The planet up close

US scientists use radar to capture every single detail of the Earth's topography

Published: Monday 15 May 2000

The space shuttle Endeavour has captured every corner of the Earth in amazing three-dimensional images. For 11 days, beginning January 31, the globe was swathed by radar waves so that scientists from National Aeronautics and Space Administration (NASA) in the US could obtain data for the most complete high-resolution maps of the planet ever designed.

A key advantage in using radar is that it can penetrate through clouds and darkness. The technology used is called radar interferometry, in which two radar images are taken from slightly different locations to create the three-dimensional effect. Endeavour was made to fly in an orbit between 60 degrees North and 56 degrees South in order that it could map the land from the southern edge of Greenland to the southern tip of South America. This covered an area encompassing 80 per cent of the Earth's land mass and 95 per cent of its population. In order to capture images, the shuttle made use of a 197-foot metal and plastic antenna mast, the longest rigid structure ever deployed in space.

Prior to the launch of the project, its chief scientist Michael Kobrick of NASA's Jet Propulsion Laboratory said: "It will be a snapshot of the planet in one 10-day period." The maps can be used for research, business, military purposes and even to plan a weekend outdoors.

However, military personnel would like the data to be published in a selective manner. Space and military policy expert with the Federation of American Scientists John E Pike said, "This information is potentially useful to other militaries also. The defense department wants to see that the data does not fall into hostile hands."

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