The first measurements of the radiation dose on the lunar surface are reported in preparation for human exploration of the Moon.

According to the characteristics of the LEO space particles radiation environment of China’s Fengyun No. 3 (FY-3) polar-orbiting meteorological satellites, in order to monitor the characteristics, and space–time distribution of charged particle radiation in the orbit space, it is proposed to install a three-directional high-energy particle detector (HEPD) in the three vertical orthogonal directions of FY-3E, so as to carry out the energy spectrum and flux observation of high-energy protons and electrons in the three directions of the satellite, namely, −X, +Y, and −Z. The on-orbit detection data acquired by these payloads can be used for space environment modeling and solar-terrestrial physics research, and provide data sources for operational space environment weather warning and forecasting. Through the ground accelerator calibration experiment and simulation analysis of the three-directional HEPDs developed in the flight model phase, the experimental results show that all the HEPDs’ measured values meet the requirements for technical indexes, such as the detection energy range (high-energy protons: 3–300 MeV; high-energy electrons: 0.15–5.7 MeV), energy span accuracy (<15%), flux accuracy (<15%), and sensitivity (<5% (ΔN/N)).

To conduct real-time monitoring of the particle radiation environment in the orbit of the Tiangong space station, the installation of an energy particle detector operating on the outside of Wentian laboratory cabin module is proposed. Monitoring the energy, flux, and direction of high-energy protons, electrons, heavy ions, and neutrons in orbital space, as well as the LET spectrum and radiation dose rate generated by them, provides an important basis for studying the mechanism of the space environment that causes harm to space stations and astronauts. It also provides the necessary space environment parameters for the scientific experiment instruments on the space station. During its ground development process, the detector was verified by various calibration methods such as standard radioactive sources, equivalent signal generators, and particle accelerators. The results show that the detector can realize discrimination of particle ingredients (electrons, protons, heavy ions, and neutrons). Meanwhile, the measurement indexes can also realize target requirements, namely, from lower limit of 20 keV for medium-energy electrons and protons to heavy ion GeV, 0.025 eV~100 MeV for neutrons, and 0.233~17,475 keV/μm for the LET spectrum and 0.1~1000 mGy/day for the dose rate produced. The measurement precisions of all indexes are better than approximately 16%.

Particle radiation on the Moon is influenced by a combination of galactic cosmic rays, high-energy solar particles, and secondary particles interacting on the lunar surface. When China’s Chang’e-7 lander lands at the Moon’s South Pole, it will encounter this complex radiation environment. Therefore, a payload detection technology was developed to comprehensively measure the energy spectrum, direction, and radiation effects of medium- and high-energy charged particles on the lunar surface. During the ground development phase, the payload performance was tested against the design specifications. The verification results indicate that the energy measurement ranges are 30 keV to 300 MeV for protons, 30 keV to 12 MeV for electrons, and 8 to 400 MeV/n for heavy ions. The energy resolution is 10.81% for 200 keV electrons of the system facing the lunar surface; the dose rate measurement sensitivity is 7.48 µrad(Si)/h; and the LET spectrum measurement range extends from 0.001 to 37.014 MeV/(mg/cm²). These comprehensive measurements are instrumental in establishing a lunar surface particle radiation model, enhancing the understanding of the lunar radiation environment, and supporting human lunar activities.

This article introduces the instrument design of the medium energy proton detector (energy range: 30 keV–5 MeV) mounted on the FY-3E satellite. Through the design and optimization of the sensor signal processing circuit, the anti-electromagnetic interference ability of the medium energy particle detector is greatly enhanced. The designed aluminum plating on sensors can effectively exclude the light pollution to the medium energy protons. The designed permanent annular magnet has a deflection efficiency of more than 95% for medium energy electrons below 1.0 MeV. Additionally, by designing the logical working mode of the sensor, the contamination by other high energy particles (high energy electrons > 1.5 MeV, high energy protons > 5 MeV, and heavy ions) is excluded. Combining the above methods, the detector achieves the detection lower limit of 30 keV for medium energy protons. Its energy resolution is better than 15%@100 keV and the mixing ratio of electrons is less than 2%.

Based on orbit detection data acquired by a positive channel Metal Oxide Semiconductor (PMOS) dose detectors on FY4-A (GEO), BD3-M15 (MEO), and YH1-01A (LEO) between November 2018 and November 2022, investigations reveal variations in total dose and the mechanism of radiation dose increase within the geostationary earth orbit (GEO), medium earth orbit (MEO), and low earth orbit (LEO) during the transition from the 24th to the 25th solar cycles. It provides the radiation dose parameters for the study of the space environment from different altitude orbits, and also provides an important basis for studying the solar minimum activity and dose generation The data indicate directional disparities in radiation doses among the orbital regions, with the hierarchy being FY4-A > YH1-01A > BD3-M15. Furthermore, the results show that the total doses of FY4-A and BD3-M15 were higher than that of YH1-01A by two orders of magnitude, with BD3-M15 > FY4-A > YH1-01A. The monthly radiation dose rates of FY4-A in GEO and BD3-M15 in MEO exhibited positive correlation with their corresponding APs during the solar minimum. Notably, for FY4-A, the monthly radiation dose rate during geomagnetic disturbed periods exceeded that of the dose rate during geomagnetic quiet periods by one order of magnitude. This analysis revealed the substantial impact of geomagnetic storms and space environment disturbances on radiation doses detected by MEO and GEO orbital satellites. These perturbations, attributable to medium- and small-scale high-energy electron storms induced by reproducible coronal holes, emerged as key driving factors of the increase in radiation doses in MEO and GEO environments.