NASA Mission Statement:
To understand and protect our home planet
To explore the universe, and search for life
To inspire the next generation of explorers, as only NASA can.

The NASA Vision
To improve life here,
To extend life to there,
To find life beyond
...as only NASA can.

National Aeronautics and Space Act of 1958:
NASA Mission Statement
To advance and communicate scientific knowledge and understanding of the Earth, the solar system, and the universe and use the environment of space for research. To explore, use, and enable the development of space for human enterprise. To research, develop, verify, and transfer advanced aeronautics, space, and related technologies.
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Notice that NASA's Mission and Vision has changed since 1958 to include the search for extraterrestrial life