The collective global duty to safeguard time

Who should decide what time it is on the Moon? That is the question facing the International Bureau of Weights and Measures (BIPM) — whose role is as fundamental to modern life as its public profile is obscure. Its mundane name hides its function as guardian of the measurement systems that underpin science and societies. From Tuesday this week, its members will meet in Versailles outside Paris for a crucial test of international collaboration in an age of geopolitical mistrust.

The BIPM’s 69 members, including great and emerging world powers, will discuss profound changes to how we track time on earth and beyond, affecting areas from financial transactions to the quest to colonise other worlds. The body was created in 1875 to standardise measurements including the kilogramme, the metre and the second — and thus time on earth.

Timing and navigation have become increasingly political issues as the world’s digital dependence raises the costs of disruption to both. Accidental outages and wartime sabotage have shown the vulnerabilities of existing methods such as the global positioning system that has become part of daily life, but relies on satellites housing ultra-accurate atomic clocks.

Interruptions to navigation and timing measurements threaten electronic systems vital in areas including communications, financial transactions and operating power plants. That has prompted a search by countries for more precise and secure technologies.

BIPM members will discuss a plan to replace the “leap second” — an adjustment applied to reconcile tiny differences in the time gauged by atomic clocks and which is calculated astronomically using the Earth’s slightly irregular rotation. The leap second, which has been added 27 times since 1972, is a pain because it requires changes to all timing-dependent infrastructure. The problem has intensified because Earth has been spinning faster since the mid-2010s, due partly to changes in its core, meaning a leap second might eventually have to be deducted rather than added.

That unprecedented alteration could play havoc with systems not adapted to deal with it. The proposal before BIPM members would replace the leap second with a leap hour, which might take 1,000 years or more to accumulate — and so in effect mean no further timing system adjustments would be required.

BIPM members will hold further discussions about efforts to set a standard time for the Moon — where time passes at 57 microseconds a day faster than on Earth due to gravitational effects flowing from the differences in mass.

The need for an agreed lunar time has been made more pressing by the new race not just to visit but to inhabit it. Both the US and China are aiming to land astronauts on the Moon in the next few years, with longer-term plans to build lunar bases. Countries and companies including SpaceX are exploring prospects for lunar mining for valuable materials.

Common timing for the Moon — and perhaps later, Mars — would be essential to any sustained future human presence there, helping ensure lunar communication network signals stay within allocated bandwidths and don’t interfere with one another. A benchmarked lunar time would be crucial to navigation, too. The difference with Earth is enough for light waves used on communications systems to travel about 17km. Failing to adjust for that could lead to catastrophic failures in attempts to land spacecraft or track the location of astronauts.

BIPM member meetings have typically not been a venue for UN general assembly-style open political warfare. Now would be a bad time for that to change.