Sunday, July 15, 2018

Book Review: The Political Value of Time, by Elizabeth Cohen

I study geologic time for a living. That’s my job, and my day to day work involves making sure that the scientific instruments we use to figure out how many billions of years old various rocks are haven’t started to malfunction in ways that can generate millions of years of errors.

Apparently, though, most people don’t live their lives across the spans of eons and millions of years.  It’s good to remind myself of this every now and then, preferably before our fridge runs out of milk. One way to do this, and to gain some perspective on other ways of contemplating time, is by reading books of academic experts who study human interaction, instead of billion years old rocks. One such study is The Political Value of Time, by Professor Elizabeth Cohen (Syracuse University, USA).

Geosciences have a variety of ways to measure time. Of course, the fundamental unit of scientific time is the second- defined by atomic oscillations, from which minutes and hours are derived. But there is also astronomical time- days, months, years, and Milankovic cycles derived from the movement of rotating or orbiting moons and planets. And there are the various radioactive decay schemes, which give us 238U time 40K time, and other lesser used decay schemes, which are generally tied to one of those two systems. Comparing and cross-calibrating these various schemes is a lot of what geochronologists have been doing over the last 20 years.

The Political Value of Time combines all of these in to scientific time- e.g. the time measured by clocks and calendars. It discusses this, as opposed to other qualitative types of time used by social scientists, such as leisure time, overtime, and quiet time. Oddly, political researchers seem to have spent less time thinking about scientific time than some of these other fuzzy sorts, and this book tries to redress this situation.

The book shows that governments appropriate the time of their citizens in a way that constitutes a political economy of time. It then shows that there are several philosophical, practical, and technical reasons for this to be so. However, it points out that, because this area is understudied and the ramifications are not thought through, many of the unconscious and structural biases that burden other economies also make the economy of time less fair than it ought to be.

As it is outside my area of expertise, I don’t have the background to critically appraise the interpretations of French revolutionary philosophers and other cited works. Taking their referenced statements as given, however, yields a book with a clear, compelling, and straightforward argument. The vocabulary is specialized, and I reached for the dictionary many times in the introduction. However, the terms are used consistently and precisely through the entire book, so once the introduction is finished, the vocabulary becomes less intimidating.

As someone who used to travel extensively internationally for work, the queuing section struck all sorts of chords on the intersection of time, money, duty, efficiency, and information technology in the area of airport customs queues.

Over all, it is a good book, clearly argued. It looks like there are lots of opportunities for future research.

Saturday, June 02, 2018

Where on Google Earth are the dearly departed?

Callan Bentley of the Mountain Beltway has announced, via Twitter and Facebook, that Ron Schott has passed away. Ron was a long time of internet advocacy for Geology, both through his blog, his twitter account, his gigapan advocacy, and other activities which I haven't kept up with. He was an enthusiastic, good-natured, and helpful geologist, and though I only met him once, in 2009, his passion for explaining the stories of geology at all scales and structures was memorable. And just as fantastic geologic events leave their stories imprinted in the rock record, so too can the traces of Ron's digital Earth Science outreach be found buried and the blogs and feeds of social media. However, like the paleontological records left behind by vanished creatures, these digital fossils serve mostly to remind us of the sense of loss that we have in knowing that we can no longer meet their creator. Rest in Peace, Ron. We miss you.

Saturday, February 10, 2018

Nomination language note

This is a brief update to last week’s post on nominating for society prizes.  There has been some discussion on twitter about biased language in letters of recommendation, particularly for junior women. This was an issue I was vaguely aware of, but didn’t especially delve into deeply at the time.
Our basic approach was to mostly focus on the science, which of course doesn’t have a gender, and explain why the science she did was so exciting. You can see my citation in the previous post. I’m not posting anyone else’s letter on this blog, but I will put the combined word cloud here, along with a list of high frequency words:

Words used ten or more times:
53                                                                                      Jenner
33                                                                                      elements
28                                                                                      data
25                                                                                      paper
23                                                                                      magma
20                                                                                      Frances
19                                                                                      element
18                                                                                      trace
16                                                                                      analytical
16                                                                                      MORB
15                                                                                      O’Neill
15                                                                                      glasses
15                                                                                      work
15                                                                                      new
14                                                                                      analysis
14                                                                                      chalcophile
13                                                                                      quality
12                                                                                      geochemistry
12                                                                                      published
12                                                                                      volcanic
12                                                                                      Carnegie
11                                                                                      differentiation
11                                                                                      magmatic
10                                                                                      papers
10                                                                                      years
10                                                                                      young
10                                                                                      many

Saturday, February 03, 2018

Nominating for society prizes

One of the great things about being a geochronologist is that you can delve back in time to when unfinished blog posts were abandoned, and drag them screaming into the present to be finished.

Sometime around about 0.0000035 Ma*, there was a push by Dr. Ball over at Magma cum Laude bemoaning the gender disparityin society prize nominations. The argument, seen here and other places in early 2014, goes something along the lines of:
-When nominated, women are about as likely as men to win society awards.
-However, nominations skew more male than the general population of scientists
-Nominators are mostly crusty old farts, and young scientists (young meaning anyone under 50) are not stepping up and nominating people.

I forgot all about this pressing issue until June (still 2014), when the MGPV division of the Geological Society of America announced that they would be awarding a new early career scientist prize. At that point, I suddenly recalled the issue, and thought, “Might this be a testable hypothesis? What happens when some random industrial scientist barely 40 years old tries nominating?”

I’d sat through a few award ceremonies before, and seen these sorts of things handed out to a wide variety of scientists, from really cool people I’d never heard of to the banal big names who had spent a quarter of a century cruising on achievements from when I was in high school. But in most cases, the nominees were very senior, old, respected scientists. And they nominated other, slightly less old but otherwise very similar scientists. I suppose their point of view is that if they’re great, other great people ought to be pretty similar.

I am not a great scientist. I’m a disorganized industry hack whose H-index can be tallied on the fingers of Count Rugen’s hand. So the way I see it, anyone I nominate for a prize should be as unlike me as possible. So from there it was an easy step to revisit the nomination gap studies, and think, “Might there be, perhaps, any women who would be appropriate for this award?” Luckily, our nominee came to mind almost immediately.

As someone who went through college loathing political correctness, my first thought was therefore, “OK, now am I cutting any more deserving nominees out here by nominating her?” As it turns out, when I was still working at the ANU (see the first three years of this blog) we had many really good grad students. However, none of them really took ownership of their favorite field of science and made it their own the way our nominee did, so I was satisfied that I had made a good choice.

The GSA Junk Mail that announced the creation of a new award came out in June 20 of 2014, I probably read it and connected it back to the earlier exhortations to nominate about a week or two later, around the end of the month. The trouble was, the deadline for nominations was the 15th of July. And I didn’t start approaching people for supporting letters until the second.

My strategy was simple: Here in Canberra, cruise the ANU hallways to figure out who was actually in town and able to put something together on zero notice. I threw the Japanese postdoc into the too-hard basket, as I didn’t personally know any of the people she worked with there, and also language barrier, and concentrated on her colleagues at DTM. I also approached some big names in the field with whom she hadn’t collaborated, to see if they thought it was a sensible nomination and would be willing to write something supportive from more of a peer review perspective.

I was pleasantly surprised at how enthusiastic most of the people I approached were. I guess the good thing about picking a good candidate, however, is that people really do get excited and are willing to get on board and turn letters around in remarkably quick timescales. I had my three supporters lines up by the seventh, and three letters in hand within hours of the deadline. In responsible, organized nominator fashion, I had my nomination letter done a whallopping three days before the deadline, and circulated it to the rest of the team for a science check and general feedback (as I had never done this before).

Around the time of the deadline, a potential referee who had been out of contact emailed me saying that he really wanted to write a fourth letter, and could the deadline be extended? So I asked the coordinator, and he said that as long as a complete submission package was in on time, we could have a week or two to get additional bonus letters in. One such letter was submitted.

Fast forward nine months:
There’s an email in my inbox from our nominee:
Hi Chuck,
Here is the letter that I woke up to today!!!! Thanks so much!!!”

And that is how Dr. Frances Elaine Jenner won the Geological Society of America’s inaugural MGPV early career award. The only sad part of the story was that I was not able to go to the GSA meeting where the award was presented, so one of the guys who wrote a letter of support gave the citation. He’s a proper academic scientist anyway, so probably had the gravitas that I lack. The citation and acceptance are on page 8-10 of thisnewsletter.

The point of all this story is this: It is possible for mid career non-academic scientists to throw together a nomination at the last minute, and get support from respected scientists, and construct a nomination package sufficient to win the prize. Don’t die wondering, folks.

Now, I should point out that I did have a few things tilted in my favor:
Firstly I attended a number of top institutions during my academic career, which put me in contact with top scientists like Dr. Jenner. Having a great candidate goes a long way towards making a case.

 Secondly, I’ve been kicking around science in one capacity or another to know her referees, several of whom were quite respected scientists. I was reasonably acquainted with three of the four supporters I got letters from, and had at least been to the fourth guy’s lab.

Thirdly, once the decision was made to go, I went all out. This isn't the sort of thing to be half-assed. I read all her papers, and tried to put together a passionate yet logical case for why they made our nominee a prizeworthy scientist.

I’m sure the greybeards who get together at annual meetings to sip nasty scotch plan out their conventional safe picks way in advance, but with a little passion, some broad thinking, and a genuine enthusiasm for science, anyone can nominate for their respective society’s awards, and win. And there’s a month and a half to go before the deadline forthe 2019 award, so don’t be shy, y’all.

* True calendar years; -0.000064 using the 1950 zero year favoured by 14C weirdos.

And in case anyone wants the really nitty gritty details, here’s the nomination I wrote in a sleep deprived haze during the first week of July 2014. Typos and all:

Nomination for Frances Jenner

Dear Division Secretary,
I would like to nominate Frances Elaine Jenner for the GSA’s MGPV division early career award for 2015.  Dr. Jenner is an outstanding young analytical geochemist who has pioneered several novel analytical techniques and applied them to igneous rocks from a wide temporal and geographical range.  Her ability to generate novel, high quality data has allowed her and her colleagues to overturn previous assumptions or hypotheses about a variety of igneous processes, giving us a better understanding of mafic volcanism over the last 3.8 billion years of Earth history.

Upon the completion of her PhD on the nature of Eoarchean rocks (Jenner et al., 2009; Jenner et al., 2013), Dr. Jenner immediately branched out into a new field of study, namely the quantification of “less commonly analyzed elements” in volcanic glasses. One such element is selenium.  In theory, selenium should be a useful proxy for sulfur in systems (such as volcanic glasses) which may have undergone partial degassing, but in practice, there was no standard analytical protocol for measuring this low abundance chalcogenide in silicate materials.  Using the electron microprobe, laser ablation inductively coupled mass spectrometry (LA-ICPMS), and the Sensitive high-resolution ion microprobe (SHRIMP), Dr. Jenner characterized a suite of commonly used reference materials (Jenner et al., 2009). This study remains the only case where the SHRIMP has been used as a negative ion trace element quantification tool.  However, despite developing this novel SIMS technique, she and her colleagues used the SIMS data to devise an analytical protocol to routinely measure selenium using LA-ICPMS. The use of the cheaper, more versatile LA-ICPMS equipment meant that selenium contents of target glasses and minerals could be determined along with other elements of interest in a wholescale manner much more economically than the use of the SHRIMP would allow.

While an analytical specialist may have been content to run this application without too much thought to the geologic implications, Dr. Jenner and her colleagues immediately put it to use in investigating the enrichment of Cu, Ag, and Au in arc-related magmas.  Their “magnetite crisis” paper (Jenner et al., 2010) uses this selenium analytical technique to generate compelling data relating to the trends of these elements with magma evolution.  This dispels the earlier, intellectually unsatisfying notion of a fugitive fluid or vapor phase, clearly showing that magnetite crystallization triggers sulfide saturation by changing the magmatic fO2.

The use of more, higher quality data to reject a long held but data-poor assumption is a hallmark of Dr. Jenner’s research.  Although she has continued to analyze selenium for the purpose of constraining sulfide saturation and chalcogenide behavior (Jenner et al., 2012; Patten et al., 2013), her next major achievement was to roll out the same approach to the rest of the periodic table, and a wider variety of sea floor volcanic glasses.

Jenner and O’Neill (2012b) is a primer for how to analyze most of the periodic table in mafic glasses, with corrections for interfered elements and methods for how to minimize analytical difficulties.  While the analysis of volcanic glasses by LA-ICPMS is not new, this study is remarkable in its thorough examination of issues of normalization and reproducibility which have not necessarily been presented in a single unified study before.

Jenner and O’Neill (2012a) then apply these techniques to hundreds of ocean floor volcanic glasses, yielding a rich, high quality dataset that allows them to realize (O’Neill and Jenner, 2012) that the mid-ocean ridge fractional crystallization model that we were all taught as undergraduates decades ago cannot explain their new, higher quality data, and needs refinement.

Once again, Dr. Jenner and her colleagues develop new tools illuminate a previously underconstrained system, yielding a novel explanation with greater predictive power. This changes the way we think about the main type of magma generation on Earth.

There are quite a few talented young geoscientists who develop new analytical techniques.  And many of them apply them to known areas of scientific debate, to build up or tear down evidence for one or more prevailing hypotheses.  But Dr. Jenner is unusual in having both the analytical skills to devise new approaches and the intellectual agility to find entirely new geological interpretations, which were not even part of the debate before her studies were carried out.

And although Dr. Jenner is very much an analytical geochemist, it is her ability to find the natural rocks to use her procedures on which underpins her success.  While she collaborates extensively with experimental petrologists, she mostly analyses natural samples of diverse provenance.  Working from the Greenland Eoarchean to modern submarine volcanics, her areas of study span more than 95% of the terrestrial rock record in geologic time.  Her onshore field areas range from the periglacial west coast of Greenland to tropical Samoa.  While ocean drilling programs do not fit the stereotypical mold of outcrop hammering and rock licking, they are none-the-less the only way we currently have of accessing the ~70% of our planet’s surface that is under water. And it is her ability to choose the right sample or samples for her new analytical methods which allows her to discover novel petrologic processes.

Finally, it is worth noting that in a competitive field like academic geology, there is an element of luck which is often a contributor to success.  Whether it is happening on just the right rock, or simply having jobs appear in a manner that allows a stable, productive workflow, simple good fortune can often be the difference between a discovery and a confirmation. Dr. Jenner has had, by far, the worst luck of anyone I know with an advanced geology degree.

I have worked in industry and government for the past seven years, so I know many of the situations which result in a person leaking out of the academic pipeline.  Dr. Jenner has experienced a large number of these “career-terminal” events.  But unlike the rest of us, she has forced her way back into the pipeline with a combination of intellectual firepower, gritty determination, and the most dedicated work eithic of anyone I have met in any field. This has allowed her to not just stay employed, but maintain control of her career trajectory, despite her three postdocs and her faculty job being on four different continents.  And despite her hardships, she is one of the most enthusiastic, positive, energetic scientists I know.  This, as much as her academic record, makes her a role model for all young scientists. Frances Jenner would be an inspirational choice for the GSA committee as the inaugural MGPV division Early Career scientist.


Jenner, F.E., Arculus, R.J., Mavrogenes, J.A., Dyriw, N.J., Nebel, O., and Hauri, E.H., 2012, Chalcophile element systematics in volcanic glasses from the northwestern Lau Basin: Geochemistry, Geophysics, Geosystems, v. 13, no. 6, p. Q06014.
Jenner, F.E., Bennett, V.C., Nutman, A.P., Friend, C.R.L., Norman, M.D., and Yaxley, G., 2009, Evidence for subduction at 3.8 Ga: Geochemistry of arc-like metabasalts from the southern edge of the Isua Supracrustal Belt: Chemical Geology, v. 261, no. 1-2, p. 83–98.
Jenner, F.E., Bennett, V.C., Yaxley, G., Friend, C.R.L., and Nebel, O., 2013, Eoarchean within-plate basalts from southwest Greenland: Geology, v. 41, no. 3, p. 327–330.
Jenner, F.E., Holden, P., Mavrogenes, J.A., O’Neill, H.S.C., and Allen, C., 2009, Determination of Selenium Concentrations in NIST SRM 610, 612, 614 and Geological Glass Reference Materials Using the Electron Probe, LA-ICP-MS and SHRIMP II: Geostandards and Geoanalytical Research, v. 33, no. 3, p. 309–317.
Jenner, F.E., and O’Neill, H.S.C., 2012a, Analysis of 60 elements in 616 ocean floor basaltic glasses: Geochemistry, Geophysics, Geosystems, v. 13, no. 2, p. Q02005.
Jenner, F.E., and O’Neill, H.S.C., 2012b, Major and trace analysis of basaltic glasses by laser-ablation ICP-MS: Geochemistry, Geophysics, Geosystems, v. 13, no. 3, p. Q03003.
Jenner, F.E., O’Neill, H.S.C., Arculus, R.J., and Mavrogenes, J.A., 2010, The Magnetite Crisis in the Evolution of Arc-related Magmas and the Initial Concentration of Au, Ag and Cu: Journal of Petrology, v. 51, no. 12, p. 2445–2464.
O’Neill, H.S.C., and Jenner, F.E., 2012, The global pattern of trace-element distributions in ocean floor basalts: Nature, v. 491, no. 7426, p. 698–704.
Patten, C., Barnes, S.-J., Mathez, E.A., and Jenner, F.E., 2013, Partition coefficients of chalcophile elements between sulfide and silicate melts and the early crystallization history of sulfide liquid: LA-ICP-MS analysis of MORB sulfide droplets: Chemical Geology, v. 358, p. 170–188.

Tuesday, October 17, 2017

Be the comet

It has been a bad month for flashbacks for victims of sexual harassment in Academia. First came the horrific stories of campus harassment from Rochester University, followed by the Antarctic harassment from Boston University, followed by the story of Harassment by a major Hollywood movie producer. At this point the producer has lost his job, and investigations continue for the two professors. And closer to home, the University of Canberra professor who was convicted of raping a student has appealed against his 4 year sentence.

As geologists, we need to figure out how to consign these dirtbags to the fossil record, preferably on a human, not geologic timescale. There are many ways to wipe out a species, but I am going to focus on what I think is an important one that is often overlooked: Habitat destruction.

It is no accident that harassment issues are constantly popping up in the academic and creative workplaces. Both sectors value their reputation, and are willing to defend the appearance of everything being fine. Both disciplines are popular career choices, with many more people willing to work in them than there are available jobs. Both sectors value intelligence to the point of considering it a virtue, or being willing to overlook other problems in the name of “Genius.” Both sectors have substantial hierarchies, with few formal checks and balances on power.

It is these problems that we should address if we want these perpetrators to go extinct. The names aren’t important- I haven’t even mentioned them above. As long as universities and studios build the perfect ecological niche for abusers to thrive in, then they will flock to the sectors. It is institutional change that is needed to actually stop the abuse.

So, specifically, what has to happen?

Firstly, reporting mechanisms need to be transparent and incorruptible. The reason that these scum can continue to wreck peoples lives for decades is that complaints, even if made, are too easy to bury. An administration that prefers ongoing, covert sexual assault on its campus over an embarrassing headline can simply use the reporting mechanism as a way of silencing victims, allowing the rapist to continue offending for decades.

Whomever victims report to, be it the police, the funding agencies, professional organizations, or some special independent body, the report receiver needs to be able to investigate allegations without being pressured from the university. In cases where potentially illegal activities have occurred and complainants are threatened, then university officials should be subject to the same treatment as organized criminals who try to intimidate witnesses.

Sexual predators are ambush predators- they need cover from which to attack, and removing administrative cover gives them fewer places to hide. There must be heavy penalties for authorities who fail to act, especially if the offender commits further offences. Administrators who cover for offenders so that they can offend again should be considered accessories.

However, these crooks are also pack animals, so a healthy culture is important towards setting an example of what is and isn’t professional behavior. This is not in itself a solution, but it makes sketchy behavior stand out more easily, and it puts the ratbags on notice that the work place is for real men, not whiney losers.

Finally, although habitat destruction is important, the offenders to have to be hunted down when spotted. This is best done by the whole work team, as uncharismatic megafauna can be dangerous in single combat. However, a habitat in which they are allowed to operate with impunity is not detrimental to them. It is by shrinking their range through a unfavorable setting that allows them to be vulnerable to catastrophic events, but those events still need to be initiated. If a change in corporate climate has weakened the terrible lizardmen, and drying their environment removes their cover and their hiding places, then it is much easier to be the comet that wipes them out.

Saturday, October 07, 2017

A charitable request

I have never been a good fund raiser or salesman.  My disjointed talents do not stretch to the power of persuasion.

Nor have I ever understood the concept of fundraising linked to an outdoor recreational activity. A few years after I hiked the Appalachian Trail, I heard of people doing it as a way to raise funds for one cause another. But why this particular recreational activity is one to be used for a cause baffles me. If you like riding a bike, ride a bike. If you like drinking beer, drink beer. Doing either to excess, like riding a hundred miles for cancer, or drinking a sixpack for dementia, never really made any sense to me.

However, this winter I signed up for the Sydney-Gong  bicycle ride, and one of the conditions of entry is to raise funds for multiple sclerosis. At first, this gave me pause. But as I considered, I reckoned, why not? If you are going to have a limit for a popular activity, why not accept, as a condition of entry, a certain amount of community assistance. And multiple sclerosis is certainly a worthy casue.

MS is an autoimmune disease. Like arthritis, or lupus, it can strike otherwise healthy people in the prime of life, and it can be debilitating, even fatal, if not treated. Like these other autoimmune diseases, treatment has improved as a result of science, but there is still a ways to go before a cure, or even a more effective system of management, can be achieved.

I do not personally know anyone in meatspace with MS; although I believe that one of our fellow geobloggers may suffer from the disease. However, I am not convinced that personal attachment should be a prerequisite for decreasing human suffering through scientific research. After all, as long time readers of this Lounge undoubtedly know, I am not a particularly empathetic person. And, as the social aspect of the internet has evolved over the past dozen or so years, I have noticed an overabundance of heartstring-tugging emotive appeals. I will not add to their din. Instead, I offer an alternative way to contribute to the betterment of society without the awkward warm and fuzzies.

So I will politely request that long time readers- those who have enjoyed this blog since the early days of Hot Chick Thermodynamics and OysterBlessings, before Hypotheses were dumped and Geosonnets began- consider a donation via my MS ride fundraising page if, at any point in the last dozen years, you have found this blog informative, entertaining, or interesting in any way.

And if, like me, you are a bit too wry to donate to an event linked to a wholesome activity like bike riding, then I have an alternative. I will crassly debase myself by putting the charity sixpack back on the proverbial table. If I can get a hundred bucks donated through the MS ride page with comments attesting that your donation is earmarked for the beer, not the ride, then I will drink six bottles at the conclusion of the ride. Because I’m the sort of guy who is willing to drink beer…. FOR SCIENCE!

Tuesday, August 22, 2017

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 rhoM/rhom)^1/3, where

R is the radius of the Primary, rhoM is the density of the primary, and rhom 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.

Monday, May 22, 2017

Can bad fashion save the icecaps?

With rapid melting in the Arctic, and potential glacial instability in Antarctica. the planet’s present cryosphere is in a spot of bother. The root cause of this is warming from the heat trapped by greenhouse gasses, mostly CO2. But while many suggestions have been made for reducing CO2 output, as yet there are relatively few mothods for capturing those emissions which are still occurring. And with international agreements lacking enforcement mechanisms, a new push for Coal in the US, and decades of record rates of emissions growths, humanity clearly needs someone to police the worlds emissions. And we don’t need any old police. We need fashion police.

Although many proposals have been made for finding ways to prevent our hunger for fossil fuels from ruining the atmosphere, not nearly enough of these strategies have included the use of tacky clothing. And yet, the potential for horrific fashion statements to save the world should not be underestimated. The reason for this is that ultimately, the easiest way to scrub carbon dioxide from the atmosphere is to react it with an alkali or alkali earth oxide, thereby forming a carbonate  mineral. While silicate weathering will do this naturally over a 50-100kA timescale, we can’t really afford to wait that long. Roasting carbonates obviously won’t accomplish anything, since that simply makes the alkali oxides available by releasing CO2. However, there are alternatives.

One way to generate an effective carbon dioxide scrubber is to split salt (from ocean water) into its component sodium and chlorine. The sodium will rapidly (on a geologic timescale) oxidize, hydrate, and carbonate, forming NaHCO3. This should be reasonably effective, so long as we can sequester the chlorine that is produced as a byproduct. And here is where the tacky clothes come in. During the latter part of the 20th century, outrageous costumes were constructed out of the polymer polyvinyl chloride. If we can simply manufacture enough disco pats, fake leather jackets, and not-so-Sunday dresses, that will sequester the chlorine from salt electrolysis in the world’s wardrobes, so that the sodium can be used for atmospheric CO2 drawdown.

Doing a bit of math here, with annual emissions of about 29 billion tons of CO2, we will need about 15 billion tons of Na to scrub our emissions. This requires approximately 55 billion tons of PVC to store the chlorine left over from the salt decomposition (powering the electrolysis is left as an exercise for the reader). Luckily, due to the large world population, this works out to only about 8 tons of PVC per person per year, or about 21 kg of PVC per day.

None of the PVC outfits I can find for sale on the internet at this hour appear to contain 21 kg of material. They are generally a little bit flimsier than that. And even with a new steampunk, burlesque, gothic, and disco outfit every day for every man, woman, and child on Earth, we are still looking to be short by a factor of 50. Buying 21 kg of new PVC outfits a day would necessitate a costume change every 7 minutes. Luckily, there are other things which PVC can be made into.

For example, the credit cards used to purchase PVC outfits by people too brazen to stoop to cash are made of PVC. And while they only weigh a few grams each, most people do have a few. Similarly, the music to which PVC clad people traditionally dance comes from an archaic form of grooved PVC platter known as a “record”. Buying 140 LP records a day will put all of the world’s citizens at their PVC quota without having to wear anything at all.

So fear not, reader. There is hope. with enough old time music and garish clothing, anything is possible.