Friday, August 29, 2008

I hate scientific writing

Activities I consider preferable are:

  • Getting knocked off a motorcycle at high speed
  • Rolling a kayak with a broken tailbone
  • Getting a hostile customs interrogation from drunk border guards

I don’t mind doing posters, and I love talking at conferences. And before I wrote my PhD thesis I actually enjoyed writing non-scientific stuff. And after a few years of post thesis shell shock, one reason I started this blog was to try and befriend words again. But after a month and a half of report writing, I’m having a relapse. So don’t be surprised if substantive blogging tails off. I’ve moved past the procrastination stage to the wimper under the desk stage. I don’t even have the motivation to ink a cartoon, which would let me post with no words at all. Goodnight people.

Tuesday, August 26, 2008

Fantasy GIS

When I was a kid, I played a fair bit of Dungeons & Dragons. Rummaging through old files this winter, I recently found a folder full of maps from a campaign I ran as DM from 8th grade through the early part of college. As they were a bit ratty looking, I decided to scan some of them, just for posterity. And that got me thinking.

One of the largest learning curves in my new job is learning GIS software. GIS, or geographical information systems, are computer programs that replace the laborious and repetitive math of map drawing with arcane buttons and incomprehensible menu selections which allow the computer to do the math for you. As I’m old enough to have learned geology in the paper and pencil era, I’m on a bit of a learning curve with plotting everything up. So I figured I’d register the adventure maps just for kicks.

A bit of sober reflection altered my plans, however. For one thing, I didn’t want all that junk on my work machine, and for another, using a format for a (very expensive) program I didn’t own seemed sort of silly. As Brian and Ron have been pointing out over the past few years, Google Earth is basically a poor man’s GIS. So I decided to use that instead.

Just like Google Earth, this ‘Google D&D’ is fully zoomable through the continental scale...

The regional scale...

And the local scale. The continuity between maps is better in some instances than others. The regional to local transition, which was done at high latitude and involved maps drawn several years before I learned trigonometry, is probably the dodgiest. But it is that scale at which the various tags and hypertext attributes start to become useful, as is shown here.

And at the dungeon level, layer control is great. Here I’ve color coded the dungeon layers so that their overlap is clear. The black ruined castle is the surface layer, while the underground layers are red, blue, and green.

And finally, we can turn off the clutter and zoom all the way down to look at the individual rooms in the adventure.

I don’t know if I would go so far as to try DMing paperless- there is a lot to be said for scribbling on maps and ticking things off. But it would be a great tool for generating things like player maps, as you can hide the DM only information just by deselecting the layer it is in. And if someone spills coke on the tactical map you can just print out another one and move the figurines.

And as a geologist, this has got me thinking. I’d love to plug the continental parameters into a coupled ocean-atmosphere GCM to see if I put the forests and deserts in the correct places. And I should probably check the orbital stability of the three moons*, as well.

I don’t know how useful this sort of thing would be for normal, well-adjusted RPG moderators. But I would have loved it 20 years ago. And I suspect it would be useful for anyone else who was socially awkward enough that they couldn’t say how a drunk goblin would react without knowing the orbital parameters, geologic setting, historical background, religious persuasion, and gardening habits of every sentient denizen of the craton.

* Unfortunately, in my ignorant youth I put the farthest moon beyond the planet’s Hill Sphere. I should really be more careful with my satellites.

Sunday, August 24, 2008

Gender inequity in the Olympics

Well, the games are finally over, so all you Americans get go ahead and forget the metric system for the next 3.95 years. But now that the results are in, I thought I’d play with the numbers a bit.

The official website breaks the medal tally down into men’s and women’s events. Looking at the statistics, I noticed that a few countries were much more successful with one gender than another. There aren’t any sensible biological or geographic reasons for why this might be the case, so I decided to graph up the results just to see who fell where. Weighting the medals so that gold=3 bronze and silver=2 bronze, I calculated the fraction won by men.

I call this number the chauvinism index, as it seems to reflect the extent to which female athletes are not brought up to the same standard as their male counterparts. So a country with male medalists and no female medalists would have a chauvinism index of 1, while one with only female medalists would have a chauvinism index of zero. One minus the chauvinism index would of course be the emasculation index, and a perfect balanced nation would score 0.5 on both scales.

The Chauvinism index for all countries with ten or more total medals is shown below:

As you can see, the French are the biggest chauvinists, while the Dutch are most pussy-whipped. As if we didn’t know that already. Note that we expect the average to be greater than 0.5, since there are more men’s events than women’s events. Extracting trends or cultural significance is left as an exercise for the reader.

Thursday, August 21, 2008

The nominal daddy

I usually associate the word nominal with spacecraft and other incredibly complex systems. But I reckon it’s great for parenting as well. If I told Mrs. Lemming that LLLL and I had a great time while she was away, then she’d feel unappreciated. Conversely, if I said it was horrible, she’d feel guilty. But nominal is just like the little bear’s porridge; by definition it requires that all parameters are operating within their correct range.
Eating? Nominal.
Sleeping? Nominal.
Play? Nominal.
Figuring out how to drink bathwater out of the floaty toys? Nominal.
Those special individual moments between father and child which we cherish forever? Nominal.
I’m going to bed soon, but I hope you all have a nominal Friday.

Monday, August 18, 2008

Daddy Time

Mrs. Lemming is off on a business trip, for her first 48 hour separation from LLLL. So it's primary parent time for this old lemming. So far, so good, with 3 hours down and 45 to go. The interesting bit will start tomorrow morning, though, probably sometime between 5:30 and 6:30. In the mean time, don't expect a whole lot of updates to this blog.

Saturday, August 16, 2008

Mars- Dwarf planet until death?

Last week, I showed how the back of the envelope planethood calculations on Hal Levinson’s website can be solved for time to determine when a dwarf planet reaches planethood.

I then mentioned how planetary migration can move planets into uncleared orbits, or scatter stuff into an orbit that had been previously cleared.

I will now combine these ideas with the geologic history of Mars to show that the red planet may have only achieved planethood after its magnetic dynamo shut down, its oceans dissipated, and the volcanic activity subsided to a few isolated vents.

Here’s the Wikipedia version of Mars geology (corrections from anyone who knows better are welcome):

There are two ways to divide up the geological history of Mars. Crater counting gives us three ages- the Noachian (heavily cratered southern highlands), the Hesperian (less cratered northern plains), and the Amazonian (recent features such as some of the newer volcanoes).

Alternatively, mineralogical mapping shows that the Noachian can be divided into the Phyllocian- dominated by clays and water-bearing minerals, and the Theiikian, dominated by sulphate salts. The younger areas of Mars are classified as Siderikan- iron oxide dominated- in this classification system. I have no idea how they assign numbers to the relative ages, but both systems are shown below.

So how do these timescales compare with the time needed by Mars to clear its orbit?

As I mentioned last week, the time needed to scatter objects out of the orbital neighborhood is dependent on the angle of inclination between those objects and the planet-to-be, in this case Mars. So, we will plug in the orbital inclination for 3 of the 4 original objects in the asteroid belt, and see what happens.

Vesta has an orbital inclination of 7.1 degrees. Plugging this into the formula gives a clearance time of 358 myr. On this time scale, Mars clears its orbit, enjoys a few hundred million years as a planet, then has to do it all again when the Late Heavy Bombardment scatters asteroidal riff-raff back into the newly cleaned neighborhood. Mars is a planet for about one quarter of the Noachian, and is a Dwarf planet the rest of the time.

If we increase the orbital inclination of the debris field to that of Ceres- 10 degrees- then Mars no longer has time to clear the neighborhood before the LHB messes it up again. The clearance time is almost a billion years, so Mars is a dwarf planet until the mid-Hesperian, or about a third of its life.

Finally, if we further increase the inclination to 13 degrees- similar to 3 Juno- then the clearance time blows out to 1.8 gyr, as shown below. This results in Mars being a dwarf planet for half of its life, and only acquiring planetary status towards the end of the Hesperian, when most planetary processes have ceased functioning. This would make Mars a posthumous planet.

The red planet has been the centre of the public’s interest in planets since the days of Edgar Rice Burroughs and H. G. Wells. It currently has more interplanetary missions operating on and around it than do the rest of the planets combined. Most of this scientific interest revolves around past habitability, specifically during the earliest, wettest eras. If Mars is demoted to dwarf planet during this period of time- as the above calculations suggest the current planet definition requires- then how useful is this definition?

The current Eriphobic planet definition didn’t just demote Pluto. It also forced Mars to die before it could join the planet club.

Friday, August 15, 2008

Thursday, August 14, 2008

Planetary mid life crisis

Last post, I mentioned how the current IAU definition of a planet causes many of the classical planets to only attain planethood late in the solar system’s history. Saying that a planet has to clear its neighborhood implies that a planet has only one neighborhood. Interpreting this law in the context of planetary migration is tricky.

For example, an abbreviated timescale is shown below.

The red area to the left is the 30-50 million year time that it took the terrestrial planets to form. As is shown, moon rocks can be found that are only slightly younger than this. The orange band is the age of the Late Heavy bombardment, which created the large lunar impact basins. This is hypothesized to have been caused by Neptune and Uranus changing their orbits. Neptune, in particular, would have ended up in a new neighborhood, and had to clear it, scattering stuff all over the solar system.

Under the IAU definition, it is unclear if Neptune ceased to be a planet during that time, and if so, when it regained planethood. Similarly, if the objects were scattered into the path of other planets (which seems to be the case), did they also lose planetary status for this period?

Many exoplanets show even more extreme examples of planetary migration. So if we want a consistent definition for all systems, it is unclear how this will apply.

Note that in the time scale above, the LHB happens long after the planets are formed. Planetary processes were well and truly underway on all terrestrial planets at the time of this bombardment, and to suddenly toss in a period of non-planetness makes no sense whatsoever.

Tuesday, August 12, 2008

Planetary puberty

Evidently there's a conference in Maryland this week that will be discussing planetary definition. So I figured I'd throw a little something together about when planets grow up.

Back in 2006, the IAU kicked Pluto out of the planet club, as I cynically predicted they would. Their new planetary definition is a bit odd, though. For one thing, it is heliocentric- planets must orbit the sun, and not any of the other estimated 99,999,999,999 stars in this galaxy (or any of the countless stars in other galaxies) in order to fit the definition. In addition, a planet has to be round (no squares in this club, ya hear Poindexter?), and it has to have cleared its orbit of any rivals.

Not long after, Hal Levinson parameterized this orbit clearing with a handwavy yet quantitative derivation which can be found on his website. He assumes that a planet can clear its orbit by either accreting or ejecting everything around it, and shows the necessary equations before plotting them against a number of the solar systems larger objects. There’s even a nice graph that shows which bodies make the planetary cut, and which are nonplanetary combatants, or whatever these second class orbiters are called these days:

As y’all know, I’m an ex-geochronologist. So to me when is just as interesting as what. I noticed that all of these equations, written to solve for planetary mass, could be rearranged to solve for t. Instead of determining if something is a planet, we can instead find out when it achieved planetary status.

As it turns out, the accretion formulas, which are more important than ejection for the inner solar system, are strongly dependent on the orbital inclination of the stuff which they are trying to pick up. I don’t know what value for i Dr. Levinson used, but I suspect it was rather large, as small i values lump Earth in with the gas giants for the purposes of gravitational focusing in the accretion equation. So below is a chart showing how long after solar system formation each planet will need to graduate from dwarf planet to true planetary status.

Note that the formula, because of its arm wavyness, assumes constant orbital radius, constant mass, etc etc etc (follow the link to Hal’s page for details).

Inclination is in degrees, time is myr since formation.

make make4.33E+083.42E+0959930050707.92E+099.79E+09

So, what do we see?
Firstly, Jupiter and Saturn don’t remain dwarf planets for very long. This is unsurprising, as they are in fact giants. Conversely, the time for Ceres and the Kupier belt objects of unusual size (Plutonoids? Plutoids? I just wish these objects were massive enough to prevent their names from evaporating away) to become planets is longer than the expected lifetime of the Sun. The ice giants and terrestrial planets are all intermediate.

Of these, however, the most interesting one is Mars. Mars spends a considerable fraction of its lifetime (between 3% and 77%, depending on inclination) as a pre-planet. And even for the fast, low angle accretion, the time is considerably longer than the 30Ma Hf-W age that comes from real rocks. So if the red planet did harbor life during its first billion years before drying out and freezing, it would have done so as a non-planetary object, according to the IAU. Indeed, waiting for a young, or even middle aged planet to fling the last interloping object out of its path to gain a title is a decidedly odd proposition. Depending on where you start the planetary clock ticking, I may have even worked on terrestrial zircons from Earth’s wild pre-planetary youth.

The start time question is important. From a geochemical point of view, a planet is 'born' when the core and mantle stop exchanging mass. The orbit doesn't really matter. But planetary orbits are not always constant. So for the purposes of planetary orbit clearing, it is probably the time since reaching their current orbital configuration, and not their original orbit, that matters. Which for our system would make T0 3850 Ma instead of 4567Ma, if we accept the Nice model. Applying the current IAU planet definition to migrating planets is so much fun that it will require a post of its own, which I’ll try to get up soon.

Monday, August 11, 2008

Willy willy

Jen recently posted an article about a willy willy (dust devil) chaser in the USA. While this seems to me sort of like chasing locusts in a plague, I figured it was as good a time as any to ask questions about these phenomena, as despite dodging them all summer (they throw sticks and gravel, demolish tents, and of course completely rearrange anything not tied down in camp), I don't know heaps about them.

What I really want to know is the origin of the inner white vortex, visible in the foreground willy willy above (click to enlarge). I was wondering if it was actually cloud- condensed water vapor- as a result of adiabatic pressure drop and cooling in the center of the vortex. Not every willy willy has them- most just look the color of the dust (in Australia, red). But these white cored ones were fairly common in summer, when the sun was stronger and the air was more humid. Any budding meteorologists out there?

Note: These were from the same trip, but a different day, as the ones shown here.

Sunday, August 10, 2008

Space carnival #66

Space carnival #66 is up at a Mars Odyssey.

Friday, August 08, 2008

Perchlorates are dangerous!

The Mars Phoenix mission has recently discovered signs of perchlorate salts in the Martian soil. So what are perchlorates?

Perchlorates are salts of perchloric acid, HClO4. In the perchlorate ion, Cl has a valence of +7, significantly higher than the -1 valence state in chlorides (like table salt). This makes it a powerful oxidizer. In the lab setting, perchloric acid is a notorious safety hazard, because it is a powerful oxidizer (ammonium perchlorate is used in solid rocket fuel), and because some perchlorate salts are shock sensitive, and will detonate if struck, dropped, or banged.

The main issue with perchlorate use is that perchloric acid needs to be used in specially designed fume hoods. The reason is that the acid fumes will react with metal ductwork and explosive perchlorate salts can accumulate in the ducts. The Oak Ridge National Laboratory describes their perchlorate decontamination program here, and mentioned another incident where

“a maintenance worker on an Atomic Energy Commission-related project was killed and two others were seriously injured in an explosion touched off by routine use of a small ball peen hammer and 6-inch chisel. The workers were dismantling a perchloric acid fume vent system when the explosion--violent enough to be heard 4 miles away--occurred.”

Marwan Bader, the OHS manager responsible for the decontamination, even deserves the quote of the day:
‘The highest concentration of perchlorates found ranged from 140,000 ppm at an elbow in a duct to 800,000 ppm on the inlet side of a filter housing. "Those are very high concentrations," Bader said’

Some of us like to refer to 800,000 ppm as 80%.

The Oak Ridge clean up has been published by Bader here.

The understatement of the week belongs to Michael Hecht of the Mars Phoenix lander mission, who said, “different types of perchlorate salts have interesting properties that may bear on the way things work on Mars”

I’ll say.

On the other hand, this part of the press release was downright irresponsible:
“It is an oxidant, that is, it can release oxygen, but it is not a powerful one…. The compounds are quite stable and do not destroy organic material under normal circumstances.”

Compare this to the University of Kentucky OHS site, which warns that
“Perchloric acid is destructive to human tissue as well as very reactive.”

Now, folks at NASA may have a different safety culture than we had in my lab, but I don’t refer to compounds that spontaneously combust or explode due to impact as “stable”.

Monday, August 04, 2008

Who is footing whose bill?

Due to increasing wholesale prices, the ACT electricity regulatory authority recently approved a 7.1% increase in electricity prices, which the utility passed on to us retail customers.

In addition to this regulated price increase, the utility also increased the ‘green energy’ surcharge (which is unregulated) by 18%.

All up, the price for green energy customers increases by 10%- much closer to the 11.3% increase sought by the utility.

The optimistic interpretation of this situation is that increased demand has driven up the price of clean energy. The pessimistic interpretation is that the utility is using its green customers to pay for increased dirty energy costs that the regulator didn’t allow it to pass on. Unfortunately, I can’t find any of the wholesale price information necessary to distinguish between these two possibilities. If any of y’all can, please post in comments.

Friday, August 01, 2008

Is organic food radioactive?

Of course it is. All living things contain potassium, and the minor isotope 40K has a 1.25 Ga half life. But pedantry is not the purpose of this blog entry. The real question is whether or not some organic food is more radioactive than it ought to be- especially compared to equivalent non-organic crops.
Organic food is defined as food that is grown without the aid of synthetic fertilizers, herbicides, or pesticides (the definition of synthetic is left as an exercise to the pedants). On the coop farm down the road from my folk’s house, this means improving the soil with chicken poop and bringing in school kids to pull weeds in a rousing synergy of outdoor education and child labor. But chicken shit is not the only source of vital nutrients such as K, N, and P.
There are a few evaporite mines where nitrates are mined, but for the most part, nitrogen fertilizer is fixed from air by industrial processes. Potassium and phosphorous, on the other hand, are generally dug up as rocks, and then processed into a bioavailable form. In all these cases, the processing includes some industrial process which excludes the products from being considered organic. Thus the use of chicken shit or other biological fertilizers, which fix K, P, and N through biological pathways.
Trouble is, this isn’t the only organic solution. According to Manning (2008), some organic farms simply use raw phosphorite rock as a natural fertilizer. Since it isn’t processed, it doesn’t qualify as synthetic, which is great for classification but lousy for whoever has to eat the food. Here’s why.
Most phosphate rocks readily concentrate uranium. Igneous phosphates incorporate U (and Th) into their crystal structures as the magma solidifies, while sedimentary phosphates gradually accumulate uranium from groundwater as it flows through the rock unit. While this is handy for geologists who like to find phosphate deposits using their scintillometers, it does mean that phosphate rocks can be significant sources of ionizing radiation. And the number one rule of radiation safety is, “Do not eat or inhale”.
In theory, the processing of phosphate ore into fertilizer products is supposed to remove the uranium. In practice, the last time I analyzed a retail bag of superphosphate, it had about 50 ppm U. And the process of crushing and reacting the rock with acids is going to release the more volatile or soluble parts of the decay chain (e.g. Radon) even if the U removal is ineffective or ignored. So the radioactivity per phosphorous atom in a synthetic phosphate fertilizer is almost certainly going to be lower than that of the natural phosphate rock. Thus, organic farmer who chose to use natural phosphorite rocks as fertilizer are almost certainly blasting their fields with a higher dosage of radiation than farmers who use an equivalent amount of synthetic fertilizer.
Of course, chickens are not radioactive, and neither is their shit. So the organic classification system lumps low dose chicken shit farmers together with the radioactive phosphate rock hotheads. So a person trying to reduce his dosage needs to know how the food was grown; looking at the certification is insufficient.
Classification is no substitute for knowledge.

Manning D.A.C. 2008 Phosphate minerals, environmental pollution, and sustainable agriculture. Elements, 4, 105-108