For a little while, Friday's maiden flight of the CST-100 Starliner spaceship, a vehicle that Boeing designed to ferry NASA astronauts to and from orbit, went very smoothly.
The Starliner had no people on board — just cargo and a crash-test dummy named Rosie — when it lifted off at 6:36 a.m. ET atop an Atlas V rocket built by United Launch Alliance. The spaceship separated from the rocket 15 minutes later, then coasted for another 16 minutes, waiting for just the right moment to ignite its main engines and fly toward the International Space Station (ISS).
That key moment came and went.
Boeing eventually recovered control of the Starliner, ignited the main engines, and pushed their ship into a "stable" orbit, NASA wrote in a blog post. After some huddling, both Boeing and NASA officials held a press conference at the launch site in Cape Canaveral, Florida, to share what they'd learned about the anomaly.
"A lot of things went right," NASA administrator Jim Bridenstine said during his opening remarks, noting the Starliner made it to orbit — just not the correct one. "This is why we test."
What apparently did not go right, though, was the ticking of a crucial clock that helps the Starliner know where it is in its flight.
As Bridenstine explained, this timing error led the spaceship's autopilot system to believe it was further along in the mission than it actually was. This glitch then kicked off a series of maneuvers that weren't yet supposed to happen, putting the mission at risk.
"We don't know what the root cause is. I think it's too early for us to make that assessment," Bridenstine said.
Why the Starliner can't make it to the space station and will instead land in New Mexico
The Starliner's autopilot never fired the main engines, a panel of officials said during Friday's briefing.
But due to the timing error, Starliner's autopilot assumed the main engines were ignited — so the system fired many smaller thrusters located around the hull of the ship to keep the ship in a position it didn't yet need to be in. During this unexpected maneuvering too soon in the flight, the Starliner chewed through fuel.
Officials also said an important signal sent from the ground to the Starliner instructing the ship to ignite its main engines — just in case the automated system had not done so — never reached the spaceship, likely due to a temporary gap in satellite communications.
The Starliner was supposed to dock with the ISS on Saturday morning, drop off food and holiday presents, stay for about a week, and then return to Earth for analysis with Rosie the dummy inside.
By the time mission controllers regained contact with the ship, though, they decided there wasn't enough fuel left to reach the space station; the smaller thrusters had consumed too much. So they cut their losses and put the Starliner on a less fuel-hungry trajectory to land at NASA's White Sands Test Facility in New Mexico.
Bridenstine said the change "was the absolute right decision" to make in the heat of the moment, hinting the spacecraft might have otherwise reentered Earth's atmosphere — though he insisted no astronauts would have been been in danger during the flight.
"There was no time at which they would've been unsafe during any of this. And had they been on board, we ... very well could be on our way to the International Space Station right now," Bridenstine said.
By this he meant NASA astronauts Mike Fincke or Nicole Mann, who are scheduled to fly aboard the first crewed mission along with Boeing astronaut Chris Ferguson, might have overridden the Starliner's autopilot, initiated the engine burn, and put the ship on course for the ISS.
"We have the capability on-board to stop that automation and take over manually to fly," Mann said.
It's now uncertain when Boeing will try to fly astronauts for the first time
Boeing privately developed the CST-100 Starliner, but its work is funded by NASA's Commercial Crew Program. The government competition aims to resurrect US spaceflight capability that the US lost when it retired the space shuttle fleet in July 2011, though with commercial vehicles.
Back in March, SpaceX (a longtime rival of Boeing and ULA) successfully launched and landed its Crew Dragon spaceship for NASA on a similar demonstration mission, called Demo-1. An abort-engine test months later ended in an explosion, but SpaceX is now on track launch its first astronauts no sooner than February 2020.
This month's Orbital Flight Test by Boeing, after years of delays, was designed to show NASA that the Starliner is safe to fly astronauts sometime in mid-2020.
Bridenstine said it's too soon to know if Boeing will need to launch a re-do of the uncrewed test mission, or if salvaging the current one might check all of the boxes Boeing needs to start launching people. If the latter, Starliner could fly astronauts Ferguson, Fincke, and Mann without having demonstrated its automated docking system in space.
But Bridenstine noted that NASA's far-larger space shuttle manually docked for decades with the ISS without issue. Meanwhile, Steve Stich, the NASA program's deputy manager, said on Friday that it shouldn't be a dealbreaker.
"It's something that is nice to have, but I wouldn't say it's a requirement for crewed flights," Stich said.
Getting the timing issue resolved is, of course, something Boeing will have to satisfactorily iron out for NASA.
"This is why we flight test, right?" Fincke said during the briefing. "We're trying to get all of the bugs, if you will, out of the system."
Boeing plans to put the Starliner through as many paces as it can over the next 48 hours, then land the Starliner in New Mexico sometime on Sunday.