NASA’s Commercial Crew Program is a multi-phased effort that began in 2010. Across the phases, NASA has engaged several companies, using both agreements and contract vehicles to develop and demonstrate crew transportation capabilities. As the program has passed through these phases, NASA has generally narrowed down the number of participants. NASA’s mission is to drive advances in science, technology, aeronautics, and space exploration, and contribute to education, innovation, our country’s economic vitality, and the stewardship of the Earth. To accomplish this mission, NASA establishes programs and projects that rely on complex instruments and spacecraft. NASA’s portfolio of major projects ranges from space satellites equipped with advanced sensors to study the Earth to a telescope intended to explore the universe to spacecraft to transport humans and cargo to and beyond low-Earth orbit.