ATK [ATK] successfully completed the last Liberty space transportation system milestone under the company’s unfunded Space Act Agreement (SAA) with NASA for the Commercial Crew Development Program (CCDev-2).

ATK said in a statement the final milestone under the SAA was a Program Status Review, during which the company presented NASA with detailed progress of the program, including integrated master schedule, system requirements, software status, flight test plan, system safety review, ground processing certification plan and schedule for initial operational capability.

The CCDev-2 Liberty SAA enabled NASA and the Liberty team to share technical information related to the Liberty transportation system during the preliminary design review phase of the program. ATK said it completed five milestones and held three Technical Interchange Meetings, all on internal funding.

Liberty’s schedule includes unmanned test flights in 2014 and 2015, followed by the first crewed with Liberty astronauts in late 2015. Commercial operational flights to take NASA astronauts to the ISS could begin in 2016, ATK said.

Liberty is a complete commercial crew system that includes a human-rated composite spacecraft, advanced abort system and a reliable, affordable and capable commercial launch vehicle.