What happens after the vote on lunar time
Key facts
- The conference has not met. Draft Resolution D can be carried, amended on the floor, or left aside. [1]Official
- A United States memorandum of 2 April 2024 asks NASA for a finalized lunar timing implementation strategy no later than 31 December 2026. [2]Official
- That deadline is national policy and does not depend on the outcome at the 28th CGPM. [2]Official
- Lunar Coordinate Time (TCL) is already defined by IAU Resolution II of 2024 and stays defined either way. [3]Official
- No lunar time scale is being computed today, and neither outcome starts one on its own. [4]Official
The title of this page assumes nothing. The 28th CGPM is scheduled for October 2026, and the outcome of a diplomatic conference is not predictable from its agenda [1]Official. Draft Resolution D can be carried, amended on the floor, or left aside.
So this page covers both outcomes. It also lists what would not change in either of them, which is the longer list of the two.
The two outcomes
If the conference carries the draft, the definition of an international lunar reference time scale, and its traceability to UTC, becomes a resolution of the CGPM. That is the subject of the text sent to member states [1]Official.
If it does not, the latest word on the subject stays where it is now: a coordinate time defined by the IAU in 2024 [3]Official, a request from the IAU that international organizations agree the relations between the scales [5]Official, and technical work in the CCTF with space agencies [4]Official.
Neither outcome produces a clock reading. That distinction is the subject of what is Coordinated Lunar Time.
What changes and what does not
| Question | If the draft is carried | If it is not | Source |
|---|---|---|---|
| Is a lunar reference scale defined internationally? | Yes, by a resolution of the CGPM | No; the IAU coordinate time of 2024 remains the latest step | [1]Official |
| Is a scale being computed? | No; a definition is not a realization | No | [4]Official |
| Is TCL still defined? | Yes, by IAU Resolution II of 2024 | Yes | [3]Official |
| Who computes the scale? | Not named in the draft | Not named anywhere | [1]Official |
| Does the US deadline of 31 December 2026 move? | No; it is set by national policy | No | [2]Official |
The deadlines that hold either way
The United States set its own dates before the conference was convened. The memorandum of 2 April 2024 asks NASA, with the Departments of Commerce, Defense, State and Transportation, for a finalized strategy to implement lunar timing standardization no later than 31 December 2026 [2]Official. The same memorandum set two earlier dates, both 31 December 2024: consideration of Coordinated Lunar Time in the annual Moon-to-Mars Architecture Concept Review, and a milestone-based approach delivered to OSTP [2]Official.
NASA announced the work publicly in September 2024 [6]Official. None of those dates is conditional on a vote in Versailles, and none of them is moved by one [2]Official.
The standards tracker carries the same dates track by track, and the timeline puts them in order with everything that came before.
What we would change on this site
If the draft is carried, the BIPM row on the standards tracker moves to the next stage, and every page that calls the text a proposal is rewritten the same day. If it is not, the row stays where it is and the page says so. The stages are defined on the tracker itself, and a row moves only when a document says it moved.
Either way, no clock value on this site changes. Our figures come from the published relativistic model, not from a resolution, and a vote does not alter physics [7].
Read next
The text under discussion is covered in what Draft Resolution D proposes; the procedure that decides it is in how the CGPM votes on a draft resolution; the other two time drafts are in three time resolutions at the 2026 CGPM [1]Official.
The primary text sits on the document page for Draft Resolution D, and the rest of our coverage is in the lunar time news hub.
Sources
- Convocation of the 28th meeting of the CGPM (O/Ref AK-CFA-2026-1001)
- Policy on Celestial Time Standardization
- Resolution to establish a standard Lunar Celestial Reference System (LCRS) and Lunar Coordinate Time (TCL)
- Latest Updates from 2025 CCTF Meeting
- Resolution on the establishment of a coordinated lunar time standard by international agreement
- NASA to Develop Lunar Time Standard for Exploration Initiatives
- Our calculation: the lunartime.org clock model
- Meetings of the CIPM: Outcomes
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