Tracy K.P. Gregg is an Associate Professor in the Department of Geology at the University at Buffalo in Buffalo, NY. Her primary research interest is lava flows, and she is not particular about where they are or their composition. She has done field work on lava flows in Idaho, Peru, Iceland and Hawaii; as well as studied volcanic morphologies on Mars, the Moon, Venus, and Jupiter's moon Io. She has personally investigated lavas at the East Pacific Rise and the Galapagos Spreading Center, more than 2500 m below sea level, from the safety of the submersible Alvin. She supervised the NASA Planetary Geology and Geophysics Undergraduate Research Program (PGGURP) for 20 years, and is now helping to run its sequel (Summer Undergraduate Program in Planetary Research, or SUPPR). Tracy is a Fellow of the Geological Society of America (GSA), and was awarded the Ronald Greeley Award for Distinguished Service from the GSA Planetary Geology Division. Rosaly Lopes is a Senior Research Scientist at the Jet Propulsion Laboratory, where she is also Manager of the Planetary Science Section. An expert on planetary volcanism, she worked on the Galileo mission to Jupiter and is currently on the science team of the Cassini mission to Saturn. Her research expertise is on volcanoes in the Solar System, particularly the active volcanoes of Jupiter's moon Io and the ice volcanoes of Saturn's icy moons. She is a Fellow of the American Association for the Advancement of Science and the Geological Society of America, and the winner of the American Astronomical Society's 2005 Carl Sagan Medal. She has published seven books and over one hundred and twenty peer-reviewed publications Sarah Fagents is a Researcher in the Hawaii Institute of Geophysics and Planetology at the University of Hawaii at Manoa. She investigates volcanic features and eruption processes on the Earth and other planets, and is a member of the science team of the upcoming Mars 2020 rover mission. Her publications cover a wide range of volcanic subject matter, including magma-water interactions, explosive volcanism on Mars and Venus, lava flow dynamics and heat transfer, and cryovolcanism on Jupiter's moon Europa. She shares her enthusiasm for planetary volcanism with the public whenever possible.