Today, the Moon is about as inhospitable to life as it gets. The little water that’s there is trapped in ice or rock. It’s otherwise dry and airless, fluctuating in temperature by hundreds of degrees anywhere the sun shines. But long ago? That’s an entirely different story.New research published in Astrobiology suggests that the Moon may have been shockingly habitable in the past during at least two periods — shortly after the Moon formed, and when volcanic activity was at its highest.The key to it all is heat and lots of energy. The Moon formed after a collision between Earth and a proto-planet astronomers call Theia. And just after the smash up, there was lots of water vapor — enough that the Moon could’ve had a fairly substantial atmosphere and pools of water on the ground. Volcanic activity was also high, which could have replenished the atmosphere with water vapor from deep in the interior.That all happened roughly 4 billion years ago.And by the time volcanic activity settled down some 500 million years after the collision, the atmosphere couldn’t cling on — and much like Mars, the Moon dried up.But in that 500 million-plus year span, all the ingredients for life may well have been present.That habitable era also fell during a period of frequent asteroid bombardment, so the inner solar system may have shared with the Moon ingredients to make life possible. Asteroids could have even struck early Earth and transported primitive bacteria to the surface of the Moon.The short span of lunar life didn’t really have long to evolve much beyond single-cell organisms.However, there’s abundant evidence that the early lunar water is still trapped within rock now. So, digging a little deeper under the surface of the Moon — in, say, a lunar exploration program — could yield greater evidence for lunar life, including the possibility of fossilized microbes trapped in rock.This article originally appeared on Discovermagazine.com<doc-sep>Story highlights A new analysis suggests that there are two windows in the moon's past when it might have been habitable Though there is no direct evidence for life yet, future missions might uncover it (CNN) — Although the moon might look desolate and pock-marked with impact craters today, new research suggests that it may have once supported life. A study published Monday in the journal Astrobiology cites two time periods during the moon’s distant past when conditions on the surface were potentially habitable. Shortly after the moon was forming from a debris disk 4 billion years ago, it was releasing water vapor and other volatile gases in mass quantities. The second event happened about 3.5 billion years ago, when volcanic activity on the moon reached a peak. On both occasions, the release of these volatile gases would have created liquid water pools on the surface, as well as a dense atmosphere that could stay in place for millions of years. It most likely had a magnetic field as well that could have protected any life on the surface from solar wind, a deadly flow of charged particles streaming out of the sun. Today, the moon doesn’t have an atmosphere but a very thin layer of gases, including sodium and potassium, that try to act like an atmosphere. “It looks very much like the moon was habitable at this time” billions of years ago, study author Dirk Schulze-Makuch, an astrobiologist at Washington State University, said in a statement. “There could have actually been microbes thriving in water pools on the Moon until the surface became dry and dead.” The new study relies on data from space missions and analysis of rock and soil samples from the moon. In recent years, studies have suggested that there is more water ice on the moon than previously believed and that water could exist beneath the surface. But what would life have looked like if it existed on the moon, and how did it originate? On Earth, the earliest evidence of life can be traced to cyanobacteria fossils between 3.5 billion and 3.8 billion years old. Cyanobacteria are microscopic single-celled organisms that produce oxygen through photosynthesis. The ingredients for life have been found in meteorites before, and it is believed that meteorites could have helped bring water to Earth in the early time of its formation. The researchers for this study propose that in the early days of our solar system, it’s possible that meteorites that came in contact with Earth and “blasted off its surface” could have also landed on the moon. This was common in the early solar system, when giant impacts and the transfer of meteorites between planets occurred, according to the study. If so, the meteorites could have carried microbes to the moon, and those microbes could have lived in pools of water on the surface. “If liquid water and a significant atmosphere were present on the early Moon for long periods of time, we think the lunar surface would have been at least transiently habitable,” Schulze-Makuch said in a statement. Now, the moon is essentially dead and dry, its surface covered with dust. But if future missions revisit the moon, the researchers believe that retrieving samples from areas dating back to the peak of volcanic activity could provide evidence of water or life. Experiments simulating the conditions on the moon 3 billion to 4 billion years ago could also be carried out in labs on Earth or the International Space Station to see whether microbes could survive, according to the study.<doc-sep>Did life ever exist on the moon? Maybe! Have scientists found evidence of life on the moon? Definitely not. Why are we talking about this? A new paper was published online today (July 23) in the journal Astrobiology with a thrilling headline: "Was There An Early Habitability Window for Earth's Moon?" Its associated press release had an even more exciting title: "Researcher sees possibility of moon life." Wowza! This is genuinely cool stuff. But it's important to understand what it's really saying and what it's not. The paper, written by a pair of astrobiologists from Birkbeck College in London and the Technical University of Berlin, offers no evidence that life existed on the moon. In fact, it doesn't present new evidence of any kind. The paper doesn't represent the conclusions of any study at all. Instead, it's an argument, aimed primarily at other scientists, that, based on existing research, there may have been a period in the moon's history when living things on its surface wouldn't have immediately died. [Top 10 Amazing Moon Facts] Today, the authors wrote, the moon is totally inhospitable to life. It has, they wrote, "no significant atmosphere, no liquid water on its surface, no magnetosphere to protect its surface from solar wind and cosmic radiation, no polymeric chemistry [the building blocks of life], and it is subject to large ... temperature variations." In their paper, they pointed to recent research from a number of sources that suggests this might not always have been the case. Thanks to the moon's more volcanically active past, they pointed out, there may have been two periods (one 4 billion years ago, just after the moon formed, and the next 3.5 billion years ago) when the moon may have been a bit more habitable for periods of a few million years. Volcanic gases could have spewed water vapor onto the moon's surface, the authors wrote, especially given recent evidence that the moon has more water than scientists once thought. The same processes might have thickened the atmosphere. The moon might also have formed a magnetic field similar to Earth's that would have deflected the worst stellar radiation, they said. That solves three of the key problems with the moon's habitability. The researchers didn't directly address the moon's temperature swings again, but perhaps an atmosphere would have resolved that issue as well. Still, there's one piece missing: the building blocks of life. No expedition to the moon has ever found amino acids or other chemicals that might link up to form living things, even as similar chemicals have turned up as far away as Mars. Perhaps, the researchers wrote, those chemicals might have formed natively. Otherwise, they might have arrived via asteroid impact — the same process some scientists think seeded Earth. This new paper is best understood as a call to look for those chemicals more closely on the moon, especially in volcanic deposits dating back to those periods. But for now, there's no reason to think that life actually existed there — just that (maybe, perhaps) it could have. Originally published on Live Science.<doc-sep>
The moon is a dry and barren place, utterly devoid of life. But has it always been this way? New research suggests that perhaps at one point in its history, the moon may have harbored microorganisms similar to those on Earth. Looking at the moon today, it’s easy to reach the conclusion that it is devoid of life. The moon has no atmosphere, no magnetic field, and what little water it does have is frozen in craters at the poles. It’s hard to think of a place more inhospitable to life, but about 3.5 billion years ago, the moon was a very different place. In that era, the moon was still relatively new, only about a billion years old. Earth's only natural satellite still had a molten core, and gases escaping from underground magma would have produced an atmosphere. That atmosphere wouldn’t have been as thick as the Earth’s, but it would have been enough to allow liquid water to form on the surface. The molten core could have also generated a magnetic field to protect the lunar surface from solar radiation. Given these facts, the early moon looks like a potential paradise for microorganisms. And there’s another piece of information that makes the possibility even more likely: life had already developed just 100,000 miles away on Earth. It’s feasible that a stray meteorite could send rocks and bacteria from the surface of Earth to the orbiting moon. We already know this exchange of meteorites happens between Earth and Mars; scientists have recovered space rocks here on Earth that match those on the Red Planet. These Mars rocks don’t have bacteria on them, but the rocks from Earth just might have. Because meteorites can travel all the way from Mars to the Earth, it’s not hard to imagine rocks from Earth landing on the moon with some bacteria that came along for the ride. The only way to find out for sure if life has ever existed on the moon is to return there and hunt for clues on the surface. The researchers behind this hypothesis have proposed a series of dedicated experiments and expeditions to collect moon samples and test whether life really could have survived in ancient lunar conditions.