Down to Earth: Crunch Time

24 October 2017

Interview with

Stuart Higgins

This week, Dr Stuart Higgins explores how the challenge of landing a space probe has been used to keep crisps crunchy and fresh.

Stuart - What happens when the science and technology of space comes Down to Earth?

This is Down to Earth from The Naked Scientists. I’m Dr Stuart Higgins and this episode is about a somewhat unusual link between landing space probes and packaging potato crisps…

Getting into space is one challenge. Getting back down to Earth again, or say landing on another planet, is a completely different problem altogether. Take, for example, the European Space Agency’s Huygens probe. In 2005, this 318 kilogram metal box was dropped from the Cassini spacecraft into the atmosphere of Saturn’s moon Titan.

In the 2.5 hours that it took the probe to reach the surface of Titan, it had to reduce its speed from over 20,000 kilometres an hour to less than 20 as it touched down on the moon’s surface. Most of the slowing down was achieved by the probe’s giant heat shield which made up nearly a third of its total mass.

Friction with the nitrogen and methane atmosphere of Titan slowed the probe down to 1.5 times the speed of sound, around 1,850 kilometres per hour, before multiple parachutes were used to slow it down even more. This approach is similar to other spacecraft landing on Mars or Earth and when the spacecraft is carrying a precious cargo, for example humans, it’s critical to understand how it will move through an atmosphere in order to ensure it’s engineered strongly enough to withstand the tough conditions.

Engineers and scientists achieve this through a mixture of aerodynamic calculations that take into account the spacecraft’s speed, the atmosphere it’s travelling through, and the mechanical properties of the vehicle itself. They also use wind tunnels to flow air across miniature models to help better understand what will happen. Developing this expertise has huge advantages in other areas too, such as designing more efficient cars and aircraft, and also in a way you might not expect... food packaging.

It turns out that being able to predict the descent of a space probe is similar to understanding how potato crisps can be put into bags without breaking. A German company, who developed the software to simulate the movement of spacecraft through atmospheres was asked to help a food packaging manufacturer to increase the speed of putting crisps into bags. Using their space expertise, they were able to speed things up by 30 to 50% without increasing the number of breakages. They used their skills in avoiding big crunches in space to help us enjoy some rather smaller crunches… back on Earth.

That was Down to Earth from The Naked Scientists and join me again soon to learn about more space technology that’s changing lives back on Earth.


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