Level 1 - Absolute Beginner

NASA is the United States space agency. It is preparing for a big mission called Artemis III. This mission will send astronauts on a powerful rocket called the Space Launch System.

The biggest part of the rocket is called the core stage. It is very tall, about 212 feet. It arrived at the Kennedy Space Center in Florida in April 2026.

The core stage is being put together with other parts of the rocket in a very large building called the Vehicle Assembly Building. Workers are preparing it for a launch in 2027.

After Artemis III, NASA plans to send astronauts to land on the Moon in a future mission called Artemis IV. Humans have not walked on the Moon since 1972. It is a very exciting time for space exploration.

NASA

the National Aeronautics and Space Administration; the US government agency responsible for space exploration

astronaut

a person trained to travel and work in space

core stage

the main central section of a rocket, which holds the fuel tanks and engines

Vehicle Assembly Building (VAB)

a very large building at NASA's Kennedy Space Center where rockets are built and prepared for launch

propellant

a substance burned inside a rocket engine to produce the force needed to lift the rocket

launch

the moment when a rocket or spacecraft leaves the ground and travels into space

orbit

the curved path a spacecraft follows as it travels around the Earth or another planet

mission

a planned trip or task, especially a scientific or space exploration journey

Level 2 - Elementary

NASA's Space Launch System, or SLS, is the most powerful rocket ever built for deep space travel. It carries astronauts in the Orion spacecraft on the Artemis programme, which aims to return humans to the Moon for the first time since 1972. The Artemis II mission successfully flew four astronauts around the Moon on April 1, 2026, in a historic 10-day journey.

NASA is now preparing the SLS for Artemis III. The most important part of the rocket, the 212-foot tall core stage, arrived at Kennedy Space Center in Florida on April 27, 2026. It made the 900-mile journey from NASA's Michoud Assembly Facility in New Orleans aboard a special ship called the Pegasus barge.

The core stage is the backbone of the rocket. It contains two enormous tanks that together hold more than 733,000 gallons of super-cold liquid propellant, liquid hydrogen and liquid oxygen, to fuel four RS-25 rocket engines. These engines are of the same type that powered NASA's Space Shuttle for decades.

Workers are now assembling the core stage in the Vehicle Assembly Building. The four RS-25 engines will be delivered separately and attached by July 2026. Artemis III is planned to launch in 2027. Although it will not land on the Moon, Artemis III will test key systems needed for Artemis IV, which is expected to put humans on the lunar surface in 2028.

Space Launch System (SLS)

NASA's powerful rocket designed to carry the Orion spacecraft and astronauts on deep space missions, including to the Moon

Orion spacecraft

the capsule that carries the astronauts on Artemis missions; it sits on top of the SLS rocket

liquid propellant

a liquid chemical mixture, such as liquid hydrogen and liquid oxygen, burned inside a rocket engine to produce thrust

RS-25 engine

a type of liquid-fuel rocket engine first developed for the Space Shuttle and reused on the SLS

Pegasus barge

NASA's specially designed flat-topped ship used to transport large rocket components by sea

lunar

relating to the Moon; for example, a lunar mission is one that travels to or studies the Moon

assembly

the process of putting together the different parts of a machine or structure

milestone

an important event in the history or development of a project or programme

Level 3 - Intermediate

Less than a month after the historic Artemis II crewed lunar flyby on April 1, 2026, which returned humans to the vicinity of the Moon for the first time in more than five decades, NASA received the next major milestone in its moon exploration programme. The 212-foot tall SLS core stage destined for Artemis III arrived at Kennedy Space Center on April 27, having left NASA's Michoud Assembly Facility in New Orleans on April 20 and completed the 900-mile sea journey aboard the agency's Pegasus barge.

At 212 feet tall, the core stage is the structural heart of the SLS Block 1 rocket. Its two main propellant tanks hold more than 733,000 gallons of super-chilled liquid hydrogen and liquid oxygen combined. Four RS-25 engines, derived from the Space Shuttle Main Engine programme, are expected to be integrated into the core stage's engine section by July 2026. When the two five-segment solid rocket boosters are included, the SLS Block 1 delivers roughly 8.8 million pounds of total launch thrust.

Artemis III's mission profile differs importantly from its predecessor. Artemis II, crewed by Reid Wiseman, Victor Glover, Christina Koch, and Canadian Jeremy Hansen, completed a free-return lunar flyby without landing. Artemis III, by contrast, is designed to test orbital rendezvous and docking between the Orion crew vehicle and SpaceX's Human Landing System, a modified Starship variant, in Earth orbit rather than lunar orbit, following NASA Administrator Jared Isaacman's February 2026 mission redesign.

The redesign reflects NASA's assessment that testing the Orion-Starship interface in Earth orbit is a safer path than attempting the link-up at the Moon before all systems are verified. Artemis IV, currently targeted for 2028, will carry the first crew to the lunar surface since Gene Cernan and Harrison Schmitt departed the Taurus-Littrow valley in December 1972. The core stage's arrival at Kennedy marks the opening of a roughly 18-month assembly and test campaign culminating in the most ambitious crewed space mission in a generation.

lunar flyby

a space mission in which a spacecraft passes close to the Moon without entering orbit or landing on the surface

rendezvous

a planned meeting in space between two spacecraft, which must match their speed and position to come together

docking

the process of physically connecting two spacecraft together while in space

solid rocket booster

a type of rocket that generates thrust by burning solid propellant, used alongside liquid-fuel engines to provide extra lift at launch

free-return trajectory

a flight path to the Moon and back that uses the Moon's gravity to return the spacecraft to Earth without needing an engine burn

integration

in rocketry, the process of physically combining major hardware components such as engines, tanks, and stages into a complete launch vehicle

Level 4 - Advanced

The arrival of the 212-foot Artemis III Space Launch System core stage at NASA's Kennedy Space Center Vehicle Assembly Building on April 27, 2026, barely four weeks after Artemis II returned the first crewed vehicle to cislunar space in 54 years, marks a pivotal inflection in the cadence of deep-space architecture. The core stage, fabricated at the Michoud Assembly Facility in New Orleans under a Boeing prime contract that has accumulated notable schedule and cost challenges across the SLS programme's history, crossed the 900-mile Gulf Coast route on the Pegasus barge and is now being oriented vertically in High Bay 2 of the VAB for integration with its engine section and solid rocket booster attach hardware.

The SLS Block 1 core stage represents the apex of heritage liquid-propulsion engineering. Its twin LH2 and LOX propellant tanks house 537,000 gallons of liquid hydrogen at minus 423 degrees Fahrenheit and 196,000 gallons of liquid oxygen at minus 297 degrees Fahrenheit, feeding four RS-25E engines, each capable of approximately 418,000 pounds of sea-level thrust, employing the staged combustion cycle that makes the SSME lineage among the most thermodynamically efficient large rocket engines ever flight-certified. When the two five-segment solid rocket boosters are included, SLS Block 1 delivers approximately 8.8 million pounds of liftoff thrust, roughly 15 percent more than the Saturn V, though its payload capacity to trans-lunar injection is 27 metric tonnes rather than Saturn V's 45 metric tonnes.

The mission profile for Artemis III, as revised by NASA Administrator Jared Isaacman in February 2026, departs substantially from the original Constellation-era plan. Rather than executing a near-rectilinear halo orbit insertion at the Moon and an in-space rendezvous between Orion and SpaceX's Human Landing System at the lunar orbit insertion point, Artemis III will conduct the critical Orion-HLS proximity operations and docking demonstration in low Earth orbit. The rationale combines risk management with schedule logic: the LEO environment is considerably more operationally forgiving in the event of an abort scenario, and testing the interface in LEO before a crewed lunar orbit insertion reduces single-point failure modes that would imperil a lunar-surface mission.

Artemis IV, which would constitute the first human lunar landing since Gene Cernan and Harrison Schmitt closed the Apollo 17 EVA on December 14, 1972, remains on the agency's planning manifest for 2028, though experienced programme watchers note that the SLS cost-plus contracting structure and the nascent status of the Artemis Base Camp infrastructure at the lunar south pole introduce schedule risk. The core stage assembly campaign at KSC is expected to run approximately 18 months, with stack rollout and pad flow targeting late 2026 for a launch window opening in early-to-mid 2027.

cislunar space

the region of space between Earth and the Moon, including the Moon's orbit; distinct from deep space beyond the lunar sphere of influence