Sarah Baatout​

Currently, no drug is fully approved for routine use in astronauts against space radiation. Most pharmacological countermeasures are still under research. Some categories being investigated include antioxidants and free radical scavengers (like vitamins C and E, melatonin), DNA repair enhancers, and modulators of inflammation. Bisphosphonates, usually used against bone loss, and statins, used for cardiovascular health, have shown some synergistic potential in radioprotection via ATM nucleo-shuttling pathways, but this is still experimental. At present, the most effective protection strategy remains physical shielding and careful mission planning to minimize exposure.

Yes, we do have some understanding. In microgravity, fluids shift from the lower body to the upper body because gravity is no longer pulling them down. The body interprets this as fluid overload and responds by getting rid of water and salt through increased urine output. Over time, astronauts therefore reduce their overall fluid volume. When they return to Earth, gravity suddenly pulls the fluids back down into the legs, but their blood volume is already reduced. This mismatch leads to dehydration and sometimes low blood pressure or fainting.

For very short sub-orbital flights, the health risks are limited compared to long missions. Passengers will experience strong accelerations during launch and re-entry, followed by a few minutes of microgravity. This can lead to temporary effects such as space motion sickness, cardiovascular stress, or disorientation, but no long-term medical consequences are expected for healthy individuals. The radiation exposure during a sub-orbital flight is also very low compared to orbital missions like the ISS.

We don’t have strong human evidence to answer this definitively—especially for space-type, chronic low dose/low dose-rate exposures. Susceptibility could vary widely by the specific condition, its severity, and concurrent medications. Some mechanisms seen in neurological disorders (e.g., oxidative stress, neuroinflammation, vascular changes) overlap with pathways affected by ionizing radiation, which makes increased vulnerability biologically plausible in certain cases. However, data are limited, astronaut cohorts are highly selected for health (so direct clinical evidence is scarce), and findings from radiotherapy or animal models don’t translate cleanly to space conditions. In short: it’s an open question; risk may be higher for some individuals, but we can’t generalize, and more research is needed.

The radiation environment on the Moon is harsher than in low Earth orbit. On the ISS, astronauts are partly shielded by Earth’s magnetic field, which reduces exposure to cosmic rays and solar particles. On the Moon or in lunar orbit (Gateway), there is no such protection, so astronauts are exposed to higher levels of galactic cosmic rays and solar particle events. That is why radiation shielding and storm shelters are critical for future lunar habitats.

Future space medicine will likely combine three pillars: preventive strategies (monitoring health in real time, personalized countermeasures), advanced telemedicine (with AI-assisted diagnostics and remote procedures), and new therapeutic approaches such as regenerative medicine or targeted pharmacology adapted to altered physiology in space. Ultimately, innovations developed for space will also benefit healthcare on Earth.

The main protection is shielding. On the ISS, astronauts move to the most shielded areas, such as the Service Module or behind water tanks. For future missions to the Moon or Mars, “storm shelters” with thicker shielding will be essential. Mission control also monitors solar activity carefully, and activities outside the spacecraft (EVAs) are rescheduled to avoid exposure.

We know that microgravity affects drug absorption, distribution, metabolism, and excretion. For example, reduced blood volume and changes in liver or kidney function can alter how medicines act in the body. This could mean that dosages need to be adapted, or in the long term, that space-specific formulations may be developed. For now, most medications used in space are the same as on Earth, but research is ongoing to see whether tailored “space pharmacology” will be needed for long-duration missions.