NASA considers high-energy solar radiation and solar flares as the greatest risks to space missions, impacting astronaut safety, spacecraft electronics, and mission autonomy. Protective measures against radiation and ensuring spacecraft independence due to communication delays are critical challenges. Ensuring Mars sample safety is also a public concern.
According to NASA, the greatest risks to space missions include high-energy solar radiation and other space weather events such as solar flares. Solar storms exacerbate exposure to radiation not only for astronauts but for high-altitude aircraft and sometimes even for individuals on Earth's surface. This is a grave concern, as an ill-timed solar outburst could severely impact an astronaut's health and career, since astronauts have a limit to how much radiation they can safely be exposed to throughout their working lives. An example being, the daily dose of radiation on the Russian Mir space station was about eight chest X-rays worth of radiation.
Solar flares pose additional risks, as they can ionize atoms in Earth's upper atmosphere and create charged particles that can build up on a spacecraft's surface. This build-up can lead to a static discharge that has the potential to damage a spacecraft's electronics, akin to getting a shock from touching a metal object after walking on a carpet. Furthermore, the inherent isolation of spacecraft in deep space necessitates highly reliable systems capable of operating autonomously, as communication delays can make quick support from Earth impossible.
For the challenge of human exploration of Mars, one major hurdle is to devise ways to protect astronauts from this solar radiation, while maintaining spacecraft efficiency and ensuring biological samples returned from Mars are kept in complete isolation to confirm their safety. Given the significant dangers posed by high-energy radiation from the sun, NASA continually strives to enhance safety measures and protective technologies for ongoing and future space missions.