Oil, Gas and Groundwater on Mars
The latest science reports about Mars make for intriguing reading. A century ago, the concept of 'canals' on Mars was all the rage - with Victorian era scientists and science fiction writers alike wondering about life on the red planet. The Viking landers in the mid-70s sent back the now familiar images of the Martian surface: our neighbouring planet is covered in arid, stony deserts. But there was still a hint of hope of life in this desolate expanse - one of the experiments conducted by Viking - the 'Labeled Release' (LR) experiment - came up positive for metabolic processes within the Martian soil (1). The Viking LR experiment was one of a series, however, whose general negativity negated this one result. Some scientists argued that the result should not have been ignored (2).
Over time, landers became rovers, and the experiments continued. One of the surprise detections on Mars has been the occasional, but very clear, detection of atmospheric methane. This gas is often associated with biological activity (biogenic methane), and may indicate the presence of microscopic organisms on, or below, the surface of Mars. Alternatively, it may relate to geophysical processes - natural processes occurring along tectonic fractures involving heat, pressure and water. Or thermogenic methane may have been produced by the breakdown of buried microorganisms (usually associated with sub-surface gas and oil reserves on Earth). The detection of methane by the Curiosity rover in 2013 caused many eyebrows to raise within the planetary science community.
The methane emission was certainly real - and has been confirmed by instruments on-board the Mars Express Orbiter (3). However, even now, 6 years on, it is not clear what the origin of the methane was. Strangely, though, the overall levels of methane in the Martian atmosphere have been found to be very low:
"The ExoMars Trace Gas Orbiter’s first analysis of the Martian atmosphere at various points around the globe finds an upper limit of methane 10–100 times less than all previous reported detections." (3)
This still corresponds to 500 tonnes emitted over the 300 year lifespan that methane is thought to have in the atmosphere. Scientists are now trying to figure out what is happening to the plumes of emitted methane that had been previously detected - is there a mechanism close to the surface that is removing methane? Mars is particularly prone to short wavelength UV radiation, which may be driving speedy chemical reactions with the methane. In other words, I wonder whether methane is extracted from the atmosphere by natural processes much quicker than it is on Earth. There are mysteries about the origins of the plumes of methane detected, as well as the overall absence of the gas in the atmosphere.
Recent arguments have been offered around the trapping of methane in permafrost, which is periodically released by tectonic activity breaking the ice (4). Could this Martian methane be associated with pockets of underground natural gas or oil? There are good reasons to consider this as a possibility. In 2000, NASA Ames research scientist John McGowan argued that the decomposition of ancient oceanic life on early life-friendly Mars could have built up the kinds of oil and gas reserves that are so familiar to us on Earth:
"If Mars possessed an Earth-like biosphere at one time in the past, Mars may contain sub-surface deposits of oil and natural gas which would constitute evidence of past life. Life might still exist in these deposits." (5)
Evidence for ancient lakes and oceans were suggestive of such a possibility 20 years ago. At that point, there was also emerging evidence of movements of ground water across the Martian surface, as well as an understanding of the changing Martian climate over long time periods, suggesting that Mars was warmer and wetter as early as 300 million years ago (6). Since then, there has been a growing recognition that water may have moved across the Martian surface in relatively recent times. It has been shown that substantial rivers flowed intermittently across the surface of Mars until perhaps just 1 billion years ago (7), in contrast to scientific orthodoxy about the much earlier 'death' of Mars. The run-off of water feeding these large rivers must have been from precipitation - Martian rain. Yet, the current thin atmosphere of the red planet is incapable of supporting this kind of weather. This implies an evolving atmosphere over time, in keeping with the highly changeable nature of Mars' orbit. Drawing upon all the most recent discoveries, I argue for this in the chapter entitled 'Meandering Mars' in my new book 'Darker Stars' (8).
Image Credit: NASA Goddard Space Flight Center
There is also evidence of a much broader and - importantly - active body of deep groundwater across Mars. Pressurised groundwater seems to be seeping up through breaks in the frozen surface, and emerging as ground water springs (9). So, it's not just methane that's bubbling up to the surface of the red planet. The impossible presence of 'recent' water across the surface of Mars demonstrates that the planet is keeping secrets from us below its surface.
These secrets may include precious 'black gold'. The timescale for the warmer and wetter Martian climate is in keeping with that of the deposition of organic materials on Earth to form oil and gas. McGowan's 2000 paper sets out how Martian oil and gas deposits could be discovered through the detection of natural gas, primarily methane, by rovers, detectors aloft upon prospecting balloons, and by on-board equipment on future orbiters (5). His scientific predictions seem to have come true. He notes that surface seepage of natural gas/methane is likely to preferentially find "large deposits near the surface that will be the easiest to study" (5). And, presumably, access. After all, any future manned colony on Mars could benefit tremendously from a readily accessible oil and gas reserve: Fuel, refining, manufacturing.
I'd go further though. We don't know what lies below the surface of Mars, but the hints we're now getting indicate incredible potential for untapped resources. The orbit of Mars fluctuates greatly, and it seems fairly obvious to me that there have been distinct ages in Martian history when its position with respect to the Sun enabled very different atmospheric conditions to proliferate.
If this is the case, then it may go some way towards explaining another Martian mystery - the anomalous relative youth of many Martian meteorites that have been found on Earth. It has been long argued by some scientists that microfossils of Martian bacteria have been discovered in meteorites that were once chipped off the Martian surface, before making their way to our planet. Recently, another candidate for fossilised Martian life has been presented in the scientific press; this one thought to be contained within the ALH-77005 meteorite (10).
The arguments presented for and against determining whether ancient bacterial life is recorded in meteorites quickly become technical, often centering around the potential for contamination on Earth, or whether these tiny structures are geophysical rather than biological. But what stands out to me in these debates is how young the meteorites are: ALH-77005 is estimated to be just 175 million years old. Mars is not thought to be a particularly active planet, lacking tectonics plates or recent volcanic activity, and its cratered surface is therefore thought to be ancient. Yet, three-quarters of Martian meteorites (the Shergottites) are less than 180 million years old (11). That means they were chipped off the planet not so long ago, in geological time. This begs the question - by comparison, why does the cratering across the Martian surface appear so ancient? This question has become known as the 'Shergottite Age Paradox' (12). Perhaps most of the known Martian meteorites were ejected from a single, relatively recent impact event? Or perhaps the age of the meteorites indicate that Mars still has secrets to share with us about its geophysical history. If its surface undergoes periodic makeovers due to extreme climate change then those processes (weathering/fluctuating glaciation) may have hidden more recent craters in affected areas (which may be extensive).
Let's say that below the Martian surface there are significant deposits of volatiles, awaiting renewed climate change as Mars' orbit fluctuates. Release the volatile ices into the atmosphere as gas, particularly greenhouse gases like carbon dioxide and water, and conditions would fundamentally change. Perhaps there is a very deep and massive collection of atmospheric gases frozen below the Martian surface, pooled into extremely deep lakes, even oceans, waiting for the warm times to return. The reason for suggesting this is the evidence of flowing rivers - which would be quite impossible without a supportive atmosphere to create a significant water cycle. There are so many other quirky features across the Martian surface, too, with ultra-deep chasms, and ultra-high calderas. Perhaps these hint at a profound geophysical asymmetry which is hidden by a relatively even distribution of frozen sub-surface groundwater/dry ice. I'm suggesting that the currently understood inventory of carbon dioxide and water on Mars (12) may have been massively underestimated, based as it is upon what can be seen upon the surface and within its thin atmosphere. Below the Martian surface lies the missing atmosphere - not driven off, but just frozen and buried... waiting.
So, if that turns out to be the case, the potential for terraforming Mars is, frankly, incredible. We wouldn't need to rely upon inventing new tech to terraform the red planet, or bringing water and carbon dioxide to the planet from comets (13). Instead, we could release and harness the atmosphere that Mars is keeping secret from us below-decks.
Written by Andy Lloyd,3rd- 12th April 2019
1) Lisa Zyga "Did 40-year-old Viking experiment discover life on Mars?" 21 October 2016
2) Gilbert Levin and Patricia Straat. "The Case for Extant Life on Mars and Its Possible Detection by the Viking Labeled Release Experiment," Astrobiology, October 2016, 16(10): pp798-810
3) ESA "First results from the ExoMars Trace Gas Orbiter" 10th April 2019
4) BBC News "Mars methane surge spotted from space" 2 April 2019
5) John McGowan "Oil and natural gas on Mars" Proc. SPIE Vol. 4137, p. 63-74, Instruments, Methods, and Missions for Astrobiology III, 12/2000
6) Jeffrey Kargel & Robert Strom "Global Climatic Change on Mars" Scientific American, 1996, 275(5): pp. 80-88
7) Mike Wall "Mars Had Big Rivers for Billions of Years" 27 March 2019
8) Andy Lloyd "Darker Stars" Timeless Voyager Press, 2018
9) Amy Blumenthal "USC researchers find new evidence of deep groundwater on Mars" 28 March 2019
10) Paul Scott Anderson "New evidence for life in a Martian meteorite?" 7 April 2019
11) L. Nyquist et al. "Ages and geologic histories of Martian meteorites". Space Science Reviews, 2001, 96: 105–164.
12) L. Nyquist, L. Borg C.-Y. Shih "The Shergottite age paradox and the relative probabilities for Martian meteorites of differing ages" JGR Planets, 103(E13): 31445-31455
13) Bruce Jakosky & Christopher Edwards "Inventory of CO2 available for terraforming Mars", Nature Astronomy, 2018, 2: pp634–639
14) Bill Steigerwald and Nancy Jones "Mars Terraforming Not Possible Using Present-Day Technology" 30 July 2018
Hubble to Scope the Kuiper Belt
A good proportion of the Kuiper belt consist of binary objects, and this has led to the idea that planetesimals initially form as pairs, rather than as solitary objects. The recent flyby of Ultima Thule by the new Horizons probe has served to intensify this debate, as this object was found to be a fascinating example of a bilobate object (1).
To test the binary hypothesis, as well as to learn more about the KBO populations, the Hubble Space Telescope will undertake a lengthy project to scope over 200 objects, measuring their binary/solitary properties, and their colour. This is the reason why these properties may be connected:
"Recent models of small body formation suggest that binaries are leftovers of the very earliest times of our solar system, when pairs of bodies could form directly from collapsing swarms of small-scale “pebbles.” Competing theories of planetesimal formation predict different size and color distributions for binary and solitary KBOs. If objects first formed through an accretion process and were merged into binaries later, scientists expect the objects in binary systems to have dissimilar colors and to have a different size distribution than solitary objects. However, if planetesimals formed through a rapid collapse process that produced some solitary objects and some binary systems from the start, scientists would expect objects in binary systems to have a similar surface color and a size distribution similar to that of solitary objects." (2)
NASA has awarded this programme, known as the Solar System Origins Legacy Survey (SSOLS), to the Southwest Institute (3). It builds upon the previous work of OSSOS and CFEPS, this time targeting previously identified candidate KBOs from these large surveys.
Written by Andy Lloyd,3rd April 2019
1) Andy Lloyd "Ultima Thule : A Tumbling Red Snowman" 2-7 January 2019
2) Southwest Research Institute "SwRI to conduct largest ever Hubble survey of the Kuiper belt", 2 April 2019
3) Alex Parker "Testing Origin Theories" SSOLS
The Early Birth of Planets and Life
How planets form remains something of a mystery - or, at least, a complicated jigsaw with some of the pieces still missing. Planet formation is usually associated with a rotating protoplanetary disk around a young star, where dust and gas from the pre-solar nebula collapses down into growing (or accreting) chunks or matter, known as planetesimals. Astronomers have been able to observe these disks separate into concentric rings around very young stars, probably indicating the presence of planetesimals within the gaps which are collecting up the dusty, gaseous materials (1). It has become clear that this is often not a sedate process, but can instead be remarkably quick (2), occurring over a few million years, or even less. The processes that take place may be complex, with the 'ring structure' of the disk shaped by resonance patterns. This means that not all the gaps may contain planets - some may arise as a result of gravitational effects associated with planets emerging elsewhere within the disk (3).
Image Credit: ALMA (ESO/NAOJ/NRAO)/ D. Fedele et al.
In the case of the protoplanetary disk AS 209, for instance, a planet appears to be quickly forming at a very significant distance from the young parent Sun-like star (which is less than a million years old):
"The outer gap is deep, wide, and largely a dust-free zone, leading astronomers to believe that a giant planet almost the mass of Saturn is orbiting here — around 800 light-minutes from the central star, and more than three times the distance between Neptune and the Sun!" (1)
If you were to place this this Saturn-sized planet into our own solar system, it would be located well beyond the Kuiper belt, and would be a massive Planet X-type object. This indicates that substantial planets can form at these distances from Sun-like stars. Astrophysicists think that planets are able to migrate to new locations within their systems, as a result in changes of gravitational attraction and gas pressures resulting from the collapsing protoplanetary disks. But they can't be sure that this exoplanet forming at the periphery of AS 209 will get dragged back into the planetary system from its distant location. Perhaps, then remotely located planets like this are commonplace - after all, the further they are away from their stars, the more difficult these objects are to detect. So, we cannot know one way or another.
At the opposite end of the planetary zone spectrum, as well as the lifespan of stars, a planetesimal has been discovered orbiting very close to a collapsed star, specifically the white dwarf known as SDSS J122859.93+104032.9. The tiny planetesimal orbits the white dwarf in just over two hours. This 600km planetesimal, which is likely to be an iron-rich rocky remnant of a destroyed planet (during the star's red giant phase), is immersed within a dusty disk of its own, thought to be emanating from what non-rocky remains are left upon this shattered world. Dusty disks around white dwarfs are known, but remnant planets are rare. For me, this begs the question whether these dusty disks might re-accrete planets? Could planets re-form, building up again from the iron-rich planetesimal cores left over following the collapse of the red giant? This would be a new example of planetary recycling, offering the opportunity for a new category of exoplanets 'born' around dead stars.
Image Credit: University of Warwick/Mark Garlick)
Another recent debating point about planetary growth involves the potential for life to get started on small planetesimals (5). The age of life on Earth is variously considered to be 4.1 billion years old, but possibly as old as 4.3 billion years. This compares with the age of the solar system at 4.6 billion years. Scientists from a broad sweep of disciplines are wondering whether life got a foothold on the smaller planetary/asteroidal bodies that eventually accreted into the terrestrial planets, including Earth (6). If so, then this would set the date that life began in the solar system way back to the pre-solar nebula, emerging from organic-rich broths within the growing planetesimals.
Separately, but potentially connected, is the idea that some of the content of the protoplanetary disk originated from beyond the solar system. The discovery of the interstellar asteroid/comet 1I/'Oumuamua, which sped through the solar system recently, has sparked a debate about how much interstellar material is available to populate the solar system (7). The answer, potentially, is quite a lot - astrophysicists think there may have been a minimum of 10 million such objects in the solar system's protoplanetary disk, and that they may have been able to seed accretion of larger planetesimals (8). Not only would this speed up the process of planetary formation, but it would also introduce ancient materials from the cosmic neighbourhood. Interstellar comets may be the progenitors of planetesimals, but they may also bring with them the seeds of life which had developed elsewhere in the Cosmos. In this way, life could get a kick-start very early on in the life of a star system, through the dispersion and propagation of life by interstellar comet seeds.
Written by Andy Lloyd,12th April 2019
1)European Southern Observatory "Young planet creates a scene" 26 February 2018
2) Phil Plait "Wait. *How* fast do giant planets form?" 4th April 2019
3) D. Fedele et al. "ALMA continuum observations of the protoplanetary disk AS 209. Evidence of multiple gaps opened by a single planet" A&A 610, A24 (2018)
4) Mike Wall "Shard of Shattered Alien Planet Spotted Around Dead Star" 4 April 2019
5) Mike Wall "Life May Have Evolved Before Earth Finished Forming" 25 April 2019
6) Lindy Elkins-Tanton "Life on Small Bodies: Breakthrough Discuss 2019" YouTube 17 April 2019
7) Phil Plait "Could interstellar visitors like Oumuamuaactually help planets form?" 25 April 2019
8) Suzanne Pfalzner & Michele Bannister "A hypothesis for the rapid formation of planets" 15 March 2019
An international team of astrophysicists have found a correlation between comet hyperactivity (particularly among the Jupiter Family Comets) and the deuterium-hydrogen isotope ratios of their ejected waters (1). Many of them, although not all, exhibit similar values for the D/H ratio as that found in ocean water on Earth.
Because of its position in the inner solar system, the Earth should have formed as a dry, desiccated husk: It is too close to the Sun for water to have survived on the protoplanet. Yet, as we know, water is available in abundance on this planet. This is a mystery which I have explored in some depth in my books 'Dark Star' (2005) and 'Darker Stars' (2018), because this could provide evidence for alternative ideas about the origin of Earth. The science in this area is complex and multi-factorial (which is why plenty of space needs to be devoted to it within a book). Nonetheless, the variation in D/H ratios across the solar system can potentially tell us much about the conditions under which the Earth formed, and whether the water was added later by comets and/or asteroids.
The new paper considers whether some of the variation in cometary D/H ratio values is down to how much of a comet's surface is active. Some of the ejected water in so-called 'hyperactive comets' has been found to be tied up in ejected dust grains from the comet, which then release the additional water into the coma by sublimation. Because these hydrated dust grains seem to preferentially combine with deuterated water, active comets ejecting the grains into space exhibit high relative abundances of deuterated water. As a result, a correlation emerges between hyperactive comets and terrestrial water values. Other less-active comets do not seem to undergo this fractionation of water in quite the same way, likely because of a lack of water ice on or near their surfaces.
If this finding could be extended broadly amongst comets (and there are plenty of reasons why it might not!) then the explanation for the origin of terrestrial water may swing back towards comet deposition through collision. The location where comets form is crucial here. If they form beyond the 'snowline' in the solar system, then their water content is explainable, and a trend towards higher deuteration could build as the distance of formation extends outwards. Again, this is complicated by the potential for many bodies in the solar system to migrate about and change their locations over time.
I've often argued that the Earth's initial position could have been further out than it currently is, to a location beyond the 'snowline' >3AU from the Sun. Such a possibility has one major advantage over the assumption that the Earth formed in its current location: it would readily explain the presence of its water. I recently put this to leading astrophysicists Michele Bannister, who replied with the following point:
"The problem is not so much migrating Earth as getting it to survive Jupiter migrating, particularly if the grand tack was indeed an event. So it doesn't tend to get moved more than a bit of an AU. Inner solar system has a lot less room to play with." (2)
I'll be honest - I have a different basis for how Earth got shunted into the inner solar system... but then that's all very speculative. I think there's some flexibility built into this, because the theoretical models generally assume that only the current set of planets are players in the early solar system, with Jupiter and Saturn (and to some extent Neptune) being major players in any major migratory events. The Nice model (incorporating the 'grand tack' Michele mentions) may be the generally accepted model (and does, to be fair, explain a fair old bit), but there remain other tantalising possibilities, too. Shunt the Earth out a bit at the beginning, and terrestrial water become a lot less of a puzzle.
Written by Andy Lloyd,24th April 2019
1) D. Lis et al "Terrestrial deuterium-to-hydrogen ratio in water in hyperactive comets" 19 April 2019
2) Correspondence from Michele Bannister replying to @darkstarandy, 23 April 2019
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