NASA: What Time Is It On The Moon? Let’s Set A Lunar Time Standard
While it has been over 50 years since the first lunar landing, returning to the Moon is still a tricky proposition. In a press release at the beginning of this year, NASA remarked it is targeting no sooner than September 2025 for the Artemis II, and September 2026 for Artemis III. While a lunar base is still a long ways off, companies are hard at work formulating ideas for how to power such a project, like Honeybee’s 100 meter tall tower that could potentially provide power and light on the lunar surface. With all the plans moving forward for an entirely interconnected system, NASA and the US government want to make sure time is on its side.
According to NASA, the lunar time will be determined by a weighted average of atomic clocks on the Moon, similar to how scientists calculate Earth’s globally recognized Coordinated Universal Time (UTC). The space agency still must determine a location, with analysts indicating atomic clocks placed at the Moon’s surface will appear to “tick” faster by microseconds per day (a microsecond is one millionth of a second). NASA and its partners are still trying to determine which mathematical models will be best suited for establishing a lunar time.
According to the American Institute of Physics, the lower gravitational pull on the Moon and its motion relative to Earth result in time moving faster there relative to an observer on Earth by approximately 58.7 microseconds per day. While the difference has been manageable, it does pose a challenge for future missions that need more precision and interoperability, such as those required by GPS-like navigation.
“For something traveling at the speed of light, 56 microseconds is enough time to travel the distance of approximately 168 football fields,” explained Cheryl Gramling, lead on lunar position, navigation, timing, and standards at NASA Headquarters in Washington. “If someone is orbiting the Moon, an observer on Earth who isn’t compensating for the effects of relativity over a day would think that the orbiting astronaut is approximately 168 football fields away from where the astronaut really is.”
Putting the numbers into perspective, we can use an analogy of a hummingbird’s wings. The tiny bird’s wings flap about 50 times per second. Each flap is about .02 seconds, or 20,000 microseconds. Therefore, while 56 microseconds may seem miniscule, when considering the vast distances in space, microseconds can quickly add up and put craft off course.
NASA’s SCaN team will continue to work on developing a time standard at the Moon in order to ensure the time difference does not negatively affect future lunar missions. The approach to time systems will also be scalable for Mars and other celestial bodies throughout the solar system.
