Sean C. Solomon is Director of the Lamont-Doherty Earth Observatory and William B. Ransford Professor of Earth and Planetary Science at Columbia University. He earlier served as Director of the Department of Terrestrial Magnetism at the Carnegie Institution of Washington and Professor of Geophysics at the Massachusetts Institute of Technology. He was the Principal Investigator for NASA's MESSENGER mission to Mercury from the initial mission concept in 1986 to the end of the project in 2017. He also served on the science teams for the Magellan mission to Venus, the Mars Global Surveyor mission, and the Gravity Recovery and Interior Laboratory mission to the Moon. A member of the US National Academy of Sciences and the American Academy of Arts and Sciences and former President of the American Geophysical Union, Solomon in 2014 was awarded the National Medal of Science by President Barack Obama. Larry R. Nittler conducts laboratory research on extraterrestrial materials and remote-sensing observations of planets at the Carnegie Institution of Washington. He served on NASA's MESSENGER mission to Mercury as Participating Scientist from 2007 to 2012 and Deputy Principal Investigator from 2012 to 2017. He earlier participated in the Near Earth Asteroid Rendezvous, Stardust, and Genesis missions and is currently a science team member on the Japan Aerospace Exploration Agency's Hayabusa2 asteroid sample return mission and the BepiColombo mission to Mercury. He received the 2001 Alfred O. C. Nier Prize of the Meteoritical Society and was named Fellow of that society in 2010. Asteroid 5992 Nittler is named in his honor. Brian J. Anderson is a Principal Professional Staff Physicist at The Johns Hopkins University Applied Physics Laboratory, Maryland, having served earlier as Magnetospheric Section supervisor and Space Physics Group supervisor. For MESSENGER he was Magnetometer Instrument Scientist from 1999 to 2009 and Deputy Project Scientist from 2007 to 2017 while also serving as a Co-Investigator from 2009 to 2017. He was spacecraft magnetics lead and is on the science team of NASA's Magnetospheric Multiscale mission. He is the Principal Investigator of the National Science Foundation's Active Magnetosphere and Planetary Electrodynamics Response Experiment. His research includes the physics of magnetospheres, plasma wave-particle physics, and planetary magnetic fields.