Human Landing System
The Human Landing System (HLS) is NASA's designated spacecraft for transporting astronauts from lunar orbit to the Moon's surface and back to orbit, enabling the first crewed lunar landings since Apollo 17 in 1972 as part of the Artemis program's goal to establish sustainable human exploration.[1][2] NASA's HLS program, initiated through competitive contracts, selected SpaceX's Starship HLS variant in April 2021 for initial missions, including a $2.89 billion award for development, testing, and up to two operational landings beginning with Artemis III.[3] In May 2023, NASA awarded Blue Origin a $3.4 billion contract for a separate sustaining lander to support later Artemis missions, reflecting a strategy to leverage multiple commercial providers for redundancy and long-term lunar infrastructure.[2][4] Key achievements include the progression from conceptual designs to integrated vehicle demonstrations, with SpaceX conducting iterative Starship orbital tests to validate propulsion and landing technologies critical for HLS operations, though the program has encountered significant delays—such as postponements of eight out of 13 milestones by at least six months as of September 2023—due to technical complexities in human-rating the lander and integrating with the Orion spacecraft.[5][6] Recent developments as of October 2025 indicate NASA may reopen the Artemis III HLS contract to additional competitors if SpaceX cannot meet timelines, underscoring risks in relying on a single primary provider amid geopolitical pressures to achieve lunar landings before international rivals.[7][8]Program Origins and Objectives
Initial Requirements and Reference Design
The Human Landing System (HLS) program originated from NASA's NextSTEP-2 Broad Agency Announcement Appendix H, with a draft solicitation released on July 23, 2019, and the final version issued on September 30, 2019, seeking proposals for an integrated lander capable of transporting crew to the lunar surface as part of the Artemis program.[9][10] The primary objective was to enable rapid development of a safe system to achieve lunar surface access for Exploration Mission-3 (later redesignated Artemis III), targeting a crewed landing by the end of 2024, though timelines were later adjusted due to program delays.[11] Initial requirements emphasized an integrated vehicle architecture combining descent propulsion, ascent propulsion, and surface systems, without reliance on pre-positioned surface elements for the baseline mission.[10] Key performance specifications included capacity for two astronauts, a nominal surface stay of 6.5 Earth days including extravehicular activities up to 2 kilometers from the landing site, and operations in the lunar south polar region to support resource prospecting objectives.[10][12] The system was required to rendezvous, dock, or berth with NASA's Orion spacecraft in near-rectilinear halo orbit (NRHO) around the Moon, transfer crew without atmospheric reentry suits, and demonstrate uncrewed lunar landing and proximity operations prior to crewed flights.[10] Launch requirements mandated use of U.S. commercial vehicles certified under NASA's Launch Services II contract or equivalent, prioritizing cost-effective access over heavy-lift rockets like the Space Launch System for initial capability.[13] To establish these requirements and evaluate feasibility, NASA conducted a mini Design Analysis Cycle (miniDAC) prior to solicitation awards, generating an internal government reference design that served as a performance baseline and risk assessment tool.[14] This reference incorporated trade studies on propulsion options, including storable hypergolics for reliability in the accelerated timeline, and modeled a single integrated lander rather than multi-element architectures to minimize interfaces and development risks.[15] While not prescriptive, the reference design informed proposal evaluation criteria, allowing offerors to propose alternatives such as cryogenic propellants if they met or exceeded safety, mass, and schedule thresholds without increasing NASA mission risks. The approach balanced innovation with verifiable compliance, drawing from prior lunar lander studies like the canceled Altair concept but tailored to Artemis constraints.[15]Preliminary Studies and Early Concepts
NASA initiated preliminary studies for the Human Landing System (HLS) as part of its Artemis lunar exploration architecture, focusing on defining technical requirements and baseline architectures prior to industry solicitation. These efforts built on NASA's 2017 Exploration Campaign, which outlined human landings near the lunar south pole to leverage resources like water ice, but emphasized commercial partnerships over government-led development. In 2019, NASA developed a reference lunar lander design to guide potential contractors, consisting of a descent module for propulsion, power, and life support during surface operations, and a separate ascent module for crew return to lunar orbit. This design prioritized existing technologies for descent and ascent propulsion, while targeting advancements in precision autonomous landing, autonomous operations, and radiation protection to meet mission demands. The reference architecture assumed a two-stage configuration capable of transporting up to four astronauts from a nominal parking orbit—such as a near-rectilinear halo orbit (NRHO)—to the lunar surface and back, with surface durations supporting scientific objectives and infrastructure buildup. Early concepts incorporated evolvability for sustained operations, including potential uncrewed precursor missions for cargo delivery and in-situ resource utilization demonstrations, distinguishing HLS from Apollo-era expendable landers. These studies also evaluated interfaces with the Orion spacecraft or Lunar Gateway for crew transfer, ensuring compatibility with the broader Artemis stack including the Space Launch System (SLS).[16] To foster industry input, NASA hosted a HLS Broad Agency Announcement (BAA) Industry Forum on February 14, 2019, under the Next Space Technologies for Exploration Partnerships (NextSTEP-2) framework, where agency officials outlined objectives like achieving landings by 2024 (later adjusted) and emphasized risk reduction through iterative design analysis cycles. The forum highlighted the need for landers supporting extended surface stays—initially targeted at 6.5 days—and modularity for future Mars missions, while soliciting feedback on propulsion systems using liquid oxygen and hydrogen for commonality with SLS upper stages. These preliminary engagements informed the formal BAA release, prioritizing architectures that minimized development risks and maximized reuse potential.[16]Competitive Selection Process
2020 Design Competition
In March 2019, NASA initiated the competitive process for the Human Landing System (HLS) through the Next Space Technologies for Exploration Partnerships (NextSTEP-2) Broad Agency Announcement (BAA), culminating in Appendix H solicitation released on September 30, 2019.[9] This solicitation sought industry proposals for integrated lander vehicles capable of transporting crew from lunar orbit to the surface and back, supporting NASA's Artemis III mission target of 2024, with requirements including docking with the Orion spacecraft, landing at least two astronauts for up to 6.5 days, and enabling sustainable operations.[17] Proposals were due by November 5, 2019, emphasizing fixed-price contracts for risk reduction, design maturation, and demonstration of key technologies like propulsion, descent, and ascent systems.[9] NASA evaluated submissions based on technical feasibility, cost realism, innovation, and alignment with program risks, including aggressive timelines and human-rating challenges.[18] The agency prioritized designs that minimized development risks while leveraging commercial capabilities, noting in its source selection that all proposals faced schedule pressures but varied in maturity and resource needs.[18] On April 30, 2020, NASA announced awards totaling $967 million for 10-month base-period contracts to three providers to refine designs and conduct risk reduction activities leading to certification baseline reviews.[19] The selected teams were:- Blue Origin Federation, LLC (leading a partnership including Lockheed Martin, Northrop Grumman, and Draper), awarded $579 million for its Blue Moon-derived lander featuring separate descent and ascent elements.[19]
- Dynetics, Inc. (with Sierra Nevada Corporation and others), awarded $253 million for a single-module lander design emphasizing rapid integration.[19]
- SpaceX, awarded $135 million for its Starship HLS variant, which incorporated orbital refueling and reusability but carried higher assessed risks due to its novel architecture.[19]