Unmanned Exploration of the Planets
Earth's Moon, Mars, Jupiter, and Saturn
Once upon a time, humans had not been to the moon, had never even been outside earth's atmosphere. Growing up in those times, a boy half-believed in fairies and witches, gods and goddesses, and read as many books as he could find in which the author imagined travelling to another world or living there. A few authors - Jules Verne, for instance, and Edgar Rice Burroughs - already had such books. And many more - Asimov, Heinlein, Clarke, for a few -were writing about as fast as he could read. Full of their speculations, he never recognized that first Robert Goddard and then Werner von Braun experimented with rockets, and they'd change his life unrecognizably.
You see, he hadn't found any fairies or witches, gods or goddesses but he had found math and chemistry and physics. And he'd discovered that engineers used them to build roads and bridges, radios and radar, airplanes and submarines. Engineering was the next best thing to magic! And he found he could get a job that would pay for his learning engineering or physics, some of both. Some of the professors even seemed like wizards!
After college, his boss told him that since he had the least seniority he'd have to take a job programming for his new group of engineers. Learning programming, he felt as if he'd fallen off a cliff into a cloud junglegym! Or, reversing Alice, he'd fallen into a world that made sense, a world of logic where relationships were mathematical. That boss must've been a fairy godfather. He also sent the boy-turned-engineer-turned-programmer to California to help fly the Lunar Orbiter around Earth's Moon and map nearly the whole satellite! Astronauts used those maps to help them choose probable landing sites.
Later another magical boss hired him to help plan pathways through space. Those pathways used the magic carpet of gravity, and the ripples in that carpet as planets moved around the Sun, to slue a robot from Earth to Mars or Jupiter or Saturn. At first the pathways were just dreams, possible ways to travel there. And then the U.S. decided to celebrate its centenary by landing two robots on Mars. A boss sent the boy-no-longer to convert some of the signals those robots sent back into information about the seismology and weather of Mars. (We learned that the two Viking landing sites were quieter seismologically than any place on Earth, and that the thin air of Mars kicked up quite a ruckus from time to time.)
Another wizard waved a wand and the afterboy found himself working with people whose programs kept telling the Voyager robots what to do as they flew by first Jupiter then Saturn, the two biggest planets in the solar system. (We learned more about Jupiter and Saturn in those weeks than we'd learned in 400 years of telescoping them.) Jupiter alone turned out to be so interesting and mysterious that the U.S. sent another robot, Galileo, to fly a daisy-petal orbit around it and visit several of its moons.
The magical adventure of exploring planets and space with robots ended for our half-believer, but it hasn't ended for others. They have two radio-carts on Mars learning from what its rocks are formed, and an orbiter remapping Mars with more sensitive instruments than before. The adventure need never end: every answer we learn invites new questions we hadn't known to ask. Every robot we build teaches us more that we can do with machines and computers and rugged-but-sensitive instruments. It really is almost as good as fairies and witches, gods and goddesses. Some would say better.