“The only illumination source on the Moon will be Earthshine, which is a different spectrum,” Deutsch said in a presentation last month at the Lunar and Planetary Science Conference. “How does that affect the perception of color and tone?”

The crew members summarized their observations in periodic updates radioed down to Mission Control on Monday. They also recorded more detailed verbal descriptions onboard the spacecraft, and were tasked with making drawings and annotations to go along with their photographs. This data will come back to Earth when Orion returns Friday.

“We tell the crew that their verbal descriptions are actually going to be the monumental scientific dataset from this mission, and that’s because, as humans, the crew provides critical perceptual context that just can’t be replicated with robotic sensors,” Deutsch said. “The crew has perception and spatial awareness and they have the ability to react and to adapt to what they’re seeing in an instant.”

This quick perception allowed the astronauts to see several brief flashes of light, each lasting a fraction of a second, on the dark side of the Moon. The flashes occurred as tiny fragments of cosmic material, or micrometeoroids, impacted the lunar surface.

“It’s a pinprick of light,” Hansen said. “I would suspect there were a lot more of them … it is just a momentary flash, no color, about the size of a star, and it really only lasts milliseconds, a half a second at most.”

This was not surprising to Neal. “It’s a reminder that the surface is continually bombarded, and this is something that we’ve tried to monitor,” he said.

Lunar impact flashes are routinely visible through telescopes on Earth. Astronomers were watching the Moon as Artemis II made its close approach Monday, and if scientists can correlate their own observations with those from the astronauts, they can get a better handle on how many impacts are missed by ground-based telescopes. Constraining the number of impact events will be important as engineers design shielding for a future Moon base.