*Cristian Robert Radulescu^1,2、Andrew Coates^1,2、Geraint Jones^1,2、Nick Achilleos^2,3、Yasumasa Kasaba⁴ (1.Mullard Space Science Laboratory, UCL, Dorking, UK、2.Center for Planetary Sciences at UCL/Birkbek, London, UK、3.Dept. of Physics and Astronomy, UCL, London, UK、4.Tohoku University, Japan )