分类: 天文学 >> 天文仪器与技术 提交时间: 2024-02-07 合作期刊: 《天文技术与仪器(英文)》
摘要:The characteristics of asteroids are vital parameters for planning asteroid exploration missions. These characteristics have been explored in close range for some typical asteroids, and are summarized in the article. This allows estimates of the characteristics of asteroid 2016HO3, the target of the first Chinese asteroid exploration mission, Tianwen 2. We obtain 80 characteristic parameters in 9 categories and analyze their impacts on the mission. By comparing three close-range exploration modes, we provide advantages and disadvantages of each, and propose suitable methods for the exploration of 2016HO3. Owing to the weak gravity and small size of 2016HO3, a combination of multiple hovering positions and active orbiting is recommended for scientific exploration.
分类: 核科学技术 >> 放射性计量学 提交时间: 2024-04-26
摘要: The aim of this study is to evaluate the uncertainty of 2πα and 2πβ surface emission rates using the windowless multiwire proportional counter method. This study used the Monte Carlo method (MCM) to validate the conventional Guide to the Expression of Uncertainty in Measurement (GUM) method. A dead-time measurement model for the two-source method was established based on the characteristics of a single-channel measurement system, and the voltage threshold correction factor measurement function was indirectly obtained by fitting the threshold correction curve. The uncertainty in the surface emission rate was calculated using the GUM method and the law of propagation of uncertainty. The MCM provided clear definitions for each input quantity and its uncertainty distribution, and the simulation training was realized with a complete and complex mathematical model. The results of the surface emission rate uncertainty evaluation for four radioactive plane sources using both methods showed an uncertainty consistency En < 0.070 for the comparison of each source, and the uncertainty results of the GUM were all lower than those of the MCM. However, the MCM has a more objective evaluation process and can serve as a validation tool for GUM results.