Book Review: "Alien Oceans: The Search For Life In The Depths Of Space" by Kevin Hand

Alien Oceans

In Kevin Hand's "Alien Oceans: The Search For Life In The Depths Of Space" we learn that Earth is just one example of a myriad ways that a world can have an ocean. And searching for life on other ocean worlds requires a combination of old tools and new approaches to using those tools.

We live on an ocean world with 71% its surface covered by a water. For all of history humans had an intrinsic bias that all inhabited worlds would have large oceans - since we do. Indeed, the large flat plains of our Moon still bear names of imaginary seas based on that bias and early telescopes. That said we held to the notion that life would arise on a world if only it had Earth's basic characteristics - one of which was large bodies of water. Well, we now know that there is more than one way to have a planet with lots of liquid water.

As we reached out into our solar system we began to discover that our world is not the only ocean world. There are many others - moons orbiting the large gas giants in the outer solar system have subsurface oceans covered by a thick ice cover. Worlds like Ceres may once have had liquid water and the Pluto/Charon system may harbor underground oceans as well. Saturn's Moon Titan has hydrocarbon lakes on its surface and may well have a watery ocean below - in other words two separate oceans.

And as we have studied our own planet's history we have discovered that it may also have had long periods when its oceans were also covered with ice - the so-called "Snowball Earth" scenario. For hundreds of millions of years Earth looked more like a moon of Jupiter or Saturn - not the verdant green and blue orb that we see today. But despite all of that ice, life on Earth persisted.

In addition to starting to learn that oceans may be common across our solar system (and one would assume other solar systems) we also discovered - at the same moment in the 1970s - that our own global ocean contains life forms miles below the surface. Located near hydrothermal vents such life was heretofore thought to be improbable - if not outright impossible. We soon learned that the conditions wherein these ecosystems thrive are analogous to what we expect to exist within these alien oceans. Indeed life on Earth may have arisen in such locations. As different as Earth may be from other ocean worlds, in many ways, it is also very much alike.

This where people like Kevin Hand come in. Kevin is a physicist/engineer/explorer who works for NASA JPL building space missions that search for life. I first met Kevin at a conference on Mars exploration in the late 1990s when he was still in college. He soon popped up at the Astrobiology Academy at NASA Ames and has managed to grab onto one research experience after another over the past 20 years. Kevin has visited abyssal ocean depths with James Cameron, searched for life in Antarctica, and now strives to build a mission that will land on Jupiter's icy moon Europa to search for evidence of life in the ocean below.

"Alien Oceans" is an introductory primer to how to search for life in weird places on Earth and on other worlds as well. Kevin gives us the basics as to what life is and is not so as to describe the various tools that let us detect it directly or, as is often the case, indirectly. Once we know how to look for life and what to look for comes the hard part: shrinking everything down to a small package that you can send somewhere.

Given that the whole space mission thing is time consuming, risky, complex and very very expensive, you need to pick the places where you have a good chance of actually learning something. Kevin provides a solar system tour of various moons and planets so as to lay out a menu of choices.

NASA has had some stunning success in landing on strange worlds which could provide answers to the prevalence of life beyond Earth. It has flown past and orbited many other worlds, and has discovered even more worlds circling other stars - some of them very similar to Earth. We have been looking for life elsewhere, armed with science, for a century - and in earnest with space missions for half a century. Despite a deluge of data we have not found another example of life - yet.

While people would be forgiven for assuming that NASA is only interested in searching for life on Mars, many scientists suspect that if we find it, that we will only find evidence of past life. But we have still only scratched the surface - literally - on Mars.

Many now think that worlds such as Europa, Enceladus, Titan - and perhaps Ganymede, Ceres, Triton, and Pluto may offer a chance to find existing life. Such is the overall focus of "Alien Oceans" - what questions do we need to ask and how can we answer them?

Most of this exploration of other worlds will be done by robots - astrobiology droids - for the foreseeable future. The way in which they are constructed and operated has more to do with the way that humans explored our world than with electronics or robotics. While these droids may operate at super cold temperatures, in a near vacuum, under the onslaught of heavy radiation, humans will be at the heart of where they go and what they do. And they will have the heart of explorers albeit vicariously.

This whole exploration mindset is why people like Kevin Hand are so necessary for these missions. He has been to improbable places - at risk to his own life - and has managed to conduct science while not passing on the chance to drink in the awe and wonderment of being there. This book is laced with that unfiltered enthusiasm and awe for what we have learned, what we are learning, and what lies ahead.

Highly recommended.

"Alien Oceans: The Search for Life in the Depths of Space" by Kevin Hand

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