In early 2001, I was a fifth-grader and had been obsessed with our solar system’s planets my entire life. But, thanks in part to the Internet, I came to realize our solar system is more than just the row of planets on my placemat. It is a dynamic system with asteroids, comets, and moons, a lot of moons which look nothing like the one in our sky, each with its own story to tell. I spent countless hours reading about them — the fiery sulfur volcanoes on Io, the nitrogen plumes on Triton, the mysterious ocean of water underneath Europa’s icy crust.
But what was I to make of Saturn’s moons? The best pictures of Titan showed a hazy, orange orb and that was essentially all we knew about it. Enceladus was unusually bright — could that harbor an ocean underneath its ice like Europa? I wondered. Iapetus was oddly two-faced, but the data available was inconclusive as to the nature of the yin and the yang. And were the rest of the moons hiding secrets as well?
I learned that a spacecraft called Cassini was set to orbit Saturn for four years beginning in the summer of 2004. Moreover, a separate probe would detach from the main spacecraft and land on Titan! It was official: for the next three years, no other year in my mind mattered more. The countdown to 2004 had begun.
Cassini teased us with a few distant images of Saturn, but the mission truly started when it made its closest (and only) approach to the small moon Phoebe. The pictures showed, in detail for the first time, a battered, icy moon that likely originated in the Kuiper Belt. A few weeks later, Cassini entered orbit around Saturn, (still) the farthest planet any spacecraft from Earth has orbited. Data and pictures started trickling in at a faster pace. I was buckled up and ready to go for the next four years.