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Two candid accounts consider the history and future of life on Mars

The Sirens of Mars: Searching for Life on Another World

Sarah Stewart Johnson
288 pp.
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Once Upon a Time I Lived on Mars: Space, Exploration, and Life on Earth

Kate Greene
St. Martin's Press
240 pp.
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Aside from Earth, Mars is the most thoroughly explored planet in our Solar System. The improbable enterprise of studying a world millions of miles away—the impetus for which arose during the Cold War space race between the United States and the Soviet Union that sent a series of robotic flybys, as well as a number of orbiting and lander missions, to the Moon and planets—has even more improbably evolved to become a thriving international activity marked by both competition and collaboration.

This month, while Earth and Mars align for a favorable launch window, three missions are setting off to our red neighbor. In the United States, NASA’s Mars 2020 rover, now named Perseverance, is set to become the fifth U.S. rover to explore Mars. Perseverance is headed for the Jezero crater, a site believed to have once been a large and long-standing lake, where orbital data point to the presence of clay deposits and where scientists hope to find sediments carried through channels by flowing water. This latest rover will not only study the surface features around its landing site but will also drill and collect samples that later missions will hopefully retrieve and send back to Earth, where scientists will use them to try to determine whether life ever took off on the red planet.

Meanwhile, the United Arab Emirates’ Hope Mars mission lifts off from Japan to study the martian atmosphere, the UAE’s first such mission, and China is making a second attempt at a Mars mission with the Tianwen-1 Mars Global Remote Sensing Orbiter. The Chinese spacecraft carries a small rover in tow, hoping to follow up on the success of the Chang’e 3 and 4 lunar missions, which carried the Yutu and Yutu-2 rovers, respectively, to study the surface of the Moon. Missing from the pack will be the ExoMars Rosalind Franklin rover, a joint effort by the European Space Agency and Russia’s Roscosmos, whose journey has been pushed back to 2022 because of an already tight engineering and testing schedule compromised by the coronavirus disease 2019 (COVID-19) pandemic.

We have had rovers and landers operating on the surface of Mars continuously for the past 16 years and orbiting spacecraft for even longer. Still, the excitement surrounding the launch of a new Mars mission captures our collective attention. And it is during these roughly year-long periods of heightened awareness of our red neighbor, which last from the launch run-up through the first few months after landing, that general audiences seem primed to consume new books about Mars.

In response, a particular type of book—the “Mars book”—has proliferated. Unlike scholarly histories, ethnographies, or sociological studies of the planet’s exploration or scientific texts about what has been found there (all of which have also multiplied), the Mars book is not necessarily concerned with engaging the reader in the great discoveries made on Mars or the marvels of engineering that make planetary exploration possible. Instead, it considers these facts and feats in the context of a larger question: Why explore Mars in the first place?

At their best, Mars books convey a level of enthusiasm about exploration and the production of knowledge that is difficult to find in their more academic counterparts. Two new Mars books published to coincide with the 2020 launch window succeed in this endeavor: Sarah Stewart Johnson’s The Sirens of Mars and Kate Greene’s Once Upon a Time I Lived on Mars. Although very different from each other, these books have at least two things in common: Both were written by accomplished women whose experiences will help define what happens next in the human story of Mars, and both answer the “why explore Mars” question in very personal terms.

The Sirens of Mars bills itself as a history of Mars exploration. Johnson, a planetary scientist, delivers a well-curated chronology of previous eras of Mars exploration and recounts the stories of those who were called by some strange and indescribable impulse to pursue the secrets of Mars, all in some of the most eloquent prose yet applied to the topic. Her account is more of a lineage than a history, however.

Johnson’s career has put her at the center of many of the major discoveries made by the Mars rovers, and she has dedicated much of her life to understanding what types of microbes might be able to survive on the red planet. The people she describes in her book are kindred spirits—some are from other eras, peering at the same fuzzy red disk through observatory telescopes or from hot-air balloon gondolas, and others are contemporaries working alongside her in university laboratories or in far-flung field sites.

At one point, Johnson describes a box of papers and ephemera from the history of planetary exploration that she keeps in her Georgetown University laboratory, all of it connected to the history she includes in the book: “I return to this collection again and again, with its crinkled pages and old-fashioned fonts, hand-drawn figures and hand-labeled graphs,” she writes. “I’ll pull it down when I’m there by myself, running a script or waiting for an experiment to finish. Even though much of the science these documents postulate is not correct, or at least not entirely correct, in them I can see the great strides forward, the longing for answers.”

Johnson herself appears infrequently in the book’s early chapters, in brief interludes where the reader is offered glimpses of her family and her childhood in a small town in Kentucky. These moments construct Johnson’s early biography, her personal connections and priorities, and the roots of her passion for math and science, but I sometimes struggled to see her perspective in the historical passages about Mars. The story really begins to shine as we encounter Johnson the scientist, the participant in history, as she recounts what it has been like to be among the first women to explore Mars, and among the first cohort of planetary scientists to incorporate the still-new biology of terrestrial extremophiles. Here, the excitement and occasional crushing disappointment of Mars science become personal.

Mars may be the most explored planet, but it nonetheless remains a place filled with many unknowns and uncertainties. Our successive missions there have not only added new knowledge about the planet, in some cases they have overthrown older findings and replaced them with more complicated questions about the planet’s past. The Jezero crater landing site may hold enough secrets, or new mysteries, for Johnson to write a second Mars book. I hope that she does.

In Once Upon a Time I Lived on Mars, Kate Greene offers readers a glimpse into her experience as a member of the first “crew” to live in the Hawai‘i Space Exploration Analog and Simulation (HI-SEAS), a facility designed to mimic the conditions of a human mission to Mars. Rather than a memoir of her time in the HI-SEAS habitat or a detailed history of the project, the book is a collection of reflective personal essays.

Greene and seven other volunteers lived for 4 months, from April to August of 2013, in a habitat on the remote volcanic slopes of the Mauna Loa volcano. Much of what she explores in her essays is perhaps, at this particular moment in time, more relatable to readers than she could have anticipated at the time of their writing. She describes in great detail, for example, the persistent and elusive problem of boredom among astronauts living in isolation. Reading this book during the COVID-19 pandemic while confined at home, it was easy for me to wonder whether the monotony of life during social distancing might be making me less aware of my surroundings and more prone to mistakes, as it did Greene and her cohort. (The challenge of developing procedures for safely leaving and reentering one’s habitat was similarly resonant.)

Greene’s essays range beyond the problems that NASA and other space agencies are attempting to work through in these simulations. But even when she writes about her marriage, her brother’s long-term illness, or other aspects of her life outside of HI-SEAS, each essay connects back to her time in the habitat and the more universal concerns surrounding space travel. How will we live with only the same few people for years on end, for example? How will our bodies hold up to long-term weightlessness and radiation? Which bodies are best suited for space?

In June of this year, we witnessed the first U.S. commercial launch of astronauts to the International Space Station and the much-anticipated return to crewed launches from U.S. soil as NASA promotes its plan to send humans first to the Moon and then on to Mars. At the same time, protests in cities across America and around the world emphasized the fact that many of the political and social problems that surrounded the 1969 Apollo 11 mission to the Moon remain unresolved. Although Greene was not writing about this present moment, one can imagine that she had something similar in mind when she reflected on the possibility of marrying equality and inclusion with the aspiration to inhabit other worlds: “All of it makes me wonder what would happen if the voices of those who traditionally haven’t had the money or the power were louder in this conversation about getting to Mars,” she writes. “And if they held that megaphone, what would they say? If more ears were tuned to listen, what could be heard? A story of human space exploration that transcends nationalist pride, capitalist power, and ordinary ego? Where might that take us?”

About the author

The reviewer is a space history curator at the National Air and Space Museum, Washington, DC 20560, USA.