The geometric characteristics of Moon-based Earth observation platforms differ significantly from those of satellite platforms, with geolocation being a key factor that impacts data quality. The geolocation of a Moon-based sensor is influenced by three key factors: lunar ephemeris (lunar position and libration), Earth orientation parameters (EOPs), and the Earth reference model. Measurement errors from these three sources can significantly affect the geolocation accuracy of a Moon-based sensor. This study proposes a new unbiased estimation method to quantify the geolocation uncertainty introduced by these factors, based on the fusion of multiversion datasets. The method avoids making assumptions about the error distribution of ephemeris parameters while providing an effective approximation of the spatiotemporal patterns of geolocation uncertainty. We integrate three types of ephemeris data, three Earth reference models, and multiple EOPs datasets to assess the overall distribution of geolocation uncertainty and separately evaluate the geolocation uncertainty introduced by each individual factor using control variates method. The results indicate that the maximum total geolocation uncertainty caused by the three factors is about 46 m. Ephemeris errors are the dominant contributor, accounting for more than 98% of the total uncertainty. In addition, measurement errors in lunar libration also account for why longitudinal uncertainty is significantly greater than latitudinal uncertainty.

A Moon-based sensor offers a unique view for continuous Earth observation. The 2-D turntable’s pointing performance is a critical factor influencing geolocation accuracy. The vast distance between the Earth and the Moon amplifies minor pointing errors of the turntable into significant geolocation inaccuracy. By establishing a geometric model, an analytic expression of Earth’s trajectory from the Moon-based view is derived. Three critical issues are discussed: 1) the Earth’s 18.6-year trajectory forms a$16^{\circ } \times 14^{\circ }$envelope, which determines the observation range for the sensor. The rotation angle and position of the envelope vary at different lunar locations, while its size and shape remain consistent; 2) geolocation errors caused by temporal interval vary periodically with a half-sidereal month cycle and can be compensated by calculating Earth’s velocity, while errors due to the step angle show irregular oscillations. Without calibration, both parameters can introduce geolocation errors on the scale of hundreds of kilometers. Reducing both parameters can significantly improve geolocation accuracy; and 3) even with optimization of both parameters, the geolocation accuracy cannot be reduced to within a single pixel. To achieve geolocation accuracy within design requirements, it is necessary to not only optimize these two factors but also adopt additional measures to improve precision. All these insights will inform the parameter optimization and design of the Moon-based sensor for future applications.

Deploying Moon-based sensors at the lunar south polar regions offers unprecedented opportunities for continuous Earth observation. However, previous studies have neglected the combined effects of lunar terrain and latitudinal libration on Earth visibility. This study systematically evaluates the Earth visibility conditions in the lunar south polar regions (80°S–90°S) using high-resolution Lunar Orbiter Laser Altimeter (LOLA) data and a novel visibility algorithm. Results reveal that terrain obstruction reduces Earth visibility by up to 80% in crater-rim and high-latitude regions, rendering the spherical Moon approximation inaccurate for these areas. A 14° maximum elevation angle threshold is identified for complete Earth visibility at lunar south polar regions. Optimal sites cluster near the lunar central meridian (0° longitude) in low latitudes (80°S–82.5°S), balancing extreme observation geometry and terrain occlusion effects. High-visibility areas (≥95%) are fragmented into small patches (82.5°S). This letter has quantitatively characterized the impact of lunar terrain on Moon-based Earth observations, offering guidance for future Moon-based Earth observation sensor deployment and lunar base planning.

Nighttime light (NTL) remote sensing data has been widely used in various fields, such as human activity analysis, urbanization studies, and economic evaluation. However, Earth’s nighttime environment is very complex so that the NTL images are seriously affected by atmospheric effect and moonlight. This complexity primarily stems from the numerous atmospheric scattering and absorption, as well as the incoming moonlight, which can significantly distort and contaminate nighttime light observed by the satellite and consequently reduce the precision and stability of NTL data. In order to improve the quantitatively quality of the NTL data, this paper proposes an innovative atmospheric correction algorithm that leverages the nighttime radiative transfer model (nRTM) considering both atmospheric effect and moonlight effect to get ground radiance of artificial lights from satellite nighttime light images. This model takes into account the complex interactions between light and the atmosphere. By simulating these processes, the algorithm is able to separate the contributions of atmospheric scattering and absorption from the original NTL images. To demonstrate the effectiveness of the proposed algorithm, this paper takes the SDGSAT-1 NTL image of Beijing as a representative case study of atmospheric correction. By comparing the corrected and uncorrected images, it is evident that the atmospheric correction significantly improves the quality of the NTL data and the ground nighttime lighting information becomes clearer and more accurate, effectively removing noise interference and enhancing data reliability. Moreover, it also found that the high-pressure sodium (HPS) lamps and LED lamps in the NTL images presented different radiance values and spectral shapes that can be helpful for classifying different lamps.

Night-time light remote sensing has been widely used in various fields, including human activity analysis, urbanization studies, and economic research. However, Earth’s nighttime environment is very complex so that nighttime light images are seriously affected by atmospheric elements and moonlight. To address this issue, this paper proposed an atmospheric correction algorithm on basis of a newly developed radiative transfer model (RTM) that aims to derive the ground radiance of artificial lights from satellite nighttime light images. The SDGSAT-1 night-time light image of Beijing is used as a case study to demonstrate the effectiveness of the proposed algorithm. Results show that the new algorithm can effectively removes the atmospheric effects and improves the data quality of nighttime light images.

The Earth’s outgoing radiation (EOR) at the top of atmosphere (TOA) is an advantageous goal of Moon-based Earth observations. In this study, we focused on the Earth’s reflected radiation (ERR), which is a component of EOR and has a strong relationship with the Earth–Moon–Sun positions. To determine ERR characteristics, we parameterized the Moon-based Earth observation geometry and proposed a method to simulate the ERR at TOA for a Moon-based sensor under clear- and all-sky conditions. The ERR was found to have the distinct cycle of a synodic month and was inversely proportional to the Earth’s phase angle. Clouds increased ERR reflected to space under hemispheric-scale observation; thus, ERR under all-sky conditions was approximately twice as much as that under clear-sky conditions. The ERR was also influenced by incoming solar radiation (ISR), and the removal of the effect of ISR on ERR helped reveal ERR characteristics clearly. The results showed that when the Earth’s phase angle was between 0° and 90°, particularly when the Earth’s phase angle was in the range of 30°–60° and 60°–90° under all- and clear-sky conditions, respectively, the ERR–ISR ratio could indicate the reflective characteristics of the Earth under hemisphere-scale observations. These results will be helpful in demonstrating Moon-based ERR monitoring.

The variation of pointing vector direction for Moon-based Earth observations are analyzed in this paper. The pointing vector direction is parameterized as two angles, namely azimuth and elevation angle. We first establish the observation geometry model to calculate the pointing vector in Moon-centered Moon-fixed (MCMF) coordinate system. Then, the azimuth and elevation angles are defined and their theoretical expressions are deduced respectively. Besides, different observation periods are considered. It is found that the pointing vector direction shows regular variations over one orbital period and 18.6 years. The combination of azimuth and elevation angles can characterize variations of pointing vector direction. They mainly depend on the lunar sub- Earth points. The elevation angle ranges from 83 ° to 97° and the azimuth angle varies from −8° to 8° in an 18.6-year period. These characteristics will give valuable guidance for application of Moon-based platform.

The Moon-based telescope with visible and near-infrared band is equipped on the lunar surface which is 360000 kilometers away from the Earth, and is expected to provide a unique observational data set for the Earth. In this paper, we first proposed an ideal telescope optical system of the Moon-based telescope, then preliminarily designed the stray light suppression structures including the outer baffle and the inner baffle. Further, the geometric model and properties of the telescope structure are established, and the stray light of the Moon-based telescope with visible and near-infrared band is simulated and analyzed by ZEMAX software. The results show that the when the off-axis angle is$4^{\circ}$, the Point Source Transmittance (PST) magnitude is 10−4; when the off-axis angle is more than$20^{\circ}$, the PST is 0. It can be seen that the baffle used in this paper can meet the requirements.

The outgoing longwave radiation (OLR) at the top of the atmosphere is a key component of Earth’s radiation budget. Moon-based OLR observations take Earth as a single point, and provide an alternative to near-Earth orbital measurements. However, in the sensitivity design of a sensor, the effects of adopted Earth’s shape on the design of the sensitivity are particularly severe in the Moon-based OLR observations, which needs to be fully considered. In this study, the observational solid angle related to the ellipsoidal Earth model during OLR measurements was analyzed to improve upon previous studies conducted under the assumption of a spherical Earth. The radiative equilibrium temperature of the Earth–atmosphere system was then applied to simulate the emitted OLR according to Stephen Boltzmann’s law. The magnitude and sensitivity of the Moon-based OLR measurements were estimated by combining the observational solid angle and the simulated OLR. The results showed that the sensitivity of Moon-based OLR measurements is on the order of$10^{-3}$W m−2K−1, and the effects of Earth’s shape on sensitivity estimates cannot be ignored. Further, quantitative estimates revealed that a more realistic (ellipsoid) shape is needed when designing the sensitivity of relevant sensors.

The Moon-based platform has different observation angular characteristics from artificial satellites due to its peculiar orbit. To illustrate the difference, we first normalize the positions and attitudes of the Sun, Earth, and Moon into the same reference system using coordinate transformations. Then, we calculate the observation angles (including viewing elevation angel, solar elevation angel and relative azimuth angle) distribution of satellites in LEO, GEO and at Lagrange L1 satellites during the same period. Furthermore, the observation angles distribution of the Moon-based platform in different seasons with the Earth observed point located at different positions are analyzed. Results revealed that compared to artificial satellites, the Moon-based platform has continuous viewing observation angles and solar observation angles. Its observation angles change with the seasons, and it provides more angular information for equatorial regions than polar regions of the Earth.

Although estimating the Earth radiation budget (ERB) by satellite platforms have become more and more reliable, it is still difficult to carry out conclusive evidence that supports whether the Earth is warming. As the important component of ERB, the measurement requirements of Earth's outgoing radiation are to acquire global-scale absolute calibration data. Observing Earth's outgoing radiation on the lunar surface is a feasible way to improve the consistency and continuity of such data. Since the Moon is a celestial body and the sensor can be equipped anywhere on the near-side of the Moon, the site selection issue of a Moon-based platform will be the most vital step. This paper mainly discusses the site selection issue of a Moon-based Earth radiation budget experiment platform from the perspective of Earth observation geometry. By analyzing observation performance, geolocation accuracy, radiation response and solar invasion effects, we suggest that the mid-high latitude will be a better position to equip sensors.

Moon-based platform is a potential platform that can realize the observations of large-scale geoscience phenomenon. Unlike existing earth observation platforms, the moon-based platform is equipped on a natural celestial body. Its position is calculated by the lunar position and libration derived from the planetary ephemeris. However, limited to the astrometric model and accuracy of observational data, no planetary ephemeris can provide absolutely accurate data, and this will lead to a platform's position error. This letter investigates the impacts of the platform's position error on geolocation for a moon-based sensor. We first made comparisons to the lunar position and libration derived from different planetary ephemerides so as to evaluate the magnitude of the platform's position error. Then, the Monte Carlo method was applied to simulate the platform's position error. According to the geometric model, the effects of the platform's position error on geolocation were presented. The results showed the effects of lunar libration error are associated with position on the lunar surface, while the differences of lunar position error effects are not evidently shown in different positions on the lunar surface. Furthermore, high-latitude regions of the moon are demonstrated to have less impact on the platform's position error, which would be suitable for equipping earth observation sensors.

To deepen the understanding of the Moon-based Earth observations, we establish a new kind of expression of the observation angle. Considering the Earth as a single point, the relative azimuth angle and viewing zenith angle of a Moon-based platform are defined. We first summarize the general procedures of the geometrical model. Based on the geometrical model, the positions of the Sun, the Earth, and the Moon can be acquired. Then, the new expressions of the observation angles are defined in the International Terrestrial Reference System (ITRS). The relative azimuth angle is related to the solar direction, while the viewing zenith angle describes the relationship between the lunar position and the Earth Equator. Results revealed the characteristics of the viewing zenith angle and relative azimuth angle, demonstrating the features of Moon-based Earth observations.

We simulate to perform Earth radiation budget on the lunar surface. This simulation is to support the study of the Earth radiation budget from a new observation strategy. There are two instruments deployed on the lunar surface for monitoring the Earth outgoing radiation and detecting changes at global scale. As opposed to small instantaneous spatial coverage of the space-borne instruments, the instruments equipped on the lunar surface will have the observational scope of whole Moon-facing hemisphere to allow for a better quantification of the Earth outgoing radiation on the planetary scale. In this paper, we make simulations of equipping multispectral camera and active cavity radiometer on the lunar surface and analyze the characteristics of the Earth outgoing radiation acquired by the Moon-based platform.

More and more attention has been paid to taking the Earth as a whole for researching. Though space-borne and airborne platform have acquired various data from the Earth, the existing Earth observation system lack the ability of long-term continuous observation at a global scale. Three-polar regions include the Arctic, Antarctic and Tibet Plateau, which characterized by its large scale and need long-term observation. This will need large-scale, constant and long-term dynamic Earth observation system. Here we established a new platform, Moon-based Earth observation platform, which focuses on the observation of global scale scientific phenomena, turning out to be an ideal platform to study Three-polar regions environment comparison research. In this paper, we propose the Moon-based observation platform, and discuss the system parameters performance briefly and next focus on the potential applications of Three-polar regions.

Although the precision of the surface parameters calculated from satellite data gets higher and higher, it is still difficult to guarantee the temporal consistency and spatial continuity for large scale geoscience phenomena. Developing new earth observation platforms is a feasible way to improve the consistency and the continuity. As the only natural satellite of the Earth, the Moon has special advantages as a platform for earth observation. This paper mainly discusses the advantages and the potential applications of moon-based earth observation, as well as the train of thoughts of further researches.

It's a new concept to set up sensors on the Moon to observe the large-scale Earth science phenomena. In order to reveal its potentials and characteristics, this paper focuses on the simulative moon-based Earth observation which makes use of the Jet Propulsion Laboratory (JPL) ephemeris and transformations of relative reference frames. By simulating the observation scenes at different time, we analyze the observation conditions, including observation time series, geometry and effective coverage. The result shows that the moon-based Earth observation has advantages in wide swath, continuous observation and large effective coverage which contributes to the monitoring and understanding of large-scale Earth science phenomena.

Global change refers to changes in earth system function at a global scale including atmospheric and ocean circulation, hydrologic and biogeochemical cycles, and changes in resource, land use and others. Global change is characterized by its large scale and needing long-term observation. Moon is an ideal platform for observing global change. In order to reveal its potentials for observing of global change sensitive regions, this paper focuses on the coverage analysis of moon-based earth observation which makes use of the JPL ephemeris and generates observation Boolean matrixes of global change sensitive regions. The result shows that the moon based earth observation has advantages in wide swath, continuous observation and large effective coverage which contribute to the monitoring and understanding of global change.