Enceladus and Europa are not only the small icy moons orbiting Saturn and Jupiter, respectively, but also the most promising places for harboring life in the outer solar system. Although their appearances show “freezing cold”, the oceans are inferred to exist beneath the ice shells of both small bodies by various observational evidences including the outgassing activity (i.e., Postberg et al. 2009; Hsu et al., 2015; Roth et al. 2014, Sparks et al., 2016; Waite et al., 2017). Today I’ll talk about the interesting story of the two little “snowmen” in the outer solar system, and about what our NTNU group works on this project to improve understanding of the chemical composition of Europa’s and Enceladus’ atmospheres and of their subsurface ocean environments.