NASA begins loading rocket with propellant in crucial test ahead of historic moon mission launch

By Jackie Wattles, CNN

(CNN) — NASA has begun a crucial test Monday of its towering Space Launch System rocket — marking one of the final steps before the vehicle launches four astronauts into deep space for the first time since the Apollo program ended more than five decades ago. The mission could launch as soon as February 8.

The hands-on test, called a “wet dress rehearsal,” involves filling up the rocket’s tanks with more than 700,000 gallons of super-chilled propellants.

A few hours into the test, NASA ran into issues with hydrogen leaks — a problem that also plagued the SLS rocket during its first round of dress rehearsals in 2022 ahead of the uncrewed Artemis I test flight. Ultimately, that mission took off about six months after NASA first attempted a wet dress rehearsal.

Kept at minus 423 degrees Fahrenheit, the liquified hydrogen, which is the primary fuel that powers the SLS rocket, is notoriously fickle because of its tiny molecular structure that makes the substance difficult to contain.

All told, the rehearsal is expected to include a run-through of the countdown on launch day — except that during the test run the clock will be halted with less than a minute to go. On Monday, NASA is counting down to a pretend launch time of 9 p.m. ET.

But there is a wiggle room built in. NASA said in a statement that ground teams have a four-hour window that ends at 1 a.m. ET on Tuesday to complete the countdown.

How this test plays out will offer hints about when NASA will be able to launch the Artemis II mission — which could occur within several launch windows between early February and late April. At launch, NASA’s Christina Koch, Victor Glover and Reid Wiseman as well as the Canadian Space Agency’s Jeremy Hansen are expected to ride atop the SLS rocket before their Orion spacecraft separates and begins a journey to circumnavigate the moon.

NASA confirmed on January 23 that the crew members had entered quarantine in Houston in preparation for their spaceflight. Astronauts are routinely kept isolated ahead of liftoff to prevent illness.

The crew is expected to arrive at their Florida launch site at Kennedy Space Center after the wet dress rehearsal is complete.

Though the astronauts are not landing on the lunar surface for this mission, their trip is set to carry them deeper into the solar system than any humans have traveled, surpassing the record that Apollo 13 astronauts set in 1970.

Before liftoff, NASA is looking to put the SLS rocket through a clean wet dress rehearsal. Ahead of the rocket’s first flight — the uncrewed Artemis I test mission in 2022 — it took multiple wet dress rehearsals over months to ensure the systems were ready for launch.

“Why do we think that we’ll be successful in Artemis II? It’s the lessons that we learned,” Charlie Blackwell-Thompson, the Artemis launch director, noted during a January 16 news conference.

“We learned a lot during the Artemis I campaign getting to launch. And the things that we learned … have all been rolled in to the way in which we intend to load the Artemis II vehicle.”

NASA, however, has cautioned that, although it expects prelaunch preparations to run more smoothly for this mission, engineers still have the option of rolling the SLS rocket and Orion spacecraft back off the launchpad and into the nearby Vehicle Assembly Building for additional work if needed.

Cold weather over the weekend delayed the initial date for a wet dress rehearsal.

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