NASA is hard at work putting together the pieces that will allow humans to go back to the moon. This time, a woman will be there. The first time humans stepped upon the lunar surface was on July 20, 1969, when Neil Armstrong made his “one giant leap for mankind” and placed his space boot upon the dry lunar surface. (That footprint will be there for a million years, because there is no atmosphere or weather on the moon to wear it away.) 
The last time humans were on the moon was in 1972. Apollo 17 astronauts Eugene Cernan and Harrison Schmitt strolled across the lunar surface, fulfilling the mission’s scientific objectives. That was 50 years ago, and now the world appears ready to return to the moon to learn more about how the solar system began, how humans might live there and later live on Mars, and what it takes to support long-term operations off-planet. Welcome to the future. 
The United States and China are in the lead of this new wave of space exploration. NASA launched its Artemis I mission on Nov. 16, 2022, testing the technologies that will one day take astronauts back to the moon. It is possible that a follow-up mission, Artemis II, may launch as early as 2024. A third mission, Artemis III, would take humans back to the lunar surface. Once that mission is accomplished, NASA has plans to launch missions to the lunar surface once a year. China has launched lunar exploratory modules since 2004, and it is expected that China will send humans to the moon by the end of the decade. From 2020 to 2030, the European Space Agency has an ambitious program to analyze samples from the moon, deploy instruments, identify potential resources for exploration and more. 
One question is, with multiple international and private sector participants engaged in exploring the moon, how will mission control centers located around the globe work together to create a shared time system for the moon?
On Earth, there are time standards that everyone agrees to use, based on Coordinated Universal Time, known as UTC. The United States is hours behind Europe, where the sun rises earlier, but we all agree to naming times based on UTC standards. It is possible that everyone will agree to use the UTC to tell the time on the moon. One thing to consider, however, is that a day on the moon is not the same length as a day on Earth. The moon’s time moves ahead of the Earth’s by 56 microseconds every day, and those microseconds add up to about a second every 50 years. That seems like a tiny difference, but it could complicate moon missions. Since space agencies will be sending satellites and equipment to the moon, and we may have a lunar base where people live and work, it is important that everyone communicate using the same time standard so that there is no confusion about who is where at what time.
One option could involve installing master clocks on the moon much like we have on Earth. The master clocks could automatically adjust for changes across the moon. Another option would be to come up with a lunar standard time. Space agencies in different countries would have to agree to a lunar standard. Even after agreeing to a standard time, though, a lunar day still won’t look like a day on Earth. The moon’s cycles of dark and light differ from those on Earth. When the Artemis III crew arrives at the moon’s south pole, they will be working in permanent sunlight. Much like the sun in the Earth’s arctic summer, the sun will appear to hover on the horizon and never set. How will astronauts sleep if they live at a lunar station? Much like people do in far northern locations in summer: with blackout curtains and blinds. Scientists try to think ahead and plan for potential problems so they can devise solutions. Finding the best answer to the question of lunar time will help future lunar missions run more smoothly and enable coordinated explorations of the moon.