THE HALEAKALA OBSERVATORY
'(<a href="http://www.j-archive.com/media/2011-03-25_DJ_08.jpg" target="_blank">Kelly of the Clue Crew reports from Haleakala Observatory in Maui, Hawaii.</a>)  The unit here fires pulses of light at mirrors on the moon & man-made satellites; the pulses reflect back to earth, allowing distances to be precisely measured; it's called an LRS, this type of ranging system'
laser