Liberty was a 2011 launch vehicle concept proposed by ATK (now part of Northrop Grumman Space Systems via the acquisition of Orbital ATK) and Airbus Defence and Space (formerly Astrium) for phase 2 of the NASA Commercial Crew Development (CCDev) program intended to stimulate development of privately operated crew vehicles to low Earth orbit.

[3][4] Liberty was proposed as a vehicle to service the International Space Station for crew and cargo, but its capacities could potentially have allowed for government and commercial satellite launches, including to Geostationary transfer orbit.

[11] ATK's stated goal prior to the CCiCAP award announcement was to begin test launches in 2015, with a crewed flight in 2016.

[12] In early August 2012, shortly before NASA announced the selectees for CCDev award, ATK Liberty manager Kent Rominger stated that the program would continue even without CCiCAP funding.

[4] The spacecraft would be made of ATK's composite space shell developed as an alternative to the Orion's aluminum lithium structure.