NASA announced ambitious long-range plans Tuesday to spend $20 billion over the next seven years to build a moon base near the lunar south pole featuring habitats, pressurized rovers and nuclear power systems. The announcement came just over a week before the of NASA's Artemis II around-the-moon mission. 

NASA Administrator Jared Isaacman kicked off a series of meetings with contractors at NASA Headquarters in Washington saying he envisioned launching two per year to establish semi-permanent astronaut occupation on the lunar surface to explore, conduct research and develop the technology needed for eventual flights to Mars.

"This revised, step-by-step approach to learn, to build muscle memory, to bring down risk and gain confidence is exactly how NASA achieved the near impossible in the 1960s," he said, referring to the agency's . "But this time, the goal is not flags and footprints. This time, the goal is to stay.

"Today, we are providing a demand for frequent crewed missions," well beyond the previously announced moon landings in 2028, Isaacman said. "We intend to work with no fewer than two launch providers with the aim of crewed landings every six months, with additional opportunities for new entrants in the years ahead. America will never again give up the moon."

The revised Artemis program was unveiled just a few weeks after Isaacman ordered major changes to near-term missions, adding a flight in low-Earth orbit next year to test rendezvous and docking procedures using Orion crew ships and moon landers being built by SpaceX and Blue Origin.

Based on the results of the Artemis II and III missions, NASA now plans to launch at least one and possibly two moon landing missions in 2028 — Artemis IV and V — using one or both privately developed moon landers before pressing ahead with a steady stream of flights to develop a base on the moon.

In the process, NASA will forego development of a planned space station in lunar orbit, known as the Gateway, and repurpose modules and systems already under development to serve as components of the planned moon base.

Under the old architecture, Gateway would have operated in a highly elliptical orbit where Orion crew ships from Earth would meet up with already docked lunar landers for descents to the surface. As it now stands, Orion astronauts will transfer directly to their landers without stopping at an orbital way station.

Gateway was intended to accommodate the propulsion capabilities of the Orion crew ship and its service module engine, which does not have the power to get into and out of a low-lunar orbit like the one used by Apollo crews.

What sort of orbits might be possible in the absence of Gateway was not addressed, but NASA is asking its contractors to help come up with workable alternatives.

"It should not really surprise anyone that we are pausing Gateway in its current form and focusing on infrastructure that supports sustained operations on the lunar surface," Isaacman said. "Despite some of the very real hardware and schedule challenges, we can repurpose equipment and international partner commitments to support surface and other program objectives."

He added that "shifting NASA workforce priority" to the lunar surface will enable the agency to use the moon as a "proving ground for future Mars initiatives" and that the policy change "does not preclude revisiting the orbital outpost in the future."

The Planetary Society, a space advocacy organization co-founded by the late astronomer Carl Sagan, estimates NASA will have spent about $107 billion on return-to-the-moon plans through 2026 in inflation-adjusted dollars. That's thanks in large part to repeated program changes over the past 20 years by successive presidential administrations.

In the wake of the shuttle Columbia disaster in 2003, President George W. Bush ordered NASA to retire the shuttle, build new rockets and return astronauts to the moon by 2020 in what became known as the Constellation program. The Obama administration concluded that program was not sustainable and ordered NASA to focus instead on a flight to a nearby asteroid.

In his first term, President Trump ordered NASA to shift its focus back to the moon for a proposed 2024 landing in what became known as the Artemis program. The Biden administration generally left Artemis alone, but the program had been slowed by the COVID pandemic, budget shortfalls and a variety of other factors.

Isaacman has repeatedly talked of Mr. Trump's continued support of the Artemis program, and the revised architecture the administrator outlined Tuesday clearly has the approval of the White House.

Speaking of past delays and budget overruns, Isaacman said "the programs we left behind in this effort were not success stories. NASA takes ownership for the shortcomings, but contributing billions more and time that we do not have was not a pathway to success."

The moon base will be built in three phases. Phase 1 will transition from infrequent, once-a-year moon missions to "a templated approach that will generate significant learning through experimentation," he said.

"We will dramatically expand lunar landings ... delivering rovers, instruments and technology payloads that test mobility, power systems ... communications, navigation, surface operations and all the science payload that can be incorporated."

Phase 2 will see development of habitats and infrastructure "supporting regular astronaut operations on the surface." Phase 3 will enable "the permanent infrastructure necessary to sustain a human presence," Isaacman said.

That includes nuclear and solar power systems, crewed and uncrewed rovers, including machines to prepare sites for construction, a cellphone-like communications network, a lunar GPS system and constellations of lunar observation and communications relay satellites.

"The moon base will not appear overnight," Isaacman said. "We will invest approximately $20 billion over the next seven years and build it through dozens of missions, working together with commercial and international partners towards a deliberate and achievable plan."

He also said NASA will accelerate work to enable commercial space stations in low-Earth orbit after the International Space Station is retired while maintaining a steady stream of planetary and other science missions like a flight to deliver multiple small helicopters to Mars.

But the moon was the agency's central focus Tuesday, and Isaacman made it clear that failure is not an option when it comes to beating China back to the lunar surface.

"Should we fail, and should we look on as our rivals achieve their lunar goals ahead of our own, we are not going to celebrate our adherence to excess requirements, policy or bureaucratic process," he said, adding later that "we are not going to sit idly by when schedules slip or budgets are exceeded."

"Expect uncomfortable action if that is what it takes, because the public has invested over $100 billion and has been very patient with respect to America's return to the moon. Expectations are rightfully very high."