Bottles of champagne may send corks sky high, but spacecraft take cork as far as Mars. Their success depends on it.
Cork reached new heights as part of the protective aeroshell that insulated the Mars Rovers Spirit, Opportunity and Curiosity from the intense heat of entering the Martian atmosphere.
Bark of the cork oak tree contains a waxy chemical called suberin. This chemical contributes to making cork bark elastic, buoyant, waterproof and fire resistant.
Unlike most trees, cork oaks regrow their bark after it is cut off, making it a sustainable natural product. Bark can be harvested every ten years or so after the tree is about 30 years old.
The structure of cork resembles honeycomb filled with gas, and one cube of cork a centimetre on each side can contain 40 million air cells. Compressing and expanding, these tiny pockets of gas make cork strong, but with enough give to make it a comfortable option for flooring and shoes.
As the bark provides insulation to the Mars rovers, so it does on the tree. Fire resistant qualities allow cork oaks to survive wildfire better than many other trees.
Harvesting can leave cork oaks more vulnerable to fires, according to a study by a European team of researchers. They found the thicker the bark, the better a cork oak survived fire. Trees with bark thicker than four centimetres were unlikely to die from heat injury.
Protecting cork oak trees from fires, Mars rovers from heat, and champagne from spoiling, cork is truly one useful bark.
Cork bark has many amazing properties. Image: Thinkstock
Quiz questions
Name the largest ocean on Earth.
What is the name of the layer of the atmosphere closest to the ground: a) stratosphere, b) mesosphere, or c) troposphere?
What is the biggest planet in our solar system?
Which of the following is not a noble gas: a) argon, b) krypton, c) helium, or d) hydrogen?
What is the name of the technology recently used to map the inside of Italy’s Leaning Tower of Pisa for the first time?
Try this: Pushy particles
You will need two syringes.
Half fill the first syringe with air.
Block the nozzle with plasticine. If you don't have superglue, put hot melt glue on the end.
Do you find it any harder compressing water rather than air?
You will need
2 large syringes (10 mL or larger)
Plasticine
Superglue, or hot melt glue with a glue gun
What to do
Pull the plunger of one syringe back about half the length of the tube.
Push a small amount of plasticine into the nozzle (narrow end) of the syringe to block it.
Inject enough glue into the nozzle over the plasticine to ensure it is fully blocked. Wait ten minutes for the glue to dry.
Try to push the syringe’s plunger down as far as it can go. How far can you push it?
Take the second syringe and remove the plunger.
Fill the tube with water.
Replace the plunger into the tube and point the nozzle up to the ceiling. Squeeze the plunger until it is half way down the tube. Careful, you might get a little wet!
Block the nozzle with plasticine and glue and wait ten minutes for the glue to dry.
Push the plunger into this syringe. How far does it move?
What’s happening?
If you ever catch a train during rush hour in Tokyo, you just might see an oshiya – an attendant who pushes passengers into packed trains.
The water in your syringe is a bit like a fully packed train. The water particles, like passengers, are free to swap seats and move about. However there’s very little space between them. Pushing on the plunger isn’t going to squeeze the water molecules any closer together.
The molecules of air in your other syringe are more like a few excited kids in a train. They run around the carriage, bouncing off walls and pushing on the oshiya. However, the oshiya could put the children down one end of the train in a smaller space, just as the plunger can push air molecules down one end of the syringe.
Applications
In engineering, gases and liquids can be used to push and pull inside tubes and containers. When gases push and pull, it’s called pneumatics. Think about the air inside a tyre – its squishiness makes tyres bouncy.
Hydraulics describes liquids being used to push and pull. The brakes and steering on many vehicles are controlled by liquids inside tubes. Pushing a pedal inside the vehicle makes liquid push the brakes on the wheels. If bubbles of gas get inside the system, the pushing is less effective.
Svalbard is a small collection of islands near the North Pole. Although it’s very cold and remote, there are heaps of creepy crawlies that live there.
Did you know?
Air pushes on everything it touches in all directions – this is called atmospheric pressure. There are tonnes of air pressing on you right now. For an adult it’s roughly the weight of a medium-sized bus.
Quiz answers
The largest ocean on Earth is the Pacific Ocean.
The layer of the atmosphere closest to the ground is the c) troposphere.
Jupiter is the biggest planet in our solar system.
d) hydrogen is not a noble gas.
Zebedee was recently used to map the inside of Italy’s Leaning Tower of Pisa for the first time.
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