SOME of the most enhanced images ever taken of the Angkor temples from the space

shuttle Endeavor in 1994 could reveal secrets of the area's hidden past.

Experts poring over the radar images say the pictures could lead to discoveries of

other settlements which had been abandoned to the jungle from the 15th century.

The Second Scientific Roundtable on Radar Imaging - where the Endeavor's images were

discussed - concludes today at Gainesville, Florida.

Archaeologists and space scientists from around the world gathered over one week

to sift through and make sense of state-of-the-art remote-sensing done of Angkor's

great palaces, temples and waterworks.

The Endeavor carried the latest in radar imaging technologies, the SIR-C/X-SAR, developed

by NASA's Jet Propulsion Laboratory with the German and Italian space agencies.

During two orbits on its fifth day in-flight in a September 1994 mission, the Endeavor's

crew switched on radar sensors as the shuttle passed over the jungles of Cambodia's

northwest.

The advantage of radar imaging is that, unlike aerial and orbital photography, it

does not have to rely on visible light to produce good pictures taken from different

angles. It is especially difficult to carry out remote sensing on tropical areas

using older technologies, say scientists, as monsoon rains often leave vast areas

obscured by clouds.

Although the radioactive signals work best on arid landscapes - where they can penetrate

to depths of five meters - they nevertheless can expose subtle disturbances in the

topography and foliage which have not been spotted before.

So far the use of radar-imagery labs has led to the discovery of the ancient desert

city of Ubar in Oman, and silk road outposts in China's northwestern reaches.

In Cambodia, the use of radar sensors has already led to the detection of 68 prehistoric

mounds near Ak-yum and Roluos. Archaeologists suspect these may date as far back

as 5000BC.

"Angkor seen from the air is defined by water features which are highly reflective

of radar energy," says Dr. Elizabeth H. Moore, researcher at the School of Oriental

and African Studies in London.

"The importance of water to the Khmer, and the sensitivity of radar for mapping

the hydraulic landscape, make the NASA SIR-C/X-SAR an ideal remote sensing tool for

Angkor."