Another article revealed Chinese interest in airborne and space-based synthetic aperture radar.

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Space debris is tracked by the United States Space Surveillance Network that uses radar that can detect an object the size of a pea at 400 miles.

BBC: By BBC News Online Science Editor Dr David Whitehouse

They came away unpersuaded of the space-track rationalization for this radar.

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The measurements were recorded via a radar altimeter onboard the European Space Agency's (Esa) Envisat satellite.

BBC: Arctic ice thickness 'plummets'

In 1994, researchers from America's airforce tested this idea by using the radio transmitter on a space probe called Clementine as a makeshift radar.

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Scientists can already study earthquakes from space, in particular through the use of radar to map the deformation of the ground that results when faults rupture.

BBC: Japan quake 'heard at edge of space'