RE-ENTRY
What happens during re-entry? [1]
Let's say the rocket is ready to come back to Earth. Once it enters the Earth's atmosphere, the entire rocket will start to glow red hot. This presents a lot of risks for the rocket itself and the passengers inside the rocket. But don't worry, that's why heat shields are there!
Keywords: re-entry, plasma, heat shields, kinetic energy
Plasma?! What's that?
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The air is made up of loads and loads of small molecules. When a rocket travels towards to Earth and enters its atmosphere, the air molecules start to behave differently. Since the rocket is travelling at such a high speed, this heats the molecules until it becomes plasma. Plasma is gas molecules with their electrons stripped away, creating electrically charged particles in the air. Eventually, plasma can return back to being a gas once it cools down. [2]
How does plasma affect the spacecraft during re-entry?
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Due to the plasma’s high temperatures, this can create a number of problems for the spacecraft. So to combat this, engineers have designed a protective barrier over the spacecraft that is built to withstand the extreme temperatures, and stop the plasma from damaging the spacecraft even further. This is called a heat shield! [3]
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How do heat shields work?
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Heat shields essentially turn the space crafts kinetic energy into heat energy. Kinetic energy is the energy an object has due to its motion. If an object has more kinetic energy, it can go faster. So converting this energy into heat means that the spacecraft can slow down. Some space crafts can also make turns and glide while re-entering to slow down and dissipate some of the heat it contract. [3]
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Other factors scientists have to consider to lower impacts of re-entry?
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It’s very important to monitor the rocket’s speed during re-entry. The rocket must slow down while re-entering the Earth’s atmosphere otherwise it could perform a meteor style landing! The friction in the air helps them to slow down. Like we mentioned at the start, the air is made up of molecules. When an object is travelling at high speeds through the air, the molecules compress and actually produce shockwaves if it’s moving faster than the speed of sound. In some cases, meteors can get crushed by their shockwaves since they travel so fast which is why it is important that spacecrafts find more ways to slow down. [3]
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That is why we use parachutes - they lower our speed which ensures a safe landing!
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Re-entry - Game
After learning about re-entry and its different aspects, why don't you try playing our Re-entry game!
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The aim is to keep the capsule upright, whilst it is falling through the sky so that it is ready when the parachute needs to be deployed.