Travelers to Mars would have to endure low levels of gravity for long periods of time, avoid large doses of radiation, contend with the chemically reactive Martian soil, and perhaps even having to ward off contamination by Martian life-forms.
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Acontend with the chemically reactive Martian soil, and perhaps even having to ward
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Bcontend with the chemically reactive Martian soil, and perhaps even warding
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Ccontend with the chemically reactive Martian soil, and perhaps even ward
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Dcontending with the chemically reactive Martian soil, and perhaps even to ward
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Econtending with the chemically reactive Martian soil, and perhaps even warding
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