Scientists at a meeting of the International Lunar Exploration Working Group argue that it doesn't mater that humans have "been there"—there is plenty we still don't know about our moon. Here are some areas that bear examination.
We still don't know for sure where the moon comes from. The idea that the residue of a massive impact of planetary bodies spun off the moon has gone from fringe to mainstream. Geology is the key to studying the past, and so far only one geologist has ever been on the moon. However, studying "the structure and composition of crust, mantle and core" will have implications for its origin—and the earliest history of Earth, the working group determined. Such research requires landing on the surface by human or robotic geologists.
The Dark Side
Even taking into account recent satellite missions, most of the best lunar data comes from Apollo crews and Russian Luna landers. These efforts focused on the near side of the moon, for obvious logistical reasons. But those small patches are not representative of the rest of the planet. The international working group in China says that "ground truth information on the lunar far side is missing and needed to address many important scientific questions." They recommend a sample return from South Pole-Aitken Basin, the deepest impact crater in the solar system, and the oldest on the moon. Every crater is a window into the past, but this one's chemistry and geology could hold answers to some lingering mysteries. Was the impact that caused it fast or slow moving? Why is the chemistry of the impact basin so different from the highlands?
The working group questions the "nature and origin of volatile emplacement and implications for resource utilization." That is a long way to go to make something exciting seem very dull. What they mean is water—how it got there and how much is available for human use. That means moon bases, permanent settlements off of earth—and we have not been there, nor done that. Recent findings from NASA and Indian missions are showing that there is likely more water in and on the moon than anyone ever suspected. But the most eye-catching study, released this week by scientists at the Carnegie Institution's Geophysical Laboratory, found that the water content has been undercounted by a factor of about 100. Where did this data come from? Analyzing a rock that Apollo 11 astronauts brought back in 1969 held the key. If robots or astronauts pluck more rocks from more areas and return them to Earth for study, who knows what other mind-bending breakthroughs could be revealed. We need to set spacecraft on the surface to solve these riddles.