Lunar time standard tracker

Six organisations and forums decide what lunar time will be. This board shows where each one stands today, what it has said comes next, and the document behind every line.

Status by track

• United States — NASA and OSTP. Two OSTP memoranda name Coordinated Lunar Time and direct NASA to deliver an implementation strategy and a reference systems plan. ^{[2]Official[4]Official[5]Official}
• BIPM and the CGPM. Lunar time is Draft Resolution D and item 17 on the provisional agenda circulated to member states for the 28th CGPM. ^{[1]Official[6]Official[7]Official}
• International Astronomical Union. The 2024 General Assembly adopted two resolutions: one defining the Lunar Celestial Reference System and Lunar Coordinate Time, one asking for an agreed lunar scale. ^{[3]Official[8]Official}
• ESA — Moonlight and LunaNet. ESA set out the case for a common lunar reference time and runs Moonlight, its lunar communication and navigation programme. ^{[9]Official[10]Official}
• China — CAS / Purple Mountain Observatory. A group at the Purple Mountain Observatory published LTE440, a lunar time ephemeris built on the IAU definition of Lunar Coordinate Time. ^[11][12]
• ICG and IOAG — cislunar PNT workshops. The UN committee on GNSS and the IOAG run joint workshops on cislunar positioning, navigation and timing, with lunar reference systems and time systems named as a focus. ^[13]Official

What the stages mean

The four stages describe how far a decision has travelled inside one organisation, not how good the decision is. A track moves one stage at a time, and only when a document says it moved.

Proposed

The organisation has said in public that a lunar time scale is needed, or has published a proposal for one. No text is on the table yet.

Drafted

A concrete text exists — a policy memorandum, a draft resolution — and it is circulating. The decision on it has not been taken.

Adopted

The body has voted the text through. The definition is settled inside that organisation. It does not mean that any clock is running.

Realized

A time scale is being computed from real clock data and published on a schedule. No track has reached this stage.

Next milestones

Nearest announced milestone28th CGPM votes on Draft Resolution D — 13 October 2026, in 50 days. ^[1]Official

No next date has been announced for International Astronomical Union, ESA — Moonlight and LunaNet, China — CAS / Purple Mountain Observatory and ICG and IOAG — cislunar PNT workshops. An empty cell here means silence in the documents, not a date we failed to find.

Changelog

Every movement on the board, newest first, with the document that justifies it.

1. 24 August 2026ICG and IOAG — cislunar PNT workshopsTrack added to the board: the joint ICG-IOAG workshops on cislunar positioning, navigation and timing, and ICG Working Group L on lunar PNT. ^[13]Official
2. 23 August 2026United States — NASA and OSTPTrack created at launch. ^[2]Official
3. 23 August 2026BIPM and the CGPMTrack created at launch. ^[1]Official
4. 23 August 2026International Astronomical UnionTrack created at launch. ^[3]Official
5. 23 August 2026ESA — Moonlight and LunaNetTrack created at launch. ^[9]Official
6. 23 August 2026China — CAS / Purple Mountain ObservatoryTrack created at launch. ^[11]

How we update this page

We re-read the six tracks every week. A row moves only when a document says it moved: a memorandum, a resolution, a convocation, a paper. The move is then written into the changelog above with the source that justifies it, so the board and its history can be checked against each other.

Nothing on this page is a forecast. Where an organisation has announced no next date, the board says so rather than offering a guess, and the vote at the 28th CGPM is listed as a scheduled item until the conference has taken it. ^[6]Official

A move on this board is what the email brief is for: it goes out when a row changes, at most weekly, with the document that justified the change — the Lunar Time Brief. The board here changes first; the mail only follows it.

Last verified 23 August 2026