WASHINGTON — Boeing and SpaceX said Aug. 19 that they expect to carry out critical test flights of their commercial crew systems this fall, with SpaceX still hopeful of launching astronauts to the International Space Station this year.

During a panel discussion at the American Institute of Aeronautics and Astronautics’ Propulsion and Energy Forum in Indianapolis, Peter McGrath, Boeing’s director of global sales and marketing for space exploration, said his company was in the final phases of preparations for an uncrewed flight test of the CST-100 Starliner spacecraft to the ISS, known as the Orbital Flight Test.

“We’re making real good progress on getting the Orbital Flight Test vehicle to the pad and ready to go,” he said. “We’re heading towards an Orbital Flight Test in October.”

That uncrewed flight would be followed shortly thereafter by a pad abort test of the spacecraft’s launch escape system, he said. However, the timing for the Crew Flight Test, which will carry NASA astronauts Mike Fincke and Nicole Mann, and Boeing astronaut Chris Ferguson, is up to the agency. “We can say we’re ready, but until NASA’s ready we won’t be flying it,” McGrath said.

He said Boeing had completed testing on various other aspects of Starliner, including its parachute system and static fire tests of the launch abort thrusters on the spacecraft’s service module. A valve problem with those thrusters last year delayed work on the vehicle, he said, but the problem has been fixed and subsequent tests in recent months verified it was working properly. “The only thing we have left is the Orbital Flight test, pad abort test and crewed flight.”

SpaceX flew its uncrewed test flight of its Crew Dragon spacecraft to the ISS last March, a mission it calls Demo-1. However, both an in-flight abort test and the Demo-2 crewed flight test were delayed after the Demo-1 spacecraft, being prepared for the in-flight abort test, was destroyed during preparations for a static-fire test in April at Cape Canaveral.

In July, SpaceX announced that the most likely cause of that accident was a check valve that allowed nitrogen tetroxide oxidizer to leak into a helium pressurization system, which then propelled it back into the valve, triggering an explosion. At the time, though, the company said it was still working through other potential causes of the failure.

That investigation is now nearly complete. “We’re almost ready to tie a bow around it,” said Hans Koenigsmann, vice president of build and flight reliability at SpaceX, on the panel, as the investigation reviews a few final parts of the “fault tree” of potential causes. “Overall, I’m optimistic we can get this done in the next month.”

The hardware fixes, such as replacing the faulty valves, are “relatively easy” to perform, he said. He estimated that the in-flight abort test would now take place in October or November. “Right after that, hopefully this year, we’ll have the Demo-2 flight,” a crewed test flight to the ISS with NASA astronauts Bob Behnken and Doug Hurley.

Development of Crew Dragon, along with ongoing launches of SpaceX’s Falcon 9 and Falcon Heavy rockets, are taking place in parallel with work on the company’s Starship next-generational reusable launch vehicle. Koenigsmann said that the company was planning “more progressive hops” of prototype vehicles at its South Texas test site. “Then we’re targeting an early orbital launch as soon as possible,” he added, noting that those efforts “are challenges to us as engineers and to us as a company from [SpaceX founder] Elon [Musk] directly, basically, and people take this very serious and work very hard to make sure we can fly as soon as possible.”

He declined, though, to give a specific schedule for those Starship tests. “I want to be a little bit cautious here and just say I can guarantee you these people work as fast as they can,” he said. “We will beat any other time schedule that’s out there.”

“One thing we want to do is we clearly want to innovate, and it’s hard to innovate in this industry,” he said. Having Starship in development while flying Falcon and Dragon is one way to do so. “I feel like it makes a very healthy company to keep, on one side, a reliable product line running, and on the other side an innovative branch or an innovative department, basically, that builds a next-generation vehicle.”