Our blue planet does not only have essential elements to support life, but its strong magnetic shield protects us from harmful space radiation — solar energetic particles (SEP) coming from the sun, and galactic cosmic rays (GCR) coming from the deep interstellar space. Leaving the Earth’s atmosphere is always a radiation hazard. Astronauts in space are already at risk and space agencies are working harder to reduce the health risks of space radiation for astronauts.
Given the risks involved with venturing out of the Earth’s magnetic field, a manned mars mission would mean putting astronauts under more space radiation, given the red planet’s thin atmosphere and its inability to filter space radiation. However, space radiation is not instantly harmful, it is the increased periods of exposure that can cause health risks. According to a study published in August, manned Mars missions could still be viable if astronauts could finish them within a fixed period of four years.
To figure out how scientists calculated this time period, one needs to understand the cyclic nature of the two main types of hazardous space radiation. Collectively, the SEP and GCR are called ionizing radiation that works like “an atomic-scale cannonball that blasts through the material it passes through, leaving significant damage behind,” as NASA describes. Solar activity has an 11-yearcycle, which means solar radiation reaches a maximum every 11th year. During the solar maximum, the sun has an increased magnetic field which shields cosmic rays more effectively from coming into the inner solar system, and hence,the galactic cosmic rays are at their minimum. As the solar activity decreases, the level of GCR rises.
Combining the radiation sources and considering that the fluctuations in the radiation are utilised efficiently, scientists simulated the exposure to space radiation to calculate how long does a body in space have before the radiation exposure reaches one sievert. An exposure of one sievert or more is dangerous as it can cause fatal cancer to five out of 100 people who were exposed, reported Reuters.
According to scientists, astronauts can manage a space journey outside the earth’s protective blanket without getting seriously harmed by space radiation, if they depart from the earth during a solar maximum and return within four years.