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The Sirens of Mars: Searching for Life on Another World by Sarah Stewart Johnson

The Sirens of Mars: Searching for Life on Another World by Sarah Stewart Johnson

Author:Sarah Stewart Johnson
Language: eng
Format: epub
Publisher: Crown
Published: 2020-07-06T23:00:00+00:00


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THERE WERE MULTIPLE cameras on Phoenix, the smallest able to resolve the surface structure of a grain of sand, and when they flipped on, the vista was incredible. The polar terrain stretched without end and looked like one of my grandmother’s well-loved old quilts. The patchwork ground had been broken into intersecting polygons, some a couple of meters in size. It was a gorgeous worn geometry, formed by the repeated expansion and contraction of subsurface ice. The team knew that their size was determined by the distance from the ice table. Some crinkling of the surface—shallow knolls and dips—had been seen from orbit, but when Phoenix landed, they saw “polygons within polygons within polygons,” all formed under different climatic conditions. It meant the periglacial environment on Mars was complicated and remarkably active.

After a few sols, Phoenix extended its robotic arm and began to take pictures beneath the lander. There were bright patches, cleared smooth by the exhaust of the retro rockets. And something shining in the sun, an absolutely pure white. Ice? Or perhaps salt? And there was something else that was odd in the images: bumps on the lander legs, bulbous half spheres of some substance that over the course of a few sols seemed to have merged like raindrops on a pane of glass. A team member from the University of Michigan suggested that these were, in fact, water droplets. “Obviously they came from somewhere—they weren’t there when we launched,” Smith told the press, puzzled. But the temperature had never reached anywhere near warm enough for water to be in a liquid form. It had never even topped minus 25 degrees Celsius.

When the robotic arm began to dig, it hit another white patch, and the rotating rasp at the end of its scoop started throwing out little chunks of bright material. Four sols later, the material had vanished. It had completely vaporized. “It must be ice,” declared Smith, for salt wouldn’t just disappear. In the next trench, the arm hit a hard patch and simply couldn’t dig any further. That patch, also gleaming white, was at the same depth. It was part of a layer. The scientists determined that it was indeed the ice they had come looking for, a pure reservoir, less than thirty centimeters beneath the lander legs.

Next came the analyses, the only time water had ever been directly investigated on Mars. The two main instruments, rising in metallic boxes from the deck of the lander, were called TEGA and MECA. Inside TEGA were eight tiny furnaces, which were designed to blaze forth in the polar cold, revealing the chemical nature of the constituents. When the furnace temperature reached its maximum—far hotter than that of the Viking ovens—the vapors driven out by the baking were “sniffed” by the mass spectrometer for tiny quantities of organic molecules. Delivering the samples proved harder than expected, but when the measurements were finally made, TEGA discovered calcium carbonate, the same stuff in Tums. The kind of mineral that was indicative of a watery past.



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