With the 2016 transition of presidential power, NASA abandoned what little agenda it had. Which isn't unusual. The agency’s mandates are always subject to the US's four-year flip-flop, despite the fact that decades-long mission plans require, believe it or not, decades. Since Trump took office, officials have debated whether to scrap missions to asteroids, whether to favor the moon over Mars, and whether to put humans aboard the very, very first mission, called EM-1 (it was a bad idea, and they won't).

Through all this, the contractors kept constructing and testing, keeping their focus simply on finishing. Until Gerstenmeier's March presentation. Finally, here was a roadmap. The first mission, according to this plan, will go to the moon's orbit in 2018.

Four years later, the rocket will launch a mission to Europa, that mystery moon on which moviemakers imagine oceanic aliens. Then, crews will shuttle to lunar orbit to build a deep-space habitat and staging area for longer-distance travel. Trips there will continue through 2029, building up the outer-space infrastructure. Four lucky people will spend a year hanging out in the ether around the moon, to see how they and the hab fare. And eventually, other astronauts will undock part of the space town and swivel it on a path toward Mars.

Stick a Pin in Orion

With those goalposts in place, NASA's contractors finally have somewhere to aim. Orbital ATK is currently proving that its hardware meets NASA's previously-established specs for safety and performance. And contractor Lockheed Martin continues to test the human capsule for NASA's deep-space forays: Orion.

As of late July, the Lockheed crew was in the throes of testing a full-size mockup of Orion. Off a road called Titan Loop in Colorado, Lockheed engineers test how the capsule fares in all kinds of weather, blasting it with sound waves to see how it handles vibration, shocking it to see if its components come out OK, putting pressure on it to see if its structure survives. “It tests all the systems in various kinds of badness,” says Christopher Aiken, an integration and test engineer.

The mockup isn’t just a shell: Its electronics and controls are silicon copies of final product. “When we fly this, it doesn’t know it’s sitting on the ground,” says Paul Sannes, manager of the test lab. The idea is that this model will feel and behave like the real thing under those same conditions, a voodoo doll of space travel. Last week, four Lockheed interns did an AMA on reddit. “Getting to see a full mock-up of the capsule every day is pretty awesome,” wrote Bailey Sikorski. “Plus I get to touch it, which is even cooler.”

Six hundred miles northwest, back at Orbital ATK, the biggest task is bureaucratic: a design certification review of the company's solid rocket boosters, which will power 80 percent of SLS's first few minutes of flight. Cast inside space-shuttle casings, the propellant's final form has the consistency of a pencil eraser. Technicians mix the solution in 600-gallon KitchenAids—209 of them per booster—and pour that liquid into the five segments that make up each booster. Then they'll cure, trim, and X-ray them to make sure they're defect-free.

When SLS goes up, it will eat through 1,385,000 pounds of that artisanal propellant in two minutes. And although the first flight won’t happen till 2019, Orbital ATK has all the booster segments finished. The design certification will stretch through the end of this year. “We provide to NASA all of the certification paperwork, all the drawings, all the test data,” says Bown. And then? Assuming all's well? “Ship, assemble, and fly,” he says.

All that prep work means more now that SLS has real, concrete plans for launching astronauts to the moon's orbit. When the space shuttle Challenger broke apart in 1986, Bown worked at this Utah site. Engineers there, then as now, built NASA’s rocket boosters. And it was a booster that failed, that cold Florida morning, 73 seconds after launch, when it was just higher than a commercial airliner. Seven astronauts died.

Bown kept working here, through decades and acquisitions and mergers and a whole lot of propellant work. “I got to go from feeling horrible to feeling good about it again,” he says.

Today, for major tests like that of the launch abort motor, NASA always sends at least one astronaut to observe. That presence means a lot: The astronauts get to meet the people they’ve trusted to make the 177-foot-tall erasers that will fire them to space. And those engineers get to meet the people that propel their work.

The two types stand side by side at the tests—both jumping involuntarily, both perhaps in the frame of one of Bown’s photos.