Recent solar conditions indicate a persistent decline in solar activity—possibly similar to the past solar grand minima. During such periods of low solar activity, the fluxes of galactic cosmic rays (GCRs) increase remarkably, presenting a hazard for long‐term crewed space missions. We used data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO) to examine the correlation between the heliospheric magnetic field, solar wind speed, and solar modulation potential of the GCRs through Cycle 24. We used this correlation to project observations from past secular solar minima, including the Dalton minimum (1790–1830) and the Gleissberg minimum (1890–1920), into the next cycle. For the case of conditions similar to the Dalton (or Gleissberg) minimum, the heliospheric magnetic field could drop to 3.61 (or 4.06) nT, leading to a dose rate increase of ∼75% (or 34%). We showed that accounting for a floor in the modulation potential, invoked by the Badhwar‐O'Neill 2014 model, moderates the projected radiation levels in Cycle 25. We used these results to determine the most conservative permissible mission duration (PMD, and  days for 45‐year‐old male and female astronauts, respectively) based on a 3% risk of exposure‐induced death (REID) at the upper 95% confidence interval in interplanetary space.

中文翻译：

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通过现代世俗的最小值，行星际空间中的银河宇宙辐射

最近的太阳状况表明太阳活动持续下降-可能与过去的太阳极小值相似。在这种太阳活动低的时期，银河系宇宙射线（GCR）的通量显着增加，这对长期载人航天任务构成了危险。我们使用了来自宇宙射线望远镜的辐射对月球侦察轨道器（LRO）的影响（CRaTER）的数据，研究了第24周期中GCR的太阳圈磁场，太阳风速和太阳调制电势之间的相关性。利用这种相关性将过去的长期太阳极小值（包括道尔顿极小值（1790–1830）和格莱斯堡极小值（1890–1920））的观测结果投影到下一个周期。对于类似于最小道尔顿（或格里斯堡）的条件，日球磁场可能降至3。约75％（或34％）。我们发现，占调制潜在的地板，由Badhwar -奥尼尔2014模型调用，温和派预计辐射水平在周期25.我们用这些结果来确定最保守允许任务持续（PMD，和 天分别是45岁的男性和女性宇航员），其基于在星际空间中95％置信区间的3％的暴露诱发死亡（REID）风险。