NASA moves critical fueling test for Artemis 2 moon rocket up to Jan. 31

NASA is progressing a little faster than originally predicted toward a critical fueling test of its Artemis 2 moon rocket.

The agency had targeted no later than Feb. 2 to complete the "wet dress rehearsal" for the Artemis 2 Space Launch System (SLS) rocket, which — if it passes that crucial test with flying colors — could launch astronauts on a mission around the moon as early as Feb. 6.

NASA now says it hopes to wrap the critical fueling and countdown simulation as early as this Saturday (Jan. 31). "Engineers have remained on track or ahead of schedule as they work through planned activities at the launch pad and are getting ready to conduct a wet dress rehearsal, leading up to a simulated 'launch,'" the agency wrote in an update on Monday (Jan. 26).

Artemis 2's SLS and Orion capsule were rolled from the Kennedy Space Center's Vehicle Assembly Building (VAB) to their pad at Launch Complex-39B (LC-39B) on Jan. 17. Since their arrival, teams have secured the vehicle's mobile launch platform for integration with LC-39B ground infrastructure and readied the rocket for its final phase of testing before launch.

The upcoming wet dress rehearsal will officially kick off about two full days ahead of its simulated T-0 liftoff time, as launch teams begin tending their stations. The most critical portion of the test will take place on Saturday, when cryogenic fuel loading of the rocket's two main stages will commence. In total, SLS will take on more than 700,000 gallons (2,650,000 liters) of cryogenic propellant and weigh approximately 5.75 million pounds (about 2.6 million kilograms) once fully fueled.

The goal will be to run the SLS mission clock down to T-33 seconds, the point at which the rocket's computer would take over system monitoring during an actual launch attempt. If all goes according to plan, after SLS' T-33 second countdown hold, mission operators will reset the simulated clock to T-10 minutes and run it down a second time, to T-30 seconds.

NASA plans to put SLS and ground teams through their paces during the test, with several "runs" during the T-10 minute terminal count period to assess operating procedures for holding, resuming and recycling the mission clock, according to the agency's update.

If everything during the SLS wet dress rehearsal goes entirely as designed, NASA could launch the Artemis 2 mission as early as Feb. 6. But there are a lot of potential hiccups that could cause a delay in that timeline.

The wet dress rehearsals for the uncrewed Artemis 1 mission (there were four of them) were plagued with fueling leaks and issues that forced SLS to be rolled back to the Vehicle Assembly Building (VAB) three times for repairs. NASA officials have voiced confidence that they have addressed those issues, but even a perfect wet dress rehearsal may not result in a Feb. 6 launch.

Weather, for one, is a major consideration, as frigid temperatures have overtaken a huge portion of the U.S., Florida's Space Coast included. While not plunged into the teens like other states, temperatures at the Kennedy Space Center are predicted to dip below freezing this weekend — an atypical occurrence for the region, and cold enough for NASA to take preliminary steps to safeguard the rocket from the inclement weather.

"Technicians are taking steps to ensure environmental control systems keeping Orion and SLS elements at the proper conditions are prepared for the cold," NASA wrote in the update.

Artemis 1's SLS famously withstood a hurricane just days before its successful launch in November 2022, but freezing temperatures are something NASA keeps a particularly close eye on. In January 1986, cold temperatures compromised rubber O-ring seals on the solid rocket boosters of the space shuttle Challenger, which led to a tragic accident that claimed the lives of seven astronauts during the launch of the STS-51L mission.

As it approaches its first crewed launch to the moon in more than half a century, NASA is keeping crew safety as a main focus. In preparations to support astronauts aboard SLS and the rocket's launch platform, engineers recently found a problem with, and replaced the brakes on, the crew escape baskets that zipline astronauts away from the tower in emergency evacuation situations, NASA's update said.

As their mission approaches, the Artemis 2 astronauts recently entered a pre-mission quarantine to ensure their health and readiness ahead of launch. Flying as Orion's first-ever passengers, the Artemis 2 crew includes NASA astronauts Reid Wiseman (the mission's commander), pilot Victor Glover, mission specialist Christina Koch and Canadian Space Agency astronaut Jeremy Hansen, also a mission specialist.

SLS will launch the quartet aboard Orion on a mission that will last about 10 days. Their first stop will be Earth orbit, where they will verify their spacecraft's systems and ready Orion for a course to the moon known as a "free-return" trajectory.

Instead of setting Orion up for an insertion into lunar orbit, the free-return trajectory will loop the spacecraft once around the moon on a figure-eight flight path back to Earth, ensuring the crew's return regardless of Orion's propulsion status, should unexpected issues crop up during flight.

While Artemis 2 won't land on the moon, the mission comes with its own historical significance beyond just returning people to lunar space. Depending on their particular launch time and specific trajectory, Orion's course around the far side of the moon has the potential to fly the Artemis 2 astronauts farther from Earth than any human has ever been.

Should Artemis 2 go smoothly, NASA plans to land astronauts on the lunar surface on Artemis 3. That mission is expected to launch sometime in 2028. By then, NASA hopes to expand its Artemis program infrastructure to include the first elements of the Gateway space station planned for lunar orbit, as well as the critical completion of the program's first Human Landing Services vehicle — a contract awarded to SpaceX and its Starship spacecraft. However, the agency recently signalled an interest in other bidders like Blue Origin, hoping that competition might lead to another crewed lunar lander being available sooner.

The upcoming Artemis 2 wet dress rehearsal is expected to begin as early as Thursday evening (Jan. 29) and operate toward a simulated launch at 9:00 p.m. EST on Saturday (0200 GMT on Feb. 1). NASA plans to broadcast the test on its streaming platform, with Space.com coverage of fueling procedures beginning Saturday.