"From the time of our birth, humans have felt a primordial urge to explore -- to blaze new trails, map new lands, and answer profound questions about ourselves and our universe." (NASA, 2009)
NASA (2009) Exploration: NASA's Plan to Explore the Moon, Mars and Beyond. [online] http://www.nasa.gov/exploration/whyweexplore/why_we_explore_main.html
