NASA prepares to fuel massive Artemis-1 rocket and complete full countdown rehearsal

Wet Dress Rehearsal tests involves loading 700,000 gallons of super-cold fuel into SLS

KENNEDY SPACE CENTER, Fla. – Launch control teams will be called to their stations Friday and begin the final test of NASA's Artemis-1 rocket before the massive vehicle can launch on a moon orbit this summer.

NASA's Space Launch System rocket and the Orion spacecraft were rolled from the KSC Vehicle Assembly Building to launchpad 39B last week. It took nearly 11 hours for the one mph roll to the pad. 

The rocket and capsule are vital pieces to NASA's Artemis program to return humans to the moon by 2025. NASA is targeting this summer to launch the SLS and Orion for the first time on an uncrewed test flight known as Artemis-1. SLS will launch Orion from Kennedy Space Center during the test mission, sending the spacecraft to orbit the moon before returning to Earth.

Now, teams are preparing the rocket for a final test known as the wet dress rehearsal (WDR), which involves loading the rocket with fuel and practicing the complete countdown to work out any issues before the bird leaves the pad. 


While the bulk of the test is happening on April 3, Launch Director Charlie Blackwell-Thompson said it really takes about two days because 700,000 gallons of super cold, or cryogenic, fuel needs to be loaded into the rocket.

"It emulates our launch countdown and really begins on the first day with power-up of the elements and the beginning of some configuration of those and preparing for cryo-load somewhere around L-minus 38 hours or so," Blackwell-Thompson said.

The SLS core and upper stage will be filled with liquid hydrogen at negative 450 degrees Fahrenheit and liquid oxygen at negative 273 degrees.

NASA's deputy associate administrator for common exploration systems development, Tom Whitmeyer, said tanking a 322-foot rocket is an interesting process. The last time NASA fueled something close to the scale of SLS was during the space shuttle program a decade ago.

"It's like watching a ballet, you know, you've got pressure, volume and temperature, and you're really kind of working all those parameters to have a successful tanking operation," Whitmeyer said.

After fueling is complete, the launch team will work through the countdown to a T-minus 10 minute hold, conduct final polling, and then pick up the countdown again.


The wet dress rehearsal will also allow teams to practice for launch holds. Several planned holds in the test will stop the countdown then recycle to T-minus 10 minutes.

The test will end at T-minus 10 seconds, and the rocket will stay firmly on Earth. Afterward, all the super-cold fuel will be de-tanked from the rocket.

The forecast also comes into play for the WDR. Blackwell-Thompson said lightning chances must be less than 20 percent within five miles of the launchpad to begin the test. Wind constraints are 37. 5 knots, and the temperature must be above 41 degrees.

"I think we're going to be OK on the temperature. And I think we're going to be OK on the winds, just looking at the forecast," she said. "We'll keep our eye on any thunderstorms that might be in the area."

If the test goes well, NASA managers said they expect to be able to set the Artemis-1 launch date.