NASA's Artemis II mission marks a significant milestone, sending astronauts to the lunar environment for the first time since the Apollo 17 mission in 1972. This flight is a crucial step in the agency's broader lunar exploration goals. The four-person crew includes Commander Reid Wiseman, Pilot Victor Glover, and Mission Specialists Christina Koch and Jeremy Hansen.

Pre-Launch and Liftoff Sequence

The Countdown Begins

The official launch sequence commences approximately 49 hours prior to liftoff. During this period, mission controllers at Kennedy Space Center execute extensive safety and engineering checks.

Astronaut Seating and Ignition

Roughly three hours before launch, the crew straps into the Orion spacecraft, positioned atop the 322-foot-tall Space Launch System (SLS) rocket. The four main engines ignite seven seconds before liftoff, following the ignition of the two solid-fuel boosters.

Clearing the Tower and Ascent

It takes about 6.5 seconds for the massive rocket to clear the launch tower. The crew will experience up to 4 G's of force as they escape Earth's gravity, breaking the sound barrier after 56 seconds of flight.

Initial Earth Orbit Operations

Booster Separation and Weight Reduction

Just over one minute into flight, at an altitude of about 30 miles, the spent solid-fuel boosters are ejected. Nonessential components, including the launch abort system, are also jettisoned to reduce overall mass.

Main Engine Cutoff and Initial Orbit

Approximately six minutes after launch, the SLS main engines consume their fuel and detach, leaving the crew in the Orion spacecraft, nicknamed "Ingenuity," in a highly elliptical orbit. The apogee, or highest point, reaches 1,400 miles—more than five times farther than the International Space Station.

Crew Activation and Systems Check

For the next 40 minutes, the crew circles Earth unevenly. Koch and Hansen unstrap to set up basic equipment like the toilet and water dispenser, and the spacecraft's solar arrays are deployed for power. This phase may challenge Hansen, as about half of first-time astronauts experience space adaptation issues.

First Orbital Maneuver

Once strapped back in, the crew oversees the first orbital maneuver, a one-to-two-minute burn using the Interim Cryogenic Propulsion Stage (ICPS). This action raises the perigee (lowest elevation) to match the apogee, establishing a more stable Earth orbit.

Second Burn and High Earth Orbit

About an hour later, a second, longer automated burn lasting around 15 minutes significantly raises the orbit. The spacecraft enters a high Earth orbit with an apogee of 43,500 miles, requiring 23.5 hours to circle the planet.

Preparing for the Lunar Trajectory

Cubesat Deployment and Break

At this high altitude, Orion will deploy four small research satellites, known as cubesats, from Argentina, South Korea, Germany, and Saudi Arabia. The crew then pauses to prepare for the departure from Earth.

Proximity Operations Testing

The ICPS separates from the rocket, and Pilot Victor Glover takes manual control of the Orion capsule for the first time. During "prox ops," lasting just over an hour, Glover performs spaceflight tests using the spent ICPS as a maneuvering target. This is vital for testing human piloting of Orion for future missions, including lunar landings.

ICPS Disposal and Rest Period

Following prox ops, the ICPS performs a final burn, sending it back toward Earth. The astronauts then exercise, eat their first meal, and sleep for about four hours. They are woken for trajectory-correction burns before another rest period.

Trans-Lunar Injection and Lunar Flyby

The Moonshot Maneuver

Upon receiving the green light to proceed, the mission executes the translunar injection (TLI). This final major burn of the ICPS occurs around 25.5 hours into the mission at perigee, using Earth's gravity to propel the craft out of orbit. A second TLI attempt is available 23.5 hours later if needed.

Free-Return Trajectory

Once TLI is complete, the crew is locked onto a "free-return trajectory," sailing around the moon and back to Earth without further major maneuvers, a trajectory not used by astronauts since Apollo 13 in 1970. For the next four days, the crew will drift toward the moon, performing exercises like zero-gravity CPR and practicing rapid spacesuit donning.