Part 1 of 3 Parts
I have blogged before about the deleterious effect that radiation can have on human health. Usually, such blog posts have been about various types of radiation exposure here on Earth but there is another problem with radiation exposure that I have not dealt with and that has to do with the danger of astronauts of the radiation in space. Now NASA is considering raising their estimation of the amount of radiation in space that astronauts can safely experience.
The Biden administration has indicated that it will support the NASA Artemis mission to the Moon which was in question because the Artemis project was conceived by the Trump administration.
There are many problems for astronauts traveling in space because human beings are best suited to live on the surface of the Earth. One of the most difficult to deal with is the effect of radiation from the Sun or cosmic events. This radiation consists of atoms that have had their electrons stripped away. Some are accelerated to almost the speed of light by events such as a star exploding in a nova or supernova. There are three types of radiation in space. Particles can be trapped in the Earth’s magnetic field. The Sun spews out particles in bursts that sweep through the solar system. This is called the solar wind. Finally, there are high energy protons and heavy ions that come from cosmic sources from outside of our solar system.
Radiation is identified as a “red risk” for astronauts in a NASA study that was published last year on the subject of high-priority health problems. Radiation can damage the DNA in human cells. This can lead to mutations which can result in the development of cancers. Radiation can also cause cardiovascular problems such as damage to the heart, narrowing of arteries and blood vessels. Radiation caused neurological can result in cognitive impairment. This was all detailed on a NASA webpage.
On the surface of the Earth, human beings are exposed to between three and four millisieverts (mSv) of radiation per year. This radiation comes from radioactivity in soil and rocks. A small amount of radiation consists of cosmic rays that penetrate the Earth’s atmosphere. On the International Space Station in Earth orbit, astronauts receive about three hundred mSv per year. Until now, a fifty-five-year-old male astronaut was restricted to an effective does of four hundred mSv over his entire career. In contrast, a thirty-five-year-old female astronaut was limited to a total exposure of one hundred and twenty mSv.
NASA is now planning on sending astronauts on much longer space mission and is currently considering raising the limit of radiation exposure to six hundred mSv for astronauts of any gender or age. Under the existing standards, some experienced astronauts could have been excluded from participating in long term space missions because they were already approaching the maximum life-time exposure limits. Younger astronauts have spent less time in space and have had less radiation exposure. This could make them more attractive for lone term space missions. However, the success of important long space missions might depend on a depth of experience that younger astronauts do not have.
Please read Part 2 next