NASA recently sent the Mona Lisa to the moon using a laser beam. A digital image of the Mona Lisa has become the first digital photograph to be transmitted via laser from the Earth to a spacecraft in orbit around the moon. The trip to the moon for the Mona Lisa was 240,000 miles.
NASA sent the Mona Lisa to the moon as part of an experiment that used the laser tracking system aboard the Lunar Reconnaissance Orbiter. NASA shoots pulses of laser light to the orbiter from its Next Generation Satellite Ranging station located at the Goddard Space flight Center in Maryland regularly. Those laser beams are aimed at the orbiter's Lunar Orbiter Laser Altimeter thati is used to locate the precise position of the orbiter as it circles the moon.
NASA researchers encoded a black and white version of da Vinci's famous masterpiece as a series of values in a grid measuring 152 x 200 pixels. Each of those values entered into the grid represented a shade of black, gray, or white that range from a value of zero to a value of 4095. NASA then piggybacked the signal required to describe each pixel on the ranging stations laser pulses.
The entire image wasn't transmitted at one time with the entire image being sent as pulses during one of 4096 incredibly small designated timeslots. The data transfer rate was about 300 bits per second according to the researchers. Once the individual laser pulses were received by the LRO in Orbit around the moon, software aboard the orbiter rebuilt the image. The orbiter software took the grayscale value for each pixel and reassembled the black-and-white image. The picture above shows the transmitted image before error correction was applied on the left side and the image after error correction was applied on the right side.
"In the near future, this type of simple laser communication might serve as a backup for the radio communication that satellites use," David Smith of the Massachusetts Institute of Technology said. "In the more distant future, it may allow communication at higher data rates than present radio links can provide."
[via NBC News]