The core stage of NASA's new rocket, the Space Launch System meant to eventually power a mission to Mars, has just passed its preliminary design review, a milestone that opens the door to building the rocket in time for a 2017 launch. The review is designed to make sure a project's timeline and costs are feasible, and that the core can successfully integrate with other parts of the rocket, like the boosters and main engines. Now, NASA says it will begin building initial versions of the parts, hoping to have a final design by the time another review comes up in 2014. "We are running ahead of schedule," says Program Manager Todd May, "and will leverage that schedule margin to ensure a safe and affordable rocket for our first flight in 2017."

The SLS is meant to be a flagship rocket for NASA, and it's being developed around the same time as Orion, a capsule that's meant to take astronauts to Mars sometime in the future. Orion is currently scheduled to be tested in 2014 and to have its first manned flight in 2021. We've also heard that a Moon base is being tentatively considered, albeit not for some time. Although NASA has leaned heavily on public-private partnerships recently, it's managing the SLS program itself, contracting with Boeing and others to build it.