Orion's propulsion limits

Orion, NASA's spacecraft designed to carry astronauts to the Moon, lacks enough fuel to reach a low lunar orbit and return to Earth. This limitation means the spacecraft cannot go close enough to the Moon's surface for a landing.

Artemis II's orbital skip

In April 2026, the four astronauts aboard Artemis II flew past the Moon without entering a low orbit. This decision was made to preserve the spacecraft’s fuel reserves for the return journey to Earth.

Rethinking the lunar landing approach

NASA had originally planned for astronauts to rendezvous with Orion in a distant lunar orbit, reducing the need for fuel. However, this approach required the lunar landers to travel farther, prompting a change in strategy after the Gateway station project was abandoned in 2026.

New propulsion system in development

At a conference on October 23, NASA Administrator Jared Isaacman announced a shift to a more powerful rocket stage. United Launch Alliance (ULA) will develop an extended version of the Centaur V rocket to assist the Space Launch System (SLS) in guiding Orion to a lower lunar orbit.

Centaur 180K's increased capacity

ULA's new Centaur 180K stage will carry about 50% more propellant than the current version, thanks to longer fuel tanks. The company will also modify materials and onboard electronics to meet safety standards for crewed missions, with a test unit and flight stage planned for an Artemis mission in 2028.

Artemis III will use a different setup

NASA will not use the new Centaur 180K stage for Artemis III, which is scheduled for 2027 and will take place in Earth orbit. Instead, teams are assembling a modified version of SLS to test the compatibility of the spacecraft with prototypes of the lunar landers.

SpaceX's fuel transfer strategy

SpaceX plans to use a series of Starship tanker launches to fill an orbital fuel depot. This depot will then supply fuel to a lunar Starship, which will travel to a high Earth orbit and join Orion. The combined system will then proceed to the Moon, requiring modifications to Orion to handle the additional thrust.

Blue Origin's direct approach

Blue Origin aims to avoid fuel transfers for its first crewed missions. The company plans four launches of the New Glenn rocket, with three to place transfer stages in orbit and a final one to launch the Blue Moon Mark 2 lander. These stages will accompany the lander to the Moon, where Orion will meet it in an elliptical orbit.

Alternative rendezvous options

NASA is also considering a rendezvous point just a few hundred kilometers from the Moon. This would allow Blue Moon to use less fuel for landing and returning, while also providing astronauts with more options for a quick return to Orion in case of an emergency.

Testing before crewed landings

Before carrying astronauts, both SpaceX and Blue Origin must complete successful uncrewed landings. NASA will then select the company responsible for the first crewed lunar landing during Artemis IV, scheduled for 2028.