Long-Haul Astronauts Risk Cosmic Cancer

Astronauts on an extended tour of duty aboard the international space station to be launched in November, face many dangers, including cancer, according to researchers at the UNSW School of Biochemistry.

Researchers have been working with NASA to discover the damage that cosmic radiation causes to human cells and the likelihood that the damage will lead to cancer. With longer space missions and the possibility of a manned mission to Mars in 2020, NASA needs an understanding of the long-term effects of radiation exposure on astronauts who spend an extended period of time in space.

Cosmic radiation is made up of protons and highly charged, energetic particles, some of which are left over from the formation of the universe and some created by the sun. On earth, the atmosphere serves as protection. In space, astronauts are vulnerable to high levels of radiation.

Questions raised by NASA are: What will the radiation do to the astronauts? Will it make astronauts prone to cancer in the long term? and, Can they be protected from the radiation?

Researchers have discovered great variation in the recovery of different cells. The liver recovered quickly. Its damaged cells died and were quickly replaced with undamaged cells. This is reassuring because a dead cell will not cause cancer. The brain was less efficient at killing and replacing the damaged cells, but the damage did eventually disappear.

Examining the gastro-intestinal tract, researchers found cause for concern. The damage to the gastro-intestinal tract increased over time. It was concluded that radiation damaged the stem-cell population (the cells that produce new cells) which began reproducing damaged cells. As the damage increased, so did the risk of cancer.

The result is that there is a possibility that exposure to the space environment and its cosmic radiation will cause cancer and there is no realistic way to protect the astronauts. The only shielding that could protect them from such strong radiation is too heavy to send easily into space. NASA wants to protect their astronauts but there is no viable way to do so.