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The Artemis II crew are heading home after getting an unprecedented view of the moon.
Canadian Space Agency astronaut Jeremy Hansen and NASA astronauts Reid Wiseman, Victor Glover and Christina Koch made history by travelling farther from Earth than any humans ever have as part of the Artemis II mission.
Satellites have photographed the moon’s far side since Luna 3 returned the first images in 1959. Artemis II marked the first time humans saw some far-side regions directly with their own eyes.
Kelsey Young, NASA’s Artemis II lunar science lead, has long said the team was looking forward to having humans see and describe lunar features firsthand.
“The human eye, especially when it’s connected to a well-trained brain, which I assure you these four people have, are capable of just in literally the blink of an eye, making nuanced colour observations,” Young said during a press conference.
The five hours of observations were made using cameras and the naked eye. All four astronauts gave detailed descriptions of what they were seeing.
One area of particular interest was the Orientale basin, a region straddling the moon’s near and far sides. It is believed to have formed 3.8 billion years ago. Hansen also pointed to colour variations stretching toward Hertzsprung, a large crater on the moon’s far side.
“We see a brownish hue and a greenish hue,” Hansen said. “I see those same brownish hues west of Orientale, and that’s a huge region, kind of like a piece of pie, with the point of pie pointing at Orientale then going up toward the northern side of Hertzsprung.”
In this view of the Moon, the Artemis II crew captured an intricate snapshot of the rings of the Orientale basin, one of the Moon’s youngest and best-preserved large impact craters, during the lunar flyby observation period. (NASA)
It might sound strange to hear that the moon has colour, but it does. You can see it by taking a photograph and increasing the saturation. The different colours come from the various minerals on the lunar surface.
But the human eye is far more sensitive than a camera. It does not need the saturation turned up.
“When you are looking for subtle differences in colour, brightness, and so on, the visual system is still a lot more discriminating than electronic systems are,” said Ralph Chou, professor emeritus at the University of Waterloo’s school of optometry and former president of the Royal Astronomical Society of Canada.
The colours of the moon can be seen in photographs if you increase the saturation, as seen here. (Nicole Mortillaro)
“The other thing is that there are built-in enhancement systems, if you will, in the [eye’s] photoreceptors, which carry through the rest of the visual system that sharpens differences and makes them more easily detectable to the human visual system. That’s not something that machine vision can do.”
Another factor is that humans are seeing the features in real time and in 3D.
Meteoroids
One of the more interesting observations from the lunar flyby was meteoroids striking the moon’s surface.
On Earth, most meteors burn up in the atmosphere. But the moon has almost no atmosphere, so any meteoroids — small bits of rock in space left over from the formation of the solar system — reach the surface. That is why the moon is so heavily cratered.
“We have seen three impact flashes so far,” Glover reported during the flyby. “I saw two, and Jeremy has seen one, undoubtedly — oh, Jeremy saw two, so that’s four total. Undoubtedly, quick impact flashes.”
NASA science lead Young was in Houston and appeared visibly overjoyed by the news.
Some Apollo astronauts reported seeing flashes in 1969, but those observations were never confirmed.
Peter Brown, Canada Research Chair in Meteor Astronomy and a professor at Western University in London, Ont., said that is another advantage of having humans observe the moon: the ability to witness transient events that cameras, with their fast shutter speeds, may not capture.
“If you’re looking down and your eyes are dark-adapted, yeah, you’re going to see impact flashes,” he said.
Impact flashes have also been capture from Earth.
A lunar impact flash image shown superimposed on the Moon. Impact flashes are most easily seen in the shadowed portion of the moon. (NASA)
He noted that the European Space Agency is sending a mission called the Lunar Meteoroid Impacts Observer (LUMIO) to see whether it can capture meteroid impact flashes on the moon’s far side.
That is not to say cameras are not useful for observing surface features. But paired with visual observations, they can teach us much more about our celestial neighbour.
“It was remarkable listening to the crew describe the stunning views during the flyby,” Jacob Bleacher, NASA’s chief exploration scientist at the agency’s headquarters in Washington, said in a news release.
“At first, their descriptions didn’t quite match what we were seeing on our screens. Now that higher resolution images are coming down, we can finally experience the moments they were trying to share and truly appreciate the scientific return provided by these images and our other research on this mission.”
