After more than 50 years, NASA is taking a key step towards its long-term return to the moon with Artemis II.
The four-person crew will go on a 685,000 mile, 10-day journey around the moon, also known as a lunar fly-by.
Here is a timeline of what the Artemis II mission will look like:
Follow live coverage of the Artemis II mission, including a 24/7 live blog from pre-launch to splashdown, and major milestones on ABC News Live and streaming on Disney+ and Hulu.
Day 1: Launch and Earth orbit
April 1 is the first launch opportunity date with a window between 6:24 p.m. ET and 8:24 p.m. ET and potential backup dates between April 2 and April 6.
The astronauts will be sitting aboard NASA's newest spacecraft, Orion, which will ascend atop the Space Launch System rocket.
About eight minutes after launch, the rocket's core stage engines will shut down and separate from the upper stage and the spacecraft and the crew will be in space, according to NASA
Orion will then deploy its four solar arrays for power and to charge its batteries.
Orion will spend 90-minutes in its initial orbit, before the second stage fires its engines twice to send Orion to a high Earth elliptical orbit.
Orion and the crew will spend about a day in high Earth orbit, testing its systems and manually flying the spacecraft in a proximity operations demonstration.
Days 2 - 4: Outbound transit
A journey to the moon takes around three days. The engine on Orion’s service module will perform a translunar injection burn, which is the last major engine firing to send Orion on its figure-eight flight path to the moon, according to NASA.
NASA said Orion will perform multiple maneuvers to place the crew on a lunar free-return trajectory. This means Earth's gravity will naturally pull Orion back home after flying around the moon.
The crew will remove their Orion Crew Survival System spacesuits and don plain clothes for the rest of the mission, aside from when they re-enter Earth's atmosphere and are recovered from the ocean.
Mission controllers at NASA's Johnson Space Center in Houston, Texas, will monitor Orion but, as the spacecraft travels to and around the moon, they will have to rely on the Deep Space Network -- an international array of giant radio antennas -- to communicate with the astronauts and to send imagery to Earth.
Day 5 - 6: Lunar fly-by
Over the course of the journey, the crew will continue to evaluate Orion's systems and practice emergency procedures in addition to other activities, according to NASA.
On day 5, Orion will enter the lunar sphere of influence, meaning the moon is the main gravitational pull. On day 6, the crew will come its closest to the moon while traveling the farthest from Earth, NASA says.
Orion will pass within approximately 4,100 miles beyond the far side of the moon.
"From this vantage point, they will be able to see the Earth and the Moon from Orion's windows, with the Moon close in the foreground and the Earth nearly a quarter-million miles in the background," NASA says.
Days 7 - 10: Return and re-entry
The crew will perform a slingshot maneuver, which is a spaceflight technique that uses gravity to change the spacecraft's direction and speed without needing to use fuel. This will adjust Orion's trajectory for Earth return.
The astronauts will continue to test systems while day 9, the last fully day in space, will see the crew studying procedures for re-entry and splashdown.
During the last few days, there will be multiple return trajectory correction burns to adjust Orion's path back to Earth.
When Orion hits Earth's atmosphere, it will be traveling at speeds of about 25,000 miles per hour, which could produce temperatures of up to 5,000 degrees Fahrenheit, testing the spacecraft's heat shield.
The Orion spacecraft will deploy a series of parachutes once through the heat of re-entry, which will allow it to slow down and splash down in the Pacific Ocean with the crew onboard, according to NASA.
The U.S. Navy will recover the capsule using divers, rigid-hull inflatable boats and helicopters to bring Orion onboard the flooded well deck of a ship and retrieve the crew.