In the ‘60s, we were beginning to plan to select sites for the astronauts to land on the moon. Now, this is a geological question. Where do you land? The place has to be safe for landing, meaning as horizontal as you possibly can because you don’t want them to land on a steep slope, or the mission would be lost. And, the place has to be free of very large rocks, so that when they land, they will land on a flat surface, where not one of the legs of the spacecraft won’t land on a high rock somewhere. The place can’t be rocky.
Now, how to figure this out? There was no way. We had no maps of the moon to tell us about the topography, and we had no high-resolution images of the moon to see which places have rocks and which ones have not. We didn’t know even know whether [craters] on the moon were formed by the impact of meteorites, or formed by explosions.
So there were all kinds of basic questions that we had no idea what the answers might be. We had to generate as good as answer as we possibly could based on looking at pictures, photographs. So we began to get a good photograph as we possibly can by unmanned missions prior to Apollo, mostly from something called Lunar Orbiter, but we also had Ranger and we had Surveyor.
So you could say our understanding and analysis of these pictures became the basis for selecting landing sites on the moon, and the following missions, and so on, and that became the basis for what we now know as the feat of remote sensing and imaging of the Earth, as well as other planets, from orbit. So we can see the features and begin to interpret them better.
So whatever we do today with images of the forest, or the land surfaces, or agricultural areas of the world, or the desert landscapes – the way they have formed and they’ve changed in time – actually all of that goes back to the origin of looking at land pictures, which we learned at the very first with the Apollo missions to the moon.