When the Mars Exploration Rovers were launched last year, The Planetary Society placed on board hidden messages as a public involvement activity in their educational Red Rover Goes to Mars project, which was conducted in partnership with the LEGO Company.
Several thousand people attempted to decode the secret messages. Of the 2,000 correct answers, one man -- Jim Gillogly of Westwood, California -- was first to decipher both messages: "Wish you were here" on Spirit's lander and "Explore to learn" on Opportunity.
The codes are depicted on Planetary Society and LEGO Company mini-DVDs mounted on the twin rovers. Visitors to The Planetary Society's web site viewed images of the DVDs on Mars taken by the rover cameras and were encouraged to try decoding the two messages, each of which was written in a different code. Gillogly deciphered the second code – the one on Opportunity -- from an image of the DVD posted by NASA before The Planetary Society even depicted the code on its website.
Spirit's DVD featured a double code where each letter was represented by a different 1, 2 or 3 digit number. Each of those digits was, in turn, represented by a binary code where "1" was depicted as "|" and "O" as "-" to further increase the code's level of difficulty.
Bruce Betts, Director of Projects, said, "The code on Spirit’s DVD is the same type of code that is used to compress text data for computers, including spacecraft computers. In such a code, the most common letters like "a" or "e" are designed to take up a smaller amount of space than less common letters."
Opportunity's code was written in Braille, an alphabet developed for the blind that forms letters by a series of dots. In 1999, The Planetary Society helped name an asteroid Braille when the organization held a contest to suggest a name of a famous inventor for asteroid 1992KD. NASA’s Deep Space 1 mission flew past the asteroid Braille in 1999.
Gillogly has a Ph.D. in computer science and was a chess programmer, a modeler of complex processes, and a cryptographic systems programmer. He was the first person outside the intelligence community to crack the cipher on the mysterious Kryptos Sculpture installed in a CIA courtyard, which had baffled amateur codebreakers for a decade.
Every two days after each image was first posted, a new clue was released to help people decode the message.
Commenting on breaking the two codes on Mars, Gillogly said, "The Spirit cipher took me a good while. I spent about two hours before the first clue, then another four or five hours before the second clue, and about half an hour after the second clue. That broke it open for me. The Opportunity cipher took about ten minutes total."
The Planetary Society will award LEGO prizes and memberships in The Planetary Society to the first 10 people who successfully broke each code as well as to 30 random winners selected from all of the cryptographers who submitted correct answers. Out of 4039 submissions, 1409 people solved the Spirit code while 639 out of 1200 cracked that on Opportunity.
Submissions were received from around the world, with the two top groups of 10, who cracked the codes first, including entrants from Finland, Canada, Slovenia, Brazil and New Zealand.
The Planetary Society, in cooperation with the LEGO Company, provided the DVDs to carry to the surface of Mars the names of four million people collected by NASA. Each DVD assembly is mounted to the landers that protected the rovers during their bounce-down landings on Mars. The DVDs will now remain on the Red Planet as time capsules for potential future human explorers to discover.
In addition to the four million names carried on each DVD, the DVD mounting structures include magnets to collect dust, colors to study color appearance under a Martian sky, and representations of robotic LEGO minifigures that have been personified as Biff Starling on Spirit and Sandy Moondust on Opportunity. Biff’s and Sandy's entertaining mission reports called the Astrobot Diaries continue to appear on The Planetary Society's website.
The DVDs are part of The Planetary Society's Red Rover Goes to Mars project, an official part of the Mars Exploration Rover mission and the first educational experiment selected for a planetary mission.
The DVDs are constructed from silica glass to withstand the high temperatures required to sterilize them of Earth microbes prior to their launch for Mars. Silica glass also enjoys a far greater lifetime than the plastic from which regular DVDs are made, perhaps lasting as long as 500 years.
Visionary Products, Inc. implemented the DVD mounting assembly, Plasmon OMS donated the silica glass DVDs and data etching, and the magnets were donated by Jens Martin Knudsen and Morten Bo Madsen, heads of the Danish team who also built the magnets mounted to the Mars Exploration Rovers.