Physics KS3 / GCSE: Orbital Rendezvous

Kevin Fong demonstrates how hard it is for a spacecraft to catch up with the International Space Station.

This is because the speed of an orbiting object is related to the height of its orbit, so when the spacecraft is closer to the Earth than the ISS, it is travelling faster, so in theory it could catch up with it.

However, as it rises higher from the Earth and closer to the orbit of the ISS, it slows down, and potentially falls behind the ISS.

A student from the audience demonstrates the technique used, using a model demonstration on the floor of the lecture theatre.

This clip is from the Royal Institution Christmas Lectures 2015.

Teacher Notes

Students could be introduced to the equations that explain circular motion, and how these can be used to explain the link that Kevin describes in the clip between altitude and speed.

Curriculum Notes

This clip will be relevant for teaching KS3 and GCSE Physics.

This topic appears in OCR, Edexcel, AQA, WJEC KS4/GCSE in England and Wales, CCEA GCSE in Northern Ireland and SQA National 4/5 in Scotland.

More from the Royal Institution Christmas Lectures 2015

What is Newton's Canon and Third Law?
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Using Earth’s rotation to launch a rocket
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How the vacuum of space effects the human body
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Resonant Frequency
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What does gas weigh?
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Why are bones weaker in orbit?
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How micro-gravity disorientates us
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The danger of orbital debris
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Demonstrating heat shield material
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Why Earth rock is found on the Moon
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Demonstrating radiation detectors
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How Earth protects us from radiation
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Why tardigrades can survive in orbit
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How to recycle urine in space
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