NASA begins stacking rocket ahead of 2027 Artemis III astronaut launch (photos)

The assembly of NASA's next Artemis rocket is well underway, with the recent arrival of one of the launch vehicle's solid fuel booster sections to the agency's integration facility at Kennedy Space Center in Florida.

The bottom segment of the left-hand solid rocket booster (SRB) that will help launch Artemis III was transported to KSC's Vehicle Assembly Building (VAB) this week, according to a NASA social media post. It's one of two SRBs that will be affixed to either side of NASA's Space Launch System (SLS) rocket, which together provide a combined 7.2 million pounds of force — more than 75% of the rocket's power at liftoff.

"Soon, assembly of the rocket will begin as we prepare to send crew aboard Orion to test the rendezvous and docking capabilities needed for future lunar landings," the NASA post said.

It took about one year for NASA to stack the Artemis II SLS once each of the rocket's components were delivered to the VAB. The same timeline gives Artemis III a small amount of wiggle room, as it progresses toward a targeted launch in mid-to-late 2027 — and stacking of the entire rocket may not begin immediately.

The Artemis III SLS core stage arrived in the VAB in May. Unlike the core stage's arrival for Artemis II, Artemis III's was delivered without the engine section. Once that's attached, it may be some time before other components are stacked onto the main vehicle. NASA Administrator Jared Isaacman has said that the agency aims to complete a wet dress rehearsal on the rocket before the end of the year. In the meantime, other SLS components and SRB segments will continue arriving at the VAB.

Each SRB stands about 177 feet (54 meters) tall. They're packed with polybutadiene acrylonitrile (PBAN), ammonium perchlorate, and aluminum powder, which bring their combined weight to 3.2 million pounds (1.45 million kg). Unlike liquid-fueled rocket engines, once the SRBs' solid propellants ignite, they cannot be turned off. Without them, the four RS-25 engines on SLS's core stage would not be powerful enough to lift the rocket off the launch pad.

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Artemis III will be the second crewed mission of the Artemis program — NASA's next-generation push to return astronauts to the moon. And, while Artemis III itself won't actually fly to the moon, it will help progress the hardware and spacecraft technologies the space agency needs to ensure success on future missions to the lunar surface.

Like Artemis II, which flew four astronauts on a 10-day mission around the moon in April, the Artemis III astronauts will launch on SLS aboard the Orion spacecraft — but they won't fly beyond low Earth orbit this time. Instead, the four-person crew will spend about two weeks testing out rendezvous and docking procedures with prototypes for the two Artemis moon landers, both of which have been privately contracted by NASA.

The space agency has partnered with SpaceX and Blue Origin for those vehicles, each of which is expected to launch once the Artemis III crew are on orbit. They'll first meet up with Blue Origin's lander, Blue Moon. After docking, the astronauts will have the opportunity to enter Blue Moon's crew cabin, where they will also have the chance to test parts of the Artemis extravehicular activity (EVA) suit designed for astronauts to wear on the lunar surface.

A rendezvous with SpaceX's Starship will follow Orion's stint with Blue Moon. SpaceX has indicated it will fly a boilerplate Starship V3 (Version 3) vehicle equipped with a docking adapter, but it will not have a crew cabin. V3 is SpaceX's newest version of Starship, which has been upgraded for high launch efficiency and capacity, but it will lack a fully developed life support system in time for the Artemis III launch next year.

If all goes according to plan and NASA is able to maintain its current mission timeline, the first moon landing of the Artemis program will take place on Artemis IV, scheduled to launch in late 2028.