On April 1, 2026, NASA's Space Launch System will lift off from Kennedy Space Center carrying four astronauts on a journey no human has made in over half a century. Artemis 2 is the first crewed mission beyond low Earth orbit since Apollo 17 in December 1972. Over roughly 10 days, the crew will fly around the Moon and return home — and for every moment of that journey, their clocks will tick slightly differently than ours on Earth.
The Crew Making History
The Artemis 2 crew represents a historic shift from the Apollo era. Commander Reid Wiseman, a Navy test pilot and former ISS crew member, leads the mission. Pilot Victor Glover, who previously flew on SpaceX Crew-1, will become the first person of color to travel beyond Earth orbit.
Mission Specialist Christina Koch holds the record for the longest single spaceflight by a woman — 328 consecutive days aboard the International Space Station in 2019-2020. She will become the first woman to fly to the Moon. Canadian Space Agency astronaut Jeremy Hansen, a former CF-18 fighter pilot, rounds out the crew as the first Canadian and first non-American to leave Earth orbit.
Mission Profile
Artemis 2 follows a free-return trajectory — a flight path that uses the gravity of the Earth and Moon to naturally guide the spacecraft home, providing an inherent safety margin. The mission unfolds in stages:
The SLS rocket launches Orion into a high Earth orbit. After systems checkout, Orion's engines fire to send the crew on a four-day journey to the Moon. The spacecraft will fly within approximately 6,500 miles (10,400 km) of the lunar surface before swinging back toward Earth. Total mission duration is roughly 10 days, ending with splashdown in the Pacific Ocean.
During the flight, the crew will put Orion's life support systems through their first crewed test — the environmental controls, radiation monitoring, communication systems, and emergency procedures that must all work flawlessly before NASA sends astronauts to the lunar surface on later missions.
Time Dilation in Real Time
Here is where the mission connects to something fundamental about the universe. As the Artemis 2 crew travels through cislunar space and passes close to the Moon, they will be farther from Earth's gravitational well. Einstein's general theory of relativity tells us that time passes faster in weaker gravitational fields — and the Moon's gravity is just one-sixth of Earth's.
This is the same effect that Coordinated Lunar Time (LTC) is designed to account for. Clocks on or near the Moon tick approximately 56.02 microseconds faster per Earth day compared to clocks on Earth's surface. Over the roughly 10-day Artemis 2 mission, the crew's onboard clocks will accumulate a small but physically real time offset from ground-based clocks.
The Apollo astronauts experienced this same relativistic drift, though they had no reason to measure it precisely. For Artemis, precision timing is critical. Future missions will depend on synchronized clocks for navigation, communication scheduling, and eventually a lunar GPS network. Artemis 2 is the first crewed step toward that infrastructure.
From Artemis 1 to Artemis 2
Artemis 1 launched in November 2022 as an uncrewed test flight, sending Orion on a 25.5-day journey around the Moon. The mission validated the SLS rocket and Orion's heat shield, which must withstand temperatures approaching 5,000 degrees Fahrenheit during reentry at 25,000 mph — the fastest any human-rated spacecraft will travel.
Engineers identified minor heat shield erosion during Artemis 1's return. Rather than replacing the shield, NASA modified the reentry trajectory for Artemis 2, using a steeper descent angle that reduces time spent in the thermal environment. Ground testing confirmed the approach stays within all structural and thermal margins.
Artemis 2 is shorter than Artemis 1 — roughly 10 days versus 25 — because its primary purpose is validating that every system works with humans aboard. The crew will also demonstrate rendezvous and proximity operations using the spent upper stage as a target, a capability needed for docking with the Lunar Gateway on future missions.
What Comes Next
Each Artemis mission builds toward a sustained human presence on the Moon:
Artemis 3, targeted for mid-2027, will test rendezvous and docking in low Earth orbit with commercially developed lunar landers — SpaceX's Starship Human Landing System and Blue Origin's Blue Moon. The crew will also test the new Axiom spacesuit designed for lunar surface operations.
Artemis 4, planned for 2028 or later, is expected to be the first mission to land astronauts at the Moon's south pole for a stay of approximately one week. By then, the need for precision lunar timekeeping infrastructure will be immediate — surface crews, orbital assets, and Earth-based mission control all need a common time reference that accounts for relativistic drift.
Track the Mission in Lunar Time
As Artemis 2 orbits the Moon, you can follow along using the live Coordinated Lunar Time clock on this site. The clock applies the +56.02 microseconds per day drift rate to UTC, accumulated since the J2000.0 epoch — the same relativistic offset that the Artemis 2 crew will experience firsthand as they fly farther from Earth than any human in over 50 years.