What Is NASA’s Human Landing System Program?

A New Philosophy for Lunar Exploration

The U.S. space agency, NASA, is executing its plan to return astronauts to the surface of the Moon for the first time in over half a century. This new era of lunar exploration is named the Artemis program, formally established in 2017 to build a sustainable human presence on the Moon and, eventually, to use that experience as a stepping stone for the first human missions to Mars.

At the very heart of this complex strategy is a single, indispensable piece of hardware: the Human Landing System, or HLS.

The HLS is the official designation for the spacecraft that will perform the final, perilous leg of the journey – the mode of transportation that will carry astronauts from lunar orbit down to the surface and, after their mission is complete, return them safely to orbit. This is the 21st-century successor to the legendary Apollo Lunar Module.

Yet, the HLS represents much more than a simple technological update. It embodies a fundamental and deliberate shift in how NASA conducts deep space exploration, a new philosophy that is as much about economics and policy as it is about engineering and science.

The Apollo program, which last landed astronauts on the Moon in December 1972, was a series of brilliant, short-duration sorties. NASA, backed by a massive federal budget, designed, owned, and operated every piece of hardware. The goal was to win a geopolitical race. When that race was won, the program was deemed unsustainable and ended.

The Artemis program has a different mandate. Its stated objective is not just to leave flags and footprints but to establish a “sustainable,” “long-term human presence” on and around the Moon. This requires a new architecture of systems. This architecture includes the Space Launch System (SLS) rocket, the Orion crew capsule, and a small, moon-orbiting space station called the Gateway. The HLS must be able to work with all of them.

To build these systems, NASA adopted the public-private partnership model that it successfully pioneered for sending astronauts to the International Space Station. Instead of NASA designing and building the lunar lander itself – a “cost-plus” contract model that defined the Apollo era – the agency is buying a “service” from a commercial provider.

This strategy is intended to “catalyze the U.S. space economy” and “stimulate the commercial space industry.” The agency’s goal is to leverage the “speed and innovation” of the private sector to drive down costs for taxpayers. In this model, NASA acts as the anchor customer, providing its decades of human spaceflight expertise, technical support, and rigorous safety oversight. The commercial companies, in turn, are responsible for the design, development, testing, and operation of their landers.

The hope is that these companies will eventually find other customers for their new lunar transportation services, creating a self-sustaining cislunar economy where NASA is just one of many clients.

The program’s management is based at NASA’s Marshall Space Flight Center in Huntsville, Alabama. This assignment is significant. Marshall was the birthplace of the Saturn V rocket that powered the Apollo missions, and it remains NASA’s core center for propulsion and complex systems integration. Placing HLS at Marshall underscores the challenge: NASA views the lander as an extraordinarily complex system, and its team provides the deep engineering collaboration needed to help its commercial partners succeed.

This “sustainable” goal also dictates the engineering requirements for the landers. They must be far more capable than the small, two-man Apollo lander. The new HLS must be able to dock with the Gateway in lunar orbit, act as a habitat and science platform for astronauts on the surface for a week or more, and support a crew of at least two, with the goal of carrying four.

Furthermore, the Artemis program is strategically focused on the lunar South Pole. This region is believed to be rich in water ice, a resource that could one day be “mined” and processed into drinking water, breathable air, and, most importantly, the components of rocket propellant – liquid hydrogen and liquid oxygen. This “in-situ resource utilization” is the key to breaking humanity’s reliance on Earth for fuel and making a permanent lunar base truly possible. The Human Landing System is the vehicle designed to get us there.

The First Contest: Appendix H

To find its new lunar lander, NASA didn’t issue a traditional government contract. Instead, in 2019, it opened a competition under a Broad Agency Announcement (BAA), a flexible acquisition tool that encourages innovative solutions. This specific solicitation was known as NextSTEP-2 Appendix H.

The call went out to industry: NASA was looking for proposals for a human-rated lunar lander, and it was willing to help fund the initial design work. The goal was to move incredibly fast – the original political timeline, set in 2019, called for the first landing to happen by 2024.

In April 2020, after a review of the proposals, NASA announced it had selected three companies (or, more accurately, three teams) for 10-month, firm-fixed-price contracts. These contracts were not to build a lander, but to mature the design concepts and demonstrate their feasibility. The agency awarded a combined total of $967 million for this initial phase.

The three finalists represented radically different philosophies for solving the same problem. They were a “who’s who” of American aerospace, pitting the established, “old space” guard against the disruptive “new space” innovators. The contenders were a Blue Origin-led “National Team,” a small but clever team from Dynetics, and the famously aggressive SpaceX.

The National Team’s Integrated Lander

The “National Team” was the establishment-backed, “safe” choice. It was led by Blue Origin, the space company founded by Jeff Bezos, which acted as the prime contractor. But it brought in a formidable collection of aerospace giants: Lockheed Martin, Northrop Grumman, and Draper.

Their proposal was the Integrated Lander Vehicle (ILV), a “three-stage lander” that was a modern-day update of the Apollo concept. Each partner was given a module based on its “proven spaceflight heritage.”

• Blue Origin, as prime, would build the descent element, based on its long-in-development Blue Moon lander, and provide the high-efficiency, deep-throttling BE-7 engine.
• Lockheed Martin, which built the Orion capsule, would be responsible for the ascent element – the part of the lander that would blast off from the Moon and return the crew to orbit.
• Northrop Grumman, which had built the Apollo Lunar Module’s descent engine and was now building modules for the Gateway, would provide the transfer element, the “space tug” to move the lander into its final orbit.
• Draper, whose engineers famously designed the guidance computer for the Apollo missions, would handle the guidance, navigation, and control (GNC) systems.

The ILV’s architecture was traditional. It was an expendable, multi-stage vehicle that would be launched in pieces and assembled in space. Its primary fuel was liquid hydrogen (LH2) and liquid oxygen (LOX), the same high-performance propellant used by the Space Shuttle and the SLS. This was the “Apollo 2.0” approach, relying on a trusted team and a familiar design philosophy.

The Dynetics “Low-Slung” Lander

The second competitor was Dynetics, an Alabama-based defense and engineering contractor (later acquired by Leidos). As the dark horse of the competition, Dynetics proposed the most innovative and, in many ways, the most practical design from a human-factors perspective.

Their vehicle, the Dynetics Human Landing System (DHLS), also known as ALPACA (Autonomous Logistics Platform for All-Moon Cargo Access), was a “single stage” lander. This meant the same vehicle, using the same set of engines, would perform both the descent and the ascent.

But its most lauded feature was its “low-slung” crew cabin. Unlike the tall, ladder-dependent landers of Apollo or the other Appendix H proposals, the DHLS was designed to be short. After landing, the crew cabin would be just a few feet off the lunar surface.

This was a stroke of engineering genius. It eliminated the need for complex, risky ladders or elevators. In NASA’s later evaluation, this design was praised for providing “easy access to the lunar surface.” It would “minimize risk of sustaining injuries during ingress and egress” and make it simple for astronauts to move scientific samples or, in an emergency, assist an incapacitated crewmate.

The lander was also designed to be “full-and-go,” launching fully integrated on a single rocket, like the United Launch Alliance’s forthcoming Vulcan-Centaur or NASA’s own SLS Block 1B. It featured large windows for excellent visibility during landing and redundant crew stations. The Dynetics proposal was the “engineer’s choice,” a design focused almost entirely on solving the practical problems of working on the Moon.

The SpaceX Starship

The third proposal came from SpaceX. And it was not on the same scale as the others.

SpaceX did not propose to build a bespoke, single-purpose lunar lander. Instead, it proposed a lunar-optimized variant of Starship, the colossal, fully reusable stainless-steel spacecraft that the company was already developing for its long-term goal of colonizing Mars.

The Starship HLS was, and is, a giant. Standing about 165 feet (50 meters) tall, it’s the size of a 15-story building. It would tower over the other designs and completely dwarf the original Apollo Lunar Module. Because of its immense height, astronauts wouldn’t climb down a ladder; they would be transported from the crew cabin near the top to the lunar surface by a mechanical elevator.

This proposal was, in a word, audacious. A common analogy at the time was that NASA had asked for a “fishing boat” to ferry two astronauts, and SpaceX had offered an “aircraft carrier” for a fraction of the price. The Starship HLS didn’t just meet NASA’s minimum requirements; it offered a 100-ton cargo capacity to the lunar surface and an internal pressurized volume larger than the entire International Space Station.

But the real complexity wasn’t the vehicle’s size; it was its mission architecture. Starship HLS would launch to low-Earth orbit (LEO) empty. To get to the Moon, it would need to be refueled. This would require SpaceX to launch a fleet of “tanker” Starships – perhaps ten or more – to rendezvous with the HLS in LEO and transfer hundreds of tons of cryogenic propellants (liquid methane and liquid oxygen).

This was the proposal’s central gamble. It hinged on mastering in-orbit cryogenic propellant transfer, a technology that had never been demonstrated at this massive scale. It also tied NASA’s entire Artemis landing timeline to the success of SpaceX’s privately funded Starship development program. It was, by any measure, the highest-risk, highest-reward option on the table.

The $2.9 Billion Decision

For a year, the three teams worked on their designs, funded by their initial NASA awards. The agency’s original plan was to foster a competitive environment. NASA had repeatedly stated its intention to select “one or two” providers in the next phase, known as Option A, to build, test, and fly the first landers. A dual-provider approach would build in redundancy and keep prices low through competition.

Then, in April 2021, NASA made an announcement that shocked the aerospace world.

The agency had selected only one provider for the Option A contract. That sole provider was SpaceX.

The firm-fixed-price contract was awarded for $2.94 billion. The decision to pick only one company, and to pick the most technologically audacious and high-risk proposal of the three, was immediately controversial.

To explain its rationale, NASA’s Source Selection Authority (the official responsible for the decision) published a detailed document. That document revealed a stunning assessment of the three proposals, based on technical merit, management approach, and price.

SpaceX’s proposal was rated as having “exceptional value.” It had received the highest rating of the three finalists on its technical and management plans and had submitted the lowest-priced proposal. The selection statement noted that SpaceX’s Starship “substantially exceed[ed]” NASA’s requirements for cargo mass, pressurized volume, and the number and duration of spacewalks (EVAs) astronauts could perform.

The review of the other two teams was scathing.

The “National Team,” led by Blue Origin, was heavily criticized. Despite its “heritage” team, the SSS document found its management approach “incomplete and provided insufficient details.” The report stated that the proposal “lacks evidence” for how its commercial approach would lower costs and “call[ed] into question” the team’s “ability to realistically execute” its plan.

The Dynetics proposal was praised for its “attractive characteristics,” especially the “uniquely responsive” low-slung design. But the evaluators found “a number of serious drawbacks” and a “significant weakness” in its underlying technical design, which “meaningfully increase[d] the risk” of successful performance.

But the final decision wasn’t just about technical merit. It was about money.

NASA’s primary public justification for the single-source award was its budget. The agency bluntly stated that it “lacked the necessary funding to make more than one award.” Congress had appropriated far less funding for the HLS program than NASA had requested.

The bids from Blue Origin and Dynetics were “significantly higher in price.” In fact, NASA’s budget “did not permit” funding a second contract, even if it wanted to. The SpaceX bid, at $2.94 billion, was so much lower than its competitors’ that it was the only one NASA could realistically afford.

The decision was a tectonic shift in aerospace contracting. NASA’s hand had been forced by a budget deficit. The technical superiority and massive capability of Starship gave the agency the justification for its choice, but the rock-bottom price was the reason it had to be a single choice. The agency had officially placed its bet for returning to the Moon on the most disruptive, ambitious, and high-risk proposal, effectively rejecting the “safe,” heritage-based models of old space.

The Lander War: Protests and Lawsuits

The selection of SpaceX as the sole provider did not sit well with the losing bidders. The decision immediately triggered a political and legal firestorm that would halt the HLS program for more than half a year.

On April 26, 2021, just days after the announcement, both Blue Origin and Dynetics filed formal protests with the U.S. Government Accountability Office (GAO). This is a standard, legal channel for contractors to challenge the government’s procurement decisions.

The filing of a GAO protest automatically triggers a “stop-work” order. By law, NASA had to instruct SpaceX to immediately suspend all work on the HLS Option A contract, pending the GAO’s ruling. The entire program was frozen.

Blue Origin’s protest was the more aggressive and public of the two. The company argued that NASA had “improperly evaluated” the proposals and had “moved the goalposts” during the competition. The core of its argument was not just that NASA had evaluated unfairly, but that the decision itself was bad policy.

In a series of public infographics and statements, Blue Origin argued that NASA was “betting on a singular solution” that the agency’s own selection statement had deemed “complex and high-risk.” This, they claimed, introduced an unacceptable amount of technical and schedule risk into America’s flagship space exploration program. They also argued that the single-source award had created a “monopoly” for SpaceX and that Starship was an “immensely complex” vehicle “purpose-designed for… Mars,” not the Moon.

On July 30, 2021, the GAO issued its decision. It forcefully denied both protests.

The GAO’s 76-page report concluded that “NASA did not violate procurement law” in its evaluation of the proposals. The auditors found that NASA’s assessment of all three companies was “reasonable and consistent” with the solicitation’s criteria. Most importantly, the GAO validated NASA’s core justification: the agency’s budget was insufficient for two awards, and NASA was well within its “broad discretion” to make a single award based on the available funds and SpaceX’s high technical rating.

But the “lander war” was not over.

In an escalation that surprised many, Blue Origin refused to accept the GAO’s ruling. On August 13, 2021, the company filed a lawsuit against the U.S. government in the Court of Federal Claims, once again challenging NASA’s “unlawful and improper evaluation.”

This legal maneuver again forced NASA’s hand. While there was no automatic stop-work order this time, NASA voluntarily paused its work with SpaceX, stating that it wanted to resolve the litigation before proceeding. The program was frozen once more.

The lawsuit was widely seen as a public relations disaster for Blue Origin, painting the company as a poor loser unable to compete. The legal challenge dragged on for months, further delaying a program that was already on a tight schedule.

Finally, on November 4, 2021, the court dismissed Blue Origin’s complaint, bringing the legal challenges to a definitive end. The judge’s ruling was a complete victory for NASA, upholding its decision-making process. NASA was, at last, free to resume work with SpaceX.

The entire “lander war” had lasted over seven months. While Blue Origin had lost the legal battle, its core argument – that relying on a single, high-risk provider was a bad policy – had gained traction in Congress. The political and public pressure from the fight had laid the groundwork for a major programmatic reversal.

Furthermore, the 7-month, lawsuit-induced pause provided NASA with a useful, non-technical justification for a schedule slip that was already seen as inevitable. When NASA later officially announced that the 2024 landing date was no longer possible and was slipping to 2025 (and eventually later), the agency explicitly blamed the “extended litigation” for the delay. The “lander war” had become the official “original sin” for the Artemis program’s first major schedule reset.

A Second Chance: Sustaining Lunar Development

By early 2022, NASA had a single lander provider, SpaceX, but it also had a major programmatic headache. The high-risk nature of Starship’s development, now the only path to the lunar surface, made many in the agency and Congress nervous. The “lander war” had made it politically clear that a single-source solution was untenable.

In March 2022, NASA announced a major strategic pivot. It was, in effect, a “course correction.”

The agency announced it would procure a second lunar landing system to create redundancy and competition. This new procurement would be run under a new solicitation: NextSTEP-2 Appendix P, known as the “Sustaining Lunar Development” (SLD) program.

The stated goal of this new program was to “bring a second entrant to market” to ensure a “robust landing capability” for the Artemis program. This was precisely what Blue Origin had been arguing for, and what NASA had wanted all along before its budget was cut.

This second lander would be developed for missions beyond the initial Artemis III landing. It would be designed to meet a new, more stringent “sustaining” set of requirements, including the ability to dock with the Lunar Gateway and transport more astronauts and cargo. This second lander would be targeted for the Artemis V mission.

On May 19, 2023, NASA announced the winner of the Appendix P contract. The $3.4 billion award went to Blue Origin.

The company had submitted a new, revised proposal for its “Blue Moon” lander. It was again backed by a “National Team,” this time including Lockheed Martin, Draper, Boeing, Astrobotic, and Honeybee Robotics. This new contract finally established the dual-provider, competitive framework that NASA had originally sought.

To ensure both landers were competing on a level playing field, NASA had also previously awarded a contract modification to SpaceX, known as “Option B.” This option funded the upgrades necessary for the Starship HLS to meet the same “sustaining” requirements as the new Appendix P lander, including the ability to dock with the Gateway for the Artemis IV mission.

This strategic pivot was a “do-over” that corrected the original programmatic weakness of the single-source award. The price tags of the two contracts were also vindicating. SpaceX’s 2021 bid was $2.94 billion. Blue Origin’s new, winning 2023 bid was $3.4 billion. This strongly suggested that Blue Origin’s original 2021 bid was, as NASA had claimed, “significantly higher” and well outside what the agency could have afforded at the time.

The HLS program was now, finally, what it was always intended to be: a high-stakes race between two well-funded, competing commercial providers.

The Evolving Artemis Mission Plan

The HLS program is not a single, static mission. It is a key component of an evolving, multi-mission campaign. The mission plan for each of the upcoming Artemis flights grows in complexity, building on the capabilities of the previous flight. The HLS landers from SpaceX and Blue Origin are central to this step-by-step plan.

The program began with Artemis I in 2022, a successful uncrewed test flight of the SLS rocket and Orion spacecraft. The next mission, Artemis II, is planned for 2026 and will be the first crewed flight, sending four astronauts on a loop around the Moon and back.

The Human Landing Systems will make their debut on Artemis III.

Artemis III: The First Return

Artemis III is the mission that will mark humanity’s return to the lunar surface. Currently planned for no earlier than mid-2027, this will be the first crewed lunar landing since Apollo 17 in 1972.

This mission will use the SpaceX Starship HLS.

The Artemis III mission profile is the “simplest” of the landing missions because it will not use the Lunar Gateway, which will not yet be in orbit. It will be a direct rendezvous between Orion and Starship.

The mission will unfold in a complex, multi-launch sequence:

1. HLS Deployment: Long before astronauts leave Earth, SpaceX conducts its ambitious orbital refueling campaign. After launching its Starship HLS to low-Earth orbit, it will launch a series of Starship tankers to fill the lander’s tanks. Once fully fueled, the Starship HLS will boost itself from Earth orbit and travel to the Moon, parking itself in a Near-Rectilinear Halo Orbit (NRHO).
2. Crew Launch: NASA will launch four astronauts from Kennedy Space Center on the SLS rocket, encapsulated in the Orion spacecraft.
3. Rendezvous and Docking: Orion will fly to the Moon and rendezvous with the waiting Starship HLS in NRHO. The two spacecraft will perform a historic docking – the first time these two vehicles will have ever linked in space.
4. Crew Transfer: Two of the four astronauts will transfer from Orion into the massive Starship HLS. The other two will remain in Orion.
5. The Landing: The Starship HLS will undock from Orion, perform its descent burns, and land near the Moon’s South Pole. The two astronauts will then live and work out of the Starship HLS, which will serve as their habitat and science base for about seven days.
6. Return to Orbit: After their surface mission, the two astronauts will board the HLS and use its ascent engines to launch from the lunar surface, returning to NRHO to rendezvous and re-dock with the Orion spacecraft.
7. Journey Home: The two astronauts will transfer from the HLS back into Orion, rejoining their crewmates. The full crew will then undock from the Starship, which will be disposed of (likely sent into a solar orbit), and the Orion capsule will fire its engines to bring the four astronauts home to Earth.

Artemis IV: Building the Lunar Outpost

Planned for 2028, Artemis IV is the second crewed landing and marks a significant increase in the program’s complexity. This mission will be the first to use the Lunar Gateway space station.

This mission will also use an upgraded SpaceX Starship HLS, developed under the “Option B” and SLD contracts to be compliant with the new “sustaining” requirements.

The mission profile for Artemis IV is a far more intricate choreography:

1. Gateway Assembly: This mission’s SLS rocket, a more powerful Block 1B version, will launch the Orion capsule and a new habitat module for the Gateway, known as the I-HAB.
2. HLS Deployment: SpaceX will once again pre-deploy its upgraded Starship HLS. But this time, the HLS will fly to the Moon and dock with the Gateway, which will be in its NRHO.
3. Crew Arrival: The Orion, carrying its crew and the I-HAB, will also fly to the Moon and dock with the Gateway.
4. Crew Transfer: The crew (which will include four astronauts, with two designated for the surface) will transfer from Orion through the Gateway’s modules and into the waiting Starship HLS.
5. Landing and Return: The HLS will then undock from the Gateway, land on the Moon, perform its surface mission, and return to the Gateway.

This mission establishes the “hub-and-spoke” model that will define the sustainable phase of lunar exploration. The Gateway will serve as a permanent command post, transfer station, and science laboratory in lunar orbit, serviced by landers and crew vehicles.

Artemis V: The Second Provider Debuts

Artemis V, planned for 2030, is the third crewed landing and the moment the HLS program’s full, sustainable architecture becomes a reality. This mission will feature the first crewed flight of Blue Origin’s Blue Moon lander.

The mission profile will be similar to Artemis IV but will prove out the dual-provider system:

1. Gateway Assembly: The SLS will again launch Orion along with another Gateway element, the Lunar View module.
2. HLS Deployment: Blue Origin will launch its Blue Moon lander and its cislunar transporter, perform its own refueling operations in lunar orbit, and then dock the lander with the Gateway.
3. Crew Arrival: Orion will arrive and dock with the Gateway.
4. Crew Transfer: Two astronauts will transfer through the Gateway’s corridors and into the Blue Origin lander for their expedition to the lunar surface.

The successful completion of Artemis V will demonstrate NASA’s desired end-state: a functional, multi-module orbital outpost (the Gateway) being serviced by two competing, commercially-owned lunar “taxi” services from SpaceX and Blue Origin. This is the foundation of the sustainable lunar presence that the HLS program was created to build.

State of the Race: Late 2025

As of late 2025, the HLS program is a tale of two vastly different development philosophies, both racing against time and immense engineering hurdles. The mid-2027 target for Artemis III is under intense pressure, and NASA has recently made a bold programmatic move to manage the schedule risk.

SpaceX: Rapid Tests and Lingering Questions

SpaceX’s development path is defined by its “fly, fail, fix, fly again” iterative testing campaign, conducted in public from its Starbase facility in South Texas. This approach, which SpaceX funds with over 90% of its own money, has led to rapid, visible progress on the core Starship-Super Heavy launch system.

As of October 2025, SpaceX has conducted 11 Integrated Flight Tests (IFT) of the full stack. The most recent, IFT-11 on October 13, 2025, was a major success. The Starship upper stage (Ship 38) completed its entire flight, including a 13-engine landing burn by the Super Heavy booster, and the Starship itself performed a controlled splashdown in the Indian Ocean. This flight was the last of the “Version 2” Starship design, and the company is now transitioning to its larger, more powerful “Version 3” vehicle, which is equipped for propellant transfer.

While the core rocket’s development is accelerating, the HLS program faces a singular, massive bottleneck: orbital refueling.

The entire Artemis III mission is impossible without mastering ship-to-ship cryogenic propellant transfer. SpaceX must launch a “depot” Starship and then successfully rendezvous and transfer propellant from at least 10 “tanker” Starships. This has never been done.

The company did demonstrate a small internal propellant transfer (about 5 metric tons) on its third test flight, but the full-scale, ship-to-ship demonstration, once planned for 2025, has been delayed and is now not expected until at least 2026.

This delay is the primary threat to the Artemis III schedule. It has caused public concern from NASA officials and former administrators, who have stated that SpaceX is “behind schedule.”

However, SpaceX has been making quiet but steady progress on the HLS-specific hardware. The company reports it has completed 49 HLS-specific milestones. This includes:

• Testing of a full-scale crew cabin mockup with life support systems.
• Successful drop tests of the full-scale landing legs onto simulated lunar regolith.
• Qualification of the androgynous docking adapter that will link Starship with Orion.
• Tests of the crew elevator with NASA astronauts in flight suits.

SpaceX is now in the process of fabricating the first flight-article HLS cabin.

The company is running two programs in parallel: its self-funded Mars rocket and NASA’s lunar lander. The HLS lander depends on the core rocket, but the core rocket’s progress doesn’t solve the unique HLS challenge. The orbital refueling demonstration remains the long-lead item that is pacing the entire Artemis program.

This schedule pressure became so acute that in October 2025, NASA made a dramatic announcement: it was “opening up” the Artemis III contract, effectively inviting other companies – namely, Blue Origin – to submit proposals on how they might be able to fly the first landing mission sooner than SpaceX.

Blue Origin: A Two-Track Approach

Blue Origin’s development philosophy is the mirror image of SpaceX’s. Instead of a rapid, hardware-rich test campaign, Blue Origin is pursuing a more traditional, “design-first” programmatic model that follows NASA’s formal review gates.

Their lunar strategy involves two distinct landers: the Blue Moon Mark 1 (MK1) and Mark 2 (MK2).

The Blue Moon MK1 is a smaller, uncrewed cargo lander. It is designed to deliver up to 3 metric tons to the lunar surface. This vehicle is serving as a “test bed” for the larger, crewed version, and its development is much further along. Its first robotic test flight is expected soon, potentially by the end of 2025 or early 2026. Its second flight is already under contract with NASA to deliver the VIPER rover, a robotic vehicle that will hunt for water ice at the South Pole.

The Blue Moon MK2 is the large, 16-meter-tall, reusable lander that will fly the Artemis V mission. This is the vehicle being developed under the $3.4 billion SLD contract.

Both landers are designed to launch on Blue Origin’s New Glenn heavy-lift rocket, which is now operational. The rocket’s second mission, carrying NASA’s ESCAPADE probes to Mars, is scheduled for November 9, 2025. The landers themselves are powered by the BE-7 engine, which has been in development since 2016 and is undergoing successful long-duration hot-fire tests simulating lunar mission profiles.

Blue Origin’s architecture also requires in-orbit refueling, but its challenge is different. The MK2 lander is designed to be refueled in lunar orbit by a dedicated “Cislunar Transporter” vehicle. Their primary engineering hurdle is managing liquid hydrogen, a very high-performance fuel that boils off easily. The company is developing new 20-Kelvin cryocooler technology to make LH2 a “storable” propellant in space.

This “design-first” approach has led to a fascinating programmatic race. As of late 2025, SpaceX, despite its 11 integrated test flights, is still working toward its Human Landing System Critical Design Review amid ongoing delays, with key demonstrations like in-space refueling planned for late 2025 or early 2026. Meanwhile, Blue Origin, which has not yet flown its lander, is now working toward its Human Landing System Critical Design Review in 2026 after completing its Preliminary Design Review in February 2024, though it did complete Critical Design Review for its Blue Alchemist lunar manufacturing subsystem in September 2025.

This highlights the dueling philosophies. NASA’s recent decision to “open” the Artemis III contract is a direct attempt to leverage this. The agency is signaling to Blue Origin: if your “design-first” approach can get your MK2 lander built and certified faster than SpaceX can solve its refueling problem, you have a chance to steal the historic first landing mission.

Summary

NASA’s Human Landing System program has evolved from a controversial, high-risk, single-provider contract into the robust, dual-provider, competitive framework that the agency’s public-private partnership model was always intended to create.

Two American companies, SpaceX and Blue Origin, are now under firm-fixed-price contracts to develop, test, and fly the vehicles that will return American astronauts to the Moon.

Both companies face monumental, but different, engineering challenges. SpaceX is rapidly proving its core Starship launch system can fly, but it remains behind schedule on mastering the cryogenic orbital refueling that is essential for its lander to reach the Moon. Blue Origin is methodically passing its formal design reviews and is preparing to test its first cargo lander, but it must also master the difficult physics of storing and transferring liquid hydrogen in deep space.

The timeline for the first landing, Artemis III, has officially slipped to mid-2027 and is under extreme pressure from these technical hurdles. NASA, in a bold move, is now using the competitive dynamic it fought to create, opening the door for Blue Origin to potentially fly the first mission if SpaceX cannot solve its problems in time.

The success of the HLS program is the foundation for NASA’s entire “Moon to Mars” exploration strategy. The return of astronauts to the lunar surface, and the dream of a sustainable human presence in deep space, now depends entirely on which of these two companies can solve one of the most complex engineering challenges in the history of rocketry, and how fast they can do it.