WASHINGTON — A NASA safety panel believes the agency’s plan to launch a SpaceX commercial crew test flight in late May is feasible, although some issues still need to be resolved before the launch.

NASA’s Aerospace Safety Advisory Panel (ASAP), meeting by teleconference April 23, said it was unable to talk with NASA’s commercial crew program during its quarterly meeting, which was held virtually because of the coronavirus pandemic. The panel’s chair, Patricia Sanders, said that scheduling issues prevented a meeting, but that her committee planned to hold a “part 2” of their quarterly meeting in early May to discuss commercial crew and other topics not taken up this week.

Sanders said the panel has been kept up to date by NASA about commercial crew activities, including plans for SpaceX’s Demo-2 crewed test flight scheduled for May 27. “We are aware of a few technical items that remain to be more fully understood,” she said, “but the path forward appears feasible.”

She did not elaborate on the technical issues that need to be addressed before launch. However, SpaceX is still wrapping up testing of the Mark 3 parachutes used by the Crew Dragon spacecraft. In an April 17 statement, the company said it had performed 12 successful multi-parachute tests, as well as their use on the spacecraft’s in-flight abort test in January, but at that time at least one more parachute test was expected.

There is also an investigation into the premature shutdown of one of the nine Merlin engines in the first stage of a Falcon 9 during a March 18 launch. That did not affect the rocket’s ability to place its payload of Starlink satellites into orbit but did prevent the stage from landing on a droneship in the Atlantic Ocean.

In a tweet hours before the April 22 launch of another set of Starlink satellites on a Falcon 9, SpaceX Chief Executive Elon Musk said the engine shutdown happened after a small amount of isopropyl alcohol, used as cleaning fluid in the engine, was trapped in a “sensor dead leg” and ignited during flight.

During the company’s webcast of the launch, Lauren Lyons, a SpaceX engineer who served as host of the broadcast, said that the alcohol couldn’t flow through that conduit and was trapped there, igniting in flight. “We did not perform that cleaning process on the rocket supporting today’s mission,” she said. The Merlin engines performed as expected on that launch, including supporting a successful droneship landing of the first stage.

NASA participated in the investigation into the engine anomaly. NASA spokesman Josh Finch said April 23 that the investigation was still ongoing and that the agency will have to agree on both the cause and corrective actions before proceeding with the Demo-2 mission. The Falcon 9 that will launch the Demo-2 mission will be a new rocket, while the first stage involved in the March launch anomaly was on its fifth flight, and the April 22 launch used a first stage on its fourth flight.

Sanders said a final decision to go ahead with the Demo-2 mission will have to take into account several factors. “Clearly, the decision on when to launch and on the duration of the test mission will be one that balances any residual risks with the vehicle design and implementation with hazards of the current pandemic environment and with the risk of insufficient manning of the International Space Station,” she said.

The Demo-2 mission’s crew, NASA astronauts Bob Behnken and Doug Hurley, will fly to the ISS, docking there within a day after launch. They will remain on the station, which currently has only three people on board, for what NASA calls an “extended” stay, the duration of which it has not announced.

The panel also weighed in on the status of Boeing’s CST-100 Starliner commercial crew vehicle after a test flight in December 2019 that suffered several problems. At the previous ASAP meeting Feb. 6, the committee revealed an issue, not previously reported, involving the spacecraft’s software that could have caused the Starliner’s service module to collide with its crew module after separation just before reentry.

An independent review ultimately found 61 corrective actions for Boeing regarding the spacecraft, and Boeing announced April 6 it would perform a second uncrewed test flight, or Orbital Flight Test (OFT), of the Starliner spacecraft late this year before moving ahead with a crewed test flight.

“Much remains to be resolved before they will be expected to be certified for human spaceflight,” Sanders said of Boeing, saying that work goes beyond a second OFT mission.

That second flight, she said, “is not sufficient to address the concerns that have arisen following the OFT, and we continue to strongly advise NASA to ensure that the underlying technical and organization or cultural shortcomings uncovered during the investigation of the mishap and subsequent reviews are fully addressed and mitigated before any attempt to launch astronauts on the vehicle.”