ATK, which teamed with Europe's Astrium, builder of the Ariane 5 rocket, wasn't selected for funding in 2011, but continued working on the project on its own dime.
For its new bid, ATK added a capsule, also called Liberty, which was originally developed for NASA as a prototype composite design for the deep-space capsule Orion. ATK also added Orion prime contractor Lockheed Martin to its team.
Depending on funding, NASA plans to award at least two - and possibly more - 21-month contracts, each worth between $300 million and $500 million. The next phase of the work would have companies integrate their spaceships with rockets and develop detailed launch, flight, operations and landing plans.
Contracts are expected to be awarded in August.
Image: Artist's impression of the slender Liberty rocket - towering at twice the height of the Statue of Liberty. Credit: ATK