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Vast stores of water ice surround Martian equator

Vast stores of water ice surround Martian equator

Ice glaciers hundreds of metres deep are lurking just underneath the Martian surface around the planet's mid-latitudes, new radar measurements suggest. from New Scientist

The discovery represents the largest cache of ice yet found beyond Mars's polar regions and bolsters the case that the planet's tilt changes periodically. The ice could also be an ideal place to study the ancient Martian climate and look for evidence of life.

The glaciers, found at latitudes between 30 and 60° in both the northern and southern hemispheres, sit underneath fields of rocky debris. The appearance of the landscape suggests the debris flowed from hills lying up to 20 kilometres away.

Mars researchers have debated the origins of these rocky fields, which are called 'lobate debris aprons.' Some suspected that small particles of ice condensed from atmospheric water vapour between rocks and dust; this ice could lubricate the material, allowing it to flow down slopes. Others suggested the rocky aprons actually hid large glaciers.

"There's been this debate about what's inside," says John Holt of the University of Texas at Austin. To investigate, Holt and colleagues used radar aboard NASA's Mars Reconnaissance Orbiter to probe the aprons around hills and mountains in the mid-latitude regions of Mars.

Tilting axis

Most of the radar signal bounced off the ground, but some reached though the upper layer of rock to bounce around the interior of large ice deposits. The deposits in Mars's eastern Hellas basin alone contain an 800-metre-thick glacier and hide 28,000 cubic kilometres of water ice - enough to coat the entire planet with a layer of water 20 cm thick.

The glaciers likely formed during a time when Mars's pole pointed more towards the Sun, says co-author James Head of Brown University in Providence, Rhode Island. Because Mars lacks a massive moon that can stabilise its tilt, the planet is thought to wobble dramatically every 120,000 years or so.

When its poles were tilted more towards the Sun during one such wobble, the more intense sunlight could have heated ice at the poles. That caused the ice to sublimate into the atmosphere and then condense down into solid ice again in areas near the equator - which at that time were colder, Head says. Rocky debris from nearby slopes then fell on the icy deposits.

Insulating layer

Over time, the upper layer of ice vaporised into the thin Martian atmosphere, concentrating the rocks so they formed an insulating layer. These rocks prevented the glacier from melting entirely when the Sun once again drenched the mid-latitude regions.

"It's kind of like the Hotel California. The ice checks in but it doesn't check out. It doesn't go back to the poles," Head told New Scientist. "[The deposits] tell you that significant amounts of water vapour can be transported from the poles to the mid-latitudes and that some of it - a lot of it - is still there."

The relatively warm weather could make the mid-latitude glaciers an ideal site to explore on future Mars missions.

Like glaciers in Antarctica's Dry Valleys, the ice deposits could hold gas bubbles that could reveal what the Martian atmosphere was like in the past, allowing researchers to build up a better picture of the planet's past climate, Head says. The ice could also preserve evidence of life.

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So, I read today that the designer of Mattel's Barbie doll was obsessed with sex. Seriously? We need a book-length study to tell us that?

We in the land of feminist academics have been teaching the pernicious sexual politics of Barbie for years. The breasts that defy gravity, the hair, the long, long legs and of course the cruel, nipped in waist. Oh, don't forget the tiny clothes, the f*ck-me pumps, not to mention the well-equipped kitchens in every Barbie Dream House. The message of Barbie seems unambiguous to me.

Still, many students (and not a few colleagues) consistently resist seeing Barbie as a miniature sex toy, claiming instead that the doll was a good role model for little girls. (One could, after all, purchase a Barbie doll dressed as a doctor.) Or claiming, equally untenably, that toys had no impact on their ideas about gender roles or their own sexuality.

These students, mostly women, want to rescue Barbie, to protect their own childhoods from academic interrogations of pop culture and what those interrogations might reveal. That's understandable. Yet, many of these same students sit in my class pouring out of tank tops, squeezed into low-rise jeans, or tugging on mini-skirts so short they are nearly impossible to sit down in. That is, dressed like Barbie.

It's an experience I regularly have as a feminist critic of popular culture: a media event, book or news story demonstrates that I'm not wrong, my ideology is not based in "over analyzing," "hyper sensitivity," or "reading too much into things" (the three most common criticisms feminists tend to encounter). It's disappointing, frankly, to stumble so often upon evidence of society's sexism and to keep having to explain that it's there. Disappointing that Barbie was so obviously a sexed-up, misogynist, bad idea for little girls and to realize how thoroughly our culture embraced the toy anyway.

So, here we are again. Feminists were right: no one but a sex-obsessed man with a perverse idea of female anatomy would create a female toy like Barbie. And, as is too too often the case for feminists, being right isn't something to celebrate.

Dr. Bean is an Associate Professor of English at Marshall University, specializing in Gender Studies, Film and Drama. She is the author of "Post-Backlash Feminism: Women and the Media Since Reagan/Bush" (McFarland & Co. 2007). She hosts a blog on mid-life and feminism at kelliebean.com.