11.   A static instrument beams radar signals down a road.

12.   Any radar signal which gets as far as the turbines bounces off the internal walls so much before it gets back out that the signal is lost.

13.   A computer interprets the radar signals.

14.   After two years of careful analysis, scientists said Tuesday that radar signals from an American spacecraft indicated the Moon is not as bone-dry as usually thought.

15.   After two years of careful analysis, scientists said Tuesday that radar signals from an American spacecraft indicated the Moon was not as bone-dry as is usually thought.

16.   But the officials said they could not definitively evaluate what caused the radar signal.

17.   By bouncing radar signals off of shifting particles in the air, researchers can measure differences in frequencies to determine in which directions winds are moving and how quickly.

18.   By bouncing radar signals from Earth off Mars, they pieced together a map of how steep its slopes were.

19.   During World War II his work on microwave theory helped develop the technology to transmit and receive radar signals.

20.   Investigators believe a bomb was set in the forward section of the aricraft because of radar signals and the way the debris is scattered in the ocean.