A crescent Earth looms above the lunar horizon in an image captured by NASA’s Orion spacecraft (seen in the left foreground). The reddish dot and the rays of light are camera artifacts. (NASA / ESA Photo)

NASA’s Orion capsule fired its main engine for three and a half minutes today during a close approach to the moon, executing a maneuver that’s meant to put the spacecraft on course for a splashdown in six days.

Orion came within 80 miles to the lunar surface during what’s expected to be the final large maneuver of its 25.5-day Artemis 1 mission. Today’s maneuver had to succeed in order to bring the uncrewed spacecraft back to Earth intact. The only other firings on the schedule are aimed at making tweaks in the trajectory.

Artemis 1, which began with the first-ever liftoff of NASA’s giant Space Launch rocket on the night of Nov. 15, is a test flight designed to blaze a trail for future crewed missions to the moon. The SLS sent Orion on a looping course that took advantage of the moon’s gravitational pull and ranged as far as 40,000 miles beyond the moon.

Although there are no astronauts aboard Orion this time, the seats are filled by three mannequins that have been hooked up with sensors to monitor radiation exposure, temperature levels and other factors that might affect future fliers.

There’s also an experimental, Alexa-style AI assistant code-named Callisto, which was built for NASA by Lockheed Martin in collaboration with Amazon and Cisco. Ground controllers and VIPs, including “Hidden Figures” actress Taraji P. Henson, have been using Callisto to check in with the capsule during the mission.

Debbie Korth, NASA’s Orion deputy program manager, said Callisto’s users found the system to be “very interactive, very engaging in terms of being able to talk to the spacecraft, turn lights on and off, write notes, play music, ask questions.”

“It’s a really very good engagement opportunity, and I think it has some potential for how we would use that further — a digital assistant or some other onboard activity,” she told GeekWire during a news briefing.

Korth said there aren’t yet any specific plans for using the technology on future Artemis missions. “We’re waiting to get back the data from this flight to see how it worked and what we can learn from how it performed,” she said.

Over the weekend, NASA reported a glitch involving a power conditioning distribution unit on the spacecraft. Four of the switches responsible for distributing power to the propulsion and heater subsystems were turned off, but NASA said the components were successfully repowered with “no adverse effects” to Orion’s navigation or communication systems.

“Teams are examining whether a potential contributor to this issue is related to a power configuration test implemented by the flight teams to investigate previous instances in which one of eight units opened without a command,” NASA said in a status update.

Orion is due to face what’s arguably its most crucial test on Dec. 11, when it hits Earth’s atmosphere at a speed of nearly 25,000 mph and faces temperatures rising as high as 5,000 degrees Fahrenheit. Assuming the spacecraft’s heat shield holds up as expected, Orion will splash down in the Pacific Ocean off the coast of San Diego at around 9:40 a.m. PT on that day.

Once the spacecraft is recovered, NASA’s teams will analyze the data from the flight and fine-tune their plans for the Artemis 2 mission, which is scheduled to send a crew of astronauts around the moon in the 2024-2025 time frame. The mission after that, Artemis 3, is due to put astronauts on the lunar surface no earlier than 2025.

“This is really the start of a campaign of several missions to get humans back to the moon and beyond to Mars,” flight director Judd Frieling said.

As Orion made today’s powered lunar flyby, the spacecraft’s cameras captured thrilling close-up imagery of the moon’s surface and snapshots of a faraway crescent Earth. Even mission managers were impressed, Korth said.

“We just had to stop and pause and look, and wow, we’re saying goodbye to the moon,” she told reporters.

Here’s a sampling of snapshots:

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