Earth needs your help—now!

Play the "Missions to Planet Earth" online card game. Help to prepare five important NASA Earth missions. The information from these missions will help scientists understand how to keep Earth in harmony and friendly to all its living things.

The five missions in the card game are just a few of NASA's missions to planet Earth. Satellites in space help us to understand our planet in ways not possible from the ground. From space, scientists can get the whole picture.

The five card game missions all measure different things. Scientists can put the information together into models of how our complex planet actually works.

Aqua: Observing Earth's water cycle

The Aqua satellite has six Earth-observing instruments that work together. The satellite's name means water. Its primary mission is to study Earth's water. Aqua's instruments measure evaporation from the oceans and water vapor in the atmosphere. Aqua studies clouds and precipitation (rain and snow, for example), water in the soil, ice on the seas and on land, snow cover, and other things.

Aqua flies in a polar orbit (passing near the Poles) in formation with several other satellites, including Aura and CloudSat. This constellation of satellites is called the "A-Train."

Aura: Looking at the atmosphere

Aura has four instruments to study the atmosphere. It gathers data about ozone, air quality, and how they may affect climate change.

Ozone is a particularly important gas because it plays many different roles. If ozone is high in the top layer of our atmosphere, it protects us from the Sun's harmful ultraviolet rays. But at lower altitudes it can act as a greenhouse gas and a harmful pollutant.

Humans help to make ozone. Automobiles and power plants give off gases that change in the presence of sunlight to produce ozone. Aura will help scientists to understand how these gases work in both the lower and upper atmosphere. Aura also flies in a polar orbit (over the North Pole and the South Pole) as part of the "A-Train."

Terra: Getting a big picture

Terra means Earth. It is also the name of NASA's flagship Earth-observing satellite. It is about the size of a school bus. It carries five advanced instruments that study the atmosphere, land, oceans, and radiant energy (heat and light), and how they all get along together. Terra flies in a polar orbit, passing over the Poles while Earth rotates beneath it.

Terra has instruments from Canada, Japan, and the United States. Since launch in December 1999, Terra has helped scientists measure

• how much carbon Earth's plants take out of the atmosphere,
• the height and movement of clouds,
• how Earth reflects and absorbs energy from the Sun,
• how many fires burn every day, and
• how pollution travels around the globe.

All of this information and other Terra measurements help scientists understand how Earth's climate works and how it is changing.

CloudSat: Looking at clouds from all sides

CloudSat studies the clouds in ways never before possible. CloudSat's radar can see right through the clouds and measure their thickness, structure, water content, brightness, and other important properties. All this information will help scientists understand their role in weather and climate.

Do clouds trap heat and make Earth's surface warmer? Or do clouds' bright surfaces reflect enough sunlight back into space to make up for their heat trapping effects? These questions must be answered for scientists to be able to predict how Earth's climate may change. CloudSat flies in a polar orbit as part of the "A-Train."

ICESat: Watching ice and sea come and go

ICESat stands for Ice, Cloud and land Elevation Satellite. It orbits Earth studying the ice sheets that still blanket the North and South Pole regions. IceSat aims to find out whether the ice is growing or shrinking, and how fast. How these ice sheets respond to global climate change affects global sea level. The ice melts (shrinks) and sea level rises. The ice freezes (grows) and sea level drops. ICESat flies in a polar orbit, passing over the Poles while Earth rotates beneath it.

ICESat will help scientists understand Earth's climate and predict how ice sheets and sea level will respond to future climate change.