Spaced out science – space junk with Mars Buttfield-Addison

Get ready to launch into fascinating fast facts about space junk, an interview with Mars Buttfield-Addison, a computer scientist and science communicator who knows a lot about space debris, and an easy orbital activity for you to try yourself at home.

Written, presented, and produced by Jenny Lynch.
Music by Purple Planet Music. Sound effects by Pixabay.

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Episode content:

00:00 Introduction and fast facts

03:28 A big collision in space

04:10 Interview with Mars Buttfield-Addison

10:49 Orbiting sock activity

Orbiting sock activity instructions:

You will need: a pair of long socks, for example, knee-high socks or football socks,

or ask if you can borrow a pair of adult-sized socks.

1. Roll up one of the socks and push it down into the other sock, so it is in the toe end of the sock.
2. Make sure you have plenty of space around you before doing this step. Hold the open end of the sock and swing the sock around in a circle, so the rolled-up sock is orbiting your hand. Make the sock swing around in a circle as fast as you can, and then slow down the speed until the sock only just stays in a nice, round circle-shaped orbit.
3. Hold the sock about halfway along the length, so the orbit is smaller. Swing the sock around again so it orbits your hand in a smaller circle. Make it swing around as fast as you can again, and then slow down the speed while keeping it in a circle-shaped orbit.

What do you notice about the speed of the larger orbit compared to the smaller orbit?

The sock can orbit a lot slower in the larger orbit compared to the smaller orbit.

This is only a model made from socks, so the forces are a bit different compared to a real satellite orbiting Earth.  In our sock model, the long sock is providing the force to keep the rolled-up sock in its orbit, so the long sock is a bit like gravity holding a satellite in orbit.

A satellite is held in orbit by the force of gravity. For lower orbits, the force of gravity is stronger and a satellite in a lower orbit has to move faster to avoid falling down to Earth. Higher orbit satellites experience less gravitational pull, and they move more slowly to stay in orbit.