Mars DVD Code Clues

When Spirit and Opportunity were launched in the summer of 2003, each of them carried one of The Planetary Society's Red Rover goes to Mars DVD's, inscribed with four million names.

On the rim of each DVD a message was inscribed in a code, a different one for each of the landers. Spirit had the much harder code. First we present several clues for the Spirit code, gradually revealing more and more information with each clue. Then, we do the same farther down the page for the Opportunity code. If you want to only look at the images and not be tempted with the clues yet, go here.

Spirit DVD Code Clues

The image below was taken by one of Spirit's Panoramic Cameras shortly after the rover's landing on Mars. It shows The Planetary Society's Red Rover Goes to Mars DVD, installed on board Spirit. Clearly visible around its rim is a message, written in a secret code of dots and lines. 

Spirit's DVD on Mars
Spirit's DVD on Mars This close-up of Spirit's Mars DVD was created by the Student Astronauts by combining three images captured through different filters on Sol 2 of its mission on Mars. Note the secret code around the edge. The Planetary Society created the DVD. NASA / JPL / Cornell / The Planetary Society

As you have probably discovered, the Mars code used for the secret message on Spirit's DVD is not easy to decipher. To help you along the way, here's some clues to help set you on the right track:

Clue No. 1, January 10, 2004:
A longer text using the same code would read:

-llll-llll-----l-ll-lll-l-l-l-ll--l---lll-------ll---llll----l----ll-l-l-llll--l---lll-l-ll-ll-----llll-ll-l--lll-ll-l-llll--l---ll---lll--l----ll----ll--ll--l---l-l-lll----l-l-ll---------lll--l-l-llll-----lll-l-l-lll-ll-lll---lll--l-l-l-ll---ll-ll--llllll-l---ll---lll-ll----ll-l---l-l--l-llll--l.---ll---lll--l-----llll-llll------lll-lll-lllll-ll-ll-llll--ll---lll----l-ll--,---ll---lll--l-----l-ll-l-lll-l-l---ll----ll--llll---llll---l-llll----l-lllll----ll--l---lllllll,---ll----ll--ll--ll----l---ll---llll---ll--l--ll---ll--llll---lll--l-ll-------ll----ll--ll-l-ll-------ll--ll--lll-l-ll-ll-l---l-l--lll---lll-l-lll-l-l---ll-ll--lll-l-----l---l-l-l-l---lll-l--------lll-l-llll--ll-l--lll--ll--ll----l---ll-----ll---lll-l-l-llll-----l---ll-llllll---l-l-l-l---lll-l-------llll-llll--lll--lll-l-ll-llll-----llll.

Clue no. 2, January 12, 2004:
The text in clue No. 1 is from Carl Sagan's Pale Blue Dot.

Clue no. 3, January 14, 2004:
The message is encoded twice. Each letter is represented by a number, and each number is represented by vertical lines (l) and dashes (-).

Clue no. 4, January 16, 2004:
Each number, representing a letter, is composed on one, two, or three digits.

Clue no. 5, January 19, 2004:
More common letters are represented by fewer digits.

Clue no. 6, January 21, 2004:
Each digit, from 0 to 7, is represented by a 3 bit binary numbering system: --l is 1, -l- is 2, -ll is 3, etc. 8 and 9 are not used.

Clue no. 7, January 26, 2004:
A, E, O, R, and S are the only letters represented by a single digit.

Clue no. 8, January 29, 2004:
Numbers representing less common letters begin with a 5 or a 6, but no letter is represented simply by 5 or 6. 0 alone represents a space, but 0 can also be a digit in two or three digit numbers that represent specific letters.

Clue no. 9, February 2, 2004:
Letters represented by three digits always begin with a 5.

Clue no. 10, February 5, 2004:
The code for "J" is 572, the code for "K" is 571, the code for "Q" is 574, the code for "V" is 570, the code for "X" is 573, the code for "Z" is 575. These are the only letters coded by three digit numbers.

Clue no. 11, February 9, 2004:
The code for "A" is 2, the code for "B" is 56.

Clue no. 12, February 13, 2004:
The code for "C" is 66, the code for "D" is 64.

Clue no. 13, February 19, 2004:
The code for "E" is 1, the code for "F" is 52.

Can you solve it now? You can check your answer on our solutions page (warning: this page contains solutions for both DVD codes, so you may want to first try solving both codes found on both DVDs before checking).

Opportunity DVD Code Clues

Similar to the DVD on board Spirit, the image below was taken by one of Opportunity's Panoramic Cameras shortly after the rover's landing on Mars. It shows The Planetary Society's Red Rover Goes to Mars DVD, installed on board Opportunity. Clearly visible around its rim is a message, written in a secret code of dots and lines.

Opportunity's DVD on Mars
Opportunity's DVD on Mars This close-up of Opportunity's Mars DVD was created by the Student Astronauts by combining three images captured through different filters on Sol 2 of its mission on Mars. Note the secret code around the edge. The Planetary Society created the DVD. NASA / JPL-Caltech / Cornell / The Planetary Society

The code on Opportunity is more straight forward than Spirit, so we only have a small number of hints:

1. This "code" is very common on Earth.

2. You might think of the code more as an alphabet.

3. The code is named for its creator, a French man.

4. A Planetary Society contest led to naming the asteroid visited by the Deep Space 1 spacecraft after the inventor of this code.

5. The code is used as a tactile writing system used by the blind and the visually impaired.

Can you solve it now? You can check your answer on our solutions page (warning: this page contains solutions for both DVD codes, so you may want to first try solving both codes found on both DVDs before checking).