Artemis I: NASA scrubs SLS launch again, citing fuel leaks

Artemis I has taken another hit. The mission was scheduled to lift off from Launch Pad 39B at 2:17 p.m. Eastern on Saturday, September 3, but yet again, the liquid hydrogen fuel lines feeding into the SLS core stage sprang a leak.

The rocket had been undergoing launch preparations, and the agency began cryogenic operations as of Saturday morning — this is the delicate and crucial process of fueling the Space Launch System rocket with propellants that must be kept at supercold temperatures.

But the rocket was once again derailed by now-familiar issues with a leak in the propellant leads feeding into the core stage of the SLS. At about 11:20 a.m. Eastern, the Artemis I team called it quits after a third attempt to fix the leak problems failed. As of the time of writing, there is no update on what the Artemis I team can do to plug the leaks or when Artemis I might launch on its journey to the Moon.

Editor’s note: This is a developing story and will be updated as new information becomes available.

Artemis I: Launch 2.0 fails

Artemis I was scheduled to launch at 2:17 p.m. Eastern on Saturday, September 3. But at about 10:55 a.m. Eastern, the Artemis I ground team recommended scrubbing the second attempt to launch. A few minutes later, at about 11:17 a.m. Eastern, the launch director Charlie Blackwell-Thompson decided to follow their recommendation and put the launch on ice once more.

“The launch director waived off today’s Artemis I launch attempt at approximately 11:17 a.m. EDT. Teams encountered a liquid hydrogen leak while loading the propellant into the core stage of the Space Launch System rocket,” writes Rachel Kraft on the NASA Artemis blog.

“Multiple troubleshooting efforts to address the area of the leak by reseating a seal in the quick disconnect where liquid hydrogen is fed into the rocket did not fix the issue. Engineers are continuing to gather additional data.”

The first sign of trouble came at 7:24 a.m. Eastern.

“Engineers detected a liquid hydrogen leak in a quick disconnect cavity and have stopped flowing the propellant to the core stage while they troubleshoot. Launch controllers are attempting to warm up the quick disconnect to attempt to reseat it to get a tight seal. Liquid oxygen flow is continuing,” Kraft updated minutes later at 7:24 a.m. Eastern.

This is a similar sounding issue to the problem detected during Artemis I’s wet dress rehearsals earlier this year.

There is no confirmed date for a third launch attempt at the time of writing.

What happened to Artemis I?

Artemis I was scheduled to lift off from Launch Pad 39B at 8:33 AM Eastern Time on Monday, August 29, on its way to the Moon. Unfortunately, NASA had to scrub the launch as a problem arose with cooling down one of the four core-stage engines.

But NASA believes this error may have been due to a sensor rather than the engine itself. If the same sensor gives a similar reading today, then engineers may ignore it, according to a BBC report.

A second attempt was slated for 2:17 p.m. Eastern on Saturday, September 3. But beset with liquid hydrogen propellant leaks, NASA delayed the big day again.

Delays in launches such as this one are not uncommon. In fact, NASA had scheduled Artemis I to launch earlier in 2022, but a fuel leak caused problems during crucial pre-launch tests.

How to watch the Artemis I launch

When NASA attempts to launch again, date TBD, you can watch the Artemis I Launch on NASA’s live-streaming channel, NASA Live.

Starting one minute after liftoff, you can follow the Orion capsule on its journey to the Moon and back on NASA’s Artemis Real-time Orbit Website, or AROW (a clever pun on the Greek goddess Artemis’ skill at archery). The site visualizes data from sensors on the Orion spacecraft, providing information about its position, speed, alignment, and other flight details. Head over to the NASA Orion Twitter account for a link.

NASA will also be sharing photos and videos from space. A few hours after launch, Orion will point its cameras back toward the rapidly receding Earth for a few photos. And throughout the mission, hardcore space fans can tune into a live stream of one of NASA’s test mannequins, nicknamed Commander Moonikin Campos, who is testing a new spacesuit for NASA: the Orion Crew Survival System flight suit. (If you want a sneak preview, Moonikin and the other Artemis I mannequins star in their own comic miniseries.)

What will Artemis I do?

Artemis I is an uncrewed (except for the mannequins) test of the Space Launch System rocket and the Orion crew capsule. Its primary goal is to make sure the rocket, the capsule, and the mission plan are all safe enough for astronauts to fly.

While Artemis I orbits the Moon, engineers back on Earth will monitor its performance, and they’ll collect more data from sensors and recorders in the capsule once it returns to Earth. Orion's seats, each occupied by a specially-designed mannequin, are rigged with sensors to measure acceleration and vibration during launch and re-entry. Each mannequin carries sensors to measure radiation exposure, and two of them are testing special vests to help protect against too much radiation.

Combined, that data will help engineers confirm that the capsule is safe enough to send astronauts to the Moon in. It will also help design more realistic, more useful training simulations for the crews of Artemis II and Artemis III.

How will Artemis I get to the Moon?

A few minutes after launch, a rocket stage called the Interim Cryogenic Propulsion Stage will fire, accelerating the spacecraft to roughly 40,000 kilometers per hour — fast enough to break free of Earth’s gravity and set off for the Moon. Mission planners call this crucial moment the trans-lunar injection burn.

Five days after launch, Orion will swoop past the Moon on its closest approach, just 96 kilometers above the rocky lunar surface. A quick firing of Orion’s boosters will slow the spacecraft down enough for the Moon’s gravity to catch the spacecraft and pull it into what’s called a distant retrograde orbit; called retrograde because Orion will orbit the Moon “backwards,” opposite the direction that the Moon rotates, and distant because at its farthest, this highly eccentric orbit will carry Orion more than 64,000 kilometers past the Moon before it swings back.

At that point, Orion will be further from Earth than any Moon mission has ever been — a whopping 450,616 kilometers away, on the far side of the Moon — beating Apollo 13’s 52-year-old distance record of 400,171 km.

NASA’s CAPSTONE CubeSat, which launched in late June, already did a trial run of this orbit to make sure it would work well for Artemis I.

Eventually, Orion will make another close flyby of the Moon, using the rocky satellite’s gravity to accelerate enough to escape lunar orbit and set a course for home.

When will Artemis I return to Earth?

After 42 days, 3 hours, and 20 minutes in space (not that anyone’s counting), the Orion capsule will plunge into the Pacific Ocean just off the coast of San Diego, California, where a recovery ship and several helicopters will be waiting to greet it.

The recovery vessel knows where to be because Orion will make a much more precise landing than the Apollo capsules were able to do. That's not only thanks to more advanced navigation equipment, but to a new re-entry technique called skip entry, which gives the incoming spacecraft a longer flight range on its way down, so it has enough time and reach to direct itself to a chosen landing spot.

It looks like a rock skipping across the surface of a pond, only it's happening at roughly 38,000 kilometers per hour. Orion will dip into the upper edge of Earth's atmosphere just long enough for the atmosphere's friction to slow it down a little, and then it will skip back out into space again before making the final descent. That first dip into the atmosphere helps spread out the heat and G-forces of re-entry, which will help make the process safer and smoother for future missions' crews.

NASA will livestream the splashdown, courtesy of cameras on the recovery ship and helicopters, on its NASA Live channel.

When will Artemis II launch, and when will we land on the Moon again?

Artemis II is scheduled to launch in 2024. With a crew of astronauts aboard, the Artemis II mission will orbit the Moon before returning to Earth. And in late 2025, Artemis III will carry astronauts to a landing site near the Moon’s south pole, where two crew members will become the first humans to set foot on another world since 1972.