The circular disk is a mini-DVD encoded with 4 million names of people around the world who signed up to send their names to Mars. The DVD is bolted onto the spacecraft with aluminum blocks in the shape of LEGO® bricks. The black mark pattern around the edge of the DVD simulates the secret coded message that was revealed to the world once images of the DVD were returned to Earth from Mars in January of 2004.

The central image is an Astrobot, a LEGO minifigure representation suited up for space. The Astrobots will tell their stories to the world. Other features include magnets in the central oval to collect Martian dust and colors to study color appearance under the Martian sky.

The Planetary Society