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 sample-return mission complexity and technical problems. One mission concept (provisionally named simply Mars Sample-Return) was originally considered by NASA's Mars Exploration Program to return samples by 2008, but was cancelled following a review of the program. A NASA-ESA concept mission was aborted in 2012. The United States' Mars Exploration Program, formed after "Mars Observer" failure in September 1992, supported a Mars sample-return. One example of a mission architecture was the "Groundbreaking Mars Sample-Return" by MacPhereson in the early 2000s. In early 2011, the National Research Council's Planetary Science Decadal Survey, which laid out mission planning priorities for the period 2013–2022 at the