Space is getting deadlier. The amount of radiation has increased from previous solar cycles, according to new measurements made by a team of researchers.
Astronauts venturing into space now face higher doses of radiation from the onslaught of highly energetic particles in cosmic rays compared to previous crews. The increasing levels of radiation could mean astronaut's space time may have to be cut back.
“The radiation dose rates from measurements obtained over the last four years exceeded trends from previous solar cycles by at least 30 percent, showing that the radiation environment is getting far more intense,” said Nathan Schwadron, lead author of the study published in Space Weather and professor of physics at the University of New Hampshire.
The researchers found increasing fluxes - a higher rate of particles in a given area - in Galactic Cosmic Rays are reaching record levels. This has dangerous repercussions for astronauts that are not properly shielded as it can cause cancer and damage vital organs, including the brain, heart, and central nervous system, over time.
The latest measurements exceed expectations. In 2014, Schwadron and his team predicted a 20 per cent rise in radiation dose rates, but they were 10 per cent short.
A previous study also led by Schwadron showed that in the 1990s an average 30-year-old male could spend just over 1,000 days in space and just under 1,000 days for 30-year-old females. Fast forward 20 years or so, and the number drops to under 800 days for 30-year-old males and about 700 for 30-year-old females.
"We now know that the radiation environment of deep space that we could send human crews into at this point is quite different compared to that of previous crewed missions to the moon," he said.
The team analysed data taken from CRaTER, a cosmic ray telescope, aboard NASA’s Lunar Reconnaissance Orbiter to detect changes of radiation over time.
The sun goes through 11-year cycles of high emission activity, followed by six to eight years of quietness, called a solar minimum, and then it flares back for about two to three years of moderate activity before flaring up again.
Scientists have observed the longest solar minimum period since 2006. Schwadron told The Register that "we actually are not in a solar minimum right now, we have gone through a solar maximum and we are headed toward a new solar minimum" near 2020.
Although solar activity is low, radiation levels can still be high. "The radiation is associated with galactic cosmic rays, or highly-charged particles, which come to us at Earth from outside the Solar System. As the Sun becomes less active, the natural shielding from magnetic fields in the Solar System weakens to allow in more galactic cosmic rays, or high-energy radiation. Therefore the number of cosmic rays that are able to get near Earth increases as solar activity decreases," he explained.
The team hope to develop new ways to understand and measure the risk and impact of changing radiation levels. ®