Geosonnet 69

An accidental drilling in the deeps
Reveals a sleeper agent- felsic melt
Invisible to seismic, magma sleeps
Until basaltic trigger card is dealt.
Diffraction limits fuzz the chamber’s sides
Viscosity impedes acoustic tests
A covert, dried out dacite simply hides
Above basaltic plumbing, long at rest.
Three hundred years, this hidden magma sleeps
Until it’s poked by hydrothermal drill.
Old pumice, cuttings from the drilled-out deeps
Show magma lurking, poised to blast and kill.
Basaltic dykes wake sleepers from their doze
Do not ignore the hazard this can pose!

 

Geology 49 521

 

Other geosonnets: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64  65 66  67 68 69

Geosonnet 68

A hickory, a dickory, a dock
Diffusion rate of mice when timing’s known
But atoms, unlike rodents, have a clock
Which contradicts the others, all alone.

“A thousand Years,” says fat man Barium.
M-g squeaks, “Nah mate, more like less than one.”
T-i says, “Where’s my honorarium?
I can’t work here, diffusion’s not begun.”
He’s right! The two plus profiles haven’t moved.
The curves are melt dilution marks instead
The timescale’s not millennia, it’s proved
It’s more like months, and barium misled.
   Basalt melts felsic crystal mush so fast
   A season’s all you get before the blast.

Geology 43 695

Other geosonnets: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64  65 66  67 68

Geosonnet 64

When Perseus, Medusa’s head in hand,

Returned triumphant from the Gorgon’s isle,

He sold himself as hero of the land,

No stony witnesses could cramp his style.

When older larger monsters were destroyed,

No Greek boast twisted dinosaurs’ last stand.

To know the source of mammals’ schadenfreude,

Interrogate the Gorgon Island’s sand.

A spherule bed is present in the rock

Old microtektites still containing glass

The argon age is Chicxulub’s great shock,

American ejecta cumulates en masse.

   Thus impact-based extinction we construe.

   With mythic monsters vanquished, ferns regrew.

Geology 46 547

Other geosonnets: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 

Sierra Sequoias from space

I wrote last year about the big trees of the Sierra Nevada mountains in California. One if the things that interested me was the ability of the Sequoia and the Sugar Pine to grow side-by-side, despite having very similar survival strategies- namely grow taller than everything else and live long enough for fire to clear our the shade tolerant trees so that your seeds can germinate.

Of course, as anyone who spends time on the forest knows, despite these trees having similar niches, they look quite different. The both have large trunks often bare of branches for the first 100 feet, but their vegetation has different forms. The Sugar Pine has very long, straight lateral branches, like the spars of a ship, while the sequoia crowns are more rounded. And because these trees are very large, it turns out that you can easily distinguish them in Google Earth. Here is a screenshot of the same grove I wrote about last year:

You can clearly see the long lateral branches on the pines (which also have somewhat bluer foliage). The larger, yellower trees with very wide trunks and rounded foliage are the sequoias.

Unfortunately, the sugar pine is in decline in many areas of its range, Here is a picture of dying trees in the national forest just south of the park:

The most obvious thing here is that the Sugar Pines are mostly dead. But there are other differences. Unlike in the National Park, here you cannot see the ground- the trees are growing too close together. One critique of the Forest Service is that it as lagged behind the Park Service in the use of controlled burns and recurrent fires. While I don't have the fire history of this exact area, the much thicker understory could be the result of decades of fire suppression. And if those trees are sucking up all the water, perhaps that has stressed the pines.

The Greenland impact crater

This is a brief note on the recent Science Advances paper on the Hiawatha Impact crater, a large, recent crater which lies under the Hiawatha glacier in extreme northern Greenland.

In the past, I have bagged out impact crater scientists and being alarmist and even dangerous. However, this discovery is the real deal. Similarly, I have occasionally criticized the “glamour-mag” approach to scientific publication, but in this instance, a big splash is appropriate, because it is a big deal, and the evidence is overwhelming.

The short version: Ice penetrating radar and analysis of glacial outwash sand show a large (31km diameter), recent impact crater under a Greenland glacier, complete with central peak. The outwash shows shocked quartz, probable melt glass, and PGE anomalies consistent with an iron (or stony iron) impactor. This is not one of those ancient, deformed, maybe-if-you-squint-you-can-see-a-circle crators, this is in your face and completely obvious to anyone who has studied even a little geology.

Like many short format papers, a lot of the details are in the supplementary materials.  For example:

This is a recent discovery because of global warming! Prior to 2012, the outlet glacer emptied into a lake. It is only ni the last 6 years that it has retreated onto land, so that the sediment they sampled and found the shocked quartz, impact glass, etc in was only exposed from beneath the melting ice sheet a few years ago.

They are planning on running conventional gravity surveys to look for rebound, but because all the ice is melting, the melt signal dominates the GRACE gravity signature.

No known impact ejecta is known from any of the North Greenland ice cores, making the crater likely to be older than the oldest of them (about 100ka). Ice cores are regularly checked for volcanic debris, and it is unlikely that they would miss something this large and close (quick math suggests the ejecta volume should be about 200-600 km3, making it a medium to large VEI-7 equivalent).

The crater overprints pre-glacial river valleys, and this is (as the authors state) probably Pleistocene in age (10ka-2.5Ma).

The melt glass should be datable via Ar/Ar dating, but it is not clear if they have recovered a large enough volume of the material to date at this stage.

I would expect a tektite field from an impact this size, but it isn’t clear where those tektites would end up. If they fell on ice (By definition, the Arctic was mostly ice-covered during most of the Pleistocene), then they would get carried to a moraine (on land), or float around until the ice was exported through the Fram Strait and melted somewhere in the NE Atlantic Ocean.

There is a controversial Younger Dryas impact hypothesis, which basically calls for an Arctic impactor as a trigger for the Younger Dryas cooling and extinction of the Clovis culture in North America. I would be careful connecting this crater to that event, as the NEEM ice core, less than 400km away, doesn’t have any reported ejecta, as known tephra are mostly basaltic. 

Finally, they report carbon in the silicate impact melt. That seems odd to me, as neither crustal gneisses nor iron meteorites have much carbon.  they should do ion probe d¹³C to get the isotopic composition. Who knows, maybe the impactor hit a peat bog.

  

Book Review: The 2020 Comission Report into the North Korean Nuclear Attacks...

Book review: The 2020 Commission Report into the North Korean Nuclear Attacks against the United States

By Dr. Jeffrey Lewis

This book is a speculative fiction story about the use of North Korean nuclear weapons in the near future- specifically early 2020. Speculative fiction is nothing new. But unlike Harry Turtledove or John Birmingham, Jeffrey Lewis is, in addition to being an author, a world expert in nuclear proliferation and arms control. The book’s format, closely paralleling the 9/11 report down to the opening paragraph, plays to this strength. However, despite the author’s academic and think tank background, this book is a gripping page-turner, make all the more compelling by its fact-based and thoroughly researched nature.

The book describes a possible scenario in which poor communications and saber rattling result in the DPRK shooting down a commercial airliner en route from the Republic of Korea to Mongolia, and the subsequent escalation and miscommunication that leads the North to launch a pre-emptive tactical nuclear strike, under the mistaken impression that it is under attack. This then escalates to an all-out war, with the DPRK’s long range missiles striking several US cities, with millions of casualties.

The book is a page turner. I read it in a single sitting the day after I got back from Korea. However, because Dr. Lewis is an arms control expert, and not a novelist, it also comes with 20 pages of references for the 270 page novel. As such, it is as much a report in narrative form (much like the actual 9/11 report) as a story in its own right. Except, of course, this book is a report on a disaster that has not (yet) happened.

Overall, it was a good read, both entertaining and educational. Dr. Lewis is obviously knowledgeable on nuclear weapons, their effects on human health, and the havoc they wreak on civilian infrastructure. And he uses his expertise to great effect. While reasonable people can argue about in what areas historical records are pertinent and in which areas technological change has made them obsolete, his well referenced arguments are an excellent place to start any discussion, whither you agree with his points or not.

I found a few things disappointing. The main thesis of the book is that the DPRK, if it believed it was under conventional, regime-changing attack, could use nuclear weapons tactically, (or at least locally) to give itself a chance. This hypothesis was never really investigated in any detail, however, which makes to difficult to judge how rational such a counter strike would be.

My main complaint, however, is that Dr’ Lewis cannot refrain from taking cheap shots at President Trump, when describing the American response. He does have some reasonable criticisms around issues like the President’s lack of appreciation for communications security and the difficulty in responding to a crisis from his various private properties. But he also takes generic liberal cheap shots, which don’t build his case and are distracting from his well researched work. More ominously, they risk politicizing nuclear war, an outcome which everyone should be trying to avoid. We all know what a debacle the polliticization of Global Warming has been; imagine how much worse things could be if the same thing happened with Nuclear War. In fact, while he doesn’t specifically mention this possibility, there are hints at how hyperpartisanship could risk nuclear stability. But that is another topic for another day.

IPCC 1.5 degrees of obfuscation

So, the Intergovernmental Panel on Climate Change released an important document today, allegedly demonstrating that 1.5 degrees of warming is preferable to 2 degrees, and that with an enormous about of effort, we might actually be able to achieve it. I, an Earth Scientist with a PhD and 17 years of professional experience, tried to read it, because it is important, and good scientist citizens ought to at least try to do the right thing.

Unfortunately, the report, as I found it on the IPCC website, is an incomprehensible tangle of bureaucratese and parenthetical rabbit holes. For example:

A1.2.
Warming greater than the global annual average is being experienced in many land regions  and seasons, including two to three times higher in the Arctic. Warming is generally higher over  land than over the ocean. ( high confidence) {1.2.1, 1.2.2, Figure 1.1, Figure 1.3, 3.3.1, 3.3.2}

A1.3.
Trends in intensity and frequency of some climate and weather extremes have been detected  over time spans during which about 0.5 ° C of global warming occurred (medium confidence). This  assessment is based on several lines of evidence, including attribution studies for changes in  extremes since 1950. {3.3.1, 3.3.2, 3.3.3}

A.2. Warming from anthropogenic emissions from the pre -industrial period to the present  will persist for centuries to millennia and will continue to cause further long-term changes in  the climate system, such as sea level rise, with associated impacts (high confidence), but these  emissions alone are  unlikely to cause global warming of 1.5°C (medium confidence ) {1.2, 3.3,
Figure 1.5, Figure SPM.1}

 It has all of the pitfalls the 9/11 report managed to avoid, in terms of failing to ensure accessability, readability, and currency to your average human being. In fact, it comes across as a fantasy edict beamed down by aliens, which is probably not too bad a description of Ivory Tower science these days. For example, It spends lots- perhaps most (I've pretty much glazed over a third of the way through the Summary for Policy Makers- you know, the part that should be clear and simple for non-specialists) of the time describing the benefits of aiming for a 1.5C warming target instead of a 2 degree target.

Of course, we aren't on course to hit a 2 degree target. We are on course for a 3 or 4 degree target. So the relevance of the report is completely at odds with the reality of the world we live in. Now, there are technical reasons why it is hard to write a report describing the difference between 4 degrees and 3.5 degrees. It has been tens of millions of years since the world was that warm, so reconstructing that climate is much more difficult than a 1 or 2 degree warmer world, which we had an order of magnitude more recently. So explaining where we are going is actually quite hard. But they don't even try, or acknowledge this. Instead they are off in this fantasy land where we all have ponies, and they want to sell us on the benefits of unicorn horns and sparkles in the manes.

However, this may be more of a dark fantasy than a rainbow pony fantasy. The "target" CO2 emission reductions curves (Figure SPM.3a) they show have no rollover or transition period, but drop precipitously from the present day at a rate comparable only with that seen in the collapse of the USSR. They don't explicitly talk about this, but there is a blathering world government waffling towards the end that goes:

D7.2.
Cooperation on strengthened accountable multilevel governance that includes non-
state actors such as industry, civil society and scientific institutions, coordinated sectoral and cross-
sectoral policies at various governance levels, gender-sensitive policies, finance including innovative
financing and cooperation on technology development and transfer can ensure participation,
transparency, capacity building, and learning among different players (high confidence). {2.5.2,
4.2.2, 4.4.1, 4.4.2, 4.4.3, 4.4.4, 4.5.3, Cross-Chapter Box 9 in Chapter 4, 5.3.1, 4.4.5, 5.5.3, Cross-Chapter Box 13 in Chapter 5, 5.6.1, 5.6.3}

In otherwords, the governments of the world, which are currently assassinating skeptical journalists,. locking up children, and dropping trillions of dollars of bombs in proxy wars which endanger millions of people,  all just have to join together and sing kum-by-yah while dismantling their transportation and industrial facilities, and we'll all be fine. Frankly, I suspect we're more likely to solve global warming with nuclear winter at this point, at the IPCC report gives me no hope that they have a more reasonable or concrete plan.

In summary, the world experts on climate got together and wrote an unreadable report.  If you piece the bits and pieces that might mean something together, it awkwardly hints that saving the planet is completely possible if the entirely of human nature and politics is magically transformed in the next year.

In other words we, every one of the 7.8 billion of us, is totally, completely, and thoroughly fucked.

Total eclipse of the Death Star

Happy Eclipse day!

Congratulations to everybody who is lucky enough to live in the eclipse path, or who made the effort to get under the shadow of the moon! I hope it was grand; I was on the wrong side of the planet this time, so I have had to enjoy it via the internet.

Of course, the Internet likes to have fun, so along with the various actual eclipse photos (which range from cool to spectacular), there have been some pictures replacing the black disk of the moon with the DeathStar.  Long time readers of this blog will know that this Lounge has a great view of imaginary spacecraft in orbit; the Death Star fits into that category nicely. So with a bit of basic math and physics, we can calculate the conditions under which the Death Star can eclipse the sun, as viewed from here on Earth.

But first, we need to define our Death Star. I won’t dig too far down into the seedy underbelly of Srat Wars fandom, but a oft repeated figure for the size of the Death Star is a diameter of 100 miles, which yields an 80km radius. As for the density (which we’ll need later for reasons I don’t want to spoil), we will go with 800kg/m3. This is the density of something that is 10% steel and 90% air, which would give it the same general construction as modern naval vessels. This makes the Death Star slightly more dence than pure ethanol, but substantially lighter than the beer which fuels this blog.

In order to eclipse the sun, the Death Star needs to subtend a larger angle of sky than the Sun. For the sake of simplicity, we will call the sun angle 0.5 degrees, or 30 minutes of arc (it actually varies slightly, as the Earth’s orbit is elliptical, and the eccentricity of this orbit changes between 0 and 6 percent depending on where in the Milanković cycle we are). So, given a 80 km radius, the Death Star can eclipse the sun if it is closer than 80/sin(0.25deg)= ~18,300 km.

This is much farther than near Earth orbit, but much closer than geosynchronous orbit (about 36,000 km altitude). It is also, of course, about 21 times closer than the Moon, which is about 21 times larger than the Death Star.  However, it means that if the Death Star was in Geosynchronous orbit (to ‘hover’ over a target, for example), it would not eclipse the sun; it would block out at most a quarter of the light, which would be barely noticeable by people down below.

On the other had, if the Death Star was in low Earth orbit, like the International Space Station, it could easily eclipse the Sun. An 80km radius space station only 360 km up would be huge from the point of view of an observer directly underneath, blotting out more than 25 degrees of arc in the sky as it zoomed past at 8 km/sec (or one diameter every 20 seconds). However, it isn’t clear if the Death Star could fly this close to our planet.

The orbital velocity of a satellite around the Earth, in meters per second, is sqrt(GM/R), where G is the Gravitational Constant (6.67E-11 m³kg^-1s^-2), M is the mass of the Earth (6E24 kg), and R is the radius of the orbit IN METERS (not km). So with an orbital radius of 6700 km (329km above the mean surface), the orbital velocity is 7728 m/s. The problem for the Empire is that the Death Star has a radius of 80km, so the guys sitting in the gun turrets facing the Earth only have an orbital radius of 6620 km. Thus they will be orbiting at 7775 km/s, 47 m/s faster than the space station. For people who live in the real world, that’s a 105 miles per hour, or 165 km/hour difference. Smashing your troops against the walls at a hundered miles per hour is going to impede their ability to fire their super laser, and it is possible that even the structural integrity of the Death Star would be under threat this close to the Earth.

Back here in Science Land, we call the closest that a satellite can get to a planet without being torn apart by this sort of differential orbital speed the Roche Limit. The Roche Limit determines the closest approach a satellite can orbit a planet without being torn apart. Technically, the Roche limit only applies to objects held together by gravity- e.g. with no tensile strength. Steel, the purported structural material of the Death Star, has substantial tensile strength- this is why it’s used for everything from bicycle spokes to suspension bridge cables. But even if the space station is held together by the tensile strength of the steel, that will be little comfort to everything and everyone that isn’t tied down; even if the Death Star could survive inside the Roche limit, the occupants wouldn’t. So in order to know if a fully operational Death Star can eclipse the sun, we need to calculate the Roche Limit, and determine whether it is closer or farther than the maximum eclipse distance of ~18,300 km calculated at the top of this blog post.

The Roche limit equation is d = R (2 rho_M/rho_m)^1/3, where

R is the radius of the Primary, rho_M is the density of the primary, and rho_m is the density of the moon. And the assumption we are using is that the density of the death star is 0.8 g/cc or 800 kg/m³ (a bit less than my second beer).

 

As for the other numbers, the Earth’s radius is 6371km, and the earth’s density is 5500kg/m³. So the Roche limit for the Death Star is 15,263 km.

This is closer than the maximum eclipse distance of 18,300 km (which is a distance, not a radius, so you can add up to 6371 more km for an equatorial eclipse viewer), so there is a range, albeit a fairly well restricted range, in the orbital radius of roughly 16,000 to 24,000 km where the Death Star is far enough from Earth to not be tidally disrupted, but still close enough to blot out the sun. But it wouldn’t be blotted out for very long. A 16000 radius orbit has an orbital velocity of 5 km/s. So even with an equatorial observer only 10,000 km away, where the shadow is largest, at 72 km wide, totality would last less than 15 seconds. This is almost the exact elapsed time from Tarkin’s “Fire when ready” to weapon discharge. And Bonnie Tyler wouldn’t even have time to get a little bit tired of listening to the sound of her tears.

Nickel and timed

One of the problems with studying the origin and evolution of life is that our mother Earth has a shady memory.  The farther back in time we go, the rarer and more fragmented the rock record becomes. What this basically means is that for most of the first third of Earth’s history, we run out of rock record before we get back far enough it time to discover the origin of various fundamental early steps in our own evolution. Even for more recent developments, like the oxygenation of the atmosphere and the recent great extinction events, the rock record is frustratingly incomplete. This has several effects.

On the observational side, it requires scientists to draw bigger and bigger conclusions from slimmer and slimmer data. Was there life in the Hadean? If all you have is a pinhead pile of ground up zircons, there is only so much evidence you can put forth.

On the theoretical side, there is of course even more speculation and unconstrained hypothesizing. With older rocks more common on smaller, deader worlds, and hypotheses like Panspermia positing that space is no barrier to the spread of life, there is literally a universe of possibilities. As a result, many theorists have lapsed into quasimystical approaches to the framework for how life has evolved from very early primitive micro-organisms to space age simians who none-the-less waste their time reading this blog. The approaches generally fall into two broad categories.

The first is the “Manifest Destiny” approach. This school of though believes that life is an unstoppable, inexorable force that will climb every mountain, contaminate every spacecraft, and spread in an inexorable evolving wave throughout the universe. Most astrobiologists subscribe to this belief, as it is easier to justify your life’s work if you think that there is actually something out there to find.

The second is the “There but for the Grace of God” approach, which envisages life as a blind, reactive encrustation to grand events and processes far beyond its control. Proponents tend to be hard rock geologists and extinction researchers.

It is important to note that these are hypothetical endmembers- most researchers lie on a solid solution between them, albeit generally closer to one end than the other. It is also important to note that although I have deliberately used non-scientific labels, as these leanings are often manifestations of inclination rather than deduction, an inclination towards one camp or another is in no way an indication that a particular research is not a great scientist. Rather, it is an attempt to colorfully illustrate two diametric approaches taken to thinking about the early history of life.

Tonight, however, I’d like to draw attention to a paper that combines these approaches in a fascinating way. Konhauser et al. 2007 posit an Archean Earth where Nickel-dependent methanogens had evolved to become the dominant life form on the planet. The oxygenation of the Earth’s atmosphere was not a result of oxidative photosynthesis evolving and outcompeting the methanogens. Rather, the decrease in high-temperature, nickel-rich komatiitic volcanism at the end of the Archean weakened the methanogens by creating a shortage of the nickel they needed to survive, reducing methane production and allowing oxygen producers to take over.

            Scientifically, this idea is appealing because increasing lines of evidence, such as that summarized in Geosonnet 21, indicate that oxygen production was going on long before the great oxygenation at a limited local level. But for hundreds of millions of years, it was never more than a transient, small scale local phenomenon.  This hypothesis is also nice in that it ties the large scale tectonic and igneous changes between the Archean and the Proterozoic with the change in atmosphere. Linking those two fundamental shifts in the Earth’s history is always nice, as having them coincidentally synchronous seems somewhat implausible.

            On a purely personal level, however, the proposed narrative reminds me of the H. P. Lovecraft novel, “At the Mountains of Madness” The difference is that the Archean overlords who ruled the hostile ancient Earth were not 3 meters tall. They were 3 microns tall instead. And it was mantle convection, not decadence in intergalactic civilizations, that allowed our distant aerobic forbearers to liberate their planet.

The wrong kind of Bang

In science education and popularization, there is a delicate balance that must be struck between overcomplicating and oversimplifying. Insufficient simplification can result in overly obtuse deviation into secondary details, which confuse and distract the readers and derail the flow of the prose.  Excess simplification can be wrong.  And this is where the Medium article by Ethan Siegel of “Starts with a Bang” fame has ended up. 

Dr. Siegel argues that the recent Philae comet lander would have more successful if it had been powered with a ²³⁸Pu RTG device instead of solar panels.  However, his simplified argument ignores the reality of ²³⁸Pu fuel production, the definition of “we”, and the nature of comets.

²³⁸Pu is a byproduct of the nuclear arms race between the USA and the USSR. It is created by neutron activation of ²³⁷Np, which in turn is a byproduct of ²³⁹Pu production for nuclear weapons. With the nuclear arms deals of the 1980’s the superpowers stopped building nuclear weapons by the tens of thousands, and the cheap source of ²³⁷Np disappeared.  The USA stopped ²³⁸Pu production in 1988, all subsequent material has come from Russia, which has almost depleted its stockpiles.

This brings us to the definition of “we”.  As the battleground over which the USA and the USSR fought, Europe never developed its own mass nuclear warhead production facilities; the UK and French arms supplies are only a tiny fraction of the size of the 20^th century superpowers.  As a result, Europe has never had its own large scale ²³⁸Pu production facilities. 

Philae was a European mission, not a USA or Russian one, so the ESA (European Space Agency) did not have access to ²³⁸Pu needed for RTG production.  NASA (USA) and the ESA (Europe) are separate space exploration entities, a point that was very unclear from this article’s frequent discussion of NASA and Philae.

Finally, RTG’s are hot, and comets are cold. The Philae lander was a very risky mission- there was a significant chance that it would not succeed at all, and in the end the lander ended up bounding off an unexpectedly hard surface several times before ending up on its side in a crater.

Comets, by definition, evaporate at low temperatures- this one is jetting out gasses despite being way out beyond the asteroid belt. So landing a heat-producing source on it, especially on a lander that ended up tipping over, would end up in a situation where the lander could drastically alter the local environment of the comet through thermal contact.  The whole point of the mission is to sample a comet in as pristine condition as possible, so potentially cooking the comet due to a landing mishap is not really a sensible design choice.

Dr. Siegel is correct that ²³⁸Pu is crucial for missions that operate beyond the orbit of Jupiter.  But the fuel used on previous missions was subsidized by the nuclear arms race.  It, and all the wondrous outer solar system exploration it allows, was an unintended byproduct of Mutually Assured Destruction, and the tens of thousands of nuclear weapons that policy produced.  Since the arms race ended, production of this isotope for the sole purpose of planetary exploration has been deemed too expensive to pursue by all the world’s governments.  Until we collectively decide to blow ourselves up again, this barrier to outer solar system exploration will continue.

A brief word on Earthquakes and fracking.

Since the Keranen et al. paper a few months ago, there has been much discussion on the relationship between earthquakes and wastewater disposal wells from unconventional hydrocarbon extraction (a.k.a. fracking).

Most of this discussion related to earthquake swarms on Oklahoma, where seismicity has dramatically increased in recent years.   However, it is worth pointing out that Oklahoma is by no means the biggest fracking state.  That is Texas, with almost ten times the oil production of Oklahoma.  The USGS produces earthquake maps of every state, ad Texas (and Oklahoma) can be seen here: 

What is immediately apparent is that despite the much larger size and production, Texas has slightly fewer quakes.  The next biggest fracking state, after Texas, is North Dakota, which has recently surpassed Alaska and California to be the USA’s second biggest oil producer (three times more than Oklahoma).  Its earthquake map looks like this:

Even the Keranen et al. paper stresses that many injection wells are aseismic, and that a mere four wells account for the majority of earthquakes. This sort of attention to detail is important to consider when evaluating this technology.  Understanding facts and details is the first step in uncovering processes which we can then use to improve our use and stewardship of natural resources.

And finally, just for comparison, here is the seismic map for Alaska, which I’m putting up here because of the beautiful Benioff zone which has nothing to do with petroleum at all.

Don’t weaponize space

On the Planetary Society  website, the normally responsible and pro-science Planetary Society has posted an opinion piece by Louis Freedman and Tom Jones asking NASA to reconsider its refusal to fund the Asteroid Redirect Mission.  In short, this is a mission to kidnap a small asteroid from elsewhere in the inner solar system, and redirect it towards the earth, hopefully parking it in the most stable lunar orbit they can find (the Moon’s uneven gravity, and the tidal interactions between the Earth and Sun, tend to make most lunar orbits unstable).  Once there, the asteroid can do three things:

1. Fall into the Moon.

2. Fall into the Earth.

3. Be ejected into an Earth-crossing orbit around the sun.

One of the goals of this project is to give manned space missions a target that is easier to get to and from than either a wild inner solar system asteroid, or the Moon.  Because this will give them a stepping stone to Mars. 

The prospect of asteroid redirection technology being used to crash asteroids into the Earth doesn’t seem to faze Drs. Freedman and Jones; they don’t lay our any risk assessment or amelioration plans.    But an asteroid strike on Earth, especially a targeted asteroid strike, could be extremely damaging, as only nuclear weapons are capable of putting as much energy into the atmosphere in a comparable amount of time. And any asteroid-fetching spacecraft could be communicated with by a dish pretty much anywhere on Earth at some points during its flight. 

Amateurs often build radio receivers, point them at the sky, and listed to NASA spacecraft.  To date, nobody has managed to hack one, but there has been very little incentive to do so.  Putting a asteroid redirecting spacecraft into the inner solar system that is a computer hack away from becoming a weapon of mass destruction seems like a pretty rash thing to do, so I am surprised that the Planetary Society is advocating this.

Never complain about your stove again

Geologist have it pretty easy, in terms of lab safety.  Compared to chemists and biologists, we have to deal with a relatively low number of lethal chemicals, and our habits confirm this.  It is not coincidence the people call us rock-lickers.  But there are still some reagents which are genuinely dangerous, and command respect.

For most rock knockers, the chief among these is hydrofluoric acid, or HF.  HF is a volatile (evaporates easily) acid which is notorious for being a contact poison.  You don’t have to drink it for you to kill you, as it will diffuse through skin, and attack muscle tissue and bone inside your body.  If the muscle it attacks is your heart, then you die.  As a result, geologists are taught from a young age to observe strict safety protocols with HF: gloves, face shields, aprons, appropriate supervision and fume cupboards are all part of the drill.

But not all fluorine health effects are as dramatic.  excess fluorine consumption can often cause dental fluorinosis, a condition in which excess fluorine is deposited in the teeth, discoloring them.  In more severe cases, fluorine deposition in the bones can lead to osteofluorosis, which can cause disfigurement, deformity, and chronic pain.

One area in which osteofluorosis is distressingly common is Guizhou, China.  Over the past decade, this disease here was linked to the combustion of high Fluorine coal.  Studies showed tha the clay that was intermixed wit hthe coal was high in F, and a steady stream of recommendations has come along describing how this must be getting aerosolized in smoke ,and adhering to food, particularly corn and chilies hung up in houses to dry.

But something didn’t add up.  People were educated to wash their vegetables, to not breathe coal smoke, and still the disease persisted.  Finally, recent studies showed that the F was not adhering to the food products.  TOF SIMS showed that  it appeared inside uncut chilies, and sometimes was associated with silica- particulate matter which should not be able to penetrate food and is biologically inactive.

This was the key to a renewed investigation into the coal.  Which, as it turns out, was not just rich in fluorine, but also rich in pyrite- fools gold.  And all of a sudden, everything fell into place.

When burned, pyrite reacts exothermically with oxygen and water to form iron oxide and sulfuric acid:

2FeS₂ + 8.5O₂ + 4H₂O -> Fe₂O₃ + 4H₂SO₄.

Sulfuric acid is not great to breathe, but it doesn’t cause fluorine poisoning.  It will, however, react with fluorite (the most common fluorine mineral like this:

H₂SO₄ + CaF₂ -> CaSO₄ + 2 HF

And there is the chemical that terrifies geochemists even in controlled lab spaces, HF, being generated in the household stove. It, in turn reacts with coal ash to form the toxic gas SiF₄, which permeates plant and animal tissues and deposits silicon inside of vegetables. In short, domestic cooking stoves are generating incredibly toxic F-bearing gases inside the home. Not even your brother-in-law’s cooking is as hazardous as this.  This was the coolest talk from the session I was fortunate enough to chair this afternoon; there is a paper here.

There’s no such thing as a climate scientist

 Here in Australia, the new Coalition government, which won office in 2013 on a head-in-the-sand approach to climate change, is busy dismantling all of the federal early warning and advisory bodies on climate.  There are snide gloating remarks floating around the internet to the effect that the climate scientists have been exposed, and that the conservatives need to cut the dole before these fake scientists can get any more government money. The election of Donald Trump to the American presidency in 2016 has generated similar chatter on their side of the internet. However, these ungracious comments also suffer from factual deficits.  There are no climate scientists; there are only scientists who study climate.

       Most of these scientists are Earth scientists. However, a substantial and growing proportion of them are also physicists, astronomers, mathematicians, meteorologists, and other physical scientists. The type of scientist generally describes how they attack scientific problems, not which problems they attack.

     A person who has mastered the physical and chemical tools that allow us to understand the Earth system can apply those tools to whatever knowledge suits their fancy.  I know el Niño experts who started out on gold mines, and frackers who started out studying el Niño.  I know isotope specialists and paleontologists who have applied their skills to both ocean heat uptake and oil & gas exploration.  Even Tim Flannery, the recently sacked chief of the climate commission, had a previous career in vertebrate paleontology.  

       So you don’t need to worry- or gloat- that the end of climate funding will mean these climate scientists will have nowhere else to go.  Sure, they will be disruptions, but the same skills that make them good at climate will let them pursue other Earth Science goals, or other careers that value the ability to constrain complex systems with limited and unusual data.  Many of these folks may even stay in climate, generating predictions that inform insurance companies who to raise rates on, or hedge funds who to divest out of. In fact, they might even end up better off.

There is an oft repeated criticism of climate researchers that they are only in it for the money. But nothing could be further from the truth.  Most recipients of university and advanced degrees in physical science are able to pull down significant salaries, because people who have these skills can solve a wide variety of important and lucrative problems. It is hard to say exactly how much a climate scientists is underpaid by, since academic career tracks are notoriously fickle, and comparative industry tracks often have share options, bonuses, profit sharing, or other financial inducements which can be difficult to predict. But by applying a broad uncertainty envelope, I think it is safe to say that from the moment a geologist finishes their undergraduate university degree, choosing a career in climate research rather than energy or mineral resource extraction generally results in a lifetime earnings deficit of somewhere between one and five million dollars. So climate researchers are not fattening up at the research funding trough. They are quite literally sacrificing a fortune to determine what kind or world we will be leaving our children.

    What this means is that the recent shuttering of government climate organizations will not mean the end of climate scientists, or even of climate science.  It simply means that Australians- and now possibly Americans- as a whole will no longer be the beneficiaries of their immense talents. Even if you, the reader, don’t have a job, these scientists will. It’s just that they won’t be working for you- or the rest of the public-  anymore; they’ll be working for someone much richer than you are, who probably doesn’t share your interests or values.

updated: 14 June 2017

Putting the Russian meteorite in perspective

Friday morning, a large meteor entered the atmosphere over the southern Ural area of Russia, detonating with enough force to shatter windows in nearby towns and injure over 1000 people.  Preliminary estimates suggest an impactor traveling at 15 to 20 km/s, and weighing 8000 to 10,000 tons, exploding at an altitude of 20-30 km with the force of a nuclear weapon.

These are hard numbers to wrap one’s head around.

Let’s start with the size. There are numerous reports around on the bolide being “bus sized.”  But buses are not made of solid rock, so this is deceptive. In this situation, mass is more important than dimensions. A bus weighs about 15-20 tons. That’s a lot less than 8000-10,000.  For example, 8000-10,000 tons is the approximate size of the naval destroyer USS Cole, which was famously attacked by Al Qaeda in Yemen in 2000. It’s a lot bigger than a bus. Of course, that ship doesn't fly in space.  Rather, it sails in the ocean at about 50 km/ hour, thousands of times slower than 20 km/ second. The International Space Station is about 450 tons.

Orbital velocity for a low earth orbit is about 8 km/second, and reentry speeds returning from low earth orbit are similar.  So this meteor was traveling at about twice orbital speed when it hit the atmosphere.  This is substantially faster than the 11 km/s reentry of the Apollo missions returning from the moon, and about twice as fast as the space shuttles (and other low earth orbit spacecraft) re-enter.  It is about 50 times faster than a handgun bullet.

The total energy released, between a quarter and a half a megaton, was similar to a modern H-bomb.  However, it was more dispersed, and released high in the atmosphere. Because the impactor was traveling at twice orbital speed, the energy would be equivalent to an orbital object of four times the mass re-entering.  32,000 to 40,000 tons is about the size of the Titanic, or a WWII battleship. 

Something similar to this has been imagined.  Below is a model of CV-6, the famous 20,000 ton WWII aircraft carrier Enterprise.

Compare that to the fictional NCC 1701 spaceship enterprise, at the same scale.

The internet gives a spaceship mass of 10 times the aircraft carrier, which seems way to heavy to be sensible. 

If we say the spaceship is twice the mass of the aircraft carrier (it is bigger, after all, even if it is also probably made from a lighter & stronger material than steel), then it would have about the same energy on re-entry as the Chelyabinsk bolide.

We can compare the videos:

Star Trek III

Chelyabinsk Friday morning:

Reality is still far more gripping than imagination. 

Finally, here is what the Earth looked like from the asteroid’s point of view an hour before impact.  A few things to note:

First, the Earth is almost full.  As a result, the side of Earth facing the asteroid was in day, so it would have been hard to spot, as the sun was behind it.  However, the US space junk tracking radars in Hawaii should have been able to pick it up.  I wonder if they did, if they passed any sort of a warning on, or even are they allowed to?  It would be a shame if the 1200 injuries that occurred were preventable, but for American government red tape.

The National Hurricane Center's Y2K bug

The following is the current forecast discussion for Hurricane Katia. Note the last line:

ZCZC MIATCDAT2 ALL
TTAA00 KNHC DDHHMM

HURRICANE KATIA DISCUSSION NUMBER 45
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
500 AM AST FRI SEP 09 2011

THE CLOUD PATTERN CONTINUES WELL ORGANIZED AND IN FACT A DRIFTING
BUOY NEAR THE CENTER OF THE HURRICANE RECENTLY REPORTED A MINIMUM
PRESSURE OF 968 MB. THE INITIAL INTENSITY IS KEPT AT 75 KNOTS.
HOWEVER WEAKENING IS INDICATED SINCE THE HURRICANE IS ALREADY
REACHING COOLER WATERS AND KATIA IS FORECAST TO BECOME
POST-TROPICAL IN ABOUT 36 HOURS.

THE HURICANE IS MOVING TOWARD THE NORTHEAST OR 050 DEGREES AT 21
KNOTS. SINCE THE HURRICANE IS ALREADY EMBEDDED WITHIN THE
MID-LATITUDE WESTERLIES....IT SHOULD CONTINUE ON THIS GENERAL TRACK
WITH AN INCREASE IN FORWARD SPEED FOR THE NEXT FEW DAYS.

NO 96-HOUR POINT IS BEING GIVEN BECAUSE FORECAST POINTS IN THE
EASTERN HEMISPHERE BREAK A LOT OF SOFTWARE.


FORECAST POSITIONS AND MAX WINDS

INIT 09/0900Z 37.6N 67.5W 75 KT 85 MPH
12H 09/1800Z 39.5N 64.5W 75 KT 85 MPH
24H 10/0600Z 42.0N 55.5W 70 KT 80 MPH
36H 10/1800Z 45.5N 43.0W 60 KT 70 MPH...POST-TROP/EXTRATROP
48H 11/0600Z 49.5N 30.5W 65 KT 75 MPH...POST-TROP/EXTRATROP
72H 12/0600Z 56.5N 10.5W 50 KT 60 MPH...POST-TROP/EXTRATROP
96H 13/0600Z...EAST OF ZERO DEGREES LONGITUDE

$$
FORECASTER AVILA

NNNN

One hundred major impacts: part two: the deep ocean

A few months ago, I guaranteed the readership of the Lounge that none of them would be killed by a meteorite impact. In laying out the estimates that allowed me to do this, I took an equal area map and bombarded it with one hundred 400m projectiles. Objects of this size hit the Earth about once every 100,000 years, and are locally devastating but globally insignificant, so this seemed like a good way to look at where an impactor “big enough to wipe out LA” was actually likely to land.

Of these 100 impactors, 71 landed in the ocean. 19 of these were within 1000 km of the coastling of an inhabited continent (e.g. not Antarctica), while the others were far out in the ocean basins.

For impacts more than 1000 km offshore, the impact effect calculator of Marcus, Melosh, and Collins suggests that the main effect would be a tsunami. The tsunami details are not in their linked paper, and the amplitudes vary significantly, but the maximum amplitude at 1000 km from the impact area is about 4 meters or smaller. This is broadly similar to that of a magnitude 9 earthquake such as those that struck Japan this year and Sumatra (and the Bay of Bengal) four years ago. The tsunami takes about 1.8 hours to travel 1000 km, so warning times would depend greatly on detecting the impactor in space and seeing the fireball with antiproliferation satellites (this impactor is equivalent to a 3000 megaton bomb, so the fireball would be far larger than that of a nuclear weapon). The seismic signal of a hit to the deep ocean would actually be fairly minor, as most of the energy would be absorbed by the water.

Of course, the main difference is timing. Half of the impacts in this simulation were in the deep ocean, so with an impact repeat rate of 1 every 100,000 years, we would expect one deep ocean impact every 200,000 years. In contrast, a magnitude 9 earthquake strikes about once every 25 years. So over a million year period, we would expect 40,000 tsunamis from earthquakes, and five from deep ocean impacts.

Japan disaster

I've been away for a long weekend, and haven't been keeping up with the news. Other people have, though.
Highly Allochthonous has a roundup on the Earthquake.

See links therein for details.

Jeff, the Arms Control Wonk, was in japan visiting the reprocessing facility at the time of the quake, and has decent information on the state of the reactors.

Geoblogger Evy's dad is a nuclear engineer, so she has posted two explanatory interviews.

An commentary on various things I heard on the radio while driving:

1. The hydrogen explosions at the nuclear plants are not the same as little hydrogen bombs.

Hydrogen bombs release nuclear energy bu fusing hydrogen into helium; basically the same reaction that makes the sun shine.

The hydrogen explosions at the Japanese nuclear plants are a chemical explosion caused by hydrogen gas igniting in air.

The hydrogen is released by the reaction of water (or possibly an acid) with a metal (M):

xH2O + M -> xH2 + MOx

Where x is one half the valence state of the oxidized metal.

The reaction can take place at low temperature in the presence of an acid or catalyst, or at high temperature in the presence of pure water. The most likely scenario is that the zirconium metal in the fuel rods are reacting. One kilogram of Zr metal will release about 44 grams, of ~500 liters, of H2 gas, so you don't need much metal to get a decent bang.

It may be possible that the seawater they have been using as an emergency coolant is boiling to produce a hot, highly saline brine that might be able to catalyze oxidation of other metal components. But you'd have to talk to an aqueous chemist and a nuclear engineer to see what metals are present and whether they could be corroded in this manner. The boric acid that they have been adding to absorb neutrons is a weak acid, and should not be able to react with anything in the reactor to produce hydrogen. There was a confirmation of exposed fuel rods this morning.

2. The earthquake in New Zealand did not cause the Japan Earthquake. They are related only in that they involve the western edge of the Pacific tectonic plate, which is sliding past the Australian plate in New Zealand, and under the Eurasian plate in Japan.

3. The uranium in the reactor may well have been mined in Australia. Japan imports uranium from Australia. It also imports natural gas and coal from Australia. It also imports uranium from Canada. I don't know how much of the non-nuclear generating capacity has been damaged, but there have been images of burning natural gas facilities in the papers.

4. I don't buy the suggestions that this quake is a foreshock for a bigger quake. This is about as big as they get, and none of the other 8.5+ quakes that I know of have been followed by similar sized quakes on the same system. On the other hand, aftershocks are likely, and some may be as big or bigger than the NZ quake.

I don't know if this makes a large quake on Japan's southern subduction zone more or less likely. That would not be a significantly bigger quake (it might even be smaller), but it would effect a more densely populated part of the island, so that could be what people mean by 'the big one'.