NASA's prototype Space Launch System (SLS) for future deep space missions has just passed a major milestone on its way to final production.

The SLS design, which has been put through various mini mock launches, simulations and individual component testing, has just passed it's Critical Design Review (CDR), enabling the design for America's "next great rocket" to finally head into production, NASA reported in an announcement Wednesday.

"Completing the CDR is a huge accomplishment, as this is the first time a stage of a major NASA launch vehicle has passed a critical design review since the 1970s," said Tony Lavoie, manager of the Stages Office at Marshall. "In just 18 months since the Preliminary Design Review, we are ready to go forward from design to qualification production of flight hardware."

According to SLS program manager Todd May, gaining approval after a mere 18 months brings the SLS production comfortably ahead of schedule.

"Our entire prime contractor and government team has been working full-steam on this program since its inception," he said in a statement, adding that the team "continues to make excellent progress towards delivering the rocket to the launch pad."

The contractor in question, The Boeing Company, sent representatives to meet up with experts from various NASA centers to assess the SLS on June 30 and July 1 at NASA's Marshall Space Flight Center in Huntsville, Ala. Data on more than 3,000 components and portions of the rocket was reviewed during this meeting, and resulted in the SLS passing the CDR.

The first fully built SLS launch vehicle will be able to lift capacity - enabling it to carry an unmanned and completed Orion spacecraft past low-Earth orbit. This will be used as part of the Orion Exploration Flight Test -1, which is slated to occur this December.