NASA has once again postponed the launch of Artemis II, the crewed lunar flyby mission, setting a new launch window for April. Although March 6 had been tentatively planned as the launch date, the US space agency revealed that a problem with the rocket has caused further delay.

According to NASA administrator Jared Isaacman, the failure was due to an interruption in the helium flow in the interim cryogenic propulsion stage of the Space Launch System (SLS). The helium flow is essential for purging the engines and pressurizing the fuel tanks. This system had functioned correctly in the two dress rehearsals conducted this month, but the failure occurred during a routine operation.

Due to the nature of the problem, NASA engineers will have to fix it from the Vehicle Assembly Building (VAB), so there’s no way to proceed with the March launch window. The rocket is on its way back to the hangar.

“I understand people are disappointed by this development,” the official stated on his X account. “That disappointment is felt most by the team at NASA, who have been working tirelessly to prepare for this great endeavor. During the 1960s, when NASA achieved what most thought was impossible, and what has never been repeated since, there were many setbacks.”

Will Artemis II be able to embark on its mission in April? NASA reported that rapid preparations have allowed it to potentially preserve the April launch window in the event of a reversal. It all depends on what the data, the repair efforts, and how the schedule comes together in the coming days.

Artemis II: The Setbacks

The mission had its first launch window between February 6 and 11. However, during the wet dress rehearsal (WDR), which is a full rehearsal with fuel, the team detected small hydrogen leaks during refueling and some minor technical glitches. After analyzing the situation, NASA concluded that the risk was considerable and could endanger the lives of the astronauts, so it decided to postpone the launch.

A second dress rehearsal, conducted on February 19, was successful. In a statement, the space agency explained that it loaded 700,000 gallons of liquid propellant with no leaks. “During the test, teams closely monitored liquid hydrogen fueling operations, which proved challenging during previous tests. Hydrogen gas concentrations remained under allowable limits, giving engineers confidence in new seals installed in an interface used to route fuel to the rocket,” NASA said.

At a subsequent press conference, mission representatives confirmed to the media that the new tentative liftoff date would be March 6. However, on February 20, the team failed to get helium to flow through the vehicle, a failure that also occurred during testing of the Artemis I mission. Isaacman noted that the cause could be due to a faulty filter, valve or connector plate.

“There are many differences between the 1960s and today, and expectations should rightfully be high after the time and expense invested in this program,” Isaacman said in his post. “I will say again, the President created Artemis as a program that will far surpass what America achieved during Apollo. We will return in the years ahead, we will build a Moon base, and undertake what should be continuous missions to and from the lunar environment.”

When it eventually launches, the Orion capsule will travel farther than any other manned spacecraft during its 10-day mission, surpassing on the sixth day the record of 400,171 kilometers set by Apollo 13. The return will conclude with Orion’s landing in the Pacific Ocean off the coast of San Diego, California.

Although there will be no lunar landing—that feat will fall to the Artemis III mission—the second launch is of crucial importance. Its success will demonstrate that NASA has the technical capabilities to return to the moon and begin a new phase of space exploration.

This story originally appeared in WIRED en Español and has been translated from Spanish.