All These Worlds Are Yours: The Scientific Search for Alien Life

All These Worlds Are Yours: The Scientific Search for Alien Life by Jon Willis

All These Worlds Are Yours: The Scientific Search for Alien Life (2016), by Jon Willis, is structured around a simple proposition: if you had four billion dollars to spend (Willis explains why that number late in the book) to seek out non-terrestrial life, where would it make the most sense to spend it? Willis gives his readers a head start by narrowing their choices at the outset to five “plausible scenarios:”

1. Mars (of course)
2. Europa
3. Enceladus
4. Titan
5. An exoplanet

Willis begins by offering up a relatively quick but sufficiently detailed overview of the conditions that apparently were necessary for life on Earth (liquid water, magnetic field, atmosphere, plate tectonics, a basic shared biochemistry, and a few others), and though he is careful to remind us multiple times throughout All These Worlds Are Yours that we should not close our minds to the possibility of other forms of life, he is realistic in the difficulty of discovering/recognizing such. After covering the famed Miller-Urey experiment (throw together some early-Earth chemicals, add some “lightning,” see what happens), he then explores in general terms the same or similar elements in non-Earth terms, discussing for instance the “habitable zone” and the amount of energy from the sun each planet receives (deciding in what may come as a surprise to readers that “there does not appear to be any point or boundary beyond which we can state definitively that the sun is too weak to support photosynthetic life”).

From there Willis moves into a detailed tour of the four possibilities within our solar system, clearly explaining the the most up-to-date science and recent discoveries regarding each planet/moon, delving, as well, into the histories and details of the various missions/probes that gave us the science. Among these are Pioneer, Voyager, Cassinni, New Horizons, and others. After going into great detail on the possible conditions for life present on each such as the presence of liquid water (covering, as well, exactly how such things have been discovered/measured), he runs through just how we might try to learn more about each planet/moon’s potential.

Willis is no starry-eyed romantic here; his “missions” are wholly grounded in reality, not simply by the laws of physics or the limitations of current technology, but also by fiscal and political reality. Nor does he ever undersell the difficulty of missions such as digging through the surface of another planet/moon or trying to fly through a moon’s geysers to take a sample of what is being expelled into space and then return the sample to Earth. He points to both past successes and failures: lost probes, successful sample returns, such as NASA’s Stardust and the Japanese Space Agency’s Hayabusa, which were able to bring back samples of comets/asteroids). One of the more interesting requirements he names is a joint lab devoted to ensuring any material brought back from space can be safely examined without risk of either contamination or, in a worst-case scenario, an Andromeda Strain-like release into our environment.

Finally, Willis leaves our solar system and offers up a nearly infinite set of possible worlds — the billions upon billions of exoplanets that we know exist out there thanks to recent discoveries via Kepler and other mostly space-based telescopes. Missions to these planets are of course impossible — the distances are simply far too great — but Willis explains how we can use better telescopes, some of which are soon to come on-line, to examine the planets’ atmospheres, which may give us some markers of life.

Willis holds off until the end to give us his own choice, neutrally and methodically laying out the pros and cons of each mission. I won’t spoil it; you’ll have to read the book to find out, which I happily recommend doing. Besides the up-to-date science clearly explained (he does a particularly nice job selecting easy-to-follow analogies to convey concepts) Willis has an engaging voice throughout that, even if it sometimes feels like he’s trying perhaps a little too hard for a light touch, carries you along smoothly through even the most complex points. I also appreciated his focus via the five options and the limited budget. Perhaps the best recommendation for All These Worlds Are Yours (a quote from a Clarke ODYSSEY novel that also earns Willis some props) is that by the very end, you want to fund all five options. And do so tomorrow. See you on Titan!