WEBVTT

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foreign

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[Music]

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Did you know that balloons were Pioneers in
the space race and were the first vehicles

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used in space exploration?
Today, NASA still uses large,

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unmanned helium balloons to carry payloads
and cargo into space environments.

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Some of the most significant balloon missions from
NASA are launched over Antarctica. Antarctic flights

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are of long duration because of the polar vortex,
a persistent low pressure system that contributes

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to very little atmospheric change, which helps
balloons stay at nearly constant altitudes.

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When a balloon is floating and moving through the
air there are four forces that act upon it called

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aerodynamic forces. The basic aerodynamic
forces are lift, drag, thrust, and weight.

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Weight is the force generated by the
gravitational attraction of the Earth.

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The magnitude of this force depends on
the mass of the balloon and its payload.

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For the balloon to float, a force must be
generated to overcome weight. This force

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is called lift. Lift is caused
by the buoyancy of the balloon.

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Buoyancy is an upward force caused by a
difference in density between two fluids.

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In the case of a balloon, the two fluids are
air and helium. Helium is less dense than air,

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so air being heavier will exert an upward
force on the balloon, causing it to rise.

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Think of how buoyancy works with
water. A jumping diver with less

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density will encounter the water with a
higher density, exerting an upward force

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of lift and allowing them to float to
the surface to experience buoyancy.

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Once the balloon is floating
it is moved horizontally by

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the force of thrust. For a balloon,
thrust is supplied by blowing wind.

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Still air in front of the balloon pushes
against the balloon and resists movement.

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This resistant force is called drag. In
order for the balloon to move forward,

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the force of thrust must be
greater than the force of drag.

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To create a neutrally buoyant balloon, the
balloon's forces of lift and weight must be

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balanced. A neutrally buoyant balloon doesn't rise
or fall, it stays in place, floating at one level.

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Launching an early 2024 for example is
NASA's ASTHROS space balloon, carrying a

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powerful telescope that will observe wavelengths
of light that are blocked by Earth's atmosphere,

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creating high resolution 3D maps of the
distribution and motion of gas in our galaxy.

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These unique capabilities of
the balloons are crucial for

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the development of new technologies for
NASA's future space flight missions.

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[Music]