NASA
Nasa Star Child: Probes to Mars (Level 2)
This site has a description of the different probes to pass by and land on Mars. Glossary, graphics, and printable version are also included.
NASA
Nasa: Mars Odyssey
Within the rocky landscape of Mars you will find the Mariner Valley. This expansive landform is as deep as the Grand Canyon and encompasses an area as wide as the distance between New York and Los Angeles.