The new White House policy directs NASA to develop a strategy for a new time standard for use on orbital missions to provide improved navigation and related services on and around the Moon.

The Celestial Time Standardization Policy in Support of the National Circular Science and Technology Strategy, released April 2 by the White House Office of Science and Technology Policy, instructs NASA to develop a strategy to establish Lunar Coordinated Time (LTC) by the end of 2026. , a new time standard based on Coordinated Universal Time (UTC) on Earth but adapted for operations on the Moon.

“As NASA, private companies and space agencies around the world launch missions to the moon, Mars and beyond, it is important that we set sky time standards for safety and accuracy,” Steve Welby, OSTP deputy director for national security, said in a statement.

The simple use of UTC in lunar space is sufficient for accurate operations, the document states. UTC depends on Earth systems, but relativistic effects mean that a second on the Moon does not have the same duration as on Earth. “For example, for an observer on the Moon, Earth time loses an average of 58.7 microseconds per Earth day, with additional periodic fluctuations occurring,” the document says.

Although this difference is negligible for most applications (a one-second offset takes almost 50 years to accumulate), it is an issue for navigation and related applications such as space exploration and approach operations where higher accuracy is required.

“Coordinated timing between operators in space is critical to the successful use of space-based situational awareness, navigation and communications capabilities that are essential to ensuring interoperability with the U.S. government and international partners,” Welby said. said.

The policy defines four main characteristics of LTC: traceability to UTC, sufficient accuracy for precision navigation and science, resilience to loss of communication with Earth, and scalability to conditions outside the lunar domain.

The policy provides little technical guidance on establishing a lunar time standard but suggests it could be done in a similar way to terrestrial time standards using a network of atomic clocks. “Just as Earth time is set by a set of atomic clocks on Earth, a set of clocks on the Moon can set lunar time,” the paper said.

In addition to giving the White House a final strategy for a lunar time standard by the end of 2026, the policy also directs NASA to include the issue in its annual review cycle of Moon-to-Mars flight architecture, which it has announced virtually. a year ago and updated at the beginning of this year. NASA will work with several other agencies on the lunar time transition strategy, including the Department of Commerce, Department of Defense, Department of State, and Department of Transportation.

NASA is working on a concept called LunaNet to provide communications and navigation services on the Moon through an interoperable network that could include commercial and international contributions. NASA and the European Space Agency have developed several versions of the LunaNet Interoperability Specification that talk about establishing a lunar time system standard, but documentation for this has not yet been developed.

In May 2023, the National Geospatial-Intelligence Agency (NGA) announced that it was working with NASA to develop a positioning and navigation system for the Moon. At the time, NGA officials said the goal was to create a system that would work “as accurately and securely as GPS on Earth” for users on the moon. This statement did not address the establishment of a lunar time standard.