Nasa’s Artemis II astronauts have described the powerful emotion they felt while soaring over the moon as they photographed impact craters, cracks and ridges and began their long journey home.
Among the eagerly awaited images captured by the crew, who worked in pairs at the Orion capsule windows, are those of the Earth rising from behind the moon, a solar eclipse and parts of the 590-mile (950km) wide Orientale impact basin that have never been observed with the naked eye.
Further images are expected to shed light on the brown, green and orange hues the astronauts reported on the greyish landscape, and possibly faint layers of moondust that may have been visible during the Earthrise.
Having swung around the far side of the moon on Monday, a manoeuvre that cut the crew’s contact with mission control for 40 minutes, the four astronauts are now hurtling back toward Earth. The quarter of a million mile return trip is due to end in a splashdown near the coast of San Diego at 8.07pm on Friday US eastern time.
The Nasa astronaut Christina Koch, who is the first woman to fly around the moon, said of observing the lunar surface at such close quarters. “I just had an overwhelming sense of being moved by looking at the moon. It lasted just a second or two and I actually couldn’t even make it happen again, but something just threw me in suddenly to the lunar landscape and it became real.”
She said she was particularly struck by the bright new craters that shone from the surface like pinpricks in a lampshade. “They are so bright compared to the rest of the moon.”
Fellow astronaut Victor Glover, the first black man to travel beyond low Earth orbit, said: “It was very moving to look out the window.
“I went straight where Christina went, and I was walking around down there on the surface, climbing and off-roading on that amazing terrain,” Glover told Nasa’s capsule command, or CapCom.
The Orion spacecraft began its journey to the moon on 1 April when it blasted off from the Kennedy Space Center in Florida on Nasa’s Space Launch System, the agency’s rocket for deep space missions. Onboard are the Nasa astronauts Koch, Glover and Wiseman, and the Canadian Space Agency astronaut Jeremy Hansen.
In a Tuesday morning phone call with Donald Trump, who asked the astronauts whether they saw “a big difference between the far side of the moon and the near side of the moon”, Hansen said: “The gravitational pull of the earth has had a profound effect on the near side of the moon, changing all those dark mares – those patches of the moon you see from earth – it’s very different on the far side.”
Hansen added: “While you see some small patches of those mares and deep craters, it’s very much absent on that side, so that’s very neat.”
Meanwhile, in response to a question from Trump on what it was like during the 40-minute communication blackout and what the astronauts did, Glover said: “I said a little prayer, but then I had to keep rolling. I was actually recording scientific observations of the far side of the moon.”
“That is actually the time when we were the farthest from Earth and the closest to the moon and so we were really able to make some of our most detailed observations of the far side of the moon up close, so we were busy up here working really hard – and I must say, it was actually quite nice,” he added.
Describing the eclipse the crew saw, Wiseman said: “The surprise of the day, we just came out of an eclipse where the sun, moon – the entire dark moon about that big right out the window that we were watching – we could see the corona of the sun, and then we could see the planet train line up, and Mars.
“And all of us commented how excited we are to watch this nation, and this planet become a two-planet species,” he added.
On Monday, the crew broke the record for the farthest humans have travelled from Earth, reaching a distance of 252,756 miles, surpassing the previous record of 248,655 miles set by Apollo 13 in 1970. On their closest approach to the moon, the Artemis II crew came within 4,070 miles of the lunar surface.
To mark the return leg of the lunar flyby, Nasa’s flight controllers in Houston flipped over the mission patches on their consoles, swapping an image of the moon in front of the Earth for the outbound trip for one with the moon behind the Earth.
In a press conference on Tuesday afternoon, the Nasa flight director, Rick Henfling, said: “We bid a temporary goodbye to the moon earlier today at 1.23pm Eastern time, that’s the milestone where we exited the lunar sphere of influence and we’re back under the control of Earth’s gravity.”
He added that each crew member will have a conference with their family members, as well as some routine medical checks on Tuesday.
Meanwhile, Kelsey Young, the mission’s lunar science lead, noted that crew members observed several impact flashes during a 30-minute observation period, largely during the time of the eclipse.
“Impact flashes are caused by micrometeorite impacts hitting the moon and they really help tell us about the dynamic lunar environment,” she said, adding: “We think they saw at least four and possibly up to six impact flashes.”
Young also pointed to the crew’s observation of colors on the moon, saying: “Right away they started describing the green around the Aristarchus plateau and different brown hues,” referring to a lunar impact crater on the north-west part of the moon’s near side.
“These colors really help tell us nuances about the chemistry of lunar material,” she added.
In response to a question about the mission’s optical communication, which uses light to transmit information over long distances, Henfling said that overnight, the ground team received 20 gigabytes from the crew in a little more than 45 minutes.
“That’s orders of magnitude more than we get via our S band telemetry system so that optical comm[unication] has been working really well,” Henfling said.
The S band telemetry system is a radio communication system that uses S-band frequencies – around 2–4GHz – to transmit data including position, speed and system health among spacecrafts, satellites and ground station.
The capsule will return to Earth after jettisoning the service module that provided power and propulsion for the trip to the moon. One of the most risky stages is re-entry when the capsule slams into the atmosphere at more than 20,000mph, causing its heat shield to reach temperatures above 1,600C (2,900F).
