NASA's Artemis 3 astronauts won't land on the moon after all. 'This is just not the right pathway forward.'

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NASA's plan to return humans to the moon has changed.

As engineers work to fix issues with the Artemis 2 mission's Space Launch System (SLS) rocket, NASA officials are reexamining what flights will follow and are shaking up plans for which of those will actually land astronauts on the moon.

In short, Artemis 3 is changing from a crewed mission to the lunar surface to an Earth-orbit rendezvous of NASA's Orion spacecraft with one or more of the program's moon landers in 2027, NASA Administrator Jared Isaacman announced on Friday (Feb. 27). The program's first moon landing will now take place on Artemis 4, in 2028, with a potential second landing that same year with Artemis 5.

In addition, SLS' design will be standardized to streamline production, and the rocket's launch cadence will be shortened from once every three years to once every10 months, if all goes to plan. To accomplish this, NASA plans to bolster its workforce in order to "rebuild core competencies," Isaacman said, "that will directly contribute to NASA's launch cadence."

It's a major shift in the architecture of NASA's Artemis program, which aims to establish a sustained human presence on the moon and in lunar orbit. A recent report from NASA's Aerospace Safety Advisory Panel (ASAP), however, cast serious doubts on the previous architecture, calling into question the agency's timeline, projected mission safety and the readiness of the Human Landing System (HLS) vehicles that NASA has contracted from private companies to perform lunar landings.

As originally designed, Artemis 3 encompassed a long list of technological firsts, with a heavy dependency on HLS, which the ASAP determined posed "significant risks at the mission level."

"This is just not the right pathway forward," Isaacman said. "Going right to the moon … is not a pathway to success."

"We want to reduce complexity to the greatest extent possible," he added. "We want to accelerate manufacturing, pull in the hardware and increase launch rate, which obviously has a direct safety consideration to it as well."

With the new framework, Artemis 3 is drastically simplified, and less dependent on the readiness of a moon lander's ability to actually land on the moon. The development of both private HLS landers chosen by NASA has fallen short of the space agency's hopeful timeline, resulting in impending delays.

NASA contracted SpaceX's Starship to land astronauts on the Artemis 3 and Artemis 4 moon missions. Starship has flown 11 suborbital test flights over the past three years but has yet to notch several critical milestones needed to qualify the spacecraft for lunar landings with astronauts onboard.

NASA picked Blue Origin's Blue Moon spacecraft, meanwhile, to land astronauts on the Artemis 5 moon mission. A Blue Moon pathfinder known as Mark 1 is currently undergoing testing at NASA's Johnson Space Center in Houston.

Before NASA will let either Starship or Blue Moon carry astronauts to the lunar surface, the vehicles will have to demonstrate their ability to transfer and store cryogenic fuels in space, rendezvous and dock with Orion, as well as execute an uncrewed moon landing and successful ascent back to lunar orbit.

Now, NASA plans to use Artemis 3 as a safe proving ground for those procedures in low Earth orbit before entrusting the landers to be 100% successful on their first flights to the moon.

Previous architecture for Artemis 4 used an upgraded version of SLS, called Block 1B, which featured the enhanced Exploration Upper Stage in place of SLS' current Interim Cryogenic Propulsion Stage (ICPS). If NASA's launch cadence with SLS remained unchanged, Artemis 4 would have launched sometime around 2030.

Space agency officials are counting on a standardized SLS configuration to shorten the wait time between launches, and are now targeting an Artemis 4 liftoff in 2028 as the program's first crewed lunar landing, with the potential for Artemis 5 to repeat the feat later that same year.

"I think what we're doing is directly in line with what ASAP asked us to do," Isaacman told Space.com during Friday's briefing. "I think it should be incredibly obvious you don't go from one uncrewed launch of Orion and SLS, wait three years, go around the moon, wait three years and land on it."

Isaacman compared the need for an increased SLS launch cadence to the United States' first lunar program, saying, "There has to be a better way, in line with our history."

"We did not just jump right to Apollo 11. We did it through Mercury, Gemini and lots of Apollo missions with the launch cadence every three months," Isaacman said. "We shouldn't be comfortable with the current cadence. We should be getting back to basics and doing what we know works."

In the meantime, teams at NASA's Kennedy Space Center continue to work toward an April launch date for Artemis 2, despite its recent relocation from the pad at Launch Complex-39B to the Vehicle Assembly Building (VAB) for repairs.

Engineers conducting routine post-fueling procedures after a Feb. 19 countdown rehearsal for the Artemis 2 rocket encountered a helium flow pressurization issue on ICPS that they could address only back inside the VAB. That countdown practice run was the second "wet dress rehearsal" for the Artemis 2 SLS, which experienced liquid hydrogen leaks and an early countdown termination during testing on Feb. 2.

"The suspected system component for the helium flow will be removed, and they're going to undergo detailed sections and assess the cause of the issue," Lori Glaze, acting associate administrator for NASA's Exploration Systems Development Mission Directorate, said on Friday. "We hope to get down to the root cause of that and make changes, not just to the hardware, but to our operational procedures, so that we don't encounter the same issue again when we roll back out to the pad."

Counting on a quick diagnosis and fix, NASA officials hope to have SLS back on the pad in time to meet Artemis 2's next launch window, which opens April 1, with additional opportunities April 3-6 and April 30.

Artemis 2 will be Orion's first mission with a crew onboard. They are NASA astronauts Reid Wiseman, Victor Glover and Christina Koch and Canadian Space Agency astronaut Jeremy Hansen. The quartet will launch on a 10-day mission to fly in a single loop around the moon before returning to Earth.

Artemis 1 successfully sent an uncrewed Orion capsule to lunar orbit and back to Earth in late 2022.