Scott G Edgington, Jet Propulsion Laboratory, Pasadena, CA, United States, Sushil K Atreya, University of Michigan Ann Arbor, Ann Arbor, MI, United States, Robert A West, Jet Propulsion Lab, Pasadena, CA, United States, Kevin Baines, Jet Propulsion Laboratory, Pasadena, United States and Leigh N. Fletcher, University of Leicester, Leicester, United Kingdom