How does space radiation affect astronauts' health?

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1. 1

   Effects of ionizing radiation in spaceflight (Wikipedia)

   WikipediaPublished Oct 1, 2026Checked Oct 4, 2026

   “Astronauts are exposed to approximately 72 millisieverts (mSv) while on six-month-duration missions to the International Space Station (ISS). Longer 3-year missions to Mars, however, have the potential to expose astronauts to radiation in excess of 1000 mSv. Without the protection provided by Earth's magnetic field, the rate of exposure is dramatically increased. The risk of cancer caused by ionizing radiation is well documented at radiation doses beginning at 100 mSv and above. Related radiological effect studies have shown that survivors of the atomic bomb explosions in Hiroshima and Nagasaki, nuclear reactor workers and patients who have undergone therapeutic radiation treatments have received low-linear energy transfer (LET) radiation (x-rays and gamma rays) doses in the same 50-2,000 mSv range.”

2. 2

   Space Radiation and Cancer Risk in Astronauts: Models, Evidence, Uncertainties, and Emerging Imaging Perspectives.

   Tomography (Ann Arbor, Mich.) (Zanon et al.)Published Jul 17, 2026Checked Oct 4, 2026

   “Earlier REID-based models suggested that the historical 3% REID threshold could be exceeded after approximately 18 months in women and 24 months in men under unfavorable solar conditions, whereas the current NASA radiation standard uses a universal career-effective dose limit of 600 mSv, applied regardless of sex or age. More recent revisions of the NASA Space Cancer Risk model and non-targeted effect scenarios suggest that exploration mission risks may be higher than previously estimated, while uncertainty remains substantial, especially for high-LET radiobiology, mixed-field exposure, and the transfer of terrestrial epidemiological data to the spaceflight setting. Future progress may also involve exploring quantitative imaging biomarkers and tomographic assessments as complementary tools for longitudinal monitoring and early detection of radiation-related tissue changes, although these approaches are not yet validated as components of operational astronaut cancer risk models.”

3. 3

   Cardiovascular risks and hazards associated with deep space exploration.

   Communications medicine (Brojakowska et al.)Published Jun 23, 2026Checked Oct 4, 2026

   “Space flight exposes astronauts to a unique environment characterized by microgravity, ionizing radiation, and other stressors that can profoundly affect the human body. Deep-space exploration-type missions to the Moon (NASA's Artemis and Gateway programs), Mars, and beyond will introduce prolonged exposure to health hazards, including but not limited to isolation and confinement, sleep disruption, and exposure to different types and quantities of particle radiation (i.e., high-energy and atomic number - HZE). There are also logistical implications of traveling farther from low Earth orbit (LEO), including limited access to medical help and supplies. Currently, the known effects of space travel on the cardiovascular system include dysrhythmias, altered vascular compliance, dysautonomia, and induction of a pro-inflammatory state. It is not known how these concerns, and other potentially unknown cardiovascular risks, will manifest during and/or after exploration-type missions. This manuscript comprehensively reviews the cardiovascular disease risks associated with deep space exploration.”

4. 4

   Space radiation health risks to hematopoietic, neural, and gastrointestinal systems in astronauts.

   Frontiers in public health (Zhang et al.)Published Sep 7, 2026Checked Oct 4, 2026

   “Preclinical animal model research indicates that even low doses of space-relevant radiation may induce cognitive decline, memory deficits, anxiety-like behaviors, and neurodegenerative alterations, though these findings remain to be validated in human astronauts. Proposed mechanisms include impaired hippocampal synaptic plasticity, neuroinflammatory activation, and mitochondrial energy metabolism imbalance. Radiation has been shown to compromise the intestinal epithelial barrier, induce intestinal stem cell senescence, and disturb gut microbiome equilibrium in preclinical models. These gastrointestinal alterations may potentially exacerbate neurocognitive dysfunction and promote chronic inflammation via the gut-brain axis, based on mechanistic evidence from animal studies. Currently, there remains an insufficient systematic understanding of the cumulative effects, sex differences, and individual susceptibility associated with long-term low-dose composite radiation exposure. Integrating aerospace medicine is imperative to address these knowledge gaps and safeguard astronaut health during future deep-space missions.”