This article is an adaptation of our weekly Science newsletter that was originally sent out on March 17, 2021. Want this in your inbox? Sign up here.
By Victoria Jaggard, SCIENCE executive editor
A popular running joke among space reporters is that we find water on Mars every few months. It’s become such a ubiquitous headline in part because we keep finding water in new places on the red planet thanks to the many, many robots we’ve sent there to explore. There’s water in the atmosphere, frozen in the polar ice caps, locked in hydrated minerals on the surface, and perhaps even buried in underground reservoirs. And NASA’s motto for a long time has been to follow the water, since the stuff is so vital to life as we know it.
But what happens when some of the water on Mars goes missing?
More technically, it has been a long-standing mystery how Mars went from a wet planet covered in lakes, rivers, and maybe oceans billions of years ago to the arid ball of dust we see today. The usual story based on available evidence was that at some point Mars lost its magnetic field, allowing radiation from the sun to start stripping away lots of its atmosphere. Any liquid water merrily burbling over the surface then evaporated and eventually escaped into space. But as Robin George Andrews reports for us this week, that story has a few plot holes, including the fact that our best measurements for the rate of escape don’t add up to enough liquid to explain the planet’s many water-carved features and water-bearing rocks.
That’s why Caltech’s Eva Linghan Scheller and her colleagues decided to look at another avenue for water loss: mineral lockup. Their new model suggests that anywhere between 30 percent and 99 percent of the past water on Mars is now squirreled away in the form of hydrated minerals throughout the planet’s crust. That finally gives scientists enough of the liquid to explain other clues to Mars’s watery past. “This paper allows for the possibility of a once-blue Mars, even for a short period of time,” planetary scientist Paul Byrne tells us.
The paper is also a really stark reminder of how lucky we are to call Earth home. Water gets lost to hydrated minerals here, too, but we have active plate tectonics, which constantly reuses and recycles all that life-giving H2O. As Shannon Stirone recently pointed out in the Atlantic, modern Mars is a hellhole, and while it’s a fun place to visit, most of us probably don’t want to live there. (Pictured above, a mosaic of the Valles Marineris hemisphere of Mars.)
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TODAY IN A MINUTE
The mystery of the floating feet: 21 human feet washed up on shore in the Pacific Northwest, many of them from the Salish Sea (part of which is pictured above). Most of the limbs were encased in sneakers. It took years—and science—to determine that a limb-severing serial killer was not involved, writes Erika Engelhaupt for Nat Geo.
New faces: How can science pursue the best avenues of inquiry if all the scientists come from a similar background? “At one social event, I was told that I should tolerate sexism and keep my experiences with microaggressions silent if I wanted a successful scientific career,” writes computational biologist Robin Aguilar for Nature. Aguilar, who is transitioning, says open-mindedness to diversity, and broader representation, is key.
Fake news, 1910 style: There also was an “infodemic” of misinformation about the return of Halley’s Comet 111 years ago that might offer lessons for us today. That’s what Scientific American writes. People knew widely back then that the comet orbited within our solar system. Yet many saw it as an agent of our demise, convinced that we would die from chemicals in the comet’s tail. Um, nope.
How recycling works: This step-by-step look at a recycling plant by Nat Geo Kids has insights for grown-ups as well. Case in point: America recycles 67 million tons a year. Check out the Richard Scarry-like illustrations by Clayton Hanmer.
INSTAGRAM PHOTO OF THE DAY
Accompanied by the northern lights: On a Europe-bound flight from Seattle, passengers and crew got to see the polar lights for more than four hours. The clear sky and 38,000-foot altitude made the polar lights appear brighter and more intense than on the ground, photographer (and pilot) Jan Scheruhn tells Nat Geo’s Jen Tse. “They seemed almost touchable,” says Scheruhn, who captured the light, coupled with the slow rise of a full moon over the Labrador Sea. From the cockpit, he has seen the Milky Way without light pollution, meteors glowing in Earth’s atmosphere, and red sprites above a thunderstorm cloud.
Glow, hiss, and pop: The weird sounds from an aurora
THE NIGHT SKIES
Moon, meet Mars: On Thursday night, look for the waxing crescent moon posing with the Pleiades star cluster. By Friday night the moon will slide next to Mars. Both worlds together will make for a dazzling sight to the naked eye. As a sky-watching bonus, look for the bright orange star Aldebaran forming a neat triangle formation with the moon and Mars. On Sunday the quarter moon will have moved toward the eastern sky, appearing nestled within the constellation Gemini, the twins. Binoculars will reveal another beautiful open star cluster known as Messier 53. Sitting about 3,000 light-years away, it contains more than 120 stars huddled together. — Andrew Fazekas
THE BIG TAKEAWAY
The brutal bottom line of air pollution: Simply put, “the more there is, the shorter the lives of those who breathe it,” writes Beth Gardiner in the April issue of National Geographic. Globally, we’re talking seven million premature deaths a year. More than 45 percent of Americans still breathe unhealthy air, Gardiner writes, a half-century after the Clean Air Act. A related story shows how the Clean Air Act helped Los Angeles and the rest of the United States. (Pictured above, a two-year-old girl is treated in a hospital specializing in pneumonia and lung disease in Ulaanbaatar, Mongolia, which has some of the world’s worst air pollution. Below left, in Delhi, India, street fires contribute to the pollution; at right, concern about pollution led Shashawnda Campbell, seated in front, and fellow youth activists in south Baltimore to help defeat plans to build an incinerator nearby.)
IN A FEW WORDS
As the first scientist in my family, I didn't have a scientist role model I could relate to when I was little. Somebody that looked and spoke like me. So I'm thrilled that voices are getting amplified. Because representation drives change, and diversity inspires innovation.
Rosa Vasquez, Biochemist; Nat Geo Explorer, From: ‘So now I honor nature through science’
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THE LAST GLIMPSE
Fast work: When a rocky shard fell from the sky over England a few weeks ago, meteorite-tracking cameras caught the fireball, and scientists swiftly recovered one piece (pictured above) from a driveway and another from a field full of sheep droppings. The fragments come from a relatively rare type of meteorite. They contain the building blocks of planets, but also compounds that may help explain how Earth got its water. “This is like the magic type of meteorite that lots of people are completely fascinated by,” meteorite expert Katherine Joy tells Nat Geo.
This newsletter has been curated and edited by David Beard, with photo selections by Jen Tse. Monica Williams and Gretchen Ortega helped produce this. Have an idea or a link? We'd love to hear from you at david.beard@natgeo.com. Thanks for reading, and have a good week ahead.
