The Extreme Ultraviolet Camera （EUVC） onboard the Chang＇e-3 （CE-3） lander is used to observe the structure and dynamics of Earth＇s plasmasphere from the Moon. By detecting the resonance line emission of helium i...The Extreme Ultraviolet Camera （EUVC） onboard the Chang＇e-3 （CE-3） lander is used to observe the structure and dynamics of Earth＇s plasmasphere from the Moon. By detecting the resonance line emission of helium ions （He＋） at 30.4 nm, the EUVC images the entire plasmasphere with a time resolution of 10 min and a spatial resolution of about 0.1 Earth radius （RE） in a single frame. We first present details about the data processing from EUVC and the data acquisition in the commissioning phase, and then report some initial results, which reflect the basic features of the plas- masphere well. The photon count and emission intensity of EUVC are consistent with previous observations and models, which indicate that the EUVC works normally and can provide high quality data for future studies.展开更多
The dual-wavelength extreme ultraviolet camera(EUC)onboard the Queqiao-2 relay satellite of the Chang'E-7(CE-7)mission will be used to investigate the global structure and dynamics of the Earth's magnetosheath...The dual-wavelength extreme ultraviolet camera(EUC)onboard the Queqiao-2 relay satellite of the Chang'E-7(CE-7)mission will be used to investigate the global structure and dynamics of the Earth's magnetosheath and plasmasphere by simultaneously capturing emissions at 30.4 and 83.4 nm.In geospace,there are two emission sources at 30.4 nm:resonantly scattered emissions from plasmaspheric He+ions and solar wind charge-exchange in the Earth's magnetosheath.The sources of 83.4 nm emission include the ionospheric outflow O+and the plasmaspheric O+ions,both of which resonantly scatter sunlight at this wavelength.Global images at these wavelengths will enhance understanding of mass and energy transportation in solar wind-magnetosphere-ionosphere couplings,crucial for comprehending space weather.The Moon is an ideal platform for global imaging,allowing the EUC's two optical heads operating at 30.4 and 83.4 nm,each with a circular field of view of 20°to capture spatial resolution of~0.1REfor the plasmasphere,~0.3R_(E)for the magnetosheath,and~0.3R_(E)for the ionospheric outflow in the meridian plane perpendicular to the Earth-Moon line.The sensitivities are as follows:0.1 counts s-1Rayleigh-1at 30.4 nm channel for an angular resolution of 0.1°and 0.07 counts s-1Rayleigh-1at 83.4 nm channel for an angular resolution of 0.3°.Sufficient sensitivity was achieved to obtain plasmaspheric images every 10 min,magnetosheath images every 10–20 min,and ionospheric outflow images every 10 min.All of the original photon signals are transmitted to the ground,allowing for flexible processing of spatial and temporal resolutions.展开更多
The dual-wavelength extreme ultraviolet camera(EUC)for the Queqiao-2 relay satellite of the Chang’E-7(CE-7)mission operates at 30.4 and 83.4 nm independently to simultaneously image the plasmasphere,magnetosheath,and...The dual-wavelength extreme ultraviolet camera(EUC)for the Queqiao-2 relay satellite of the Chang’E-7(CE-7)mission operates at 30.4 and 83.4 nm independently to simultaneously image the plasmasphere,magnetosheath,and ionospheric outflow from a lunar orbit.Each channel of the EUC is consisted of a concave multilayer mirror and a photoncounting imaging detector.This simple system achieves a large field of view(FOV),high spatial resolution,and optimized photon transmission efficiency to capture high-quality images of very weak extreme ultraviolet emissions in Earth space.Here we present the detailed design,tests,and calibrations of the EUC.Ground geometrical tests showed that the FOV was 20.2°for the 30.4 nm channel and 20.3°for the 83.4 nm channel,and the spatial resolution was 0.09°for both channels.Geometric distortion was corrected to be less than 1%.Pixels can be further binned on the ground to achieve higher sensitivity.Radiometric calibration results demonstrate that the sensitivity is 0.103 counts s^(-1)Rayleigh^(-1)pixel^(-1)at 30.4 nm channel and 0.061 counts s^(-1)Rayleigh^(-1)pixel^(-1)at 83.4 nm channel,with a calibration accuracy of~12%.The exposure can be flexibly set between 1–1500 s,with a longer exposure time achievable through time-delay integration during ground processing.The performance of the EUC fulfills the requirements of the scientific targets for the CE-7 mission and could significantly contribute to investigations of the solar wind-magnetosphere-ionosphere coupling system.展开更多
文摘The Extreme Ultraviolet Camera （EUVC） onboard the Chang＇e-3 （CE-3） lander is used to observe the structure and dynamics of Earth＇s plasmasphere from the Moon. By detecting the resonance line emission of helium ions （He＋） at 30.4 nm, the EUVC images the entire plasmasphere with a time resolution of 10 min and a spatial resolution of about 0.1 Earth radius （RE） in a single frame. We first present details about the data processing from EUVC and the data acquisition in the commissioning phase, and then report some initial results, which reflect the basic features of the plas- masphere well. The photon count and emission intensity of EUVC are consistent with previous observations and models, which indicate that the EUVC works normally and can provide high quality data for future studies.
基金supported by the National Natural Science Foundation of China(Grant Nos.42222408 and 41931073)the National Key Research and Development Program of China(Grant No.2021YFA0718600)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.Y2021027)。
文摘The dual-wavelength extreme ultraviolet camera(EUC)onboard the Queqiao-2 relay satellite of the Chang'E-7(CE-7)mission will be used to investigate the global structure and dynamics of the Earth's magnetosheath and plasmasphere by simultaneously capturing emissions at 30.4 and 83.4 nm.In geospace,there are two emission sources at 30.4 nm:resonantly scattered emissions from plasmaspheric He+ions and solar wind charge-exchange in the Earth's magnetosheath.The sources of 83.4 nm emission include the ionospheric outflow O+and the plasmaspheric O+ions,both of which resonantly scatter sunlight at this wavelength.Global images at these wavelengths will enhance understanding of mass and energy transportation in solar wind-magnetosphere-ionosphere couplings,crucial for comprehending space weather.The Moon is an ideal platform for global imaging,allowing the EUC's two optical heads operating at 30.4 and 83.4 nm,each with a circular field of view of 20°to capture spatial resolution of~0.1REfor the plasmasphere,~0.3R_(E)for the magnetosheath,and~0.3R_(E)for the ionospheric outflow in the meridian plane perpendicular to the Earth-Moon line.The sensitivities are as follows:0.1 counts s-1Rayleigh-1at 30.4 nm channel for an angular resolution of 0.1°and 0.07 counts s-1Rayleigh-1at 83.4 nm channel for an angular resolution of 0.3°.Sufficient sensitivity was achieved to obtain plasmaspheric images every 10 min,magnetosheath images every 10–20 min,and ionospheric outflow images every 10 min.All of the original photon signals are transmitted to the ground,allowing for flexible processing of spatial and temporal resolutions.
基金supported by the Chinese Lunar Exploration Projectsupported by the National Natural Science Foundation of China(Grant Nos.42222408&42441809)+1 种基金the National Key Research and Development Program of China(Grant No.2021YFA0718600)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.Y2021027)。
文摘The dual-wavelength extreme ultraviolet camera(EUC)for the Queqiao-2 relay satellite of the Chang’E-7(CE-7)mission operates at 30.4 and 83.4 nm independently to simultaneously image the plasmasphere,magnetosheath,and ionospheric outflow from a lunar orbit.Each channel of the EUC is consisted of a concave multilayer mirror and a photoncounting imaging detector.This simple system achieves a large field of view(FOV),high spatial resolution,and optimized photon transmission efficiency to capture high-quality images of very weak extreme ultraviolet emissions in Earth space.Here we present the detailed design,tests,and calibrations of the EUC.Ground geometrical tests showed that the FOV was 20.2°for the 30.4 nm channel and 20.3°for the 83.4 nm channel,and the spatial resolution was 0.09°for both channels.Geometric distortion was corrected to be less than 1%.Pixels can be further binned on the ground to achieve higher sensitivity.Radiometric calibration results demonstrate that the sensitivity is 0.103 counts s^(-1)Rayleigh^(-1)pixel^(-1)at 30.4 nm channel and 0.061 counts s^(-1)Rayleigh^(-1)pixel^(-1)at 83.4 nm channel,with a calibration accuracy of~12%.The exposure can be flexibly set between 1–1500 s,with a longer exposure time achievable through time-delay integration during ground processing.The performance of the EUC fulfills the requirements of the scientific targets for the CE-7 mission and could significantly contribute to investigations of the solar wind-magnetosphere-ionosphere coupling system.
