Starship Asterisk*

As part of the first demonstration of laser communication with a satellite at the moon, scientists with NASA's Lunar Reconnaissance Orbiter (LRO) beamed an image of the Mona Lisa to the spacecraft from Earth.

Click to play embedded YouTube video.

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The iconic image traveled nearly 240,000 miles in digital form from the Next Generation Satellite Laser Ranging (NGSLR) station at NASA's Goddard Space Flight Center in Greenbelt, Md., to the Lunar Orbiter Laser Altimeter (LOLA) instrument on the spacecraft. By transmitting the image piggyback on laser pulses that are routinely sent to track LOLA's position, the team achieved simultaneous laser communication and tracking.

"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."

Typically, satellites that go beyond Earth orbit use radio waves for tracking and communication. LRO is the only satellite in orbit around a body other than Earth to be tracked by laser as well.

"Because LRO is already set up to receive laser signals through the LOLA instrument, we had a unique opportunity to demonstrate one-way laser communication with a distant satellite," says Xiaoli Sun, a LOLA scientist at NASA Goddard and lead author of the Optics Express paper, posted online today, that describes the work.

Precise timing was the key to transmitting the image. Sun and colleagues divided the Mona Lisa image into an array of 152 pixels by 200 pixels. Every pixel was converted into a shade of gray, 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. The complete image was transmitted at a data rate of about 300 bits per second.

[i]To clean up transmission errors introduced by Earth's atmosphere (left), Goddard scientists applied Reed-Solomon error correction (right), which is commonly used in CDs and DVDs. Typical errors include missing pixels (white) and false signals (black). The white stripe indicates a brief period when transmission was paused. [b](Image courtesy: Xiaoli Sun, NASA Goddard)[/b][/i]

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The laser pulses were received by LRO's LOLA instrument, which reconstructed the image based on the arrival times of the laser pulses from Earth. This was accomplished without interfering with LOLA's primary task of mapping the moon's elevation and terrain and NGSLR's primary task of tracking LRO.

The success of the laser transmission was verified by returning the image to Earth using the spacecraft's radio telemetry system.

Turbulence in Earth's atmosphere introduced transmission errors even when the sky was clear. To overcome these effects, Sun and colleagues employed Reed-Solomon coding, which is the same type of error-correction code commonly used in CDs and DVDs. The experiments also provided statistics on the signal fluctuations due to Earth's atmosphere.

"This pathfinding achievement sets the stage for the Lunar Laser Communications Demonstration (LLCD), a 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 (LADEE)," says Goddard's Richard Vondrak, the LRO deputy project scientist.

The next step after LLCD is 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.

http://en.wikipedia.org/wiki/Beam_me_up,_Scotty wrote:
<<"Beam me up, Scotty" is a catchphrase that made its way into popular culture from the science fiction television series Star Trek. It comes from the command Captain Kirk gives his chief engineer, Montgomery "Scotty" Scott, when he needs to be transported back to the Starship Enterprise. Though it has become irrevocably associated with the series and movies, the exact phrase was never actually spoken in any Star Trek television episode or film.

"Beam me up, Scotty" is similar to the phrase, "Just the facts, ma'am", attributed to Jack Webb's character of Joe Friday on Dragnet, "It's elementary, my dear Watson", attributed to Sherlock Holmes, "Luke, I am your father", attributed to Darth Vader, or "Play it again, Sam", attributed to Ilsa Lund in Casablanca and "We don't need no stinkin' badges!" attributed to Gold Hat in The Treasure of the Sierra Madre. All five lines are the best known quotations from these works for many viewers, but not one is an actual, direct quotation.>>

http://en.wikipedia.org/wiki/Mona_lisa wrote:

<<The Mona Lisa (La Gioconda or La Joconde) is thought to be a portrait of Lisa Gherardini, the wife of Francesco del Giocondo, painted between 1503 and 1506. The ambiguity of the subject's expression, frequently described as enigmatic, the monumentality of the composition, the subtle modeling of forms and the atmospheric illusionism were novel qualities that have contributed to the continuing fascination and study of the work.

The painting's title Mona Lisa stems from a description by Giorgio Vasari: "Leonardo undertook to paint, for Francesco del Giocondo, the portrait of Mona Lisa, his wife...." In Italian, ma donna means my lady. This became madonna, and its contraction mona. Mona was thus a polite form of address, similar to Ma’am, Madam, or my lady in English. Vasari's account of the Mona Lisa comes from his biography of Leonardo published in 1550, 31 years after the artist's death. In 2005 when a scholar at Heidelberg University discovered a margin note in a volume of Cicero printed in 1477. It had been written by Leonardo's contemporary Agostino Vespucci and states that Leonardo was at that time working on a painting of Lisa del Giocondo and is dated October 1503. At his death in 1525, Leonardo's assistant Salai owned a portrait named in his personal papers as la Gioconda which had been bequeathed to him by the artist. Italian for "jocund", "happy" or "jovial", La Gioconda ("the jocund one") was a pun on the feminine form of the sitter's married name Giocondo.

Some scholars have argued that Lisa del Giocondo was the subject of a different portrait, identifying at least four other paintings as the Mona Lisa referred to by Vasari. Several other individuals have been proposed as the subject of the painting including Isabella of Naples, Cecilia Gallerani, Costanza d'Avalos, Duchess of Francavilla, Isabella d'Este, Pacifica Brandano or Brandino, Isabela Gualanda, Caterina Sforza, and Leonardo himself.>>