Don’t take a star trek unless you want to arrive demented.
According to Science Daily, prolonged exposure to cosmic radiation accelerates the development of dementia, including Alzheimer’s Disease. The headline says it: “Space Travel May Be Harmful to the Brain, Study Suggests; Prolonged Cosmic Radiation Exposure Could Hasten Alzheimer’s.” The press release at the University of Rochester put it this way: “Houston, We Have Another Problem.”
A study published in PLoS ONE (open access) found that mice at Brookhaven National Lab exposed to radiation levels similar to those in space had accelerated levels of dementia. This damage adds to the well-known cancer risks and potential for muscle atrophy for long trips in weightlessness. The new study shows that galactic cosmic rays not only have cardiovascular and musculoskeletal impacts – they slowly destroy the brain.
Why is galactic cosmic radiation so damaging? Can’t NASA guard against it? The press release explains,
While space is full of radiation, the earth’s magnetic field generally protects the planet and people in low earth orbit from these particles. However, once astronauts leave orbit, they are exposed to constant shower of various radioactive particles. With appropriate warning, astronauts can be shielded from dangerous radiation associated with solar flares. But there are also other forms of cosmic radiation that, for all intents and purposes, cannot be effectively blocked.
That’s because cosmic rays are so energetic; shielding cannot stop them, or else it creates a shower of lower-energy particles that are also damaging. Heavy iron particles sent out from galaxies would be impossible to deflect: “One would have to essentially wrap a spacecraft in a six-foot block of lead or concrete,” co-author M. Kerry O’Banion said. Try launching that out of Earth gravity.
There aren’t as many cosmic particles as those in the solar wind, but the damage they cause accumulates. “Because this radiation exists in low levels, the longer an astronaut is in deep space, the greater the exposure.” At this rate, forget star travel; the effects may be too harsh for astronauts on NASA’s drawing-board proposals for a 3-year mission to Mars.
Update 1/07/13: Science NOW reported on results from the Mars500 mission simulation, during which six practice crewmen lived in the confinement of a space capsule for 520 days – the length of time for a Mars round trip. In short, they became couch potatoes: lethargic, bored, and unenthusiastic. This is another reality that mission planners will have to take into account.
This updates an entry from 9/23/2006, showing that the problem has not gone away with six more years of research. The take-home lesson should be gratitude for the safety bubble we inhabit in the cosmic shooting gallery, allowing us to live, love, and enjoy the beauty of creation. Safe within our bubble, Hollywood screenwriters can envision epic space voyages (acted out by actors in Earth-bound studios), and astronomers can search out the most distant galaxies and strive to understand the entire universe from a protected platform – our Privileged Planet.