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Hazard: Distance From Earth

Instructions, new supplies, medical care, and more become increasingly challenging to receive from Earth as astronauts venture deeper into space.

An illustration of the Moon and Mars above the Earth's horizon.

Mars is, on average, 140 million miles from Earth. Rather than a three-day lunar trip, astronauts bound for Mars would be leaving our planet for roughly three years.

Given this distance, planning and self-sufficiency will be essential to successful missions to Mars. Facing a communication delay of up to 20 minutes one way, the possibility of equipment failures or medical emergencies, and a critical need to ration food and supplies, astronauts must be capable of confronting an array of situations with minimal support from teams on Earth. Learn more about how NASA studies the challenges that will arise as space missions venture farther from Earth:

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Artist's illustration showing two astronauts on the surface of Mars. A pressurize rover is in the background. One astronaut is on top of a lander, using a crane to lower instruments to the astronaut on the ground.

Getting Humans to Mars

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The Human Body in Space

For more than 50 years, NASA’s Human Research Program (HRP) has studied what happens to the human body in space. Researchers…

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