Satellites really could be used to spot ancient archaeological treasures buried underground, two researchers in Israel have shown.
Scientists had previously suspected that certain types of imaging system could look beneath the surface of the Earth under some circumstances, but no-one had the proof.
Future satellites could have archaeological missions
Dan Blumberg and Julian Daniels, of the Ben Gurion University, told New Scientist magazine how they were able to detect flat squares of aluminium which they had buried at different depths in the sand of the Negev desert.
The pair used radar sensors on board an aircraft.
"Now we have systematic proof. Buried objects can be detected from airborne systems," Dr Blumberg said.
Desert and ice
Images from US space shuttle missions in the 1980s appeared to show ancient river drainage patterns beneath the Sahara desert.
Subsequent imaging turned up ring structures beneath the ice of Antarctica.
Satellites have revealed ancient river beds beneath the Sahara
But until now no-one has been entirely sure that these images definitely showed real objects.
The Israeli pair used P-band microwave sensors.
These penetrate farther underground that other microwave sensors offering better resolution.
Dr Blumberg said he hoped P-band sensors could be added to satellite sensor packages.
Wet and dry
He said the imaging technique might be used to find fossils, geographic structures, underground buildings and pipes and perhaps even mass graves.
The principal drawback seems to be that the technique only works on very dry ground, because liquid water absorbs microwave radiation.
But, as Dr Blumberg said, that still left 15% of the Earth's surface dry enough to work on.
The Negev experiment used aluminium plates buried up to 40 centimetres beneath the sand but working systems might be able to penetrate up to nine metres into the Earth.