Secret Science of Santa Claus: How do reindeers fly Santa’s sleigh around the world?

This is an article that I wrote for RTE’s Brainstorm website. The original article can be found here.

For more information on the Secret Science of Santa Claus check out information on my book “Secret Science of Santa Claus“.

In a matter of days, Santa Claus will set out on an incredible round-the-world trip to deliver presents to millions of children. Every year, his schedule gets busier, due in part to the ever-increasing world population. To help him achieve this Christmas delivery goal, Santa uses a truly unique form of transport: a flying sleigh that is guided by a troop of flying reindeers. But how does the sleigh fly? And does it fly in a sustainable way?

Before looking at the science behind Santa’s flying sleigh and flying reindeer, why did Santa Claus pick reindeer to pull the sleigh in the first place? As you already know, Santa Claus’ base of operations is located in the Arctic Circle, which contains parts of Canada, the US, Greenland, Sweden, Norway, Finland, and Russia. The Arctic Circle is home to many animals such as the Arctic fox, the Arctic hare, polar bears, snowy owls, and of course reindeer.

According to the 2018 Arctic Report Card from NOAA’s Arctic Program, there are roughly two million reindeer in 23 major herds in Arctic regions. For centuries, people living in Arctic regions such as the Sami and Nenets have used reindeer to transport people and goods across vast distances. So you could say that Santa Claus is just copying an old tradition.

Nonetheless, it is puzzling that the sleigh and reindeer don’t have wings like modern aircraft. Well, aeroplanes didn’t exist when Santa Claus and his elf-scientists were creating their reindeer-based flying system in the early 18th century. The first successful flight of any aircraft with an engine took place near Kitty Hawk, North Carolina on December 3rd 1903. The pilot that day was Orville Wright, who along with his brother Wilbur built an aircraft known as the Wright Flyer I. This means that Santa’s designs couldn’t have been influenced by the work of the Wright Brothers or any other aviation pioneers. And the sleigh doesn’t have jet engines because jet engines were only developed in the middle of the 20th century.

Of course, Santa Claus and the elf-scientists could have invented mechanical wings that could be worn by the reindeer during flight. But these would more than likely have been very awkward to wear for the reindeer. Plus the reindeer are harnessed quite close to each other and they wouldn’t have been able to fully extend their wings. Instead of wings and jet engines, Santa and the elf-scientists turned to something more astounding and sustainable. They turned to magnetic levitation.

What the heck is magnetic levitation?

A magnet – just like that used to keep your summer holiday souvenirs on your fridge – has two magnetic poles, a north pole and a south pole. If you’ve ever played with magnets you’ll know that unlike poles attract like poles repel.

Magnets are being used in modern transport systems such as magnetic levitation or maglev trains. Just like a traditional train, a maglev train travels along a track but, unlike a traditional train, a maglev train does not touch the track. The train essentially floats above the track because magnets on the bottom of the train push off the magnets on the track. Importantly, the magnetic lifting force counteracts the weight of the train due to the force of gravity; otherwise the train could never levitate. Typically maglev trains float about 10cm above the track.

One maglev approach is known as electrodynamic suspension (EDS) and involves the use of superconducting electromagnets. Superconductors are super by name and by nature. When these materials are cooled to very low temperatures, they have zero electrical resistance and generate a magnetic field. In an EDS maglev train, superconducting magnets are located inside the train. As the train passes over the track, the magnetic fields in the track and train repel each other leading to a levitating or floating train.

Because of the lack of friction with the track and the aerodynamic shape of maglev trains they can reach incredibly fast speeds. The fastest speed for a maglev train is 603 km per hour, which was achieved in April 2015 in Japan by JR Central’s L0 train!

Santa’s magnetic levitating reindeer

One of the big problems with superconducting materials is that they need to be cooled to very low temperatures before they can start to act like a magnet. This requires the use of expensive cryogenic cooling systems where liquid helium or liquid nitrogen is used to cool the materials to freezing temperatures.

But Santa Claus doesn’t need to worry about carrying cryogenic cooling systems on his sleigh. That’s because Santa Claus and the elf-scientists have developed the “holy grail” of superconducting materials: a room-temperature superconducting material. This is a material that behaves as a superconductor at much warmer temperatures, i.e. around 20 °C.

Santa and the elves installed this material on the runners of the sleigh and in the shoes worn by the reindeer. When Santa Claus passes electricity through the superconductors they generate a magnetic field. To levitate, this magnetic field needs to push off a second magnetic field, which is the Earth’s magnetic field. Although the Earth’s magnetic field is quite weak (the magnetic field from a fridge magnet is 100 times stronger), Santa’s technology compensates for this. When the sleigh’s magnetic field is high, Santa and the sleigh can fly higher and faster. And when the strength of the sleigh’s magnetic field is decreased, the sleigh flies lower and slows down. 

Just like a car needs a battery to help kick start the engine, Santa’s sleigh also carries a battery to switch on the sleigh’s magnetic field. Rather than using a lithium-based battery (which won the Nobel Prize in Chemistry 2019), Santa and his elves have opted for an advanced recyclable sodium-based battery. Added to that, the levitating sleigh emits no greenhouse gases or toxic substances into the atmosphere, which can only be a good thing for the environment. So in effect the sleigh is carbon neutral. 

The only minor issue with the whole flying process is that Santa’s reindeer emit methane in the form of reindeer flatulence (basically reindeer farts) during their round-the-world trip. But don’t worry: Santa Claus and the elf-scientists have that covered too!

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