UP, UP AND AWAY: The Kepler satellite, scheduled to take flight March 6, is lifted for attachment to its launch rocket at Cape Canaveral Air Force Station in Florida. Kepler will look for Earth-like planets that may be hospitable to life.
NASA

Next week brings a milestone in the search for extraterrestrial life with the scheduled launch Friday of NASA's Kepler satellite. The mission, named for 16th- and 17th-century German astronomer Johannes Kepler, will study a group of stars for three-plus years in search of subtle, periodic dips in stellar brightness—the telltale signs of planetary orbits. Although more than 300 planets outside the solar system have already been found using this method, among other techniques, Kepler's strength will lie in its instruments' sensitivity to smaller, cooler planets more hospitable to life and more like our own.

In a new book, planetary scientist Alan Boss, who studies stellar and planetary formation at the Carnegie Institution of Washington and is a member of the Kepler scientific team, argues that the mission should throw open the door to finding life outside the solar system. With any luck, Boss says, Kepler should indicate that billions of habitable planets exist in our galaxy alone, with an almost unfathomable tally of sextillions across the entire universe. (Where are Jules Verne and H. G. Wells when you need them?) We spoke to Boss about the thesis of his book.


[An edited transcript of the interview follows.]

Your new book is called The Crowded Universe. What does the title mean?
The point of the book is to show why one can claim that the universe is likely to be teeming with life. I make the argument throughout the book that we already know that Earths are likely to be incredibly common—every solar-type star probably has a few Earth-like planets, or something very close to it. To my mind, at least, if one has so many habitable worlds sitting around for five billion or 10 billion years, it's almost inevitable that something's going to start growing on the majority of them.

If they've got water on them, and they've got some comets coming in dumping in some amino acids and other interesting prebiotic chemicals, how are you going to keep those things from growing some sort of life?

Life is so tenacious and willing to seek out a toehold anywhere it can, my feeling is that it is going to originate anywhere it has a chance. It may not necessarily be little creatures like in a Steven Spielberg movie, but there will be some kind of archaealike or bacterialike microbes crawling around or bubbling along. Those are going to be creating output like oxygen and methane, and those are things we can see in the atmosphere. We may not be able to tell if a planet has intelligent life or dinosaurs, but we can at least tell if it has slime mold. So we're going for the slime mold.