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Manned Mission to Mars Grounded. Radiation Risk too HighResearchers must create new means to handle radiation risks |
By Gabriel Gache, Science News Editor
1st of April 2008, 11:38 GMT
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On Earth, we are protected against radiation by the powerful magnetic field of the planet, however in space it's an entirely different ballgame. Radiation can severely damage or even destroy living cells inside the human body. Even on the space station, which receives a fair share of protection from Earth's magnetic field, astronauts feel the damaging effect of radiation, such as white flashes of light in their eyes, caused by high-energy cosmic ray particles ionizing substances in their bodies.
The first manned missions to the Moon were somehow fortunate, even NASA approves, as a dangerous burst of solar
radiation would have put the astronauts in serious danger. A return manned mission to the Moon or a future mission to Mars would require serious investigation related to the risks at which humans are exposed while being placed in a radioactive environment, such as space. The National Research Council evaluating the situation argues that with the current knowledge, a manned mission to Mars cannot be allowed to be carried out.
Radiation risk
According to ex-NASA space radiation program scientist and committee member at the National Research Council, Walter Schimmerling, there are still many uncertainties regarding the actual risk posed by space radiation to living beings. This means that safety margins are not yet well defined and still remain high, in order to compensate. This ultimately limits the astronauts' stay in space, ruling out for now any possible long-term missions to bodies in the solar system, other than Earth.
"The way to deal with that problem is to reduce the margins of uncertainty," said Schimmerling.
Further radiation biology research is needed, however the recent funding cuts applied by NASA disable even low-priority research, thus limiting the knowledge of the health risks of radiation, such as cancer or neuronal damage and degenerative tissue disease. Secondly, the space radiation biology research program conducted by NASA's Space Radiation Laboratory is dependent on the U.S. Department of Energy's heavy ion physics program, meaning that if the DoE suddenly decided to restrict access to NASA, then the Space Radiation Laboratory would have no testing facility.
"No one knows how long the window of opportunity if for how long this laboratory is available - 10 or 15 years seems a reasonable guess," said Schimmerling.
Radiation shielding
The best shielding substance would be lead, however lead is extremely heavy, thus researchers turn to the next best thing: lightweight, high-density plastic. "Lava tubes on the moon might also be useful as habitats from a shielding point of view. I don't know how realistic the idea is, but they would have the advantage of reduced exposure to radiation," adds Schimmerling.
Radiation is experienced in space in two forms, cosmic rays coming from the surrounding stars and solar wind, dangerous radiation emitted by the Sun. The greatest source in our solar system is the Sun, but the impact of such radiation could be minimized relatively easily by forecasting solar eruptions.
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