Humans have not yet stepped foot on the surface of Mars, however, about 15,694 pounds of human garbage is already spread across the planet. In order for humans to explore and research the planet, we have sent 14 different missions to Mars. These missions, sent by several nations, have equated to thousands of pounds of discarded hardware, and inactive or crashed spacecraft. The 15,694 pounds figure only accounts for the human technology that is not currently in use. 

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