LIFE IN THE SOLAR SYSTEM
I was drawn by the sirens of Titan
Carried along by their call
Seeking for a way to enlighten
Searching for the sense of it all
Like a kiss on the wind I was thrown to the stars
I was drawn by the sirens of Titan (as are we all)
As are we all
—Al Stewart, from his song “The Sirens of Titan,”
based on the Kurt Vonnegut novel
There’s no place like home, at least here in our own solar system. There’s no other world in our solar system on which we could survive even a few minutes outside without a spacesuit, and no other world that has so much as a puddle of liquid water on its surface. As I’ve explained over the past three chapters, this latter fact almost certainly means that we’ll find no other intelligent life in our solar system, because surface water seems a clear requirement for the evolution of complex beings like ourselves.
But a lack of intelligent life does not necessarily mean a lack of all life, and, remarkably, there may be a half-dozen or more worlds in our solar system that offer at least the potential of harboring some type of life. If life actually exists on any of these worlds, it will not only give us the opportunity to learn much more about the general nature of biology, but also change the equation for the search for life elsewhere. If life happened more than once in just our own single solar system, then it seems inevitable that it has also happened on countless worlds around other stars.
Now, a half-dozen possible homes to life may seem a lot in one sense, but if you’re a science fiction fan it might seem ridiculously limited. After all, there are a lot more “worlds” than that in our solar system. There are the 8 or 10 or more planets, depending on whether you count objects like