New Maps to Show Earth's Contours in Detail

Sept. 14, 2000 -- There was once a time when space missions were planned to explore the moon, Mars and, well, space. Now they can be designed to probe things much closer to home, like the fine details of Earth.

A research project combining efforts from NASA and the National Imagery and Mapping Agency (NIMA) is taking mapping planet Earth to a new level. Thanks to advanced technology and a recent space shuttle mission, a team of scientists will soon know with unprecedented precision the contours of the Earth. The end-product will provide the military — and even, to some extent, the public sector — with detailed digital maps.

Measuring Interference

In February, the crew on the space shuttle Endeavor scanned approximately 90 percent of Earth’s land masses — excluding the north and south poles — using what’s called interferometry radar. Typically, radar measures the strength and the round-trip time of a radio wave emitted from an antenna and reflected off a distant object. Interferometry radar combines two sources of radar that beam microwaves in two separate passes at Earth’s surface and record the backscattered reflection from points on the ground.

One advantage of using this type of technology is that radar can scan through clouds and can operate day or night, allowing the collection of quality data 24 hours a day.

“[Another] advantage of using this type of radar interferometry is that you get a three dimensional model,” Steitz said. “The data is more accurate than anything that has been measured on Earth. You get an actual, digital, 3D model.”

Using radar booms, the space shuttle took elevation readings of most of Earth’s surface every 30 square meters.

The resulting digital radar images, composed of many pixels, show bright features that indicate a protrusion on Earth’s surface and dark features that imply a depression. Using this data, scientists have begun constructing computer-generated topographical maps which can even detail what type of substance composes the rises and falls in elevation. For example, David Steitz, spokesman for the Earth studies division at NASA pointed out, a desert area would absorb energy, whereas mountains made of granite would reflect it.

The job of sifting though all of the digital radar information — which amounts to some 9.8 terabytes, or more than 15,000 CDs worth, of data — will take three years. And when the readings are finally analyzed, the agency will know Earth’s contours in unprecedented detail.

Instant Digital Maps

The conversion of the large amount of raw radar and support data collected during the space shuttle flight will be done in two phases, said Jennifer Lafley, spokeswoman for NIMA. The first phase is under way at the Jet Propulsion Laboratory in Pasadena, Calif., and will produce preliminary elevation information. Those data sets will then be further refined by NIMA production contractors to put the information into a final finished form, format and content to fit first and mainly the U.S. military’s requirements.

The three-dimensional digital maps will be used for military applications such as improved flight simulators, logistical planning, missile and weapons guidance systems, and battlefield management and tactics. Once a limited number of maps become available to the public, environmentalists, urban planners, and engineers can use the information of maps such as roads, buildings, forests or swamps.

“In Desert Storm, information was put on paper and shipped on airplanes and sometimes it just sat around on pallets,” saidRobert Zitz, director of the agency’s Initiatives Group.

With today’s computers and the new research coming out of this project, better, more precise, digital maps, containing much more information, will be able to travel across networks, almost instantly.

Terrain maps for tracking natural disasters, plate tectonics and even urban sprawl are another goal of the project. (So far, officials are not sure when this will be available to the public, but they say that only limited amounts of information would be publicly available, due to security reasons.) And the maps will help improve Global Positioning System (GPS) applications.

“To get this level of accuracy, it would take years for a human on the ground,” said Speitz. “Some of the areas, especially in the Amazon, hasn’t been seen before, and it was hidden from satellite imagery.” ABCNEWS.com’s Melanie Axelrod, Erica Rowell and The Associated Press contributed to this report.