[music] Narrator: There is good reason why the Earth is called the "water planet." Unlike all other known planets, Earth has an abundance of oceans and white clouds and ice all strikingly visible from space. At least 70% of the Earth's surface is covered by ocean, and sizable portions of the land are covered by water in the form of soil moisture, ice and snow. Water is also a major component of the Earth's atmosphere and is essential to all known forms of life Clouds typically cover at least half the Earth and water vapor is even more pervasive throughout the atmosphere. Water vapor is by far the most important greenhouse gas, helping to make our planet habitable. To understand our climate and to understand life on Earth, we need to understand how water systems work. Launch Announcer: Operations here at Vandenberg Air Force Base are going well this morning for the launch of the Aqua satellite on a Delta II launch vehicle. Liftoff is scheduled to occur on time at 2:55 a.m. Pacific Time. Six, five, four, three, two one ... and we have have liftoff of NASA's Aqua spacecraft, designed to study the Earth's water systems. [rocket sound] Narrator: NASA's Aqua spacecraft was launched on May 4th, 2002, , carrying six Earth-observing instruments to collect data about many aspects of the Earth's atmosphere, oceans, ice, land, and biosphere, with a major focus on water in all its forms. The Aqua spacecraft measures water vapor and clouds in the atmosphere liquid water and sea ice in the oceans, and glaciers, snow cover, and soil moisture on the land. To make these measurements, Aqua carries six Earth-observing instruments four from the U.S., one from Japan, and one from Brazil. All of them measure radiation, but different ones measure different kinds of radiation. For example, visible radiation, which is the type of radiation our eyes can see, is measured by three of teh Aqua instruments. This type of radiation is excellent for monitoring invisible phenomena like cloud cover. But just like our eyes, if an instrument only measures visible radiation it will have a hard time seeing through clouds, or seeing anything during periods of darkness. That's why Aqua's instruments also measure radiation outside the visible range in the infrared and microwave regions. Microwaves reaching Aqua's instruments are coming from the Earth's system and hence are not dependent on sunlight. And some of the microwaves pass straight through most clouds, giving Aqua the ability to see the Earth's surface, even on a cloudy day, and even during darkness. Every day, data pour down from the Aqua satellite and these data are processed for a wide range of users. Scientists use the data to improve our understandings of the Earth's very complicated and interconnected system, and weather forecasters, farmers, policmakers, businesses, and relief agencies use the Aqua data to make vital decisions that affect us all. [beep beep, beep beep, beep beep]