【Saigon Sunset】

NASA will try to fly its megarocket to the moon again on Saigon SunsetSaturday, Sept. 3, after the team encountered an engine issue during a much-anticipated launch attempt earlier this week.

Mission managers regrouped Tuesday afternoon and decided they'd take another crack at Artemis I this weekend. For the second try, they'll start the fueling process earlier, hoping that will allow them more time to cool the engines to the right temperature before ignition.

The crew wasn't able to chill all four core stage engines to approximately -420 degrees Fahrenheit on Monday, with the third engine about 30 to 40 degrees warmer than the others, said John Honeycutt, manager of the Space Launch System rocket. Engineers fear if the engines don't reach the optimal cold temperature, they could break from the sudden stress of super-cold fuel.

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Technicians will also do some work at the launchpad to try to address a leak in a liquid hydrogen line. Then, managers will reconvene on Thursday to review whether the team — and the rocket — are indeed ready.

The two-hour launch window will begin at 2:17 p.m. ET on Saturday, Sept. 3. Thanks to Florida's fickle late summer weather, sporadic rain and thunderstorms could roll in again and stall takeoff. There's currently a 60 percent chance of weather restrictions during that time frame, said Mark Berger, NASA's weather officer.

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If storms cause the team to postpone the launch again, the next chance to go to the moon could be Monday, Sept. 5, said launch director Charlie Blackwell-Thompson, due to the time it takes to replenish the fuel. But if something more complicated arises, like an equipment malfunction, it could mean hauling the rocket back to its enormous hangar, the Vehicle Assembly Building, four miles from the pad.

Such a move would delay the mission for weeks.

Artemis I, named after Apollo's twin sister in Greek mythology, is NASA's first deep space flight of a capsule built for astronauts in a half-century. If all goes according to plan, the new Orion spacecraft atop the rocket will travel 1.3 million miles over six weeks.

No one will be inside the capsule, but a successful uncrewed flight will clear the way for passengers aboard Artemis II, slated for 2024.

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The goal of the program is to one day build a lunar-orbiting moon base, see the first woman and person of color walk on the moon, and spend long stretches in outer space to train for an eventual human voyage to Mars.

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Thousands of tourists flooded Cape Canaveral, Florida, over the weekend for a chance to catch a glimpse of a fireball in the sky. Many space enthusiasts hope the new lunar program can rekindle the magic of the 1960s space race.

With the countdown clock halted at 40 minutes until liftoff, NASA bailed on the launch Monday in the face of a leak, confounding engine difficulty, and looming storm clouds. Though mission managers had seemed confident ahead of countdown, many offered practical comments following its cancellation.

"I'll say what our deputy administrator told her family when they were coming for her launch," said Jim Free, associate administrator for exploration systems development, after the scrub. "Plan a week trip to Florida for vacation, and you might see a launch."

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"I'll say what our deputy administrator told her family when they were coming for her launch. Plan a week trip to Florida for vacation, and you might see a launch."

Leaks like the one experienced Monday are extremely common in rockets. During the fueling process, the team was able to compensate for the loss and completely fill the tanks.

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Liquid hydrogen has been NASA's fuel of choice for decades because it has the lowest molecular weight in existence. That's ideal for keeping the tanks as light as possible for blasting into space. It also burns with extreme ferocity.

But those teensy molecules are hard to corral, seeking out any hair-thin crevice to escape. The super-cold temperature of the fuel can cause the metal container to contract and shrink.

"It can actually cause a little bit of a gap," said Mike Sarafin, Artemis mission manager, at a news briefing Monday afternoon.

Charlie Blackwell-Thompson leads the Artemis I launch team. Credit: NASA / Isaac Watson

Honeycutt suspected the engine giving high temperature readings might actually be fine, but a sensor measuring it could be giving inaccurate data. The team knows of no other reason why the third engine would be performing differently from the others.

Regardless, the team has chosen to take another run at a launch without replacing or recalibrating the sensor.

"We could get access [to it at the launchpad], but it's not ideal," Honeycutt told Mashable during a news briefing Tuesday. If the launch team decides they need to change the instrument, however, Honeycutt said that would mean rolling the vehicle back to NASA's giant rocket shop, the Vehicle Assembly Building.

He'd rather the team determine the engines are cooling appropriately "using the data that we've got access to today."