometry in the mid-low latitude regions, especially the loss of the sampling of the relative azimuth angle.
... During 2016-2019, Ye and Guo established an improved geometric model and analyzed the coverage performance and observation duration of the Moon-based platform. Furthermore, they investigated the variation regularity of the looking vector direction and the relationship with the sensor's position, and later on proposed an ideal location for the Moon-based platform [10,[38][39][40][41][42]. The result shows that Moon-based observations have large spatial coverage advantages in the study of three-polar regions and latitude between 30 • N-80 • N or 30 • S-80 • S are the ideal locations for the Moon-based Earth observation platform [10,40]. ...
... This fluctuation showed a change period of 18.6 years, which was consistent with the fluctuation frequency of the nadir points of the Moon. This is because every 18.6 years, the angle between the orbit of the Moon plane and the Earth equator plane reaches a maximum of 28.65 • [38]. The detail of the annual coverage time range for different latitudes is shown in Figure 8. ...
The Antarctic and Arctic have always been critical areas of earth science research and are sensitive to global climate change. Global climate change exhibits diversity characteristics on both temporal and spatial scales. Since the Moon-based earth observation platform could provide large-scale, multi-angle, and long-term measurements complementary to the satellite-based Earth observation data, it is necessary to study the observation characteristics of this new platform. With deepening understanding of Moon-based observations, we have seen its good observation ability in the middle and low latitudes of the Earth’s surface, but for polar regions, we need to further study the observation characteristics of this platform. Based on the above objectives, we used the Moon-based Earth observation geometric model to quantify the geometric relationship between the Sun, Moon, and Earth. Assuming the sensor is at the center of the nearside of the Moon, the coverage characteristics of the earth feature points are counted. The observation intervals, access frequency, and the angle information of each point during 100 years were obtained, and the variation rule was analyzed. The research showed that the lunar platform could carry out ideal observations for the polar regions. For the North and South poles, a continuous observation duration of 14.5 days could be obtained, and as the latitude decreased, the duration time was reduced to less than one day at the latitude of 65° in each hemisphere. The dominant observation time of the North Pole is concentrated from mid-March to mid-September, and for the South Pole, it is the rest of the year, and as the latitude decreases, it extends outward from both sides. The annual coverage time and frequency will change with the relationship between the Moon and the Earth. This study also proves that the Moon-based observation has multi-angle observation advantages for the Arctic and the Antarctic areas, which can help better understand large-scale geoscientific phenomena. The above findings indicate that the Moon-based observation can be applied as a new type of remote sensing technology to the observation field of the Earth’s polar regions.
... The analysis of solar invasion effects on sensors at a Moon-based platform requires a theoretical model of the Moon-based Earth observation geometry. The theoretical geometric model presented in this paper is based on the model published by Ye et al. [13] and and Guo et al. [14]. In this section, the theoretical geometric model of a Moon-based platform is introduced briefly. ...
... According to the analysis of the line-of-sight condition to the Earth and pointing accuracy, the site selection issue of a Moon-based sensor have been discussed in References [13,14,26]. However, the site selection issue, considering the stray light of the sensor, was not mentioned. ...
The solar invasion to an Earth observation sensor will cause potential damage to the sensor and reduce the accuracy of the measurements. This paper investigates the effects of solar invasion on the Moon-based Earth observation sensors. Different from the space-borne platform, a Moon-based sensor can be equipped anywhere on the near-side of the Moon, and this makes it possible to reduce solar invasion effects by selecting suitable regions to equip sensors. In this paper, methods for calculating the duration of the Sun entering of the sensor’s field of view (FOV) and the solar invasion radiation at the entrance pupil of the sensor are proposed. By deducing the expressions of the proposed geometrical relationship between the Sun, Earth, and Moon-based platform, it has been found that the key parameter to the effects of solar invasion is the angle between the Sun direction and the line-of-sight vector. Based on this parameter, both the duration and radiation can be calculated. In addition, an evaluation approach based on the mean value and standard deviation has been established to compare the variation of solar invasion radiation at different positions on the lunar surface. The results show that the duration is almost the same wherever the sensor is placed in the permanent Earth-observation region. Further, by comparing the variation of solar invasion radiation at different positions on the near-side of the Moon, we suggest that equipping sensors on the mid–high latitude regions within the permanent Earth-observation region will result in less solar invasion affects.
A Moon‐based sensor can observe the Earth as a single point and achieve disk‐integrated measurements of outgoing longwave radiation (OLR), which significantly differs from low orbital, geostationary, and Sun–Earth L1 point platforms. In this study, a scheme of determining the disk‐integrated Earth’s OLR based on a Moon‐based platform is proposed. The observational solid angle was theoretically derived based on the Earth’s ellipsoid model and the disk‐integrated observational anisotropic factor was estimated to eliminate the effects of the Earth’s radiant anisotropy. The simulated disk‐integrated Earth's OLR obtained from a Moon‐based platform varies periodically, due to changes in the observation geometry and Earth's scene distribution within the observed Earth’s disk. Clouds, meteorological parameters, and the land cover distribution notably affect the disk‐integrated Earth’s OLR. By analyzing the disk‐integrated Earth’s OLR from a Moon‐based platform, significant variabilities were investigated. Additionally, the Earth’s shape and radiant anisotropy that affecting the disk‐integrated Earth’s OLR were estimated. In conclusion, a more realistic Earth’s shape, the latest version of the angular distribution model (ADM), and accurate land cover and meteorological datasets are needed when determining the disk‐integrated Earth’s OLR. It is expected the unique variability captured by this platform and its ability to complement traditional satellite data make it a valuable tool for studying Earth’s radiation budget and energy cycle, and contributing to diagnostic of the climate General Circulation Models (GCM) performance.
The imaging performance of the lunar-based synthetic aperture radar (LBSAR) is susceptible to the orbital perturbation effects. In particular, the perturbations of orbital inclination and right ascension of ascending node (RAAN) could give rise to the temporally varying orbit drift of LBSAR and further lead to Doppler errors in the radio signal. As a result, the LBSAR image performance might be influenced by such effects. This study comprehensively probes into the phase error induced by perturbations of orbital inclination and RAAN, and its effects on the LBSAR imaging performance are further explored. It is found that the LBSAR imaging performance in terms of focusing quality and geometric fidelity is affected by the perturbations of orbital inclination and RAAN, wherein the deterioration of focusing quality is closely associated with the synthetic aperture time. In this regard, the azimuth resolution on a decameter level is optimum for Earth observation of LBSAR with satisfactory image quality. Regarding the geometric fidelity, the accuracy requirement for the orbit determination of the LBSAR under perturbations of the orbital inclination and RAAN is proposed. The analysis results show that the LBSAR orbit determination in terms of the position and velocity determinations is most strenuous in the z-direction. Finally, point target responses are simulated to illustrate the preceding analysis.
Increasing attention is being paid to the monitoring of global change, and remote sensing is an important means for acquiring global observation data. Due to the limitations of the orbital altitude, technological level, observation platform stability and design life of artificial satellites, spaceborne Earth observation platforms cannot quickly obtain global data. The Moon-based Earth observation (MEO) platform has unique advantages, including a wide observation range, short revisit period, large viewing angle and spatial resolution; thus, it provides a new observation method for quickly obtaining global Earth observation data. At present, the MEO platform has not yet entered the actual development stage, and the relevant parameters of the microwave sensors have not been determined. In this work, to explore whether a microwave radiometer is suitable for the MEO platform, the land surface temperature (LST) distribution at different times is estimated and the design parameters of the Moon-based microwave radiometer (MBMR) are analyzed based on the LST retrieval. Results show that the antenna aperture size of a Moon-based microwave radiometer is suitable for 120 m, and the bands include 18.7, 23.8, 36.5 and 89.0 GHz, each with horizontal and vertical polarization. Moreover, the optimal value of other parameters, such as the half-power beam width, spatial resolution, integration time of the radiometer system, temperature sensitivity, scan angle and antenna pattern simulations are also determined.
The moon has always been a goal for humanity in history to reach and discover. Since the 1950s, many missions have been carried out in order to achieve this goal. Wireless sensor networks can be a good tool for discovering some of the features of the moon and acquiring very important information for the missions to the moon and beyond to be performed soon. The deployed seismic, monitoring, light, temperature, pressure, etc. types of sensors on the surface of the Moon can collect vital data for the missions. Therefore, in this paper, the wireless sensor deployment problem on the surface of the Moon is studied to maximize coverage. Since the deployment of sensors on 3-D terrain is an NP-hard problem, a hybrid memetic algorithm is developed to solve. The real 3-D digital elevation model of the surface of the Moon for two different terrains near the South Pole is used to test the performance of the proposed algorithm with 64 scenarios and the results are compared with local search and simulated annealing algorithms. According to the results, the proposed hybrid memetic algorithm has better coverage values than the others in acceptable CPU times.
