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Science Objective
The Ultraviolet Imager (UVI) is a small sophisticated
camera, which from Earth orbit, will detect and produce images
of the ultraviolet light of the aurora, day and night. As such,
it is one of eleven instruments onboard the Polar spacecraft,
which is part of the International
Solar Terrestrial Physics (ISTP) Program.
The UVI is able to detect and provide images
of very dim emissions with a wavelength resolution never achievable
before. The highly sensitive instrument will conduct observations
of the polar aurora in the far ultraviolet wavelengths and help
quantify the overall effects of solar energy input to the Earth's
polar regions. Its scientific objectives are to image the aurora
simultaneously, to measure the total energy and characterize
the energy that is deposited in the auroral regions, to characterize
the space and time variations of the aurora, and to correlate
events in the auroral regions to other regions in the magnetosphere.
Energetic particles, including electrons and
protons, emanate from the Sun comprising what is called the solar
wind. As these particles stream by the Earth at speeds up to
one million miles per hour, they are redistributed and accelerated
by the Earth's magnetic field in a region of space known as the
magnetosphere. This redistribution of solar energy results in
channeling large amounts of energy, equivalent to as much as
100 million kilowatts of energy each day, down into the Earth's
atmosphere in the polar regions. These energetic particles collide
with the elements of the upper atmosphere at altitudes between
90 and 150 kilometers resulting in the emission of light known
as the aurora. The aurora can be thought of as the "footprint"
of events and energetic processes occurring in the Earth's magnetosphere.
The objective of ISTP is primarily three fold:
To measure the energy and particle flow from the Sun into the
Earth's magnetosphere and atmosphere and how the flow changes
in time; To improve the understanding of the processes that determine
this flow; and To determine the importance of the variations
of this flow to the Earth's atmosphere. |
