These particle radiation conditions present important environmental factors for space travel and space weather and must be carefully studied and accounted for in the planning and design of future missions to the moon, Mars, asteroids and beyond. Galactic Cosmic Rays (GCRs) can do damage to spacecraft electronics and, in large enough doses, can cause radiation sickness in astronauts, or longer-term problems such as cancer.
The rise in GCR levels is related to a prolonged stretch of low solar activity, which ebbs and flows on an 11-year cycle. During active phases, the Sun's magnetic field spreads throughout the solar system more extensively (by the flow of charged particles known as the solar wind), and it deflects more incoming GCRs.
But an active Sun poses its own problems. Solar flares and coronal mass ejections — powerful blasts that send huge clouds of superheated plasma rocketing out into space at millions of miles per hour — can also raise radiation levels significantly. And big solar outbursts aren't limited to active periods in the solar cycle. Indeed, a series of solar outbursts in September 2017 raised deep-space radiation levels significantly.
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