The effects of cosmic radiation may hinder potential missions to Mars, according to preliminary NASA research. In a lecture at Dunsink Observatory yesterday, Prof Denis O'Sullivan of the Dublin Institute for Advanced Studies said commercial air crews also absorb these rays, but at much lower levels.
Cosmic radiation, which originates outside the solar system, does not reach the surface of the earth, though even earth-bound humans are affected by solar and many other forms of radiation.
A trip to Mars would expose an astronaut to 400 times the yearly dose of an average person in Ireland, Prof O'Sullivan estimated. A return trip to Mars would expose the astronaut to one sievert of radiation, while a person who gets a yearly X-ray, and never flies, probably takes in 2.5 millisieverts of non-cosmic radiation, he said.
"Even with the level of exposure the astronauts would be subject to, the risk of contracting a fatal cancer would only be increased by a small percentage. If three astronauts out of a hundred are likely to get cancer, though, that might be a mitigating factor for space flights."
Building thicker or stronger space vehicles would not affect the level of radiation, as cosmic rays can penetrate great thicknesses of metal, he added.
Air crews were in no danger of getting cancer at higher rates, he said. European Commission legislation which comes into effect next year limits the levels of radiation pregnant flight crew members could be exposed to. "At one millisievert a year, this is a very conservative limit," he said.
Though flight crews were exposed to more radiation than workers at nuclear power stations, the levels were still "nothing to worry about. A pilot who logged 600 hours in the air per year would be well within prescribed international recommendations."
The research was carried out by putting detectors on planes on different routes over the past five years, but much work needed to be done, Prof O'Sullivan said. "We are beginning to understand the physics of this type of radiation, but its effect on human tissue is relatively unknown," he said.