Fifty years ago this summer, Apollo 11 landed on the moon. Now, NASA’s talking about going back.But is it worth it?We talk to lunar geologists about what we’ve already learned from the first Apollo missions, and what’s left to discover.Then, we take a trip, not through space, but through time—back to a scientific expedition in Greenland almost a century ago. The science done there might have seemed insignificant at the time, but has since proved an important first step towards our current understanding of global warming.Further reading:Brian's in-depth explainer on moon rocksJon Gertner's book about epic Greenland expeditions, The Ice At The End of The WorldFor more on ice coring, this National Geographic article is great, as is this 60 Minutes episode