NASA has completed a pivotal safety evaluation ahead of its planned lunar flyby, and during a press briefing on Thursday, officials announced a revised launch date while outlining how they examined the risks facing the four astronauts assigned to the mission.

The agency is now targeting April 1 for liftoff of Artemis II, with launch scheduled for 6:24 p.m. ET at the earliest. Should that opportunity slip, backup windows are available on April 2, 3, 4, 5, 6 and 30.

The review — formally called a Flight Readiness Review (FRR) — spanned two days and represents a major milestone before launch. During the process, mission leaders gather to decide whether the rocket, spacecraft and supporting ground systems are fully prepared for flight.

John Honeycutt, who leads the Artemis II Mission Management Team, declined to provide a precise numerical estimate of the overall risk tied to this specific rocket and spacecraft.

In past programs, NASA publicly released probabilities for “Loss of Mission” or “Loss of Crew.” Similar figures have accompanied many previous flights. Ahead of the uncrewed Artemis I test in 2022, for example, NASA calculated a 1 in 125 chance that the Orion capsule — the same model that will carry Artemis II astronauts — could be lost.

“We’ve looked at Loss of Mission and Loss of Crew metrics before, but I’m not sure those numbers fully capture reality,” Honeycutt said, noting that such projections often rely on assumptions.

He emphasized that Artemis II will only be the second flight of the Space Launch System (SLS), leaving limited historical data to support firm statistical conclusions.

“We’re likely not at 1 in 50 for everything going perfectly, but we’re also not at 1 in 2 like on the first flight,” Honeycutt said of the SLS rocket, which will send Orion toward the moon. “We’re choosing not to anchor this mission to a specific probability.”

“I wouldn’t assign a number to it either,” added Lori Glaze, NASA’s acting associate administrator for the Exploration Systems Development Mission Directorate.

Glaze stressed that thousands of engineers, technicians and specialists have contributed to preparing the mission for flight.

“The conversations were extremely detailed and transparent,” she said. “We carefully examined our risk posture and the steps we’ve taken to reduce those risks.”

She added that Artemis II astronauts Reid Wiseman, Victor Glover, Christina Koch and Canadian Space Agency astronaut Jeremy Hansen participated in the review remotely from Houston.

“Their involvement underscored how important open and candid dialogue is during this process,” Glaze said.

No dissenting concerns

According to Glaze, the astronauts were especially interested in discussions about Orion’s heat shield — the protective layer that will safeguard the crew when the capsule reenters Earth’s atmosphere at the end of their 10-day journey around the moon.

After Artemis I returned in 2022, engineers found unexpected charring, cracks and surface damage on the heat shield. NASA has since spent more than a year investigating the issue. Artemis II will use a comparable shield, though the agency plans to lower risk by adjusting the capsule’s reentry trajectory — a strategy that has drawn some outside skepticism.

Despite earlier concerns, Glaze said NASA leadership agrees that the heat shield is ready.

“We’re confident in the heat shield,” she said. The astronauts listened closely to confirm that all aspects were addressed, including communication procedures with mission control during the intense reentry phase.

Historically, flight readiness reviews have sometimes involved intense debate. During the Space Shuttle era, these meetings could stretch over several days and include pointed exchanges before a final decision was made.

This week’s FRR began Wednesday morning and wrapped up Thursday afternoon ahead of a 3 p.m. ET press conference, a NASA spokesperson confirmed.

“We intentionally allowed time for anyone to voice concerns,” Honeycutt said. “No dissenting opinions were raised.”

Technical questions

Even so, Artemis II managers worked through a range of technical matters.

In the weeks leading up to the review, the SLS rocket encountered multiple challenges. Engineers detected hydrogen — an ultra-cold fuel known for its tendency to leak — escaping at levels beyond acceptable limits during an early fueling test. Because hydrogen ignites easily, excessive buildup could pose a serious hazard.

As teams addressed that issue, another complication emerged in late February: helium was not flowing correctly to the rocket’s upper stage. Helium plays a critical role in clearing propellant lines and maintaining tank pressure.

The helium problem eliminated potential March launch dates and led NASA to roll the rocket back from the launchpad for additional work. The vehicle currently remains inside the Vehicle Assembly Building, about four miles from the pad.

NASA plans to move the SLS back to the launch site on March 19, a careful transport that typically requires 10 to 12 hours.

Officials have previously indicated that the rocket’s earlier trip to the pad may have contributed to some of the hydrogen leaks.

It remains uncertain whether hydrogen seepage could recur once the rocket returns to launch position.

However, NASA confirmed that the helium flow issue has been resolved by repairing a blocked seal within a cable linking the rocket to ground support equipment.

The agency also decided against conducting another wet dress rehearsal — a full fueling practice run that simulates launch preparations.

The most recent rehearsal in late February went smoothly but concluded shortly before the helium issue was discovered.

Glaze explained that avoiding another fueling test helps preserve the rocket’s propellant tanks, since repeated fueling cycles gradually reduce their lifespan.

“We also want to protect every available day in our April launch window,” she said.

Artemis II is part of NASA’s broader effort to send astronauts beyond low Earth orbit for the first time in more than 50 years, marking a significant step toward sustained human exploration of deep space.