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"This is the first time anyone has achieved one-way laser communication at planetary distances," said David Smith, the Lunar Orbiter Laser Altimeter's principal investigator, in a press statement. "In the near future, this type of simple laser communication might serve as a backup for the radio communication that satellites use. In the more distant future, it may allow communication at higher data rates than present radio links can provide."
At Goddard, scientists split the image of the Mona Lisa into an array of 152 pixels by 200 pixels. "Every pixel was converted into a shade of gray," NASA explained, "represented by a number between zero and 4,095. Each pixel was transmitted by a laser pulse, with the pulse being fired in one of 4,096 possible time slots during a brief time window allotted for laser tracking." NASA says the image was eventually transmitted to LRO at 300 bits per second.
So hey, why did the NASA Goddard researchers choose the Mona Lisa for its experiment and not, say, an image of Pat Patriot? Well, according to Goddard's Xiaoli Sun, the principal author of the paper, it all comes down to the iconic nature of the painting. "[The Mona Lisa] is a familiar image with lots of subtlety," Sun told NBC. "You can immediately feel whether the image looks right, and how much information got lost."