NASA’s Michoud facility is less than two weeks away from readying the final “tool” needed to build the massive fuel tanks for the rocket that will propel astronauts to Mars.

Michoud in New Orleans is building the Space Launch System’s “core stage,” which holds the tanks that provide fuel to the rocket’s engines, spokeswoman Kimberly M. Henry said.

The core stage is more than 200 feet tall and contains a liquid oxygen tank, a liquid hydrogen tank, an inter tank and an engine section.

“Actual flight hardware is being built now as we speak,” Henry said.

Earlier this week, NASA announced it had approved moving the Space Launch System from formulation to development. The last exploration-class vehicle to reach the development stage was the space shuttle.

Congress has approved $7 billion in funding to build the initial SLS model, which will be able to lift a 77-ton load into orbit; that’s roughly three times the payload of a space shuttle. The initial flight will not include a crew and is expected to take place no later than September 2018.

“We are on a journey of scientific and human exploration that leads to Mars,” NASA Administrator Charles Bolden said. “And we’re firmly committed to building the launch vehicle and other supporting systems that will take us on that journey.”

Meanwhile, NASA is scheduled to cut the ribbon on Michoud’s final tool, the vertical assembly, on Sept. 12, Henry said. The vertical assembly will be the world’s largest friction-stir weld tool.

In friction-stir welding, metals are heated into a plasticlike state and stirred together under pressure. The technique produces a nearly defect-free, high-strength bond.

Michoud’s tools basically make either “a barrel, a ring or a dome,” Henry said. Nine of those pieces, when combined, form the core stage. The pieces will require close to a quarter-mile of welds.

Michoud has already produced six of the rings, which measure nearly 28 feet in diameter.

NASA is investing about $250 million from the Space Launch System program at Michoud, which includes upgrades to the facility and tools, Henry said. About 690 employees are supporting SLS at Michoud. The total includes NASA civil servants, Boeing prime contractor employees and subcontractors, and Jacobs Engineering support services personnel and contractors who guard the facility.

NASA contractors at Michoud also are producing the Orion module that will hold a crew of up to four people. Separately, the Dream Chaser, a space plane that will look like a little brother to the familiar shuttle, is under development at Michoud.