Whenever I watch a MESSENGER press briefing I always find myself musing about the different personalities of missions that result from the different teams of scientists that staff each one. The MESSENGER science team is full of people who are really, really, really enthusiastic about topics that seem a little esoteric to the general public -- magnetic fields, exospheres, ultraviolet emissions, and wrinkle ridges. Bless their hearts, they do try to explain what's so very exciting about their wiggly lines and field strength measurements. (Many a comedian from the American South has noted that you can say anything you want to about somebody as long as you accompany it with "bless his heart.") But they can't quite seem to bridge the gulf that separates their real excitement and enthusiasm and the general public -- they can't quite bring their space science down to Earth.
Because I have a Master's degree in planetary geology, focusing on structural geology and geophysics, I don't (usually) have a problem following what the MESSENGER geologists and geophysicists are talking about. But I'll readily admit to only the most tenuous of understanding of what those magnetosphere and exosphere guys are talking about. Mars missions, especially Mars surface missions, are typically much more accessible, because they're staffed by many people who see roving around Mars as little different from hiking around Earth's back country; it's just that they've got a rover instead of hiking boots and a rock hammer. Most people can relate to hiking around the mountains or a desert, so you can connect with the public on that level and take them forward into Martian geology from there. And with the Moon, at least we have the experience of seeing the Apollo missions -- we have that human perspective on the landscape. With the outer planet moons, a great deal of our current exploration is "wow, aren't those ridges/lumps/geysers/craters/whatever cool!" I don't think our enjoyment of the landscapes of places like Ganymede, Enceladus, and Miranda are diminished at all by our uncertainty as yet about what made their landscapes look like they do.
It's harder to relate to MESSENGER and its study of invisible fields and impossibly thin atmosphere at Mercury. But the team really is trying to tell me why it's so exciting to study, and they're doing a fabulous job of telling us all about what they think they're learning almost as soon as they have a handle on it themselves. I'll keep listening, and if I manage to come to a better understanding of all this "magnetic connection" and "sodium tail" business, and what it's telling us about Mercury's past and present, I'll let you know!