Boeing will move its Starliner capsule from its launchpad in Florida on Thursday back to the building where it was stacked aboard the rocket that was to carry it to space, Boeing officials said late Wednesday.

The decision to return the spacecraft and its Atlas V booster to what’s known as the vehicle integration facility (VIF) came after NASA and Boeing investigators were unable to determine what had caused a sensor to indicate that a valve on the vehicle wasn’t in the proper position, forcing officials to cancel its long-awaited launch Tuesday, the company said.

Boeing said inspections of the vehicle would continue in the facility. It gave no timetable for how long those inspections might take or whether they would require separating the capsule from its booster or disassembling the spacecraft. Others familiar with spacecraft engineering suggested it would undergo a lengthy inspection period that could keep it grounded for several weeks.

“Boeing is working to understand unexpected valve position indications in the Service Module propulsion system that led the company to scrub yesterday’s launch attempt early in the countdown,” Boeing said in a statement.

Boeing said “troubleshooting of the valves while the Starliner and Atlas V were on the launchpad has ruled out a number of potential causes, including software.” It also said “the severe storm that occurred on Monday also appears to be an unlikely cause, but the team will closely inspect for water or electrical damage while the spacecraft is in the VIF.”

“The team is steadfast in its commitment to identify root cause and determine next steps,” the statement said, quoting John Vollmer, vice president and program manager of Boeing’s Commercial Crew Program. “Developing solutions in a disciplined manner and letting the data drive our planning is critical and the team is working to ensure our spacecraft flies when ready.”

A lengthy investigation could add to what has already been a humiliating chain of events for Boeing.

Starliner’s first test flight, in December 2019, ended when a software problem put the capsule in a wrong orbit and forced ground controllers to bring it home without reaching the International Space Station. Boeing then rewrote the capsule’s software, taking 80 “corrective actions” and waiting for a launch window that aligned with available docking space at the space station.

In the ensuing 19 months, Boeing’s rival, SpaceX, delivered three astronaut crews to the station.

NASA declined to say when the next available launch window might come. “NASA and Boeing will look for the next available opportunity after resolution of the issue,” a NASA spokesperson said via email.

There’s a slim chance the problem could be fixed this week, according to aerospace engineers not affiliated with Boeing or NASA.

But what’s more likely is a weeks-long delay as teams attempt to locate the source of the problem before beginning the multistep process of fixing it, putting the pieces back together and running safety tests.

Boeing attributed the scrubbed mission to “indications that not all valves were in the proper configuration needed for launch.”

Boeing revealed little about the valves except that they were located in the spacecraft’s service module, the rear portion of the spacecraft that contains its propulsion system and is jettisoned before the capsule returns to Earth.

The valves in question may be used to help guide the spacecraft in the right direction in space, according to Sven Bilén, a professor of aerospace engineering at Pennsylvania State University.

“If your car is misaligned, you’ll be constantly pulling on the steering wheel to get it straight,” he said. “In a spacecraft, it wouldn’t maneuver the way that you expect it to. You risk not getting to the space station, or it burns up in the atmosphere coming back because it wasn’t oriented the right way.”

Based on the information released by Boeing, it seems like a complex issue to solve, Bilén said.

“If the valve is broken, if they have to pull it out and replace it, you’re talking weeks at a minimum,” Bilén said. “If it’s a sensor issue, and it’s easy to replace,” a relaunch could happen sooner. But there may be a concern that “the same issue is on other valves,” he added.

Boeing was originally scheduled to repeat its December 2019 test flight last Friday, but that retest was postponed after a misfire of thrusters on a Russian module attached to the International Space Station sent the space station into a barrel roll. NASA officials rescheduled that flight for Tuesday to give it time to be certain the incident, which NASA said caused the space station to roll over one and a half times, hadn’t damaged key components.

Boeing cannot simply relaunch Starliner whenever it wants. NASA determines safe mission dates and times based on a blend of factors, including the launch site availability, room to dock at the International Space Station, weather and orbital needs.

“A low Earth mission with specific timing needs must lift off at the right time to slip into the same orbit as its target,” NASA says on its website. The space agency also has a SpaceX trip to the space station set for later this month and a big mission to study asteroids associated with Jupiter no earlier than Oct. 16.

For Boeing, relaunching Starliner is critical. NASA has paid the company more than $4 billion for developing the capsule and flights, and any repairs now are added to the company’s expenses.