Music [waves crashing] The Earth is changing. Understanding those changes and their consequences is perhaps the most significant scientific challenge of our time. On December 18, 1999, NASA launched Terra, the first of three Earth-observing system missions. It observes our planet's land, water, and atmosphere from a height of more than 700 kilometers. Terra carries a suite of five instruments, including one from Japan and one from Canada. Each is designed to provide different, complementary view of Earth. Terra's instruments collect 72 different types of measurements, helping scientists build a more complete picture of how Earth's climate and environment work. Those measurements now span ten years. Norman Loeb: The Terra spacecraft and the instruments on them are really a critical part of understanding how the system is changing. Having a dedicated spacecraft with the synergy of the instruments, the accuracy these instruments provide on the platform that's in a stable orbit really has enabled us to do things that we couldn't do prior to Terra.NASA, along with scientists and engineers from the the United States, Japan, and Canada, keep the satellite and its pioneering instruments in orbit and sending valuable data back to Earth. Over the past decade, Terra's satellite observations have led to a wide range of discoveries, published in more than 3,000 scientific journal articles around the world. Terra instruments provide the most detailed daily view of Earth. Over time the images show seasonal patterns of plant growth more clearly than ever before, helping scientists understand how plants, critical to life on Earth, are responding to our changing climate.Chris Justice: For the first time we actually have a scientific instrument designed for measuring the land surface on a daily basis. It's been a major breakthrough for all of us. I'm astounded at how much uptake there's been in this data and how many people are using it to study the land surface, both for applications, such as food security and agricultural monitoring, in addition to forest monitoring, and looking at the more scientific questions of land use change and carbon and energy cycles. Terra's instruments together also show the impact of fire around the world. Thousands of fires burn everyday, transforming the landscape and releasing carbon into the atmosphere. Terra revealed that large fires inject smoke high into the atmosphere. That smoke and other pollution travel long distances, affecting air quality half a world away. And for the first time, Terra showed that the pollution we put into the atmosphere actually changes clouds. These changes happen all over the world but they're easiest to see over the ocean, where ships leave a trail of pollution in a pristine sky.Michael King: The particles have two effects: they can, just like haze, they cause a blanket, reflect more sunlight and they can cool the Earth and cool the the surface, actually blocking sunlight. That's so-called aerosol direct effect. The indirect effect is particles modify clouds cause then to get smaller drops, reflect more, and that has a cooling effect, too. It can counterbalance greenhouse effect. The largest uncertainty in climate is associated with indirect effect.[Thunderclap] By changing clouds, people alter rainfall and the way the Earth reflects and absorbs energy from the sun. Both impact our climate. And climate, in turn, impacts our lives. That's why for the last ten years, Terra's been dedicated to learning more about the world around us. With its daily observations over many years, Terra helps scientists understand how our world is transforming today, and how the consequences of those changes will shape our future on planet Earth. Music.