The future of human space exploration, such as visiting our moon or even Mars, could be essential for upcoming generations. But despite that and the recent renewed interest in space travel thanks to companies like SpaceX, humans traveling beyond our moon will require a paradigm shift in space propulsion.
According to NASA, a round-trip Mars mission involving humans would take an estimated three years. That includes a six-month journey to the Martian planet, 18 months on the surface awaiting Earth to line up correctly for the shortest trip possible, and another 6-month journey back home. During that time, NASA research shows that, on average, a human would be exposed to approximately 1,200 millisievert of radiation. That's equivalent to thousands of chest x-rays and around 60 percent of NASA's career exposure limit for a 35-year old astronaut.
Quicker flights through the vacuum of space equal less radiation to the crews making the journey, and a couple of ideas are in the works to make that possible: nuclear thermal propulsion and ion propulsion, both meant to speed up flight times and lower radiation exposure.
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