The crew of NASA's Artemis II space mission were giving their first press conference after returning to Earth when its commander Reid Wiseman was asked a question that seemed even more unlikely than being quizzed about the malfunctioning on-board toilet.

Having warned the four-strong crew that the question would be 'a little bit deep,' Kristin Fisher, host of the space-related YouTube channel The Endless Void, asked them if they'd had a spiritual moment way up in space.

When Apollo 14 astronaut Edgar Mitchell was returning from the moon, he had an experience so profound that when he returned to Earth, he devoted the rest of his life to studying the nature of human consciousness, Fisher explained.

'Do any of you feel as though you had an experience similar to what Mitchell described - the sense of universal connectedness,' she asked. 'And did you experience somehow a shift in consciousness?'

Wiseman simply answered, 'Yes.' He said he could best explain by recounting a story of how when they were on a navy vessel after landing back on Earth, he asked to talk to the navy chaplain.

'I'm not really a religious person but there was really no other avenue for me to explain anything or experience anything, so I asked for the [ship's] chaplain to just come visit us for a minute.'

He went on: 'I'd never met him before in my life, but I saw the cross on his collar and I just broke down in tears.'

'It's very hard to fully grasp what we just went through….when the sun eclipsed behind the moon, I think all four of us…I turned to Victor [Glover, the Artemis pilot] and I said, "I don't think humanity has evolved to the point of being able to comprehend what we are looking at right now," because it was otherworldly and it was amazing.'

Captain Glover, sitting next to Wiseman, supportively patted his commander on the shoulder. He'd been in the room, he revealed, when the chaplain came in and it had been 'a really special moment.'

He said: 'The only thing I would add is that I am a religious person, but everything else is the same. There is something in there and as we start to process I'll have to tell you next week, but I haven't had a chance to really unpack it all yet.'

It's something that a surprisingly large number of space travelers have found themselves 'unpacking' over the decades.

While space exploration has long been wrapped in science, the experience of seeing the Earth from space has left astronauts undergoing a profound and very unscientific shift in consciousness.

For often that mind-expanding experience involves a conviction that there may be something out there that science cannot explain.

It may be premature to seize on mission commander Wiseman's very personal admission - as some Christians have done - as proof that he had some sort of Damascene conversion, (he didn't actually say he'd suddenly found religion). But he is far from the first space traveler to return to Earth with feelings about the divine that are rather stronger than when he left.

There is even a name for the phenomenon - the 'Overview Effect' - frequently experienced by astronauts as they view the Earth from afar. In some viewers, it has produced an intense feeling of common humanity and a desire to protect a fragile planet, in others it provokes an equally profound feeling of awe as they comprehend man's insignificance amid the immensity of space.

For the religious, it often simply confirms what they already believe - that humanity is special and has a higher purpose. However, it is sometimes transformative, changing people's lives forever. Astronauts often admit it reduces them to tears, although skeptics claim it is usually a passing emotion.

'The overview effect describes the cognitive and emotional transformation that astronauts experience when gazing at Earth from space,' said neuroscientist Dr. Claudio Waisburg. 'The experience generates awe, a sense of transcendence and a keen awareness of interconnectedness. Everyday concerns dissolve. The sense of belonging to something greater than oneself becomes overwhelming.'

Apollo 14 astronaut Edgar Mitchell called it an 'explosion of awareness' and an 'overwhelming sense of oneness and connectedness... accompanied by an ecstasy... an epiphany.' Other spacemen have alluded to it by remarking that while astronauts go into space to see new planets, the most telling revelation they find is actually about the Earth.

All four of the Artemis II crew described experiencing something profound.

'I just had an overwhelming sense of being moved by looking at the moon,' said Artemis astronaut Christina Koch. '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.'

Victor Glover told CBS News on Easter Sunday: 'You guys are talking to us because we're in a spaceship really far from Earth. But you're on a spaceship called Earth that was created to give us a place to live in the universe, in the cosmos.'

Space experts note that throughout history societies have looked to the stars for spiritual answers, so it's hardly surprising that astronauts experience a spiritual effect when they actually get into space.

Frank White, a space philosopher who coined the phrase 'overview effect' in 1987 after interviewing myriad astronauts, has compared it to Zen Buddhism, in that it is impossible to explain in words.

He said: 'Part of it is seeing the Earth itself. Part of it is seeing the Earth against the backdrop of the universe. You're actually seeing the universe for the first time in a way that no human has seen it.'

Other factors - such as the way astronauts are moving around the Earth frequently, their weightlessness and the passage of time changing (due to Einstein's theory of relativity, clocks in space tick faster than those on Earth because of weaker gravity, but faster velocity makes them tick slower) - all contribute to them feeling dislocated from Earth and experiencing the overview effect, said White.

According to the philosopher, not all astronauts experience the overview effect and the strength of the experience depends on how far they get from Earth. If you are in so-called low-Earth orbit, for example, and only able to see part of the planet, the overview effect is unlikely to be as intense as seeing the planet in its entirety against the backdrop of the cosmos.

As with Artemis II commander Wiseman, reduced to tears by the sign of the cross, the overview effect is often framed in religious terms - a fact that from the early years of space travel has caused controversy.

According to NASA, of the astronauts who visited the moon during the Apollo program, 23 were Protestant and six Catholic, with a high proportion of them as church leaders in their congregations. Some astronauts believe that early space travel was so dangerous that those willing to do it needed to have some sort of religious belief to buoy them up.

On Christmas Eve 1968, Apollo 8 crewmen Jim Lovell, Frank Borman and Bill Anders - the first astronauts to orbit the moon - did a memorable live TV broadcast as they went into lunar orbit and were able to show pictures of the Earth and moon as seen from their spacecraft. They'd wanted to send a message of peace but decided it was too controversial with the US involved in the Vietnam War, so they found an alternative in the Bible.

Announcing they had a message 'for all the people of Earth,' they took turns reading from the Book of Genesis, starting - predictably - with: 'In the beginning God created the heavens and the earth' and ending with '…and God saw that it was good.'

Borman signed off, saying: 'Good night, good luck, a Merry Christmas, and God bless all of you - all of you on the good Earth.'

One in four people back on Earth were estimated to have listened to the reading. The US was, of course, a much more church-going country in those days, but the broadcast still managed to outrage Madalyn Murray O'Hair, a militant atheist who launched a lawsuit against NASA that alleged the reading had violated the First Amendment.

The case was dismissed in the courts, but NASA became paranoid about astronauts - perhaps spiritually awakened by the overview effect - delivering further religious homilies from space.

The agency told crews to tone down religious statements and, when it actually came to the historic Apollo 11 lunar landing the following year, NASA bosses urged the devout Buzz Aldrin - an elder in his Presbyterian church - not to recite any Scripture while he was on the moon's surface.

That didn't stop Aldrin - who'd taken bread and wine with him into space after his pastor gave him permission to celebrate Communion up there.

On the night before they touched down, he used a TV broadcast to read a passage from the Bible - Psalms 8:3-4 - that some have dubbed the 'lunar-landing Bible verse.'

Listeners back on Earth heard him intone: 'When I consider thy heavens, the work of thy fingers, the moon and the stars, which thou has ordained; What is man that thou art mindful of him? And the Son of Man, that thou visitest him?'

Later, just before he and Neil Armstrong became the first people to step on to the moon's surface, Aldrin radioed Mission Control in Houston to 'request a few moments of silence,' saying, 'I would like to invite each person listening in, wherever and whomever he may be, to contemplate for a moment the events of the past few hours and to give thanks in his own individual way.'

Aldrin said he was one of many astronauts who believed it was part of God's plan that mankind venture into space. And he certainly wasn't the last astronaut to risk embarrassing NASA by daring to bring up the G word - God - when they were up there.

During the Apollo 15 mission in 1971, astronaut James B Irwin was exploring the moon's surface in the Lunar Roving Vehicle when he radioed Mission Control to say that it reminded him of one of his favorite Scripture passages: 'I will look unto the hills from whence cometh my help.'

NASA crews have repeatedly celebrated communion in space, including Space Shuttle astronauts Sid Gutierrez, Thomas Jones and Kevin Chilton (a Catholic layperson authorized to assist priests with the Eucharist) who did on a 1994 flight.

In 2013, astronaut Mike Hopkins, a Catholic on board the International Space Station, was allowed to take up enough consecrated supplies to have weekly Communion for the 24 weeks he was in space.

And given that people have worshipped the moon and stars for centuries, perhaps it's no surprise that getting there can be a religious epiphany.