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Metro Science: Astronauts' back problems, oceans on Mars, and fake news from space

Your most interesting science stories of the week.

Japanese astronaut Norishige Kanai, a member of the main crew to the International Space Station (ISS).

Dmitri Lovetsky / AP POOL

Japanese astronaut Norishige Kanai, a member of the main crew to the International Space Station (ISS).

DECODED: Why do astronauts get taller in space (but not 9 cm taller)?

This week, Japanese astronaut Norishige Kanai tweeted a truly tall tale from the International Space Station: He’d grown 9 centimetres during one month in orbit. That turned out to be too out-of-this world to be true. He’d measured wrong, and was actually just 2 cm taller than his Earth height — normal in microgravity, but enough to cause the back problems many astronauts suffer. In fact, new science shows surprising things happen to the spine in space.

Under normal gravitational conditions on Earth, the lower (lumbar) back holds up about half the body's weight. That load puts healthy stress on muscles that wrap around the spine, particularly one called multifidus, and keeps them strong. The force of gravity and the structure of the muscles give the spine its natural shape: slightly curved, in the shape of an S.

In space, where astronauts experience about 10 per cent less gravity, the muscles around the spine shrink from disuse, and, with less gravitational force on it, the back straightens, increasing height by up to 6.6 cm. Previous theories assumed the soft disks between our backbones expand under microgravity. Kanai even mentioned this in his tweet. But recent MRI and ultrasound studies have found no evidence it's true.

Science story: Blue on the red planet

Erosion has exposed sheets of water ice on the Red Planet.

JON WADE / AFP

Erosion has exposed sheets of water ice on the Red Planet.

If future astronauts get thirsty on Mars, they might be in luck. Erosion has exposed sheets of water ice on the Red Planet, starting one to two metres underground and extending hundreds of metres down. It may have originally fallen as snow, and could be useful for future manned missions. Whether it contains any signs of life is TBA. 

Science story: That's dark

Some male birds of paradise have “superblack” feathers.

Some male birds of paradise have “superblack” feathers.

Some male birds of paradise have “superblack” feathers that absorb 99.95% of light. It’s thought to make the other colours pop, attracting mates.

Sound Smart: Your science vocabulary word for the week

Andres Plana

DEFINITION: In biology, diurnal means during the day. It’s the opposite of nocturnal.

USE IT IN A SENTENCE: Deborah’s diurnal goat yoga routine is annoying the neighbours.

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