The four Artemis II astronauts have returned to Earth — delivering not only themselves but also a precious trove of images from their lunar journey. And the geologists supporting the mission can hardly wait to dive in.

“The images are spectacular, absolutely,” Gordon Osinski, a crater specialist and planetary geologist at Canada’s Western University who has been deeply involved in the Artemis II crew’s geology training, told Live Science after seeing the first photos of the crew’s seven-hour lunar flyby.

Osinski said that the small batch of images transmitted to Earth so far hint at big discoveries about the moon’s geology — and could help shape the hunt for lunar samples in NASA’s upcoming crewed moon landings, starting with Artemis IV as soon as 2028. Two geological findings stand out so far. One of these is impact flashes — brief but bright flashes of light from when space rocks slam into the moon, leaving craters behind.

Artemis II astronauts Reid Wiseman and Jeremy Hanson reported seeing at least five of these flashes during their lunar flyby. Geologists hope to review the crew’s images, once they return to Earth, to potentially identify the craters associated with the impacts. “The conditions that [the crew] had to view those was perfect,” Osinski said, referring to the crew’s passage over the lunar terminator — the stark dividing line between the moon’s bright day-side and dark night-side, where contrast is heightened and flashes are easier to spot.

Secondly, mission scientists are eager to investigate the crew’s descriptions of lunar colors. Geologists have only heard a few quick impressions from the crew so far, mainly over voice communications open to the public. But the Artemis II crew was recording more lunar flyby observations by voice and in notes in an archive that will take weeks to review.

The astronauts reported some intriguing things, such as patches of green and brown on the lunar surface. “We do know there is color on the lunar surface,” Osinski said. The human eye, he added, is more sensitive to color than the cameras on board Artemis II, so “that’s definitely going to be something interesting to follow up.”

For years, Osinski has been giving geologic training to Artemis II crew members. Hansen is a repeat contributor to Osinski’s remote Canadian crater expeditions, often done alongside Indigenous groups. During Artemis II preparation, mission specialist Christina Koch and Canadian Space Agency backup astronaut Jenni Gibbons joined Hansen and Osinski on a 2023 expedition to a moon-like crater in northern Labrador, Canada.