suffered from confirmation bias. Thatâs what got her into trouble twenty years ago, a fervent belief that had swayed her thinking and muddied her scientific objectivity. And despite all the damage it had caused, she still clung to this belief. She hadnât learned a damn thing from her mistakes.
*Â Â Â *Â Â Â *
Sarah had been a different person back then: more outgoing and fun-loving, less wary and introspective. After getting her Ph.D. from Cornell at the precocious age of twenty-six, she landed a plum job at NASAâs Johnson Space Center in Houston. Better still, she returned to Texas with the man she loved, a fellow researcher sheâd met at Cornell. Heâd also landed a job at NASA, and they got engaged a month after they started working there.
It was 1996 and NASA was laying the groundwork for the planetary rovers it would send to Mars over the next fifteen yearsâSojourner, Spirit, Opportunity, and Curiosity. To determine which scientific instruments to put on the rovers, the agency assigned Sarah to study the best evidence of Martian geology it had: meteorites that had traveled from the Red Planet to Earth. Every million years or so, an asteroid hits Mars with such force that the explosive impact blasts rocks off the Martian surface and hurls them into space. After orbiting the sun for eons, some of the rocks get sucked in by Earthâs gravity and land intact on the surface. Sarahâs boss gave her one of these meteorites to study, a rock that had been ejected from Mars fifteen million years ago. Her task was to slice the meteorite into sections and use a powerful microscope to observe its crystalline structure.
At first the observations baffled her. The rock had crystallized from Martian lava during an era when the Red Planet was covered with oceans. In the cracks and pores of the meteorite Sarah found tiny globules of carbonate minerals that had most likely formed after water seeped into the rock. And within those globules she found even tinier structures that looked like rice grains and segmented tubes. She showed the microscope images to some of her colleagues and friends, hoping one of them might know what could have created the odd features. The answer came from another NASA researcher, Tom Gilbert, who had expertise in astrobiology and also happened to be Sarahâs fiancé. He said heâd seen similar structures inside rocks found on Earth. They were the fossilized remains of ancient bacteria.
The next month was a frenzy of activity. Sarah gathered her evidence and showed it to her bosses. She spent months writing the research paper, carefully choosing her words. She couldnât say whether life still existed on Mars. Even if those tiny tubes were indeed fossils of microorganisms, the primitive creatures had probably gone extinct after the planet became drier and colder. But it was a momentous discovery nonetheless. It showed that Earth wasnât unique. Life could develop on many worlds across the galaxy.
NASA scheduled a press conference to announce the results. Unfortunately, someone leaked the news beforehand, and dozens of reporters flocked to Johnson Space Center. Sarah was delighted by all the attention, but when she came to the podium to answer the journalistsâ questions she spoke a bit too impetuously. She said the evidence for past life on Mars was clear and convincing. âWe now have proof that weâre not alone,â she declared. âExtraterrestrial life is probably so abundant that weâre bound to see more of it soon.â
The reaction was swift. When a twenty-six-year-old researcher makes such sweeping statements and receives so much attention from the media, it can irritate people whoâve spent decades investigating the topic. Several scientists argued that the minuscule tubes inside the Martian meteorite werenât all that similar to the microfossils of Earth bacteria. Other researchers noted that ordinary
*Â Â Â *Â Â Â *
Sarah had been a different person back then: more outgoing and fun-loving, less wary and introspective. After getting her Ph.D. from Cornell at the precocious age of twenty-six, she landed a plum job at NASAâs Johnson Space Center in Houston. Better still, she returned to Texas with the man she loved, a fellow researcher sheâd met at Cornell. Heâd also landed a job at NASA, and they got engaged a month after they started working there.
It was 1996 and NASA was laying the groundwork for the planetary rovers it would send to Mars over the next fifteen yearsâSojourner, Spirit, Opportunity, and Curiosity. To determine which scientific instruments to put on the rovers, the agency assigned Sarah to study the best evidence of Martian geology it had: meteorites that had traveled from the Red Planet to Earth. Every million years or so, an asteroid hits Mars with such force that the explosive impact blasts rocks off the Martian surface and hurls them into space. After orbiting the sun for eons, some of the rocks get sucked in by Earthâs gravity and land intact on the surface. Sarahâs boss gave her one of these meteorites to study, a rock that had been ejected from Mars fifteen million years ago. Her task was to slice the meteorite into sections and use a powerful microscope to observe its crystalline structure.
At first the observations baffled her. The rock had crystallized from Martian lava during an era when the Red Planet was covered with oceans. In the cracks and pores of the meteorite Sarah found tiny globules of carbonate minerals that had most likely formed after water seeped into the rock. And within those globules she found even tinier structures that looked like rice grains and segmented tubes. She showed the microscope images to some of her colleagues and friends, hoping one of them might know what could have created the odd features. The answer came from another NASA researcher, Tom Gilbert, who had expertise in astrobiology and also happened to be Sarahâs fiancé. He said heâd seen similar structures inside rocks found on Earth. They were the fossilized remains of ancient bacteria.
The next month was a frenzy of activity. Sarah gathered her evidence and showed it to her bosses. She spent months writing the research paper, carefully choosing her words. She couldnât say whether life still existed on Mars. Even if those tiny tubes were indeed fossils of microorganisms, the primitive creatures had probably gone extinct after the planet became drier and colder. But it was a momentous discovery nonetheless. It showed that Earth wasnât unique. Life could develop on many worlds across the galaxy.
NASA scheduled a press conference to announce the results. Unfortunately, someone leaked the news beforehand, and dozens of reporters flocked to Johnson Space Center. Sarah was delighted by all the attention, but when she came to the podium to answer the journalistsâ questions she spoke a bit too impetuously. She said the evidence for past life on Mars was clear and convincing. âWe now have proof that weâre not alone,â she declared. âExtraterrestrial life is probably so abundant that weâre bound to see more of it soon.â
The reaction was swift. When a twenty-six-year-old researcher makes such sweeping statements and receives so much attention from the media, it can irritate people whoâve spent decades investigating the topic. Several scientists argued that the minuscule tubes inside the Martian meteorite werenât all that similar to the microfossils of Earth bacteria. Other researchers noted that ordinary
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