NASA shoots laser at moon as part of deep space communications test

January 18, 2013

NASA shoots laser at moon as part of deep space communications test

Why would NASA send the Mona Lisa to the moon?

NASA has successfully sent the Mona Lisa to a spacecraft orbiting the moon almost 240,000 miles away, part of a planned trial run of a newly devised laser technology.

The new technology, which may become common practice soon, was able to send the famous painting to the spacecraft via a laser beam, making Leonardo da Vinci’s Mona Lisa the first digital image to be beamed to space. Measuring just 30 inches by 21 inches, the Mona Lisa, an oil on a poplar wood panel, is arguably the most famous work of art in existence.

The painting was sent to NASA’s Lunar Reconnaissance Orbiter, which has been orbiting the moon for three and half years. The Orbiter contains a laser-tracking system called the Lunar Orbiter Laser Altimeter (LOLA), which NASA scientists send laser pulses to from Next Generation Satellite Ranging station at Goddard Space Flight Center in Maryland. By sending pulses to the Obiter, NASA scientists can find the space probe’s exact location around the moon.

Last March, a team of scientists sent a black and white copy of the Mona Lisa to the Lunar Reconnaissance Orbiter by entering a series of numbers in a 152 by 200 pixel grid. The values that were entered by the NASA team ranged from zero to 4,095 and each presented a different color black.

The number of each pixel of the image was then translated into laser-tracking pulses. Every one of the laser pulses was released between one and 4,096 extremely short time slots. The pulses were fired at around 300 bits per second. According to NASA, precise timing was the key to transmitting the image.

Up near the moon, LOLA received the pulses and figuring out the time that each was sent, the software was able to piece together the exact color of black that was entered for each pixel. Ultimately, LOLA re-created the original black and white image of the Mona Lisa all the way at the moon.

LOLA’s Mona Lisa, was not entirely perfect, however. Even in calm skies, the Orbiter experienced atmospheric turbulence that caused transmission errors of the laser pulses. Ultimately, interference caused a 15 percent error rate when putting the picture together. In order to perfect these imperfections, the NASA scientists used Reed-Solomon data coding. This type of coding is most commonly used to right the wrongs that may be acquired when playing CDs and DVDs back.

The Orbiter then returned the Mona Lisa back to the NASA scientists on Earth using its standard radio communication system to be sure the painting made it with no problems. Amazingly, the Lunar Reconnaissance Orbiter was also able to continue its routine mapping tasks while copying the Mona Lisa.

“This is the first time anyone has achieved one-way laser communication at planetary distances,” says LOLA’s principal investigator, David Smith of the Massachusetts Institute of Technology. “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.”

While the project seems a bit strange, NASA noted that it has a very practical purpose. The space agency said the successful conclusion of the test means it can  now begin work on the Laser Communications Relay Demonstration (LCRD), NASA’s first long-duration optical communications mission. LCRD will help develop concepts and deliver technologies applicable to near-Earth and deep-space communication, according to space agency officials.

The test comes as NASA has refocused its efforts on studying the lunar surface. The U.S. space agency recently crashed a pair of orbiting probes into the side of a pair of lunar mountains, part of an experiment to test the composition of the lunar soil. NASA has announced plans to return to the moon, although recent budget cutbacks may hinder the agency from meeting its stated goals.

The experiments were conducted by a team of NASA researchers led by Xiaoli Sun, who works for the Goodard Space Flight Center.

 


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