Space.com writes to say (freeform improved quote):
The LLCD (Lunar Laser Communication Demonstration) space terminal is designed to beam data from the moon at a rate six times faster than the best advanced radio communications systems available today. The system consists of a laser mount on the LADEE (Lunar Atmosphere and Dust Environment Explorer) spacecraft which fires a 0.5-watt laser through a 10-centimeter telescope... The primary ground station, called the Lunar Lasercom Ground Terminal, is located in White Sands, New Mexico, near Las Cruces and features a set of four 40-centimeter telescopes to receive the signal.
Wikipedia indicates 4 db/km attenuation in optical fibres was achieved decades ago. In free space, the attenuation would be higher; which brings me to my questions:
- How much power does the LLCD lose in transit from Lunar orbit to the ground station?
- Could the gas in the laser module freeze when in space?