Re: Is there a mirror on the moon and which mission put it there?

Hi Janelle,

There are several mirrors on the Moon, mostly left there by NASA Apollo missions. They are actually designed for visible light (lasers), not radio. The basic design is called a "corner reflector". If you arange 3 mirrors in a shape like the corner of a rectangular box, with the reflectors on the inside, then any light which hits the reflectors, at essentially any angle, will bounce off each mirror and end up heading back exactly the direction from which it came. This makes such a mirror arrangement very useful, because you always get a nice strong reflection. http://www.exploratorium.edu/snacks/corner_reflector.html is a good place to look for more about corner reflectors.

For descriptions of the reflectors left on the Moon by the Apollo 11, 14, and 15 missions, see http://nssdc.gsfc.nasa.gov/cgi-bin/database/www-nmc?69-059C-04
http://nssdc.gsfc.nasa.gov/cgi-bin/database/www-nmc?71-008C-09
and http://nssdc.gsfc.nasa.gov/cgi-bin/database/www-nmc?71-063C-08.

For some information about how the reflectors were used to measure the distance to the Moon, see http://www.eso.org/outreach/spec-prog/aol/market/experiments/middle/skills206.html, www2.jpl.nasa.gov/files/universe/un940729.txt and http://www.ridgenet.net/~do_while/sage/v2i2f.htm

Feel free to E-mail me at stevenlevin@we.mediaone.net if you have further questions.

-Steve Levin

__________________________________________________________
DISCLAIMER: Just because I work for JPL/NASA/Caltech doesn't mean
anything I say is in any way official. This is just me talking,
not NASA, JPL, or Caltech.