Orion cannot land on the Moon. It was never designed to. What actually puts Artemis astronauts on the lunar surface is a separate vehicle — the Human Landing System, or HLS — pre-positioned in lunar orbit, rendezvousing with Orion there, carrying the crew down and back up, and then being discarded. NASA is buying this service from two independent providers, which is a choice worth understanding on its own.
What an HLS Has to Do
Landing humans on the Moon is not, in itself, a 1960s-solved problem. Apollo's Lunar Module landed two astronauts at a time at equatorial sites for stays of under three days. Artemis's concept of operations is different:
- Two to four astronauts, rather than two.
- South polar landing sites, which are harder to reach (higher energy cost) and harder to land on (lower Sun angles, more complex lighting, uneven terrain).
- Surface stays of a week initially, growing to a month or more on later missions.
- Return to a spacecraft in near-rectilinear halo orbit, not low lunar orbit, which requires more delta-v on both ends of the surface mission.
- Eventually, delivery of cargo as well as crew.
None of these are impossible, but together they push the HLS well beyond anything flown since Apollo. Mass and propellant requirements are substantially higher, and the vehicle needs to survive the extended surface stays in a harsh thermal environment.
Starship HLS
SpaceX's HLS is a variant of Starship, the company's fully-reusable super-heavy-lift vehicle. In the HLS configuration, Starship launches on Super Heavy, is refuelled in low Earth orbit by multiple tanker launches of additional Starships, transfers to lunar orbit, rendezvouses with Orion at Gateway or in an NRHO, accepts the crew, lands on the Moon, supports surface operations, launches from the surface, and returns the crew to Orion. The Starship HLS does not return to Earth.
The vehicle is unusually large for a lunar lander. Starship is roughly 50 metres tall as a standalone upper stage, significantly taller than the Apollo Lunar Module, with much more internal volume and surface-launch propellant. That provides substantial cargo capacity but creates its own engineering problems: the crew-transfer interface with Orion is very high off the surface, and the landing footprint is correspondingly large. SpaceX is developing a dedicated crew elevator to move astronauts between the habitable section of the vehicle and the lunar surface.
The critical technology that makes Starship HLS viable at all is orbital propellant transfer — the ability to refuel one vehicle from another in orbit with cryogenic propellants. This has not been done at scale before. SpaceX has flown early demonstrations of propellant transfer between Starship's tanks, but the full architecture (multiple tanker launches, aggregating propellant in a depot, then transferring to the HLS in a single event) is still ahead. Artemis III depends on this working.
Blue Moon Mk 2
Blue Origin's HLS, selected by NASA in 2023 as a second provider for Artemis V and later missions, is Blue Moon Mk 2. The architecture is substantially different.
Blue Moon uses liquid hydrogen and liquid oxygen as propellants, with a BE-7 engine family developed by Blue Origin specifically for lunar landing. Hydrolox gives excellent specific impulse, but hydrogen is notoriously difficult to keep liquid; the long cruise from Earth to the Moon is a thermal management problem. Blue Origin's approach relies on advanced cryogenic-insulation technology and, like Starship, on in-orbit refuelling — though at a smaller scale, using a dedicated hydrogen transporter spacecraft rather than full-sized tankers.
Compared with Starship HLS, Blue Moon is smaller, lower to the ground, and closer in architectural philosophy to Apollo-era landers, though scaled up for the Artemis mission profile. Its crew access is a conventional ladder and elevator system from a vehicle roughly the size of a two-storey house, not a tower.
Why Two Providers
NASA's original HLS award went to SpaceX alone in 2021. Blue Origin protested the sole-source award; the protest was partially successful and pushed NASA toward a dual-provider model. The current architecture has:
- SpaceX Starship HLS on Artemis III and IV.
- Blue Origin Blue Moon Mk 2 on Artemis V and subsequent alternating missions.
The strategic argument for two providers is redundancy: if one vehicle has a serious failure or cost overrun, Artemis does not collapse entirely. The historical lesson from the Shuttle era — one vehicle, no alternative, two losses of vehicle and crew — is the backdrop for that decision.
There is also a technology-hedge argument. Starship and Blue Moon are using different propellants, different architectures, and different philosophies of reuse. Whichever works better will shape the next generation of lunar infrastructure. Having both in flight simultaneously gives NASA (and Congress) actual data to choose on rather than just proposals.
What Still Has to Work
As of the mid-2020s, neither HLS has landed on the Moon. Starship HLS needs to complete its uncrewed lunar demonstration flight before Artemis III, including full orbital refuelling, TLI, lunar descent and ascent, all uncrewed. Blue Moon's first Pathfinder demonstrator is earlier in its development path and has its own uncrewed demo ahead of it. Timelines on both vehicles have slipped and will slip again.
The rest of the architecture — Orion, SLS, lunar spacesuits, Gateway — has its own dependencies. See Artemis II for the last crewed prerequisite that has actually flown, and Spacesuits for the other gating technology for lunar surface operations.