How Artemis program Works

The Space Launch System (SLS) stands as the most powerful rocket NASA has ever built, generating 8.8 million pounds of thrust at liftoff—15% more than the Saturn V that carried Apollo astronauts. This massive rocket burns liquid hydrogen and liquid oxygen in its core stage, supplemented by two solid rocket boosters strapped to its sides. The SLS launches from Kennedy Space Center's Launch Complex 39B, the same facility modernized from the Apollo and Space Shuttle eras.

Once ignited, the SLS burns for approximately eight minutes during its initial ascent, with the solid boosters separating after two minutes and the core stage continuing alone. The rocket's upper stage, called the Interim Cryogenic Propulsion Stage (ICPS) in early missions and the more powerful Exploration Upper Stage (EUS) in later flights, then fires to push the Orion spacecraft out of Earth orbit. This stage performs the trans-lunar injection burn, accelerating Orion to approximately 25,000 miles per hour—the speed necessary to escape Earth's gravity and begin the journey to the Moon.

Unlike the Apollo missions that entered standard lunar orbit, Artemis utilizes a Distant Retrograde Orbit (DRO) that takes Orion thousands of miles beyond the Moon's far side. This orbit is "distant" because it extends up to 40,000 miles from the lunar surface, and "retrograde" because the spacecraft travels opposite to the Moon's rotation around Earth. The DRO provides exceptional stability with minimal fuel requirements, allowing Orion to remain in lunar space for weeks while consuming very little propellant for course corrections.

In this orbit, Orion serves as the crew's home base and command center while the Human Landing System (HLS) ferries astronauts to and from the surface. The spacecraft's life support systems recycle air and water, its solar arrays generate power, and its heat shield protects the crew from temperature extremes ranging from 500°F in sunlight to -280°F in shadow. Gateway, a small space station planned for later Artemis missions, will occupy a different orbit called a Near-Rectilinear Halo Orbit (NRHO), which brings it as close as 1,000 miles to the lunar surface at its nearest point while swinging out to 43,500 miles at its farthest, completing one orbit every seven days.

The Human Landing System for Artemis III is a modified version of SpaceX's Starship, standing over 160 feet tall and capable of carrying large crews and substantial cargo to the surface. Unlike the cramped Apollo Lunar Module that housed two astronauts in a space the size of a closet, Starship HLS offers a spacious interior with separate areas for living, working, and conducting science. The vehicle uses liquid methane and liquid oxygen engines—propellants chosen partly because they can eventually be manufactured on the Moon or Mars using local resources.

Descent begins when Starship HLS undocks from Orion in the Distant Retrograde Orbit and fires its engines to slow down and drop toward the Moon. The spacecraft must execute a complex series of burns to gradually lower its altitude, using a dozen engines that can be throttled to control the rate of descent precisely. During the final approach, the lander flips from horizontal to vertical orientation, and uses just three engines to hover and maneuver laterally, allowing the crew to avoid hazards and select a safe landing spot.

The landing site for Artemis III lies within the lunar South Pole region, where some craters remain in permanent shadow while nearby ridges enjoy nearly constant sunlight. Starship's tall design presents challenges—astronauts must descend via an elevator from a cabin door positioned high above the surface. After their surface mission concludes, the same vehicle launches directly back to orbit using its methane engines, requiring no separate ascent stage like Apollo used.

Artemis astronauts will wear next-generation spacesuits called the Exploration Extravehicular Mobility Unit (xEMU), designed by Axiom Space to provide far greater flexibility than Apollo's stiff suits. These suits feature bearings at the hips, knees, and ankles that allow astronauts to walk naturally rather than bunny-hop, and shoulder joints that permit full arm rotation for reaching, climbing, and operating tools overhead. The suits maintain pressure at 8 pounds per square inch and can support spacewalks lasting up to eight hours, with life support systems that scrub carbon dioxide, regulate temperature, and provide drinking water.

The lunar terrain vehicle, a pressurized rover planned for later Artemis missions, will transform exploration capabilities by allowing astronauts to travel dozens of miles from their lander without wearing spacesuits. Inside this cabin-sized vehicle, crews can eat, rest, conduct experiments, and plan their next moves in a shirt-sleeve environment. When they identify interesting geological features, they don their suits and exit through an airlock, then return to the rover's comfort between sampling sites.

Scientific priorities focus on understanding the Moon's water ice deposits, which could provide drinking water, breathable oxygen, and rocket propellant for future missions. Astronauts will drill into permanently shadowed craters, collect samples of volatile-rich regolith, and deploy instruments that measure moonquakes, heat flow, and the lunar magnetic field. Each Artemis surface mission will last at least a week, compared to Apollo's maximum of three days, enabling more thorough exploration and scientific research.

The Gateway space station will serve as Artemis's orbital outpost, assembled module by module beginning in 2025 and growing into a facility where astronauts can live for months at a time. Its initial configuration includes a habitation module providing living quarters, a logistics module for supplies, and a propulsion module that maintains the station's orbit and can move it to different positions around the Moon. Unlike the International Space Station, which requires constant reboost to avoid falling back to Earth, Gateway's Near-Rectilinear Halo Orbit requires minimal fuel to maintain, making long-term operations feasible.

On the lunar surface, Artemis plans to establish a base camp near the South Pole, consisting of a habitat module, a rover garage, and power systems using solar arrays positioned on sunlit ridges. The habitat will support crews for missions lasting up to two months, equipped with advanced life support that recycles nearly all water and oxygen, reducing the need for resupply from Earth. Radiation shielding incorporated into the habitat's walls and potentially supplemented by lunar regolith piled on top will protect astronauts from cosmic rays and solar particle events that pose health risks during extended stays.

Developing this sustained presence requires solving numerous engineering challenges, from building structures that withstand the Moon's temperature swings of 500°F between day and night, to creating reliable power systems that function during the two-week lunar night. In-situ resource utilization experiments will test equipment that extracts oxygen from lunar regolith and processes water ice into usable forms. These technologies developed for lunar sustainability will directly inform planning for Mars missions, where astronauts will face even greater isolation and must rely even more heavily on living off the land.