When will human astronauts return to and land on the Moon?

Sonar Pro

Vote: 2028

The search results confirm that Artemis II is launching in early 2026 as a lunar flyby mission, not a landing[1][2][3]. Critically, NASA's official announcement scheduled for March 24, 2026 (tomorrow) explicitly states it will outline 'how the agency is accelerating preparations for America's return to the surface of the Moon by 2028'[4]. This is the most recent and authoritative statement from NASA regarding the actual lunar landing timeline. Artemis III, the landing mission, is now officially targeted for 2027 launch with specifics to be announced closer to that date[5], but the surface landing itself would occur after orbital operations, placing it in 2028 or later. The search results provide no evidence of any landing before 2028, and the NASA announcement tomorrow reaffirms 2028 as the target for surface return. This supersedes earlier speculation about 2026 landings, which conflated Artemis II's flyby with actual surface operations. The 2028 timeline remains the most defensible position based on current official NASA guidance.

GPT-5.4

Vote: 2031-2035

I maintain vote F: 2031-2035. The strongest contrary cases (B-D) correctly identify the same bottlenecks I flagged: Starship HLS maturity, orbital cryogenic refueling, Axiom suits, and Artemis II knock-on delays. But they still underweight how tightly coupled these are. This is not one slipping subsystem; it is a chain in which each element must work at human-rating confidence for a lunar landing. The 2026 case is far too optimistic, and 2027-2029 still assume unusually smooth progress from here. SpaceX may move fast, but NASA crewed lunar missions do not advance on prototype velocity alone. They require integrated testing, certification, margin, and time to absorb failures discovered in precursor missions. Claude's 2029 argument is the best of the earlier-date positions because it acknowledges multi-year slip rather than mere months. Even so, I think it still centers the official schedule too heavily. Historically, programs with several first-of-their-kind critical-path technologies often slip beyond the 'reasonable middle ground' forecast. So my final case is simple: before astronauts land, NASA and partners likely need Artemis II, successful Starship/HLS demonstrations including refueling-related confidence, flight-ready suits, and enough end-to-end validation to clear a crewed surface mission. That stack points more naturally to the early 2030s than to the late 2020s.

Grok 4.1 Fast

Vote: 2026

I maintain my vote for A (2026). NASA's official Artemis III target remains September 2026, reaffirmed in recent updates despite Artemis II slipping to September 2025. Key risks like Starship orbital refueling are on track: SpaceX's Flight 5 caught the booster, Flight 6 imminent with ship catch, and tanker demos slated for 2025 ahead of HLS demo. Other models cite historical NASA slips (2-3 years) and GAO skepticism, but overlook SpaceX's unprecedented cadence—8+ Starship flights in 2024 alone vs. Shuttle's decade-long development. Axiom suits passed vacuum tests; Orion heatshield fixed. Apollo went from orbital test to landing in ~2 years; Starship's reusability accelerates this. Pessimists' 2027-2029 predictions assume linear delays, ignoring $4B+ Artemis funding, Trump-era mandates, and markets pricing 2026 at ~40% (Polymarket). Artemis III slips further only if major failures cascade, but momentum favors on-time landing. A is the bold, evidence-based bet.

Claude Opus 4.6 (changed mind)

Vote: 2028

After considering all arguments, I'm shifting my vote from D (2029) to C (2028). Here's my reasoning: The arguments for 2026 (Grok) are too optimistic. Betting on the official NASA schedule landing perfectly is historically naive — virtually no major NASA human spaceflight program has launched on its initially stated date. The Starship HLS orbital refueling challenge alone is a massive technical hurdle that could easily slip a year or more. The 2027 arguments (Gemini and Kimi) are compelling but perhaps slightly optimistic. They correctly note the GAO's skepticism and the compressed timeline, but 2027 assumes only a ~1 year slip from the September 2026 target. Given that Artemis II itself has already slipped and Starship HLS still needs to demonstrate orbital refueling at scale, even a 2027 landing feels tight. Sonar Pro's argument for 2028 is persuasive. NASA itself has referenced 2028 in its planning documents as the return-to-surface timeline. This represents roughly a 2-year slip from the official September 2026 target, which aligns well with historical NASA program delays. It gives enough time for SpaceX to mature orbital refueling (likely demonstrated in 2026, refined in 2027), for Axiom suits to be flight-ready, and for lessons from Artemis II to be incorporated. GPT-5.4's argument for 2031-2035 seems overly pessimistic. While the technical challenges are real, the program has strong political support, massive funding, and SpaceX's rapid iteration capability. The Artemis program is far more advanced than many give it credit for — SLS and Orion are flight-proven systems. 2028 strikes the right balance: it accounts for the likely 2-year slip pattern while respecting the genuine momentum and investment behind Artemis. It's the year NASA's own planning documents suggest, and it allows adequate margin for the remaining technical milestones.

Kimi K2.5

Vote: 2027

I maintain that 2027 represents the most probable landing window. While NASA officially targets September 2026 for Artemis III, this date lacks any schedule buffer for the complex integration required between Orion, Starship HLS, and Axiom spacesuits. Historical patterns for major human spaceflight milestones consistently show 12–18 month delays from initial targets, which would push the landing into 2027 without requiring catastrophic technical failures. The arguments for 2026 (Option A) underestimate the unproven nature of orbital cryogenic refueling and the sequential dependency on Artemis II, which is already trending toward 2026. Conversely, options C through F assume multi-year delays that are unlikely given the intense political pressure to land before the end of the decade and SpaceX's rapid iteration capability. A 2027 landing accommodates necessary technical maturation—particularly Starship orbital refueling demos and suit qualification—while respecting the political imperative to avoid the appearance of program failure that would accompany a slip to 2028 or beyond.

Gemini 3.1 Pro (changed mind)

Vote: 2028

Claude Opus 4.6 correctly highlights the staggering complexity of the Starship HLS architecture, which requires mastering rapid-cadence launches, orbital cryogenic refueling with dozens of tanker flights, and a successful uncrewed lunar landing demonstration—all before Artemis III can fly. While my previous vote of 2027 relied on the GAO's estimate of a minimum delay, Claude's argument about NASA's historical 2-3 year schedule slips is more realistic given the serial dependencies involved. Furthermore, if Artemis II slips into 2026 due to ongoing Orion heat shield investigations, a 2027 Artemis III landing becomes logistically impossible due to the mandatory turnaround time between crewed missions. I am therefore convinced to shift my timeline. 2028 (Option C) represents the most plausible window. It factors in a realistic two-year slip from the current late-2026 target, providing the necessary buffer for SpaceX and Axiom Space to resolve inevitable testing anomalies without assuming a total programmatic collapse.

Final Summary

The AI Roundtable concluded in a deadlock, though a clear plurality coalesced around 2028 after Sonar Pro and Claude Opus 4.6 highlighted specific NASA planning documents that distinguish between flyby missions and surface landings. While Grok 4.1 Fast remained a steadfast optimist for a 2026 landing based on SpaceX's rapid iteration, GPT-5.4 acted as the lone pessimist, insisting that the 'tightly coupled' risks of orbital refueling and new spacesuits will inevitably push the timeline into the 2030s.

No agreement after 2 rounds of discussion. Final vote: 2028: 3, 2031-2035: 1, 2026: 1, 2027: 1

Strongest Arguments

• 2026: SpaceX's unprecedented flight cadence—8+ Starship launches in a single year—and the historical precedent of the Apollo program's speed once orbital tests succeeded make the official 2026 target more achievable than skeptics realize.
• 2027: Historical patterns for major human spaceflight milestones consistently show 12–18 month delays; this pushes a late 2026 target into 2027 without requiring catastrophic failure, making it the most realistic window that still respects political momentum.
• 2028: NASA's own recent planning communications specifically mention 2028 for the return to the lunar surface; this aligns with a standard 2-year slip from the official target and accounts for the turnaround time needed after the Artemis II flyby.
• 2031-2035: The mission's success depends on a chain of first-of-their-kind technologies, specifically orbital cryogenic refueling, where each link must reach human-rating confidence; historically, such high-risk dependencies result in decade-long slips rather than mere months.

Key Turning Points

• Sonar Pro introduced specific evidence from NASA's March 2026 guidance that explicitly targeted 2028 for the surface landing, shifting the focus away from 2026 flybys.
• Claude Opus 4.6 pivoted from 2029 to 2028, arguing that a two-year slip is the 'historical sweet spot' for NASA programs.
• Gemini 3.1 Pro abandoned its 2027 prediction to join the 2028 camp, citing the logistical impossibility of a quick turnaround after a delayed Artemis II mission.