HOUSTON — As the Artemis II astronauts inexorably return to Earth, with a splashdown scheduled for April 8, scientists on the ground are already reviewing data collected during a historic flight around the Moon.
“We actually need to be scientists doing science,” says Marie Henderson, Artemis II deputy lunar science lead, from NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The four Artemis II astronauts, Reid Wiseman, Christina Koch and Victor Glover of NASA, as well as Jeremy Hansen of the Canadian Space Agency, achieved the first flyby of the moon in more than 50 years, on April 6. The crew spent about seven hours conducting carefully choreographed scientific observations, with two astronauts at a time positioned in front of the Orion spacecraft’s windows, taking photos and making recordings while the other two communicated with the ground.
The astronauts, who had prepared for the mission with in-depth training in science and geologyregularly called to mission control with scientific “sit reps” or situation reports. The crew’s evocative descriptions of lunar features included handprints, points of light shining through a lampshade, islands in a sea of darkness, deep holes, a healing wound, a frozen rough sea, and a dinosaur footprint.
“We trained them to describe it as they see it,” said Kelsey Young, Artemis’ lunar science manager, during an April 7 press briefing.
For scientists, the best may be yet to come. The thousands of photos and audio recordings of detailed observations are still beamed back from the spacecraft to Earth, and scientists debate their meaning. “Morale is very high,” Young said.
Here’s a tantalizing glimpse of the scientific treasure these data may hold.
Impact Flashes
One of the things that scientists are most interested in is astronauts’ observations of impact flashes. These brief flashes of light are caused by micrometeorites that strike the dark lunar surface.
Toward the end of the flyby, the crew oriented the spacecraft so that the moon blocked the sun from the astronauts’ perspective for nearly an hour, creating a solar eclipse. If impact flashes were going to appear, it would have been then.
“I don’t know if I expected the group to see one on this mission,” Young said.
But astronauts reported seeing flashes whenever they intentionally looked for them.
“The eclipse happened, and then we had five minutes of human emotional response looking at this orb floating in the vastness of space,” mission commander Reid Wiseman said during a teleconference with the science team on April 7. “Then right after that, someone in the cabin said, ‘Let’s look for impact flashes,’ and immediately we saw one, two or three.”
Some of the reported flashes could be duplicates, with two astronauts seeing the same thing. But the crew believes they saw at least four and as many as six over a 30-minute period.
“You probably saw the surprise and shock on my face,” Young said during the press briefing. “And even though I wasn’t in the scientific evaluation room, I heard audible screams of joy.”
The astronauts described the flashes as colorless points of light that lasted a few milliseconds, sending details about when and where they saw the flashes on the moon. Observations from the ground and from NASA’s Lunar Reconnaissance Orbiter look for evidence of the same flashes. LRO may be able to see any new craters formed from impacts.
That would be cool, but it’s also important information for planning future missions. When the astronauts are on the surface of the Moon, these micrometeorites will fall on their heads and on their habitat. Knowing how common they are and what damage they could cause will help keep future astronauts safe.
See in color
One of the main advantages human astronauts have over robotic space explorers is their sensitivity to color. Human eyes can pick up subtle changes in color and brightness that cameras simply can’t pick up.
“I looked forward to seeing if they saw colors other than black, white and shades of gray,” Young said. “They actually did, right away.”
Astronauts described green hues around the bright Aristarchus crater. Elsewhere, the moon looked brown.
“These colors really help us learn the nuances of the chemistry of lunar material,” Young said.
The astronauts also surprisingly described how other elements interfered with their color perception. When the Earth was in their field of view, it changed the appearance of the Moon, Glover reported. The difference between the Earth and the Moon was like “the difference between an LED screen and a painting: You can do things with light that you can’t do with paint colors,” he said. “The Earth seemed out of place. And it continued to decrease albedo [ or brightness] and the color that was previously apparent on the moon.
Koch agreed. “The moon turned into a sponge of light,” she said. “As soon as Earth got close enough to be in my field of vision and see them both at the same time, [the moon] blunted, it turned into a sponge, it’s almost as if it had become matte. It also looked more like an olive brown, whereas before “I would have said it was electric gray.”
Items inside the spacecraft itself, like orange Kapton tape or a white Abort sticker, also made observing the moon difficult. At one point, Koch asked Wiseman to help him cover the objects in the capsule with a black t-shirt so they wouldn’t be reflected in the windows. She suggested sending a darkroom cloth or similar as part of the kit for future missions.
“A Geologist’s Cheat Code”
Another place where astronauts saw color was in and around impact craters. Impact craters are “kind of like a geologist’s cheat code,” Young said, because they can extract material from great depths that you couldn’t otherwise access.
As the flyby began, the crew suggested new names for two small craters: Integrity, the nickname of their spacecraft, and Carroll, named after Commander Wiseman’s late wife. The team will submit the names to the International Astronomical Union when they return to Earth to make them official.
At their science conference after the mission control flyby, the astronauts had a long discussion about rays of bright material extending from Ohm Crater, an impact crater with a flat floor interrupted by central peaks. Scientists think these peaks mean the moon rock liquefied during the impact and splashed out like pond water.
“This has many implications for future Artemis missions and hardware and impacts on color,” Young said.
The astronauts noticed that the rays varied in color and brightness and contrasted with the darker matter around them. This suggests that the rays could be made of material that was taken from deep within the moon’s surface and sprayed onto older material.
Glover reported seeing layers in the crater wall itself and that the crater floor was the same color as the outer surface but a different color than the wall.
“It’s these kinds of nuanced observations that could ultimately inform future ground missions, future crewed missions, to understand where can we go to maximize scientific value,” Young said. “These ultimately lead to the solar system timeline.”
It was clear that future missions were on everyone’s minds. During the eclipse, astronauts were able to see other planets lined up in the dark. An astronaut noticed that one of them looked red.
“It’s Mars,” Young said. “You’re looking at your future.”