Artemis II Is Entering Its Most Dangerous Phase: Four Astronauts, One Fireball, and No Margin for Error

The landing is the most difficult part.

After a record-setting trip around the Moon, Artemis II now faces the part of the mission where everything gets brutally simple: survive reentry.

On April 10, 2026, the Orion spacecraft will slam into Earth’s atmosphere at nearly 24,000 mph, enduring temperatures around 5,000°F (2760 degrees Celsius). The four astronauts on board will ride out a communications blackout, deploy 11 parachutes in sequence, and hit the Pacific under conditions that leave little room for failure.

The vacuum of space is a cakewalk. The real problems start in the atmosphere.

Energy and Heat

As you read this, the Orion spacecraft, aptly named Integrity, is hurtling toward Earth at a speed of over 23,000 mph. That doesn’t mean much when you’re in the vacuum of space. But for the four people inside (Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen), things will change dramatically when Orion enters the atmosphere. For the first time in over half a century, we aren’t just coming back from the neighborhood of the ISS; we are screaming home from the Moon.

That matters because Orion will be faster than shuttles coming from the ISS. A spacecraft returning from the International Space Station enters at roughly 17,500 mph. Orion will arrive at about 23,864 mph. The energy involved in a lunar return is about double that of a low Earth orbit return.

This energy has to go somewhere.

Most of it becomes heat. The rest becomes stress on the spacecraft and on the human bodies inside it. During peak reentry, Orion’s exterior will face temperatures hot enough to melt steel. Inside, the crew will endure intense deceleration as the capsule punches deeper into the atmosphere.

Orion’s reentry begins at the point engineers call the Entry Interface, 400,000 feet above Earth. From there, the capsule will start to break and turn energy into heat.

×

Get smarter every day...

Stay ahead with ZME Science and subscribe.

Daily Newsletter
The science you need to know, every weekday.

Weekly Newsletter
A week in science, all in one place. Sends every Sunday.
No spam, ever. Unsubscribe anytime. Review our Privacy Policy.

Thank you! One more thing...

Please check your inbox and confirm your subscription.

The Heat Shield

The danger that astronauts face is very concrete. Too steep a break and the spacecraft can overheat or break apart; too shallow, and it could skip off the atmosphere and be lost. The survivable corridor is narrow.

If there is one piece of hardware that has to perform for Artemis II, it is the heat shield.

At 16.5 feet across, Orion’s shield is the largest ablative heat shield ever built for a crewed spacecraft. Its job is to burn away in a controlled fashion so the spacecraft beneath it does not.

But Artemis I left NASA with an uncomfortable surprise.

During the unscrewed test flight in 2022, engineers found more than 100 places where pieces of it had broken loose, carving divots into the protective layer. The shield still worked and the capsule survived, but it didn’t behave the way models predicted.

The culprit, according to post-flight analysis, was gas pressure building up inside the material as it charred under peak heating. If those gases could not vent fast enough, they created internal stresses strong enough to fracture chunks of the shield.

RelatedPosts

Freakish heatwave is causing record temperatures in the Arctic and Antarctica
The average adult catches a flu only twice a decade
Wutip becomes earliest ever super-typhoon, with gusts over 180 mph
Abnormal chromosomes and mitochondrial DNA might explain why suicide seems to favor some people

How Orion Will Land

After peak heating comes the communications blackout. Then, if everything remains intact, the parachute sequence begins. And here again, success depends on timing, mechanics, and luck behaving themselves all at once.

At about 22,000 feet, Orion jettisons its forward bay cover and deploys two drogue parachutes to stabilize the capsule. At 9,500 feet, three pilot chutes pull out the mains. By 6,000 feet, Orion’s three 116-foot main parachutes should be fully open, slowing the capsule from about 130 mph to 17 mph for splashdown.

The system is designed to work even if one of the parachutes fails. But not two.

And even a nominal splashdown brings another risk. Because of its center of gravity, the capsule can land upside down in what engineers call Stable 2. If that happens, Orion must inflate five uprighting airbags to roll itself over before recovery teams can safely proceed.

All in all, NASA has taken many precautions and a great deal of protective engineering has been deployed. But there are always risks.

But the astronauts themselves don’t seem particularly concerned. In fact, they seem excited about it.

“I’ll be honest and say, I’ve actually been thinking about entry since April 3, 2023, when we got assigned to this mission,” Artemis II astronaut Victor Glover said of reentry during an event with media Wednesday. “One of the first press conferences, we were asked, what are we looking forward to? And I said, splashdown. And it’s kind of humorous, but it’s literal as well — that we have to get back. There’s so much data that you’ve seen already, but all the good stuff is coming back with us. There’s so many more pictures, so many more stories.”

Artemis II Re-entry Timeline

The expected timeline for the shuttle (in EST time) is as follows:

• 3:05 a.m.: Crew sleep begins
• 11:35 a.m.: Flight Day 10 crew wakeup
• 1:50 p.m.: Orion cabin configuration for re-entry begins
• 2:53 p.m.: Return trajectory correction burn
• 6:30 p.m.: NASA+ coverage begins
• 7:33 p.m.: Crew module and service module separation
• 7:37 p.m.: Crew module raise burn
• 7:53 p.m.: Entry interface
• 8:07 p.m.: Splashdown in the Pacific Ocean

Some two hours after that, there should be a press conference announcing what happened.

Godspeed, Orion!