Mars Exploration Rover NASA's twin rovers, named Spirit and Opportunity, launched separately in 2003 and landed three weeks apart in January 2004. They made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life. Although Spirit ceased communicating with Earth in March 2010, Opportunity continues its work on the Red Planet.

Number of sheets: 2 Sheets
Difficulty: Moderate
Assembled Size: 3.67" x 3.35" x 2.34" (9.4 x 8.6 x 6 cm)