[piano music, LRO title]
[piano music, LRO title] Narrator: NASA scientists routinely use lasers to track the
position of the Lunar Reconnaissance Orbiter's laser altimeter as it orbits the moon.
Recently, however, they also tried something a little...different. In addition to tracking
the instrument, they used the laser to send a picture of the famous Mona Lisa in the first demonstration
of laser communication with a satellite at the moon. To do this, the LRO team
used the existing laser tracking signal--sent by the Next Generation Satellite Laser
Ranging Station at NASA's Goddard Space Flight Center. The image was divided into pixels,
which were then sent to the spacecraft one at a time by re-timing the regular tracking pulses.
By delaying the tracking pulses by specific amounts, LRO scientists
could use the difference between the expected arrival time and the actual arrival time to indicate the brightness
of an individual pixel. Once the image was sent, scientists corrected for
transmission errors caused by the Earth's atmosphere using common techniques used in CDs and
DVDs. They also studied signal fluctuations due to Earth's atmosphere.
The final image was verified when it was returned to Earth using LRO's radio telemetry system.
This test--and the data obtained from it--sets the stage for future
high data-rate laser communication demonstrations that will be a central feature of NASA's next
moon mission, the Lunar Atmosphere and Dust Environment Explorer. So, while
lasers are currently being used to track NASA satellites, in the future they may also be used to communicate
with them, sending not only data, but perhaps images that one day wil be as famous as...
the Mona Lisa. [piano music, Mona Lisa image]
[piano music, beeping, satellite flies by Earth]
[piano music, beeping, Goddard Space Flight Center information]
[piano music]
[piano music fades, black screen]