Artemis III boosters fully stacked inside Kennedy's Vehicle Assembly Building

The rocket that will carry the next crew of NASA astronauts off the Space Coast is taking shape at Kennedy Space Center. Engineers with NASA's Exploration Ground Systems program finished stacking the twin solid rocket boosters for Artemis III on Wednesday, Sept. 30, completing integration of the aerodynamic nose cones atop both boosters inside High Bay 3 of the Vehicle Assembly Building, according to NASA.

The milestone caps nearly three months of work on the boosters for the Space Launch System rocket, which is slated to launch four astronauts from Launch Pad 39B no earlier than June 2027. For Brevard County and the thousands of Floridians who work on and around Kennedy, it means the next crewed Artemis flight is moving steadily from hardware deliveries into final assembly.

A summer of stacking in High Bay 3

Booster stacking began July 13, when crews placed the first pair of aft segments on Mobile Launcher 1 inside the Vehicle Assembly Building. The right aft-center segment followed Aug. 12, and the center segments were lifted and stacked Aug. 20, right booster first and left booster second, according to NASA and NASASpaceflight.com reporting.

The final step was the forward assemblies. Each one includes an aerodynamic nose cone, a forward skirt that houses avionics, and a frustum that contains motors used to separate the boosters from the SLS core stage after launch, NASA said. The nose cones give the boosters the smooth, pointed shape that reduces drag and keeps the rocket stable as it climbs through the atmosphere.

The five-segment boosters, built by Northrop Grumman in Utah, provide more than 75% of the rocket's total thrust at liftoff, according to NASA. Combined with the four RS-25 engines on the core stage, the SLS produces more than 8.8 million pounds of thrust. The final shipment of Artemis III booster segments left Northrop Grumman's facility in Corinne, Utah, on June 2 aboard specialized rail cars bound for Kennedy, following an earlier shipment that arrived in April.

The core stage is being assembled in Florida for the first time

While the boosters went up in High Bay 3, the rocket's core stage was coming together next door. The Artemis III core stage arrived at Kennedy aboard NASA's Pegasus barge on April 27 and was offloaded April 28. It was moved into High Bay 2 of the Vehicle Assembly Building to be joined with its engine section and boat-tail, marking the first time core stage assembly operations have taken place at Kennedy, according to NASA.

Engine installation began Aug. 24. The four RS-25 engines assigned to Artemis III all flew previously on space shuttle missions, NASA said. One of them, engine E2048, helped power shuttle Atlantis on STS-129, the mission on which Artemis III commander Randy Bresnik first flew to space, and shuttle Discovery on STS-95 in 1998, which carried Sen. John Glenn. Each engine weighs about 7,700 pounds and produces nearly 500,000 pounds of thrust.

Orion is powered up

At Kennedy's Operations and Checkout Building, technicians have completed umbilical connections between the Artemis III Orion crew module and its European Service Module, which supplies power, propulsion and life support. The crew module was powered through those umbilicals for the first time, confirming the electrical connection between the two modules ahead of further integrated testing, according to NASA and NASASpaceflight.com.

A different kind of Artemis III

Artemis III is no longer the lunar landing mission NASA once planned. In June, NASA described it as a test flight in Earth orbit that will practice rendezvous and docking with test versions of the commercial lunar landers being developed by SpaceX and Blue Origin. NASA has said Artemis IV, planned for 2028, is the first mission now expected to put astronauts at the Moon's south pole.

NASA named the Artemis III crew on June 9. Bresnik, a former Marine colonel, will command. European Space Agency astronaut Luca Parmitano of Italy will serve as pilot, the first ESA astronaut assigned to an Artemis mission. NASA astronauts Andre Douglas and Frank Rubio will fly as mission specialists, and NASA astronaut Bob Hines is the backup. Rubio holds the American record for the longest single spaceflight, at 371 days.

The roughly two-week mission calls for the crew to spend about two days docked with a Blue Origin lander test article, then undock and link up with a SpaceX Starship pathfinder for about a day of checkouts before returning to Earth with a splashdown in the Pacific Ocean, according to NASA and published reports. NASA Administrator Jared Isaacman said in the crew announcement that "Artemis III will demonstrate the power of American innovation and international partnership."

The crew has been training at Johnson Space Center in Houston, including water survival and post-landing emergency exit courses, spacesuit work in the Neutral Buoyancy Lab, and integrated simulations with flight controllers, NASA said in August.

Building on Artemis II

The work follows Artemis II, which launched from Kennedy on April 1 and sent Reid Wiseman, Victor Glover, Christina Koch and Canadian astronaut Jeremy Hansen around the Moon on a nearly 10-day flight, the first crewed lunar flyby since the Apollo era. Their Orion capsule splashed down in the Pacific on April 10 off San Diego and returned to Kennedy's Multi-Processing Payload Facility on April 28 for de-servicing and analysis, including inspection of its heat shield.

A busy month on the Space Coast

The Artemis milestone comes during a crowded stretch at Florida's spaceport. A SpaceX Falcon 9 launched NASA's Crew-13 mission from Cape Canaveral Space Force Station on Thursday, Oct. 1, carrying NASA astronauts Jessica Watkins and Luke Delaney, Canadian Space Agency astronaut Joshua Kutryk and Roscosmos cosmonaut Sergey Teteryatnikov to the International Space Station for a roughly six-month stay.

Next up for NASA is CRS-35, a SpaceX cargo Dragon resupply mission targeted for no earlier than Tuesday, Oct. 13, at 6:33 a.m. from Space Launch Complex 40, according to launch schedules. The mission is set to deliver another pair of roll-out solar arrays to the station, with the Falcon 9 first stage expected to land back at the Cape.

SpaceX's first Starship launch from Florida could also be approaching. A date of no earlier than Oct. 30 for Starship Flight 16 from Launch Complex 39A appeared in a Federal Aviation Administration air traffic planning document, according to NASASpaceflight.com, which described the date as highly provisional. SpaceX has not formally announced it, and the date could shift. That flight matters for Artemis III as well, because the crewed mission depends on Starship being ready to meet Orion in orbit.

Kennedy remains one of Florida's largest economic engines. A NASA economic impact report credited spaceport activity with supporting more than 27,000 Florida jobs, with Brevard County capturing the largest share.

What's next

With the boosters complete, the next major step is lifting the finished core stage from High Bay 2 and mating it between the boosters on Mobile Launcher 1. The remaining upper elements and, eventually, the Orion spacecraft would follow before the fully stacked rocket rolls out to Pad 39B for final testing and launch. NASA continues to target no earlier than June 2027 for liftoff.