18. Planetary Exploration "Opportunity" and "Phoenix" are two of the robotic explorers on Mars. Opportunity landed at 2° south latitude, where Mars' radius is about 2110 miles. Phoenix landed at 68° north latitude, where Mars' radius is about 790 miles. Mars rotates on its axis once every 24.6 Earth-hours. How far does each explorer travel as Mars rotates by l radian? How many hours does it take Mars to rotate 1 radian? Using this answer, how fast is each explorer traveling around Mars' axis in miles per hour?