Artemis II: The Health Challenges of Deep Space Travel

The Artemis II crew landed back on Earth after a record-breaking mission to the far side of the moon, where they travelled further from their home planet than anyone in history.

Astronauts Reid Wiseman, Victor Glover, Christina Koch and Jeremy Hansen reached a distance of 252,756 miles from Earth on a mission which NASA hopes will pave the way for longer lunar visits and eventually, trips to Mars.

Humans have been through millions of years of evolution to become perfectly adapted to life on Earth, so spending time in space - with no gravity, no sunlight and different levels of radiation - poses a real challenge physically.

Space radiation is a primary concern. Astronauts are exposed to high-energy radiation in space, unlike on Earth, where the atmosphere and planetary magnetic field provide a shield against it. This can lead to DNA damage, increased cancer risk, neurodegenerative effects, cardiovascular issues and immune system dysregulation.

While the International Space Station (ISS) is somewhat protected by Earth's magnetosphere, deep space travel removes this shield. Dr Haig Aintablian, director of space medicine at UCLA, notes that once beyond low Earth orbit, radiation becomes one of the real challenges of deep space.

Microgravity also presents significant health hurdles. The body is built to live and work in gravity, and its absence causes the inner ear to recalibrate, muscles and bones to be used differently, and fluids to shift upward. This can result in changes in balance, strength, and vision. Astronauts often lose bone density—roughly 1% per month without precautions—and experience muscle atrophy. Additionally, headaches, motion sickness, dizziness, and sleep disruption are common.

NASA monitors crew health closely using flight surgeons and real-time tracking. The Artemis II mission included radiation monitoring, exercise countermeasures, and a structured post-landing medical recovery plan. Data collected from this mission is considered essential for preparing crews for longer lunar missions and future travel to Mars.