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Moon May Have Been Habitable 3.5 Billion Years Ago

posted by martyb on Tuesday July 24 2018, @08:32PM   Printer-friendly
from the what-about-the-cheese? dept.

takyon writes:

Earth's Moon Could Have Been Habitable 3.5 Billion Years Ago

A new paper by Ian Crawford from the University of London and myself [Dirk Schulze-Makuch], just published in the journal Astrobiology [open, DOI: 10.1089/ast.2018.1844] [DX], claims that Earth's Moon might have been habitable about one billion years after its formation, when pools of liquid water may have existed on the lunar surface. Today, of course, the Moon has no atmosphere and no liquid water. It's uninhabitable and certainly lifeless. But 3.5 billion years ago, a billion years after it formed, the lunar environment was quite different.

During this period of extreme outgassing from lunar magma, the Moon is estimated to have had an atmospheric pressure of 10 millibar, or one percent of Earth's current atmosphere. This is thicker than the current atmosphere on Mars, and would have been substantial enough for liquid water to pool on the lunar surface, perhaps for many millions of years.

Combine this with recent findings that lunar rocks are more water-rich than previously thought [DOI: 10.1038/ngeo2845] [DX], and we can hypothesize that lakes, even an ocean, could have stably existed on the Moon for a substantial amount of time. There is also evidence that the early Moon had a magnetic field [DOI: 10.1016/j.icarus.2010.08.012] [DX], which might have partially protected its surface from solar and cosmic radiation. This would have resulted in a temporarily habitable world, at a time when life on Earth had already gained a foothold.

Also at Motherboard and Astronomy Magazine.

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  • (Score: 2) by The Shire on Wednesday July 25 2018, @02:19AM (5 children)

    by The Shire (5824) on Wednesday July 25 2018, @02:19AM (#712110)

    Water is one of the singular most common molecules in the universe, its literally everywhere. It's presence clearly does not by itself denote life, nor does it even mean there is a possibility of life. A thousand other factors are required just for life to survive and we don't even know what complicated chemistry is needed for it to spontaneously evolve. One thiing is certain, there are exactly ZERO theoretical models of evolving life that include a near vaccuum atmosphere. Organic chemistry just isnt going to do anything fancy under those conditions.

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  • (Score: 2) by takyon on Wednesday July 25 2018, @02:40AM (4 children)

    by takyon (881) <{takyon} {at} {soylentnews.org}> on Wednesday July 25 2018, @02:40AM (#712120) Journal

    Take it up with the authors of the "forum article":

    Here, we merely note that outgassing 500 ppm water during the LMO phase (which would be required to bring the higher original values predicted by Lin et al. [2017] into agreement with current estimates) could in principle result in a surface water layer of an order of 1 km thickness. Of course, this would be a very optimistic estimate for the depth of any early lunar oceans—water would only be stable at the surface if protected by a sufficiently dense atmosphere, and significant losses would be expected owing to impact erosion (e.g., Melosh and Vickery, 1989)—but it illustrates how much water might potentially have been available.

    Needham and Kring (2017) have suggested a second phase of outgassing, and associated peak in lunar atmospheric pressure, as a result of mare basalt eruptions ∼3.5 billion years ago. Gases derived from lava outpourings may have built up an atmosphere of about 10 mbar, which is above the triple-point pressure of water and about 1.5 times the present atmospheric pressure on Mars (and about 3 times as massive as the current martian atmosphere, given the difference in surface gravities). For comparison with the discussion above, Needham and Kring's estimated outgassing of water (∼1014 kg) would equate to a global layer having an average depth of ∼3 mm.

    [...] Based on these loss rates, Needham and Kring (2017) estimated a lifetime of ∼70 million years for the transient atmosphere generated by lunar volcanic activity, and the duration of a hypothetical denser and earlier atmosphere immediately following LMO crystallization could have been even longer. In principle, liquid water could have existed on the lunar surface during these times, and perhaps even more likely in protected subsurface environments such as interstitial pore spaces within the impact-generated mega-regolith.

    [...] Of course, habitability requires much more than just the presence of a significant atmosphere and liquid water. Other constraints that need to be satisfied have been elaborated elsewhere (e.g., Schulze-Makuch et al., 2011; Cockell et al.,2016). We do not know whether there were any intrinsic organic compounds on the Moon at that time, but even if not, these would likely have been delivered from Earth, carbonaceous asteroids, and perhaps other sources, via meteorite impacts (e.g., Pierazzo and Chyba, 1999; Crawford et al.,2008; Burchell et al.,2010; Matthewman et al.,2015; Svetsov and Shuvalov, 2015). Thus, sources of organics on the lunar surface may have been available. Moreover, as the early Moon appears to have had a magnetic field (e.g., Hood, 2011), its surface may have been partially protected from solar and cosmic radiation.

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    • (Score: 2) by The Shire on Wednesday July 25 2018, @03:01PM (3 children)

      by The Shire (5824) on Wednesday July 25 2018, @03:01PM (#712398)

      Based on these loss rates, Needham and Kring (2017) estimated a lifetime of ∼70 million years

      70 million years. Life on earth, an infinitely better protected environment, doesn't appear to have formed until after around 700 million years. They're making ridiculous propositions that "Hey, it could have happened, you can't prove it didn't". That's not how science works. You find the evidence and you propose a theory. All these guys have is data that suggests there could have been water on the moon, nothing more. The whole "life" spiel is pure fantasy to drive clicks.

      Of course, habitability requires much more than just the presence of a significant atmosphere and liquid water. Other constraints that need to be satisfied have been elaborated elsewhere. We do not know whether there were any intrinsic organic compounds on the Moon at that time

      All they're saying is there "might" have been water which, as I pointed out, is incredibly common in the universe owing to the fact that oxygen and carbon are the second most prevalent byproducts of nuclear fusion (helium being #1). And since hydrogen is omnipresent, H2O is found literally everywhere. It's not a sign of life, it's a sign that stars are nuclear furnaces.

      • (Score: 2) by takyon on Wednesday July 25 2018, @03:29PM (2 children)

        by takyon (881) <{takyon} {at} {soylentnews.org}> on Wednesday July 25 2018, @03:29PM (#712415) Journal

        doesn't appear to have formed until after around 700 million years.

        The start date for life on Earth has been pushed back continuously.

        Oldest Evidence of Life on Earth Found in 3.77-4.28 Billion Year Old Fossils [soylentnews.org]

        That's a range, but you can see we are getting a bit closer to the 4.5 billion mark.

        The forum article claims that the window for Moon habitability could be much longer than 70 million years, with water being maintained much longer in caves and subsurface pools, and that life might be able to form within a short amount of time with the right conditions and ingredients:

        It is instructive to put this time frame into perspective from a natural history point of view: Lazcano and Miller (1994) speculated that the time it took from the formation of suitable building blocks of life to the first cyanobacteria was no more than 10 million years. If they are correct, the transition from a nonliving to a living system might have taken place in considerably less of a time span, perhaps as little as a few thousand years. On the other hand, Orgel (1998) has argued that we simply do not understand how life, particularly its replication system, originated on primitive Earth; thus it is not possible to come up with a reliable time estimate. If abiogenesis is able to occur on short timescales, then an origin of life on the Moon cannot be excluded.

        Also note that their proposed habitability window begins at 3.5 billion years ago, not 4.5 billion years ago. The Moon could have been habitable at a point when there was already life on Earth, and life could have been carried from the Earth to the Moon by asteroid strikes. And it should be much easier for the Earth and Moon to exchange material than Earth and Mars, or Earth and Europa, etc.

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        • (Score: 2) by The Shire on Wednesday July 25 2018, @03:54PM (1 child)

          by The Shire (5824) on Wednesday July 25 2018, @03:54PM (#712432)

          You're doing the same thing they are - you're pushing the envelope of probability for the sake of click bait. It's a massive stretch to even say it's possible when then can't even prove that water was there, only that it might have. It's pointless speculation with zero evidence. Let's just stick to science instead of touchy feely wouldnt it be cool assertions.

          • (Score: 2) by takyon on Wednesday July 25 2018, @04:13PM

            by takyon (881) <{takyon} {at} {soylentnews.org}> on Wednesday July 25 2018, @04:13PM (#712445) Journal

            Or it's a useful thought experiment that will help inform further scientific study of the Moon. Since we now have countries planning to put scientists on the surface full time.

            Also it's kinda hard for me to clickbait when you're already here.

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