Why NASA unexpectedly halted a major moon rocket test

"It has been one of the more interesting 48 hours."
 By 
Elisha Sauers
 on 
NASA testing moon megarocket at launch pad

UPDATE: Apr. 6, 2022, 3:21 p.m. EDT NASA called off another attempt to fill the mega moon rocket's tanks on Tuesday, after encountering more problems. The team discovered a malfunctioning vent valve, which relieves pressure on the rocket's large core while the fuel loads. NASA hasn't yet announced a date for when the simulation test will resume.

First, thunderstorms delayed the dress rehearsal for NASA's megarocket over the weekend, the final crucial step before launching it to the moon.

Then, lightning "struck twice" for the simulation test — figuratively speaking.

Mission operators said they needed to stop mid-rehearsal on Sunday to sort out a problem in the mobile tower that supports the rocket, known as the Space Launch System, on the ground. A fan that keeps hazardous gases out of the launcher wasn’t working. When it failed, technicians tried to use a backup fan to proceed, only to discover that it wasn’t working either. Each one was having a different issue, officials said.

The fans are intended to prevent gases that could cause a fire from entering the launchpad during the fueling process, said Charlie Blackwell-Thompson, launch director at Kennedy Space Center in Cape Canaveral, Fla. This is called "positive pressurization."

Without the fan system, the NASA team didn’t believe it was safe to put the propellant into the rocket.

"We decided that we wanted to really understand that, given it was the first time loading the vehicle, and we made the decision to stand down to get in a configuration to go troubleshoot that and then be ready to make another run at it," she said during a briefing with reporters on Sunday.

By Monday, it appeared the space agency had resolved the fan issue and was prepared to continue the dress rehearsal.

NASA is readying the 32-story, 5.75 million-pound rocket for a mission to the moon, known as Artemis I. It's the first in a series of deep space exploration voyages that could blast off as early as May. The upcoming launch won't include astronauts, but the monthlong flight will allow the United States to send a crew on the next, more complex mission, Artemis II.

The rocket is thought to be the most expensive ever built with each launch estimated to cost over $4 billion.

It's been a long time since NASA had a rocket of this magnitude, capable of sending large payloads — astronauts and cargo — into deep space. Not only is the Space Launch System, or SLS, built to travel to the moon, it's expected to one day put millions of miles on the odometer during the first crewed flight to Mars. Robotic scientific journeys to Saturn and Jupiter also could be in its future.

At its Florida launchpad, the fully assembled rocket, capped with the Orion spacecraft, is undergoing a two-day demonstration that involves filling the rocket with liquid fuel, practicing a countdown that stops right before ignition, and draining the tanks.

NASA testing SLS at the launch pad
Credit: NASA/Ben Smegelsky

The four main engines, fueled with 700,000 gallons of super-cold fuel, will produce a thrust powerful enough to keep eight Boeing 747s aloft. Filling the humongous tanks will take about eight hours.

Only after successfully completing this so-called "wet dress rehearsal" will NASA set a date for the first lunar mission, agency leaders have said. Officials have said Artemis could lift off as early as May, though it’s more likely it will happen this summer, given the tight schedule.

As of Sunday evening, NASA didn’t believe the storms and lightning in the vicinity of the launch pad had anything to do with the fans malfunctioning. Mission representatives said the system ran normally during the foul weather.

When NASA said it was "go" for tanking fuel, it wasn’t immediately clear to the public how the agency addressed the fan problem overnight.

Mike Sarafin, Artemis mission manager, told reporters on Sunday the events surrounding the rocket rehearsal, including four lightning strikes inside the launch pad perimeter the day before, have been unusual.

"It has been one of the more interesting 48 hours that I've had in the context of working missions leading up to a launch, and, in this case, leading up to a key test," he said.

Topics Innovations NASA

Mashable Image
Elisha Sauers

Elisha Sauers writes about space for Mashable, taking deep dives into NASA's moon and Mars missions, chatting up astronauts and history-making discoverers, and jetting above the clouds. Through 17 years of reporting, she's covered a variety of topics, including health, business, and government, with a penchant for public records requests. She previously worked for The Virginian-Pilot in Norfolk, Virginia, and The Capital in Annapolis, Maryland. Her work has earned numerous state awards, including the Virginia Press Association's top honor, Best in Show, and national recognition for narrative storytelling. For each year she has covered space, Sauers has won National Headliner Awards, including first place for her Sex in Space series. Send space tips and story ideas to [email protected] or text 443-684-2489. Follow her on X at @elishasauers.

Mashable Potato

Recommended For You
Artemis 2: Next steps for NASA's moon rocket after historic roll to pad
Artemis 2 SLS rocket rollout to Launch Pad 39B on Jan. 17, 2026


Artemis 2 wet dress rehearsal livestream: Watch the rocket test live
NASA preparing the SLS for Artemis 2

NASA is all but certain it won't fly to the moon in March for good reason
Rolling the Space Launch System rocket to the launch pad

Moon phase today: What the moon will look like on January 4
An image of a full moon.

More in Science
The Earth is glowing in new Artemis II pictures of home
One half of the Earth is seen floating in space through the open door of the Orion spacecraft.

Doomsday Clock now closest to midnight ever
A photograph of the Doomsday Clock, stating "It is 85 seconds to midnight."

Hurricane Erin: See spaghetti models and track the storm’s path online
A map showing the predicted path of Tropical Storm Erin.

Tropical Storm Erin: Spaghetti models track the storm’s path
A prediction cone for Tropical Storm Erin.

NASA to build a nuclear reactor on the moon by 2030, report states
The lunar surface.

Trending on Mashable
NYT Connections hints today: Clues, answers for April 3, 2026
Connections game on a smartphone

Wordle today: Answer, hints for April 3, 2026
Wordle game on a smartphone


NYT Connections hints today: Clues, answers for April 2, 2026
Connections game on a smartphone

What's new to streaming this week? (April 3, 2026)
A composite of images from film and TV streaming this week.
The biggest stories of the day delivered to your inbox.
These newsletters may contain advertising, deals, or affiliate links. By clicking Subscribe, you confirm you are 16+ and agree to our Terms of Use and Privacy Policy.
Thanks for signing up. See you at your inbox!