Whole Earth Review

By Aaron M. Cohen
U.S. and Japan combine resources to map the Earth’s topography via satellite imagery.

Scientists and amateur Earth watchers may now see the planet in sharper and more complete detail than ever before. A new topographic map of the Earth combines millions of stereoscopic digital pictures taken via satellite to chart the appearance, temperature, and elevation of 99% of the planet. The map is the result of a joint effort between the United States and Japan. Officially known as the Global Digital Elevation Model (GDEM), it is available online, and can be downloaded for free.

The digital images were created by a specially designed piece of technology called the Advanced Spaceborne Thermal Emission and Reflection Radiometer, or ASTER. ASTER was engineereed in Japan before being placed aboard NASA’s Terra satellite as part of NASA’s Earth Observing System.

ASTER’s sensors are constantly recording and transmitting data, so the GDEM is not a static but a dynamic map; its quality will continue to improve as the process is refined over time and the technology advances. Think of the version currently available as an early draft or a beta release.

This ever-evolving map has a number of practical applications. For instance, cataloging the planet’s topography and generating environmental observational data over the long term will better enable scientists to forecast when and where natural disasters might strike. Scientists and researchers will also be able to detect and map environmental disasters such as floods, hurricanes, wildfires, and earthquakes as they are happening. In addition, the map is a powerful tool for monitoring global climate change and determining its effects.

Here’s how ASTER works: Three separate telescope modules, each capturing a different part of the electromagnetic spectrum, continually record images as the satellite orbits our planet. The image data is then transmitted from the satellite to Earth and assembled to form a map of the Earth. The entire process is automated and only takes about a year from start to finish — an incredibly fast rate of production.

ASTER is sensitive not only to light but also to heat (via infrared waves on the electromagnetic spectrum), which enables it to survey and record geographic temperatures as well. The higher the temperature, the more infrared radiation is emitted, resulting in a brighter image.

A major aspect of the project’s mission is to provide information and resources not only to scientists in the field but to the general population as well, in the democratizing spirit of the Internet. It’s not unlikely that general enthusiasts in addition to highly trained specialists will be combing through the data to create accurate forecasts and breakthroughs as well.
About the Author

Aaron M. Cohen is a staff editor for THE FUTURIST.

For more information: NASA, www.nasa.gov.