Human Lunar Return (HLR)¶
Summary. The first segment: "Initial capabilities necessary to re-establish human presence on and around the Moon" (ADD Rev C, p. 22). It covers the first Artemis missions, the first crewed landing, initial Gateway deployment and uncrewed cargo delivery, with eight elements from SLS and Orion to CLPS, plus the Gateway Logistics Element. No technology gap lists this segment, but 17 of the 19 lunar data gaps do. ADD Rev C names Artemis III as the landing mission; a March 2026 fact sheet has since moved the landing to Artemis IV.
All page numbers below are ADD Rev C unless marked otherwise. For what segments are, see Segments and Architecture framework.
Description¶
- "The Human Lunar Return segment includes the initial capabilities, systems, and operations necessary to re-establish human presence and initial utilization (science, etc.) on and around the Moon for the first time in over 50 years. This segment primarily focuses on establishing supporting infrastructure to perform crewed missions to the Moon. Segment systems and capabilities span Earth, cislunar orbiting platforms, and foothold capabilities on the lunar surface. Initial utilization focuses on human-conducted science, sample collection, human research, and more" (p. 22).
- It "includes the inaugural Artemis missions" and "will demonstrate initial systems to validate performance and establish core capabilities for follow-on segments. It comprises missions that test crew and cargo transportation systems, deploy initial cislunar capabilities to support lunar missions, establish lunar orbital communication relays, and send crew members to the lunar surface and return them safely to Earth" (p. 24).
- Risk reduction. "A variety of other efforts support data-gathering and risk-reduction activities in the Human Lunar Return segment to help inform future architecture definition. These include the Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment (CAPSTONE) mission, instruments on Commercial Lunar Payload Services (CLPS) provider landers, Artemis mission secondary payloads, and more" (p. 24).
Objectives¶
Objective codes are quoted as printed; the prefixes are the goals on Objectives: the ten goals.
- Missions. "This segment began with the successful Artemis I mission and continues with Artemis II, which sends crew around the Moon, and Artemis III, which lands crew on the lunar surface" (p. 24). See Changes since Rev C.
- Science, "identified by NASA's Science Mission Directorate" (pp. 24–25):
- exploring the South Pole region "to understand chronology, composition, and structure" (LPS-1, LPS-2)
- "volatile composition and the environment of shallow permanently shadowed regions near the lunar South Pole" (LPS-3)
- "the history of the Sun as preserved in lunar regolith" (HS-2)
- "space weather dynamics to enable future forecasting capabilities" (HS-2)
- "plant, model organism/systems, and human physiological responses in partial-gravity environments" (HBS-1)
- Done so far. Artemis I "tested crewed transportation to and from cislunar space (TH-1, TH-2), supporting ground infrastructure (OP-4), communications and tracking systems (OP-2), and more" (p. 25).
- Next steps. "transporting crew to and from cislunar space, initial Gateway deployment (OP-6), rendezvous and docking in lunar orbit, uncrewed demonstrations of human landing systems, landing humans on the Moon (TH-2) and returning them to cislunar space, realizing a surface extravehicular activity (EVA) capability, and uncrewed payload and cargo delivery" (p. 25).
The lunar objective decomposition spreadsheet's "HLR" sheets give 39 objectives, 44 use cases and 58 functions for this segment, with an allocation to assets: see Lunar objectives and Lunar function allocation. The ADD cites OP-4 here, but the HLR sheet has no OP-04 LM (Lunar objectives).
Reference missions¶
"Reference missions provide examples of how NASA can group use cases together to accomplish a particular concept of operations. … These reference missions demonstrate how architectural capabilities could be used; they are not specific missions NASA will conduct" (p. 25). The full lunar use-case list is ADD Appendix B.2.1, on Lunar use cases; the 44 the HLR sheet uses are on Lunar objectives.
| Reference mission | What it covers (p. 25–26) |
|---|---|
| Crewed Initial Lunar Surface Mission | "returns crew to the lunar surface for the first time since the Apollo Program". Transport use cases: Earth to cislunar space, "staging crewed lunar surface missions from cislunar space, assembling integrated assets in cislunar space", cislunar space to and from the surface, and return to Earth. Surface use cases: "crew operations on the lunar surface, frequent crew surface EVAs, and crew-conducted utilization activities". |
| Crewed Gateway and Lunar Surface Mission | Adds "more capabilities in cislunar space", "particularly for lunar orbital operations". Gateway, "a habitable outpost located in near-rectilinear halo orbit (NRHO)", lets crew conduct utilization in cislunar space, lets ground and science teams "directly engage with astronauts on the surface and in lunar orbit", supports deploying science instruments in lunar orbit "with long-term remote operation", and "includes autonomous/semi-autonomous mission operations in cislunar space". |
Elements¶
From the table on p. 26, checked against the PDF. Each element has a page; see the elements index. The element pages give what each one does in this segment, such as the two-crew initial HLS, LCRNS relay coverage from 80° S (SCaN), SLS Block 1 and Block 1B Crew (SLS), and the Gateway Crew-Capable Configuration.
| Element (as named on p. 26) | Sub-architecture | ADD section | Mapping |
|---|---|---|---|
| Commercial Lunar Payload Services | Transportation Systems | 2.3.1 | B.3.1 |
| Exploration EVA Systems | Mobility Systems | 2.3.2 | B.3.2 |
| Exploration Ground Systems | Infrastructure Support | 2.3.3 | B.3.3 |
| Gateway Crew-Capable Configuration | Habitation Systems | 2.3.4 | B.3.4 |
| Gateway Logistics Element | Logistics Systems | 2.3.4.1.4 | B.3.4.1.1 |
| Human Landing System | Transportation Systems | 2.3.5 | B.3.5.1 |
| Orion Spacecraft | Transportation Systems | 2.3.12 | B.3.12 |
| Space Communications and Navigation Networks | C&PNT Systems | 2.3.14 | B.3.14 |
| Space Launch System | Transportation Systems | 2.3.15 | B.3.15 |
Six of the seven sub-architectures that have elements anywhere are represented; the missing one is Power Systems, whose only element is Foundational Exploration's. Transportation has four of the nine rows.
Areas of future work¶
"This segment also includes some unallocated functions (see Appendix B.5) that are not yet met by existing systems, reference missions, or planned operations" (p. 26). The areas listed:
- "Increasing utilization down-mass capabilities to the lunar surface"
- "Accommodating extravehicular utilization payloads (i.e., interfaces, resources)"
What Appendix B.5 lists for this segment. One function, FN-C-205 L, "Provide a coordinated lunar time scale", under four use cases: South Pole PNT (UC-C-202 L, UC-C-203 L), crew identification of samples (UC-U-103 L), and sample collection (UC-U-301 L). "All the use cases listed above share a single unallocated function for the Human Lunar Return segment" (p. 167). The lunar spreadsheet's HLR sheet marks the same function Unallocated, under the same four use cases (Lunar function allocation). The element mappings for the segment (B.3, pp. 148–165) are on each element page above.
Gaps that list this segment¶
- Technology gaps: none, by design. The tech-gap spreadsheet lists only Foundational Exploration, Sustained Lunar Evolution and Humans to Mars (derived from its Segments column; tech gaps spreadsheet). The ADD explains why: "The Human Lunar Return Segment contains technology development and investment by the current programs, so the technology gaps captured in this document do not trace to Human Lunar Return" (p. 79; see gaps index).
- Data gaps: 17, all lunar except DN-006 L and DN-007 L (data gaps spreadsheet, Segment column): DN-001 L to DN-005 L (site characterization), DN-008 L to DN-016 L (natural environment), and DN-017 L to DN-019 L (induced environment). For data gaps the segment is when "the data is needed, but not necessarily when it is collected" (Key sheet). See the data gaps index.
In the February 2025 workshop briefing¶
The Moon to Mars Program Office briefed both February 2025 workshops on the Artemis campaign as then planned, ten months before Rev C. The deck names no segments, so setting it on this page is the wiki's choice (Program Office updates deck, slides 3–13; the partners' copy differs only in captions and where one science line sits). Its five missions (slide 3): "ARTEMIS I, First Mission (Uncrewed Flight Test)", "COMPLETE"; "ARTEMIS II, First Crew"; "ARTEMIS III, First Human Surface Landing"; "ARTEMIS IV, First Lunar Space Station Assembly Mission"; "ARTEMIS V, Crewed Mobile Surface Exploration, Gateway Expansion".
- Artemis III: "Human landing in South Pole region and return"; "Orion to human landing system direct mission including crew docking activity"; "Use of Near Rectilinear Halo Orbit (NRHO)"; "Four astronauts to lunar orbit"; "Two astronauts to lunar surface". New elements: Orion's docking systems, the "Starship human landing system", "Advanced spacesuits and tools" (slide 8).
- Artemis IV: "Crewed mission to Gateway"; "Crew transfer from Orion to human landing system (HLS) via Gateway". New elements: SLS Block 1B, Mobile Launcher 2, "SpaceX Sustaining Starship HLS", and the Gateway's PPE and HALO "(pre-staged in orbit)", the "International Habitat (launched on SLS Block 1B alongside the crew aboard Orion)" and Deep Space Logistics (slide 10).
- Artemis V: first crew use of the LTV; "Use of second lunar lander design"; new elements "Blue Moon human landing system", "LTV unpressurized rover with scientific instruments", and the Gateway's "ESPRIT Refueling Module" and "Canadarm3 robotic arm" (slide 12).
No slide gives a year. The plan matches Rev C's Artemis III landing (p. 24) and was overtaken in 2026 (below).
In the February 2024 workshop briefing¶
The Program Office's deck a year earlier has the same five missions and the same elements on Artemis IV and V (Program Office updates, February 2024). What differs, by the wiki's comparison: Artemis III's new elements name their providers, "SpaceX Starship human landing system" and "Axiom advanced spacesuits and tools"; Artemis IV's logistics flight is not yet a "Precursor"; Artemis II lacks the abort-system and proximity-operations firsts of 2025. The deck also shows "Artemis II, First crew", "CREW SELECTED", and an Artemis III milestone chart "As of 2/15/2024" with "HLS Uncrewed Mission Milestones" (Human Landing System).
What changed by Rev C (the wiki's comparison): Rev C assigns no lander provider to a mission (p. 55); the February 2024 plan, like the 2025 one, was superseded in March 2026 (below).
Changes since Rev C¶
- Artemis III no longer lands. The fact sheet's "Updated Plan —announced Feb 2026" makes Artemis III a "Human landing system & EVA suit test mission in Earth orbit — 2027" and Artemis IV "Astronauts return to the lunar surface — early 2028" (Going back to the Moon, pp. 1–2). ADD Rev C (Dec 2025) still has Artemis III landing crew (p. 24), and repeats it in the Crew Return tenet's examples: Artemis III "will demonstrate complex operations, including transferring crew across vehicles and conducting an initial lunar landing and EVA" (p. 90; RT-3). The newer source wins (open question 22).
- Gateway. This segment's next steps include "initial Gateway deployment (OP-6)" (p. 25), and one of its two reference missions is built around Gateway. The Users Guide says SR-1 Freedom repurposes "the Power and Propulsion Element originally planned for the Gateway space station" (Users Guide, p. 2), and Gateway appears only in the fact sheet's "Original Plan" column (Going back to the Moon). HALO hardware is also being repurposed for Moon Base surface demonstrations (Gateway). None of the wiki's sources says how the HLR segment changes as a result.
- Artemis II has flown (April 2026), per photo captions in the Users Guide (Orion).
Moon Base relevance¶
Not established by the sources so far. No source maps this segment to a Moon Base phase, and the wiki does not assume one. The Users Guide places a "First crewed Moon Base mission" in Phase 1 without naming the Artemis mission (open question 9).
Related pages¶
The ACR25 lunar power white paper names "the Human Landing System, Lunar Terrain Vehicle, Pressurized Rover" as examples of the self-sufficient elements this segment relies on (lunar power white paper, p. 1). The element table above lists the HLS but neither rover (open question 33).
A 2023 white paper on how HLR landing sites are chosen (close to their targets, sunlit "for approximately 6–6.5 days", Earth in view for direct-to-Earth communications, and dependent on "when the crew launches") is on Lunar site selection.
Segments · Foundational Exploration · Architecture framework · Elements · Data gaps index · Moon Base missions and assets
Sources¶
ADD Rev C, pp. 22, 24–26, 79, 90 · Data gaps spreadsheet · Tech gaps spreadsheet · Going back to the Moon, pp. 1–2 · Users Guide, p. 2 · Program Office updates deck, Feb 2025, slides 3, 8, 10, 12 (partners' copy)