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[music]

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Narrator:  There is good reason why the Earth is called the "water planet."

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Unlike all other known planets, Earth has an abundance

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of oceans and white clouds and ice all strikingly visible from space.

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At least 70% of the Earth's surface

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is covered by ocean, and sizable portions of the land are covered by water

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in the form of soil moisture, ice and snow.

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Water is also a major component of the Earth's atmosphere and is

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essential to all known forms of life

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Clouds typically cover at least half the Earth

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and water vapor is even more pervasive throughout the atmosphere.

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Water vapor is by far the most important greenhouse gas, helping to make

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our planet habitable. To understand our climate

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and to understand life on Earth, we need to understand how

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water systems work.

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Launch Announcer: Operations here at Vandenberg Air Force Base are going well this morning

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for the launch of the Aqua satellite on a Delta II launch vehicle. Liftoff is scheduled to

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occur on time at 2:55 a.m. Pacific Time.

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Six, five, four, three, two

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one ... and we have have liftoff of NASA's

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Aqua spacecraft, designed to study the Earth's water systems.

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[rocket sound]

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Narrator: NASA's Aqua spacecraft was launched on May 4th, 2002,

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, carrying six Earth-observing instruments to collect data about many

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aspects of the Earth's atmosphere, oceans, ice, land, and biosphere,

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with a major focus on water in all its forms.

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The Aqua spacecraft measures water vapor and clouds in the atmosphere

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liquid water and sea ice in the oceans,

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and glaciers, snow cover, and soil moisture on the land.

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To make these measurements, Aqua carries six Earth-observing instruments

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four from the U.S., one from Japan, and one from Brazil.

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All of them measure radiation,

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but different ones measure different kinds of radiation.

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For example, visible radiation, which is the type of radiation our eyes can see,

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is measured by three of teh Aqua instruments. This type of radiation is excellent for monitoring

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invisible phenomena like cloud cover.

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But just like our eyes, if an instrument only measures visible radiation

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it will have a hard time seeing through clouds, or seeing anything

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during periods of darkness. That's why Aqua's instruments

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also measure radiation outside the visible range in the

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infrared and microwave regions.

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Microwaves reaching Aqua's instruments are coming from the Earth's system and hence are not dependent

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on sunlight. And some of the microwaves pass straight through most

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clouds, giving Aqua the ability to see the Earth's surface,

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even on a cloudy day, and even during darkness.

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Every day, data pour down from the Aqua satellite

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and these data are processed for a wide range of users.

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Scientists use the data to improve our understandings of the Earth's very

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complicated and interconnected system, and weather forecasters, farmers,

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policmakers, businesses, and relief agencies use the