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Review: Beyond Earth


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Beyond Earth: Our Path to a New Home in the Planets
by Charles Wohlforth and Amanda R. Hendrix
Pantheon, 2016
hardcover, 320 pp., illus
ISBN 978-0-804-19797-7
US$27.95

One thing that appears to be settled, after years of debate, is where humans should go in space. There’s widespread agreement—at NASA, in Congress, among industry, and in other nations—that the long-term goal of human spaceflight is humans to Mars. There is still plenty of debate of how to get there, and what steps to take along the way, but even those who advocate for efforts like human lunar bases acknowledge that they are stepping-stones to the “ultimate” or “horizon” goal of humans to Mars.

“There’s plenty we don’t currently know about Titan,” they write. “But we do know that, if we could get there, we could live there.”

But, perhaps, that question isn’t settled. In Beyond Earth: Our Path to a New Home in the Planets, science writer Charles Wohlforth and planetary scientist Amanda R. Hendrix argue that neither the Moon nor Mars are suitable destinations for permanent human settlements. Instead, they advocate for Titan, Saturn’s largest moon, as the best place in the solar system beyond Earth for humans to live. It’s an intriguing argument, but one that doesn’t get as much discussion as it should in a sprawling book about the future of humans in space.

The case for Titan they sketch out in the book is that it has more of the resources needed to support humans than the moon or Mars: hydrocarbons on the surface, water ice below it, and a dense atmosphere. They contrast that with the Moon and Mars, seeing them as barren, irradiated worlds where resources are limited and people would likely have to live underground. “There’s plenty we don’t currently know about Titan,” they write. “But we do know that, if we could get there, we could live there.”

Getting there, of course, is the problem, and one that they largely wave away with a brief discussion later in the book of advanced propulsion technologies that—maybe, some day—shorten the travel time to Titan to reasonable lengths. (Of course, they would also make trips to Mars relatively brief by comparison.) What humans will do in space while waiting for those new propulsion systems isn’t entirely clear.

A debate about the merits of Titan versus the Moon, Mars, or other inner solar system destinations would, in and of itself, make for an interesting book. But that debate is quickly abandoned as the authors turn their attention to the various challenges facing humans in space, from exposure to radiation and weightlessness to the psychological issues of long-duration spaceflight. These are certainly important issues, but they’re issues regardless of whether you’re going to Titan or Mars.

The authors attempt to tie these issues together with a fictional account, weaved in throughout the book’s chapters, of efforts to establish a human settlement on Titan by an increasingly dystopian Earth, wracked by climate change and political strife. Those passages are predictions of the future based on reasonable extrapolations of the present, they argue, although sometimes odd or even cartoonish: at one point, it depicts a corporate-owned Titan-bound ship called the ExxonMobil Titan that hits a “well-charted space rock” shortly after Earth departure and “spilled a debris field” because its captain drank too much the night before.

The authors dismiss Musk’s Mars vision it with a wave of a hand at the end of the book, calling it “a dream of colonizing Mars that simply will not work.” It seems unlikely Musk will be convinced by that statement.

Wohlforth and Hendrix put a lot of faith into the private sector, arguing that they have the ability to break out of NASA’s stifling bureaucracy, lower the cost of space access, and make their dreams of Titan possible. Sometimes it seems they are almost uncritical in their trust of those companies: the authors tour SpaceX, and their guide is the person responsible for the second stage of the Falcon 9. “I know my stage is good,” she says when asked if she’s nervous about carrying astronauts on the rocket. This is, evidently, before the Falcon 9 launch failure last year linked to a problem with struts in the that second stage, which is briefly mentioned later in that chapter. (The pad explosion of a Falcon 9 linked again to the second stage, this time perhaps because of an issue with the fueling process, is understandably too late to make it into the book.)

But, despite their enthusiasm for entrepreneurial space ventures like SpaceX, company founder Elon Musk is fixated on establishing a permanent human presence on Mars, and has clearly put a lot of thought into it, as demonstrated by the development of his Mars mission architecture he unveiled in September. The authors, though, dismiss it with a wave of a hand at the end of the book, calling it “a dream of colonizing Mars that simply will not work.” It seems unlikely Musk will be convinced by that statement.

And why go to Titan, or anywhere else in the solar system, at all? Like so many others, the authors fall short here: a chapter titled “Why go into space?” doesn’t do much to answer the question. It discusses the life and pursuits of Carl Sagan, and concludes that a human presence off Earth answers a “spiritual need.” The chapter, strangely, then goes on to discuss issues like food production in space; an issue of how, not why.

Ultimately, Wohlforth and Hendrix try to do too much in Beyond Earth. They try to make the case for humans to Titan, versus the Moon or Mars, as well as discuss all of the issues associated with human spaceflight regardless of destination, and throw in some science fiction as well to try and tie it all together. Had they gone into more detail about why Titan was a better destination for human spaceflight than the Moon or Mars, and skipped the more general spaceflight and speculative fiction aspects, it would have been a compelling book that, perhaps, could work its way into the broader policy debates about the goals and rationales for human spaceflight. Instead it’s a broad examination of the issues facing the future of humans beyond Earth, with a particular, and peculiar, emphasis on Titan.


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