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[piano music, LRO title]

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position of the Lunar Reconnaissance Orbiter's laser altimeter as it orbits the moon.

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Recently, however, they also tried something a little...different. In addition to tracking

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the instrument, they used the laser to send a picture of the famous Mona Lisa in the first demonstration

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of laser communication with a satellite at the moon. To do this, the LRO team

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used the existing laser tracking signal--sent by the Next Generation Satellite Laser

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Ranging Station at NASA's Goddard Space Flight Center. The image was divided into pixels,

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which were then sent to the spacecraft one at a time by re-timing the regular tracking pulses.

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By delaying the tracking pulses by specific amounts, LRO scientists

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could use the difference between the expected arrival time and the actual arrival time to indicate the brightness

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of an individual pixel. Once the image was sent, scientists corrected for

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transmission errors caused by the Earth's atmosphere using common techniques used in CDs and

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DVDs. They also studied signal fluctuations due to Earth's atmosphere.

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The final image was verified when it was returned to Earth using LRO's radio telemetry system.

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This test--and the data obtained from it--sets the stage for future

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high data-rate laser communication demonstrations that will be a central feature of NASA's next

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moon mission, the Lunar Atmosphere and Dust Environment Explorer. So, while

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lasers are currently being used to track NASA satellites, in the future they may also be used to communicate

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with them, sending not only data, but perhaps images that one day wil be as famous as...

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the Mona Lisa. [piano music, Mona Lisa image]

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[piano music, beeping, satellite flies by Earth]

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[piano music, beeping, Goddard Space Flight Center information]