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Science notes / Physiology, astronomy

Armor took a heavy toll

Note to aspiring knights in shining armor: Make sure to tuck a few Clif bars into your cuirass. According to a study by Graham Askew, a University of Leeds-based physiologist, medieval warriors expended a lot of energy trucking across the battlefield in their plated mail. Obviously.

But Askew thought it would be "interesting to get figures." So he recruited a group of historical interpreters -- guys accustomed to charging around in iron pants -- and placed them on treadmills, using a respirometer to measure how much air they were sucking in and, therefore, how much energy they were expending. Turns out, it's nearly twice as much as when wearing their casual duds. And interestingly, they used more energy than they did when carrying a suit-of-armor's worth of weight in a backpack.

"A suit of medieval armor loads the lower limbs," Askew writes. "You have 7 or 8 kilos -- 15 to 18 pounds -- of armor on the legs, so when you swing your legs, your muscles are having to do much more work." The study was published in Britain's Proceedings of the Royal Society; it's easier to read the description on the technology blog at www.popularmechanics.com.

-- Popular Mechanics

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Europa may have hosted life

For explorers searching for life beyond Earth, the siren song of Europa, Jupiter's icy moon, trills sweetly.

"Europa has the best chance of having life there today," said Britney Schmidt, who studies the moon at the University of Texas at Austin. Astrobiologists think so because NASA's Galileo probe found strong evidence for a deep, briny ocean covering the entire moon deep under the icy surface.

A theory published by Schmidt and colleagues in the journal Nature is sure to raise the volume of the siren call. The scientists suspect liquid lakes lurk just under the moon's cracked and mottled surface.

The lakes themselves could provide a second habitat for life, said Don Blankenship, a geophysicist and Europa specialist also at the University of Texas. More intriguingly, such lakes would also provide channels for organic compounds on Europa's surface to be drawn into the deep ocean. Without that material from the surface, the ocean would not contain the elements needed for life.

"If Europa is habitable, we need to get material from the surface down into the deep interior, down into the ocean," Schmidt said.

Subsurface lakes would also explain Europa's "chaos terrains." These huge expanses of jumbled-up icebergs cover half of Europa's surface. But they have puzzled scientists since 1995, when Galileo began beaming pictures of Europa back to Earth. If such subsurface lakes exist on Europa, they would hold more water than all five Great Lakes, Schmidt said.

-- Washington Post