WEBVTT

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>> The tethered aerostats are inflated with two different types of gases.

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There's a helium chamber inside the aerostat,

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which is the lifting gas that raises the aerostat.

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There is also ambient air pumped inside the aerostat

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so that we can maintain a constant aerodynamic shape of the aerostat

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as it is subjected to different air pressures as it goes up and down.