 As a part of the flight evaluation program that was to explore and validate technologies to be used in the OSP, NASA initiated the X-37 program, selecting Boeing Integrated Defense Systems as the prime contractor.However, the OSP received heavy congressional criticism for being too limited in mission ("...the primary shortcoming of the OSP is that, as currently envisioned, it leads nowhere besides the space station") and for costing as much as US$3 to $5 billion.Then, in 2004, NASA's focus changed yet again, from the OSP to the Crew Exploration Vehicle (CEV), and the X-37 project was transferred to DARPA, where some aspects of technology development were continued, but only as an atmospheric test vehicle.