New Maps to Show Earth's Contours in Detail
Sept. 14 -- 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.
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