Staff writers
The Biden Administration has called on NASA to develop a standard time zone for the Moon as it pushes ahead with a cislunar science and technology strategy.
That strategy, first published by the White House in 2022, is intended by the United States to support “responsible, peaceful, and sustainable exploration” in cislunar space – the region between the Earth and Moon, but beyond geosynchronous orbit (a boundary just over 35,000km above the Earth’s surface).
The strategy was formed in response to the escalation of spacefaring activity by established and emerging space nations.
A memo from Arati Prabhakar, the director of the White House’s Office of Science and Technology Policy (OSTP) confirmed the new undertaking.
Lunar Coordinated Time (LTC) will be developed by NASA along with the US Departments of commerce, Defense, State and Transportation, to be implemented by the end of 2026.
The move will seek to address the disparity – thanks to gravity – that sees time on the Moon pass quicker on Earth, by just 58.7 microseconds each day (that’s 0.000059 seconds). This distortion of time between celestial bodies of differing sizes is fundamental to principles of general and special relativity, and directly referenced in the White House document.
LTC will be, according to Prabhakar, “foundational” to the new era in space exploration and “position, navigation and timing infrastructure” essential to this future. Rather than being a time zone for the Moon, it’s a standard that will be ‘traceable’ to Coordinated Universal Time (UTC) – the benchmark time zone on Earth set by atomic clocks dotted around the planet.
“Due to general and special relativity, the length of a second defined on Earth will appear distorted to an observer under different gravitational conditions, or to an observer moving at a high relative velocity,” Prabhakar’s memo says.
Developing LTC will enable spacefaring nations and companies to have a more accurate timeline to perform space science, and will improve calculations for Moon-orbiting craft, missions and communications.
While it’s less of a ‘time zone’ in the way days are calibrated on Earth, it will effectively act as a reference for Earth-based operations and space personnel to precisely perform calculations and measures in the cislunar region.
“Exploration of Cislunar space opens a new sphere of human activity and offers opportunities to advance scientific understanding, exploration, and economic growth,” says the White House. “With a shared vision and unity of purpose across departments and agencies, the United States will lead the responsible, peaceful, and sustainable exploration of Cislunar space and application of discoveries in this area.”