“…For example, irradiation of pale yellow S 8 results in the development of the metastable short-chain molecules S 3 and S 4 , which range from brownish-yellow to grayish-yellow to orange (Nash and Fanale, 1977;Nelson and Hapke, 1978;Steudel et al, 1986;Hapke and Graham, 1989;Nelson et al, 1990). Red materials tend to be very ephemeral, and fade over a period of a few months at most vents (McEwen et al, 1998a;Geissler et al, 2004).…”