Curiosity (rover) conditions favorable for microbial life, including investigation of the role of water; and planetary habitability studies in preparation for human exploration. In December 2012, "Curiosity" two-year mission was extended indefinitely. On August 5, 2017, NASA celebrated the fifth anniversary of the "Curiosity" rover landing and related exploratory accomplishments on the planet Mars. The rover is still operational, and as of , "Curiosity" has been on Mars for sols ( total days) since landing on August 6, 2012. "(See current status.)" "Curiosity" design will serve as the basis for the planned Mars 2020 rover. As established by the Mars Exploration Program,
Mars Pathfinder Tony Spear. This mission was the first of a series of missions to Mars that included rovers, and was the first successful lander since the two "Vikings" landed on the red planet in 1976. Although the Soviet Union successfully sent rovers to the Moon as part of the Lunokhod program in the 1970s, its attempts to use rovers in its Mars program failed. In addition to scientific objectives, the "Mars Pathfinder" mission was also a "proof-of-concept" for various technologies, such as airbag-mediated touchdown and automated obstacle avoidance, both later exploited by the Mars Exploration Rover mission. The "Mars Pathfinder" was