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Mars Exploration Rovers


The twin Mars Exploration Rovers (MER) -- Spirit and Opportunity -- were designed to study the history of water on Mars at their landing sites and to uncover geologic clues about whether Mars had any environments wet enough in the past to have been hospitable to life. Spirit launched for the Red Planet on June 10, 2003, Opportunity followed on July 7, 2003, each blasting-off from Cape Canaveral Air Force Station. After nearly 7 months, Spirit landed at Gusev Crater on January 3, and Opportunity bounced to a stop in Meridiani Plaunum on January 24, Pacific Standard Time (PST).

The names Spirit and Opportunity were selected by NASA in a student essay contest that drew nearly 10,000 entries, sponsored by The Planetary Society. Larger than their toy-wagon size predecessor, Sojourner, the MER rovers are about the size of a small dune buggy. Each is equipped with a robotic arm that features a drilling tool, and three spectrometers, as well as four pairs of stereo cameras mounted in different positions on their frames, one of which allows them to have a human-like, 3-D view of the terrain. With the capability of traveling 100 meters a day, the MER rovers function as robot field geologists exploring the cold, barren Martian environment where humans cannot yet go.

By the end of April 2004, Spirit and Opportunity successfully completed their 90-day primary missions. Now, more than a year and a half after landing, the rovers continue exploring, gaining renown as one of the most remarkable Mars missions in space exploration history. From all cameras combined, the rovers have together returned more than 75,000 images so far, which, along with other geologic data from the rovers, have provided unprecedented evidence about wet environmental conditions in Mars' past.