Learn about back pain from space; how cats track their owners; and what davemaoite tells us about Earth’s lower mantle.
Learn about back pain from space; how cats track their owners; and what davemaoite tells us about Earth’s lower mantle.
Space travel causes back pain, and doctors need to find a fix by Cameron Duke
Cats track their owners with mental maps by Cameron Duke
Scientists found a once-theoretical mineral inside a diamond that tells us more about the Earth's lower mantle by Grant Currin
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CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from Discovery. I’m Cody Gough, and I’m your host today. Ashley’s back tomorrow. Today, you’ll learn about why space travel causes back pain; how cats track their owners’ movements; and a mineral that scientists found inside a diamond that tells us more about the Earth’s lower mantle.
Let’s satisfy some curiosity.
If your back hurts, it could be because you hurt yourself or because you’re getting older. Or… maybe you’ve been to space! A new report from Johns Hopkins University found that back pain is surprisingly common in astronauts. It’s one more way that leaving the comfort of Earth’s gravity appears to be bad for the human body.
So let’s talk about what I mean when I say “bad.” The review looked at data from 722 space flights and found that roughly 52 percent of astronauts report back pain within the first two to five days of arriving in orbit. 52 percent!! It’s so common that it even has a name: “space adaptation back pain.”
Given the high-level performance expectations from every member of an ISS crew, this condition poses certain risks. Although the pain is relatively minor most of the time, it’s a common enough problem to cause concern.
As for WHY this happens: our bodies are very well adapted to being on Earth, and Earth’s gravity is a big part of that. Our spines are finely-tuned to hold our bodies upright against forces that would pull us down. Our weight compresses our spines into a natural curve on Earth, but in space, we’re not under that kind of force.
Without those stresses, our spines stretch out — and our bodies in general. Astronauts who spend significant lengths of time in orbit grow by roughly three inches, or 7 and a half centimeters because of this. That growth spurt comes at a cost: our spines straighten as they stretch.
This is not as good of a thing as it sounds, though. The natural curve of our spines allows them to act as a shock absorber when we walk.
Astronauts have been fighting the effects of microgravity ever since the dawn of the space age. For example, daily resistance exercises help to keep their muscles and bones from withering away in the low-gravity environment.
But none of this seems to be a great substitute for the effects of good ‘ol gravity itself. So what if we brought gravity to space? The researchers say that one way to do that would be to use centrifugal forces, the kind you might see in the spinning spacecraft of science fiction. More practically, they suggest designing special spinal compression suits that maintain constant pressure on the shoulders and hips. But when similar devices have been tested, astronauts have complained that they reduce range of motion and flexibility. So the hunt for a good solution is still ongoing.
But hey! Nobody said going to space was easy.
Cats are very good at hiding from humans — if they don’t want you to know where they are, you won’t. But it turns out we’re not as good at hiding from cats. A recent experiment found that cats use sound to create a mental map that tracks their owner’s location, which suggests there might be a lot more going on in the feline mind than previously thought.
The experiment took place in a lab at Kyoto University in Japan. The researchers used 50 felines that were either house cats or lived at cat cafes. Each cat was placed in a room with two loudspeakers hidden behind doors or windows on opposite ends of the room.
One of the speakers — like the one behind the door, for example — would play a recording of either the cat’s owner or a stranger saying the cat’s name. The cat might look toward the door, or, more likely, do nothing. If the owner’s voice played a second time from the same direction, the cat would continue to act completely aloof.
But when the same voice was projected from the opposite side of the room, the cat seemed to take notice. Their ears would perk up in surprise upon hearing their owner’s voice coming from an impossible direction, as if they had teleported from one place to another.
The researchers say that this suggests something really special about cats. They argue that cats make mental maps of their surroundings based on audio cues. When they would hear their owner’s voice come from a particular direction, they would place their owner on a mental map in that direction. They wouldn’t be surprised if the next voice they heard came from the same location. But the cats were surprised when the second cue disagreed with their mental map.
This shows that cats have a sense of object permanence, or an awareness of objects existing even when they can’t see them. It’s an ability that humans don’t even fully develop until we are eight to twelve months old. We’ve seen it in cats before, along with other non-human animals like primates, bears, dogs, and Eurasian jays. But this is the first time scientists have demonstrated that cats can use audio cues, not just visual cues, to track the location of a hidden object.
In this case, it should be called object purrrrmanence.
Workers at a diamond mine in Botswana recently uncovered a gift from deep in the Earth. It was a quote-unquote “flawed” diamond that contained a mineral scientists had never seen before. They’d suspected that it existed — and now they finally have proof, it’s helped us learn more about the Earth’s lower mantle.
As you might expect, it’s really hard to directly observe things that are thousands of miles below the Earth’s surface. I mean, the deepest hole humans have ever dug is just over 7 and a half miles, or 12.2 kilometers. Anything that lies deeper than that is usually out of our grasp. That’s a shame because things are very interesting in the deeper parts of the planet, where the weight of Earth bears down with incredible force. The high pressure there protects delicate minerals that can’t exist up here on the surface.
This new mineral is dubbed davemaoite, after a famous high-pressure geophysicist named Ho-kwang (Dave) Mao. And long before the mineral was found, scientists had predicted its existence in laboratory experiments. They think davemaoite accounts for about 6 percent of Earth’s lower mantle, which itself accounts for more than half the planet’s volume. At some point a long time ago, a tiny piece of it was trapped inside a diamond as it formed. Diamond is tough stuff, so it managed to hug the mineral tightly enough to keep its crystal structure from rearranging as it ascended from as deep as 1700 miles under the surface. That’s a journey of 2700 kilometers.
Like I said, geologists have never seen the lower mantle, but they can infer a lot based on their knowledge of matter, pressure, and Earth itself. Researchers can also collect evidence by subjecting minerals to very, very high pressure and seeing what happens. But the diamond-encased fleck of davemaoite shows there’s no substitute for the real thing. Experiments had led most researchers to think davemaoite was almost pure calcium silicate perovskite. It turns out the real thing contains a lot of potassium.
Davemaoite wasn’t the only high-pressure treasure sealed inside the diamond. It also contained a super-compact type of ice and a mineral called wüstite. The sample also contained clues that could help researchers figure out where on Earth — make that where in the Earth — they can find deposits of the radioactive elements that seem to be keeping the inside of our planet toasty warm. This all goes to show that what they say is true: diamonds are a geophysicist’s best friend. Some friend.
Let’s recap the main things we learned today
[ad lib optional]
CODY: Today’s writers were Cameron Duke and Grant Currin. This episode was produced and edited by me, Cody Gough. Curiosity Daily is distributed by Discovery.
[AD LIB SOMETHING FUNNY] join us again next time to learn something new in just a few minutes.
And until then, stay curious!