I've now been writing about science for nearly a dozen years, which means my career more or less overlaps with that of the Cassini probe. Unlike that spacecraft, fortunately, nobody's directed me to burn up in the atmosphere of Saturn. But, given the overlap between us, you might think I'd be saddened and nostalgic when the last signal arrived from the ringed planet, which, due to the distance, arrived well after Cassini tumbled out of control and came apart. After all, we'd no longer be graced by the steady flow of stunning pictures from a set of worlds that are amazingly foreign.
I am a bit saddened by Cassini's planned destruction, but it's not going to leave a hole in my emotional well-being, at least not in death. Instead, the sadness came years ago, from the realization that Cassini would probably be the last of its kind in my lifetime.
Why so sad?
Will I miss the stunning photos? A bit, I guess. But I wasn't the sort of person to carefully pay attention to JPL's servers to track when new pixels made their way in from Saturn. And, to a certain extent, Cassini was a victim of its own success. Over the years, it sent home so many spectacular images of Saturn, its rings, and its moons, that the newer ones tended to have an air of familiarity about them.
I won't really miss the science either. Papers will keep coming out of the Cassini data for years. Even if we get our act together and send additional spacecraft to Saturn, Cassini will still provide the baseline. After all, we're still interpreting Jupiter and Venus based in part on information we obtained from missions that are decades old. So the spacecraft will probably be a major player in the science landscape until well after I retire from science writing.
So if it's not the beauty, and it's not the science, what is there to be sad about?
I miss what Cassini represented. I was 10 years old when the Voyagers launched, and a lot of my formative years were spent following their treks across the Solar System. They made a big impression on me and were one of the reasons I ended up in science. But part of what made them exciting was the sense that we'd follow up on them, sending the hardware needed to fully understand everything the Voyagers hinted at.
And for a while, NASA did its best to keep me believing that. Galileo went to Jupiter and, despite being bandwidth-starved due to an antenna that failed to unfold, it gave us a much better understanding of Europa and Io, two of the most intriguing worlds in our Solar System.
Cassini was Galileo done right—the pinnacle of post-Voyager exploration. A big probe with lots of hardware, it performed flawlessly during its entire time at Saturn. It gave us much better data than the Voyagers' vintage instruments could, and stayed long enough to watch Saturn and Titan change with the seasons. It discovered geysers erupting from the moon Enceladus, and then managed to sample the material those geysers spewed into space.
With instrumentation ever-improving, there were two more worlds waiting for their post-Voyager close ups. It's a promise that has been painfully unfulfilled. Uranus and Neptune, it turns out, are typical of some of the most common planets in our galaxy. Understanding them would not only help us understand the Solar System, its origins, and the interactions that define the outer border of its planets. It would help us make sense of the galaxy as a whole.
Plus those planets have a collection of moons that has the potential to include Enceladus-level surprises. And Uranus is tilted on its side—its axis of rotation is more or less on the plane of the Solar System, rather than pointing perpendicular to it. And its magnetic field is 60º off that axis. It's hard to imagine there's not some amazing stuff to learn there.
But we're only just now starting to think about planning for sending something to one of the ice giants. If anything happens in my lifetime, I'll be pleasantly surprised. And, if hardware does go, it's almost certainly not going to be the same class as Cassini, which cost over $2.5 billion to launch and operate. NASA can afford projects of this scale, but it's decided to send them to places we already visited repeatedly: Mars and Jupiter. Places where we already have big picture understanding.
So, I'm not saddened so much by the loss of Cassini as I am by the recognition that there's not going to be anything like it again. The dream that the Voyagers would be the first step in a process is dead. There may be Cassini-equivalent hardware sent out at some point in the future, but that will only be when the cost of hardware drops to meet our reduced expectations.