1.) In the distant past, liquid water was widespread across the surface of Mars. Today, most of that water is long gone. In part, this is because Mars does not have a protective ozone layer to shield it from the Sun's UV radiation, which is energetic enough to dissociate water molecules into separate hydrogen and oxygen components. a.) If Mars has an average surface temperature of 210 K, what is the peak thermal speed of oxygen molecules in its atmosphere? (One molecule of O2 has a mass of 5.32 x 10 -26 kg.) b.) What is the peak thermal speed of hydrogen molecules in its atmosphere? (One molecule of H2 has a mass of 3.34 x kg.) 10-27 c.) What is the escape speed from the surface of Mars? (Mars has a mass of 6.39 x 1023 kg and a radius of 3.4 x 106 m.) d.) A planet will typically retain a gas in its atmosphere only if the escape speed is 6 times (or more!) larger than the peak thermal speed of the gas. Can Mars hold on to a molecular oxygen atmosphere? What about a molecular hydrogen atmosphere? e.) Given your answer above, how does this explain the red color of Martian soil? For a given temperature, most molecules in an atmosphere will zoom around at speeds near the peak thermal speed.