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Scientist discovers how Santa does it
Why, with a sleigh longer than two football fields that orbits the Earth at 23 times the speed of sound, of course
By PETER CALAMAI Toronto Star
TORONTO — A Canadian space scientist has calculated how Santa Claus manages to deliver presents to almost a billion children around the world during Christmas Eve — at least the ones who haven’t been naughty.
All it takes is precise orbital mechanics, fast-working elves, multiple time zones and a helping hand from NASA’s shuttle, says Andrew Yau at the University of Calgary. It also requires a sleigh longer than two football fields that orbits the Earth at 23 times the speed of sound.
Yau worked out the details at the behest of a federal granting agency, the Natural Sciences and Engineering Research Council of Canada, which posted a summary on its website, www.nserc.gc.ca.
"It’s about as believable a story as you can get but it’s still got holes," says Yau, who specializes in the study of space weather.
Santa begins his long night aboard a sleigh NASA’s shuttle has carried into an orbit 300 kilometres high, just 100 kilometres below the space station.
That altitude lets the reindeer really move, says Yau, because there’s almost no air to slow them down. Of course, everyone has oxygen masks and protective suits.
The sleigh travels at 28,000 kilometres an hour, the same as many orbiting satellites, which works out to 23 times the speed of sound. That may explain why some children report hearing reindeer bells on Christmas Eve. It’s really sonic booms.
That speed whips Santa around the Earth every 90 minutes, from the North Pole to the South and then back again as the world revolves beneath.
But Santa delivers only during the first half of the orbit because it’s late morning on the other side of the globe as he heads back to the North Pole.
Explained Yau, "We wouldn’t want Santa to show up in the middle of the day while the children are still up, would we?"
Every time the sleigh returns above the North Pole, elves reload it in two minutes from presents pre-positioned there in orbit by the space shuttle.
Although the size of Santa’s sled is a secret, the Calgary professor was able to figure that out, too.
Even if each gift is in a small box roughly 2 1/2 centimetres by 10 centimetres by 15 centimetres, that still works out to about 23,500 cubic metres of gifts for each of the 16 orbits.
"You want the sleigh to be as narrow in the front as possible, to reduce drag, just like a bobsled going down a hill," says Yau.
Based on eight reindeer, the scientist calculated the sleigh had to be a minimum 10 metres wide. To keep it stable in flight meant a height of 10 metres.
That’s a cross-section of 100 square metres so dividing that into 23,500 cubic metres means the sleigh has to be 235 metres long.
Not so simple is getting the presents down to each child’s house from a platform whizzing along 300 kilometres above the Earth.
"That’s the tricky part," Yau agrees. He figures St. Nick has some special slingshot apparatus. "But it’s unknown to science," the researcher admits.
http://www.thechronicleherald.ca:80/Canada/548921.html
Why, with a sleigh longer than two football fields that orbits the Earth at 23 times the speed of sound, of course
By PETER CALAMAI Toronto Star
TORONTO — A Canadian space scientist has calculated how Santa Claus manages to deliver presents to almost a billion children around the world during Christmas Eve — at least the ones who haven’t been naughty.
All it takes is precise orbital mechanics, fast-working elves, multiple time zones and a helping hand from NASA’s shuttle, says Andrew Yau at the University of Calgary. It also requires a sleigh longer than two football fields that orbits the Earth at 23 times the speed of sound.
Yau worked out the details at the behest of a federal granting agency, the Natural Sciences and Engineering Research Council of Canada, which posted a summary on its website, www.nserc.gc.ca.
"It’s about as believable a story as you can get but it’s still got holes," says Yau, who specializes in the study of space weather.
Santa begins his long night aboard a sleigh NASA’s shuttle has carried into an orbit 300 kilometres high, just 100 kilometres below the space station.
That altitude lets the reindeer really move, says Yau, because there’s almost no air to slow them down. Of course, everyone has oxygen masks and protective suits.
The sleigh travels at 28,000 kilometres an hour, the same as many orbiting satellites, which works out to 23 times the speed of sound. That may explain why some children report hearing reindeer bells on Christmas Eve. It’s really sonic booms.
That speed whips Santa around the Earth every 90 minutes, from the North Pole to the South and then back again as the world revolves beneath.
But Santa delivers only during the first half of the orbit because it’s late morning on the other side of the globe as he heads back to the North Pole.
Explained Yau, "We wouldn’t want Santa to show up in the middle of the day while the children are still up, would we?"
Every time the sleigh returns above the North Pole, elves reload it in two minutes from presents pre-positioned there in orbit by the space shuttle.
Although the size of Santa’s sled is a secret, the Calgary professor was able to figure that out, too.
Even if each gift is in a small box roughly 2 1/2 centimetres by 10 centimetres by 15 centimetres, that still works out to about 23,500 cubic metres of gifts for each of the 16 orbits.
"You want the sleigh to be as narrow in the front as possible, to reduce drag, just like a bobsled going down a hill," says Yau.
Based on eight reindeer, the scientist calculated the sleigh had to be a minimum 10 metres wide. To keep it stable in flight meant a height of 10 metres.
That’s a cross-section of 100 square metres so dividing that into 23,500 cubic metres means the sleigh has to be 235 metres long.
Not so simple is getting the presents down to each child’s house from a platform whizzing along 300 kilometres above the Earth.
"That’s the tricky part," Yau agrees. He figures St. Nick has some special slingshot apparatus. "But it’s unknown to science," the researcher admits.
http://www.thechronicleherald.ca:80/Canada/548921.html
